[v5,4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk

  Low level Arch functions were created to support hibernation.
swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
cpu state onto the stack, then calling swsusp_save() to save the memory
image.

Arch specific hibernation header is implemented and is utilized by the
arch_hibernation_header_restore() and arch_hibernation_header_save()
functions. The arch specific hibernation header consists of satp, hartid,
and the cpu_resume address. The kernel built version is also need to be
saved into the hibernation image header to making sure only the same
kernel is restore when resume.

swsusp_arch_resume() creates a temporary page table that covering only
the linear map. It copies the restore code to a 'safe' page, then start
to restore the memory image. Once completed, it restores the original
kernel's page table. It then calls into __hibernate_cpu_resume()
to restore the CPU context. Finally, it follows the normal hibernation
path back to the hibernation core.

To enable hibernation/suspend to disk into RISCV, the below config
need to be enabled:
- CONFIG_ARCH_HIBERNATION_HEADER
- CONFIG_ARCH_HIBERNATION_POSSIBLE

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 arch/riscv/Kconfig                 |   6 +
 arch/riscv/include/asm/assembler.h |  20 ++
 arch/riscv/include/asm/suspend.h   |  19 ++
 arch/riscv/kernel/Makefile         |   1 +
 arch/riscv/kernel/asm-offsets.c    |   5 +
 arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
 arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
 7 files changed, 552 insertions(+)
 create mode 100644 arch/riscv/kernel/hibernate-asm.S
 create mode 100644 arch/riscv/kernel/hibernate.c
  

On 3/8/23 09:06, Sia Jee Heng wrote:
> Low level Arch functions were created to support hibernation.
> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
> cpu state onto the stack, then calling swsusp_save() to save the memory
> image.
>
> Arch specific hibernation header is implemented and is utilized by the
> arch_hibernation_header_restore() and arch_hibernation_header_save()
> functions. The arch specific hibernation header consists of satp, hartid,
> and the cpu_resume address. The kernel built version is also need to be
> saved into the hibernation image header to making sure only the same
> kernel is restore when resume.
>
> swsusp_arch_resume() creates a temporary page table that covering only
> the linear map. It copies the restore code to a 'safe' page, then start
> to restore the memory image. Once completed, it restores the original
> kernel's page table. It then calls into __hibernate_cpu_resume()
> to restore the CPU context. Finally, it follows the normal hibernation
> path back to the hibernation core.
>
> To enable hibernation/suspend to disk into RISCV, the below config
> need to be enabled:
> - CONFIG_ARCH_HIBERNATION_HEADER
> - CONFIG_ARCH_HIBERNATION_POSSIBLE
>
> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>   arch/riscv/Kconfig                 |   6 +
>   arch/riscv/include/asm/assembler.h |  20 ++
>   arch/riscv/include/asm/suspend.h   |  19 ++
>   arch/riscv/kernel/Makefile         |   1 +
>   arch/riscv/kernel/asm-offsets.c    |   5 +
>   arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
>   arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
>   7 files changed, 552 insertions(+)
>   create mode 100644 arch/riscv/kernel/hibernate-asm.S
>   create mode 100644 arch/riscv/kernel/hibernate.c
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index c5e42cc37604..473c2a1a6884 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -707,6 +707,12 @@ menu "Power management options"
>   
>   source "kernel/power/Kconfig"
>   
> +config ARCH_HIBERNATION_POSSIBLE
> +	def_bool y
> +
> +config ARCH_HIBERNATION_HEADER
> +	def_bool HIBERNATION
> +
>   endmenu # "Power management options"
>   
>   menu "CPU Power Management"
> diff --git a/arch/riscv/include/asm/assembler.h b/arch/riscv/include/asm/assembler.h
> index ba59d38f8937..44b1457d3e95 100644
> --- a/arch/riscv/include/asm/assembler.h
> +++ b/arch/riscv/include/asm/assembler.h
> @@ -59,4 +59,24 @@
>   		REG_L	s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
>   	.endm
>   
> +/*
> + * copy_page - copy 1 page (4KB) of data from source to destination
> + * @a0 - destination
> + * @a1 - source
> + */
> +	.macro	copy_page a0, a1
> +		lui	a2, 0x1
> +		add	a2, a2, a0
> +1 :
> +		REG_L	t0, 0(a1)
> +		REG_L	t1, SZREG(a1)
> +
> +		REG_S	t0, 0(a0)
> +		REG_S	t1, SZREG(a0)
> +
> +		addi	a0, a0, 2 * SZREG
> +		addi	a1, a1, 2 * SZREG
> +		bne	a2, a0, 1b
> +	.endm
> +
>   #endif	/* __ASM_ASSEMBLER_H */
> diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
> index 67e047445662..02f87867389a 100644
> --- a/arch/riscv/include/asm/suspend.h
> +++ b/arch/riscv/include/asm/suspend.h
> @@ -21,6 +21,11 @@ struct suspend_context {
>   #endif
>   };
>   
> +/*
> + * Used by hibernation core and cleared during resume sequence
> + */
> +extern int in_suspend;
> +
>   /* Low-level CPU suspend entry function */
>   int __cpu_suspend_enter(struct suspend_context *context);
>   
> @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid, unsigned long context);
>   /* Used to save and restore the CSRs */
>   void suspend_save_csrs(struct suspend_context *context);
>   void suspend_restore_csrs(struct suspend_context *context);
> +
> +/* Low-level API to support hibernation */
> +int swsusp_arch_suspend(void);
> +int swsusp_arch_resume(void);
> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
> +int arch_hibernation_header_restore(void *addr);
> +int __hibernate_cpu_resume(void);
> +
> +/* Used to resume on the CPU we hibernated on */
> +int hibernate_resume_nonboot_cpu_disable(void);
> +
> +asmlinkage void hibernate_restore_image(unsigned long resume_satp, unsigned long satp_temp,
> +					unsigned long cpu_resume);
> +asmlinkage int hibernate_core_restore_code(void);
>   #endif
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index 4cf303a779ab..daab341d55e4 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)		+= module.o
>   obj-$(CONFIG_MODULE_SECTIONS)	+= module-sections.o
>   
>   obj-$(CONFIG_CPU_PM)		+= suspend_entry.o suspend.o
> +obj-$(CONFIG_HIBERNATION)	+= hibernate.o hibernate-asm.o
>   
>   obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
>   obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
> diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
> index df9444397908..d6a75aac1d27 100644
> --- a/arch/riscv/kernel/asm-offsets.c
> +++ b/arch/riscv/kernel/asm-offsets.c
> @@ -9,6 +9,7 @@
>   #include <linux/kbuild.h>
>   #include <linux/mm.h>
>   #include <linux/sched.h>
> +#include <linux/suspend.h>
>   #include <asm/kvm_host.h>
>   #include <asm/thread_info.h>
>   #include <asm/ptrace.h>
> @@ -116,6 +117,10 @@ void asm_offsets(void)
>   
>   	OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
>   
> +	OFFSET(HIBERN_PBE_ADDR, pbe, address);
> +	OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
> +	OFFSET(HIBERN_PBE_NEXT, pbe, next);
> +
>   	OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
>   	OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
>   	OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
> diff --git a/arch/riscv/kernel/hibernate-asm.S b/arch/riscv/kernel/hibernate-asm.S
> new file mode 100644
> index 000000000000..effaf5ca5da0
> --- /dev/null
> +++ b/arch/riscv/kernel/hibernate-asm.S
> @@ -0,0 +1,77 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Hibernation low level support for RISCV.
> + *
> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> + *
> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> + */
> +
> +#include <asm/asm.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/assembler.h>
> +#include <asm/csr.h>
> +
> +#include <linux/linkage.h>
> +
> +/*
> + * int __hibernate_cpu_resume(void)
> + * Switch back to the hibernated image's page table prior to restoring the CPU
> + * context.
> + *
> + * Always returns 0
> + */
> +ENTRY(__hibernate_cpu_resume)
> +	/* switch to hibernated image's page table. */
> +	csrw CSR_SATP, s0
> +	sfence.vma
> +
> +	REG_L	a0, hibernate_cpu_context
> +
> +	suspend_restore_csrs
> +	suspend_restore_regs
> +
> +	/* Return zero value. */
> +	mv	a0, zero
> +
> +	ret
> +END(__hibernate_cpu_resume)
> +
> +/*
> + * Prepare to restore the image.
> + * a0: satp of saved page tables.
> + * a1: satp of temporary page tables.
> + * a2: cpu_resume.
> + */
> +ENTRY(hibernate_restore_image)
> +	mv	s0, a0
> +	mv	s1, a1
> +	mv	s2, a2
> +	REG_L	s4, restore_pblist
> +	REG_L	a1, relocated_restore_code
> +
> +	jalr	a1
> +END(hibernate_restore_image)
> +
> +/*
> + * The below code will be executed from a 'safe' page.
> + * It first switches to the temporary page table, then starts to copy the pages
> + * back to the original memory location. Finally, it jumps to __hibernate_cpu_resume()
> + * to restore the CPU context.
> + */
> +ENTRY(hibernate_core_restore_code)
> +	/* switch to temp page table. */
> +	csrw satp, s1
> +	sfence.vma
> +.Lcopy:
> +	/* The below code will restore the hibernated image. */
> +	REG_L	a1, HIBERN_PBE_ADDR(s4)
> +	REG_L	a0, HIBERN_PBE_ORIG(s4)
> +
> +	copy_page a0, a1
> +
> +	REG_L	s4, HIBERN_PBE_NEXT(s4)
> +	bnez	s4, .Lcopy
> +
> +	jalr	s2
> +END(hibernate_core_restore_code)
> diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
> new file mode 100644
> index 000000000000..8fab50122e54
> --- /dev/null
> +++ b/arch/riscv/kernel/hibernate.c
> @@ -0,0 +1,424 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Hibernation support for RISCV
> + *
> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> + *
> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> + */
> +
> +#include <asm/barrier.h>
> +#include <asm/cacheflush.h>
> +#include <asm/mmu_context.h>
> +#include <asm/page.h>
> +#include <asm/pgalloc.h>
> +#include <asm/pgtable.h>
> +#include <asm/sections.h>
> +#include <asm/set_memory.h>
> +#include <asm/smp.h>
> +#include <asm/suspend.h>
> +
> +#include <linux/cpu.h>
> +#include <linux/memblock.h>
> +#include <linux/pm.h>
> +#include <linux/sched.h>
> +#include <linux/suspend.h>
> +#include <linux/utsname.h>
> +
> +/* The logical cpu number we should resume on, initialised to a non-cpu number. */
> +static int sleep_cpu = -EINVAL;
> +
> +/* Pointer to the temporary resume page table. */
> +static pgd_t *resume_pg_dir;
> +
> +/* CPU context to be saved. */
> +struct suspend_context *hibernate_cpu_context;
> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
> +
> +unsigned long relocated_restore_code;
> +EXPORT_SYMBOL_GPL(relocated_restore_code);
> +
> +/**
> + * struct arch_hibernate_hdr_invariants - container to store kernel build version.
> + * @uts_version: to save the build number and date so that the we do not resume with
> + *		a different kernel.
> + */
> +struct arch_hibernate_hdr_invariants {
> +	char		uts_version[__NEW_UTS_LEN + 1];
> +};
> +
> +/**
> + * struct arch_hibernate_hdr - helper parameters that help us to restore the image.
> + * @invariants: container to store kernel build version.
> + * @hartid: to make sure same boot_cpu executes the hibernate/restore code.
> + * @saved_satp: original page table used by the hibernated image.
> + * @restore_cpu_addr: the kernel's image address to restore the CPU context.
> + */
> +static struct arch_hibernate_hdr {
> +	struct arch_hibernate_hdr_invariants invariants;
> +	unsigned long	hartid;
> +	unsigned long	saved_satp;
> +	unsigned long	restore_cpu_addr;
> +} resume_hdr;
> +
> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
> +{
> +	memset(i, 0, sizeof(*i));
> +	memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
> +}
> +
> +/*
> + * Check if the given pfn is in the 'nosave' section.
> + */
> +int pfn_is_nosave(unsigned long pfn)
> +{
> +	unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
> +	unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
> +
> +	return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
> +}
> +
> +void notrace save_processor_state(void)
> +{
> +	WARN_ON(num_online_cpus() != 1);
> +}
> +
> +void notrace restore_processor_state(void)
> +{
> +}
> +
> +/*
> + * Helper parameters need to be saved to the hibernation image header.
> + */
> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
> +{
> +	struct arch_hibernate_hdr *hdr = addr;
> +
> +	if (max_size < sizeof(*hdr))
> +		return -EOVERFLOW;
> +
> +	arch_hdr_invariants(&hdr->invariants);
> +
> +	hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
> +	hdr->saved_satp = csr_read(CSR_SATP);
> +	hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
> +
> +/*
> + * Retrieve the helper parameters from the hibernation image header.
> + */
> +int arch_hibernation_header_restore(void *addr)
> +{
> +	struct arch_hibernate_hdr_invariants invariants;
> +	struct arch_hibernate_hdr *hdr = addr;
> +	int ret = 0;
> +
> +	arch_hdr_invariants(&invariants);
> +
> +	if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
> +		pr_crit("Hibernate image not generated by this kernel!\n");
> +		return -EINVAL;
> +	}
> +
> +	sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
> +	if (sleep_cpu < 0) {
> +		pr_crit("Hibernated on a CPU not known to this kernel!\n");
> +		sleep_cpu = -EINVAL;
> +		return -EINVAL;
> +	}
> +
> +#ifdef CONFIG_SMP
> +	ret = bringup_hibernate_cpu(sleep_cpu);
> +	if (ret) {
> +		sleep_cpu = -EINVAL;
> +		return ret;
> +	}
> +#endif
> +	resume_hdr = *hdr;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
> +
> +int swsusp_arch_suspend(void)
> +{
> +	int ret = 0;
> +
> +	if (__cpu_suspend_enter(hibernate_cpu_context)) {
> +		sleep_cpu = smp_processor_id();
> +		suspend_save_csrs(hibernate_cpu_context);
> +		ret = swsusp_save();
> +	} else {
> +		suspend_restore_csrs(hibernate_cpu_context);
> +		flush_tlb_all();
> +		flush_icache_all();
> +
> +		/*
> +		 * Tell the hibernation core that we've just restored the memory.
> +		 */
> +		in_suspend = 0;
> +		sleep_cpu = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp, unsigned long start,
> +				unsigned long end, pgprot_t prot)
> +{
> +	pte_t *src_ptep;
> +	pte_t *dst_ptep;
> +
> +	if (pmd_none(READ_ONCE(*dst_pmdp))) {
> +		dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
> +		if (!dst_ptep)
> +			return -ENOMEM;
> +
> +		pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
> +	}
> +
> +	dst_ptep = pte_offset_kernel(dst_pmdp, start);
> +	src_ptep = pte_offset_kernel(src_pmdp, start);
> +
> +	do {
> +		pte_t pte = READ_ONCE(*src_ptep);
> +
> +		if (pte_present(pte))
> +			set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
> +	} while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
> +
> +	return 0;
> +}
> +
> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp, unsigned long start,
> +				unsigned long end, pgprot_t prot)
> +{
> +	unsigned long next;
> +	unsigned long ret;
> +	pmd_t *src_pmdp;
> +	pmd_t *dst_pmdp;
> +
> +	if (pud_none(READ_ONCE(*dst_pudp))) {
> +		dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
> +		if (!dst_pmdp)
> +			return -ENOMEM;
> +
> +		pud_populate(NULL, dst_pudp, dst_pmdp);
> +	}
> +
> +	dst_pmdp = pmd_offset(dst_pudp, start);
> +	src_pmdp = pmd_offset(src_pudp, start);
> +
> +	do {
> +		pmd_t pmd = READ_ONCE(*src_pmdp);
> +
> +		next = pmd_addr_end(start, end);
> +
> +		if (pmd_none(pmd))
> +			continue;
> +
> +		if (pmd_leaf(pmd)) {
> +			set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
> +		} else {
> +			ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start, next, prot);
> +			if (ret)
> +				return -ENOMEM;
> +		}
> +	} while (dst_pmdp++, src_pmdp++, start = next, start != end);
> +
> +	return 0;
> +}
> +
> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp, unsigned long start,
> +				unsigned long end, pgprot_t prot)
> +{
> +	unsigned long next;
> +	unsigned long ret;
> +	pud_t *dst_pudp;
> +	pud_t *src_pudp;
> +
> +	if (p4d_none(READ_ONCE(*dst_p4dp))) {
> +		dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
> +		if (!dst_pudp)
> +			return -ENOMEM;
> +
> +		p4d_populate(NULL, dst_p4dp, dst_pudp);
> +	}
> +
> +	dst_pudp = pud_offset(dst_p4dp, start);
> +	src_pudp = pud_offset(src_p4dp, start);
> +
> +	do {
> +		pud_t pud = READ_ONCE(*src_pudp);
> +
> +		next = pud_addr_end(start, end);
> +
> +		if (pud_none(pud))
> +			continue;
> +
> +		if (pud_leaf(pud)) {
> +			set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
> +		} else {
> +			ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start, next, prot);
> +			if (ret)
> +				return -ENOMEM;
> +		}
> +	} while (dst_pudp++, src_pudp++, start = next, start != end);
> +
> +	return 0;
> +}
> +
> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp, unsigned long start,
> +				unsigned long end, pgprot_t prot)
> +{
> +	unsigned long next;
> +	unsigned long ret;
> +	p4d_t *dst_p4dp;
> +	p4d_t *src_p4dp;
> +
> +	if (pgd_none(READ_ONCE(*dst_pgdp))) {
> +		dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
> +		if (!dst_p4dp)
> +			return -ENOMEM;
> +
> +		pgd_populate(NULL, dst_pgdp, dst_p4dp);
> +	}
> +
> +	dst_p4dp = p4d_offset(dst_pgdp, start);
> +	src_p4dp = p4d_offset(src_pgdp, start);
> +
> +	do {
> +		p4d_t p4d = READ_ONCE(*src_p4dp);
> +
> +		next = p4d_addr_end(start, end);
> +
> +		if (p4d_none(p4d))
> +			continue;
> +
> +		if (p4d_leaf(p4d)) {
> +			set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
> +		} else {
> +			ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start, next, prot);
> +			if (ret)
> +				return -ENOMEM;
> +		}
> +	} while (dst_p4dp++, src_p4dp++, start = next, start != end);
> +
> +	return 0;
> +}
> +
> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start, unsigned long end, pgprot_t prot)
> +{
> +	pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
> +	pgd_t *src_pgdp = pgd_offset_k(start);
> +	unsigned long next;
> +	unsigned long ret;
> +
> +	do {
> +		pgd_t pgd = READ_ONCE(*src_pgdp);
> +
> +		next = pgd_addr_end(start, end);
> +
> +		if (pgd_none(pgd))
> +			continue;
> +
> +		if (pgd_leaf(pgd)) {
> +			set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
> +		} else {
> +			ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start, next, prot);
> +			if (ret)
> +				return -ENOMEM;
> +		}
> +	} while (dst_pgdp++, src_pgdp++, start = next, start != end);
> +
> +	return 0;
> +}
> +
> +static unsigned long relocate_restore_code(void)
> +{
> +	void *page = (void *)get_safe_page(GFP_ATOMIC);
> +
> +	if (!page)
> +		return -ENOMEM;
> +
> +	copy_page(page, hibernate_core_restore_code);
> +
> +	/* Make the page containing the relocated code executable. */
> +	set_memory_x((unsigned long)page, 1);
> +
> +	return (unsigned long)page;
> +}
> +
> +int swsusp_arch_resume(void)
> +{
> +	unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
> +	unsigned long start = PAGE_OFFSET;
> +	int ret;
> +
> +	/*
> +	 * Memory allocated by get_safe_page() will be dealt with by the hibernation core,
> +	 * we don't need to free it here.
> +	 */
> +	resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
> +	if (!resume_pg_dir)
> +		return -ENOMEM;
> +
> +	/*
> +	 * Create a temporary page table and map the whole linear region as executable and
> +	 * writable.
> +	 */
> +	ret = temp_pgtable_mapping(resume_pg_dir, start, end, __pgprot(_PAGE_WRITE | _PAGE_EXEC));


Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set. 
Shouldn't you use PAGE_KERNEL_EXEC instead?


> +	if (ret)
> +		return ret;
> +
> +	/* Move the restore code to a new page so that it doesn't get overwritten by itself. */
> +	relocated_restore_code = relocate_restore_code();
> +	if (relocated_restore_code == -ENOMEM)
> +		return -ENOMEM;
> +
> +	/*
> +	 * Map the __hibernate_cpu_resume() address to the temporary page table so that the
> +	 * restore code can jumps to it after finished restore the image. The next execution
> +	 * code doesn't find itself in a different address space after switching over to the
> +	 * original page table used by the hibernated image.
> +	 *
> +	 */
> +	start = (unsigned long)resume_hdr.restore_cpu_addr;
> +	end = start + PAGE_SIZE;
> +
> +	ret = temp_pgtable_mapping(resume_pg_dir, start, end, __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> +	if (ret)
> +		return ret;


You set the linear mapping as executable so no need for this.


> +
> +	hibernate_restore_image(resume_hdr.saved_satp, (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> +				resume_hdr.restore_cpu_addr);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP_SMP
> +int hibernate_resume_nonboot_cpu_disable(void)
> +{
> +	if (sleep_cpu < 0) {
> +		pr_err("Failing to resume from hibernate on an unknown CPU\n");
> +		return -ENODEV;
> +	}
> +
> +	return freeze_secondary_cpus(sleep_cpu);
> +}
> +#endif
> +
> +static int __init riscv_hibernate_init(void)
> +{
> +	hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context), GFP_KERNEL);
> +
> +	if (WARN_ON(!hibernate_cpu_context))
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +early_initcall(riscv_hibernate_init);
  

On 3/8/23 10:08, Alexandre Ghiti wrote:
>
> On 3/8/23 09:06, Sia Jee Heng wrote:
>> Low level Arch functions were created to support hibernation.
>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
>> cpu state onto the stack, then calling swsusp_save() to save the memory
>> image.
>>
>> Arch specific hibernation header is implemented and is utilized by the
>> arch_hibernation_header_restore() and arch_hibernation_header_save()
>> functions. The arch specific hibernation header consists of satp, 
>> hartid,
>> and the cpu_resume address. The kernel built version is also need to be
>> saved into the hibernation image header to making sure only the same
>> kernel is restore when resume.
>>
>> swsusp_arch_resume() creates a temporary page table that covering only
>> the linear map. It copies the restore code to a 'safe' page, then start
>> to restore the memory image. Once completed, it restores the original
>> kernel's page table. It then calls into __hibernate_cpu_resume()
>> to restore the CPU context. Finally, it follows the normal hibernation
>> path back to the hibernation core.
>>
>> To enable hibernation/suspend to disk into RISCV, the below config
>> need to be enabled:
>> - CONFIG_ARCH_HIBERNATION_HEADER
>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
>>
>> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
>> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
>> ---
>>   arch/riscv/Kconfig                 |   6 +
>>   arch/riscv/include/asm/assembler.h |  20 ++
>>   arch/riscv/include/asm/suspend.h   |  19 ++
>>   arch/riscv/kernel/Makefile         |   1 +
>>   arch/riscv/kernel/asm-offsets.c    |   5 +
>>   arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
>>   arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
>>   7 files changed, 552 insertions(+)
>>   create mode 100644 arch/riscv/kernel/hibernate-asm.S
>>   create mode 100644 arch/riscv/kernel/hibernate.c
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index c5e42cc37604..473c2a1a6884 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -707,6 +707,12 @@ menu "Power management options"
>>     source "kernel/power/Kconfig"
>>   +config ARCH_HIBERNATION_POSSIBLE
>> +    def_bool y
>> +
>> +config ARCH_HIBERNATION_HEADER
>> +    def_bool HIBERNATION
>> +
>>   endmenu # "Power management options"
>>     menu "CPU Power Management"
>> diff --git a/arch/riscv/include/asm/assembler.h 
>> b/arch/riscv/include/asm/assembler.h
>> index ba59d38f8937..44b1457d3e95 100644
>> --- a/arch/riscv/include/asm/assembler.h
>> +++ b/arch/riscv/include/asm/assembler.h
>> @@ -59,4 +59,24 @@
>>           REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
>>       .endm
>>   +/*
>> + * copy_page - copy 1 page (4KB) of data from source to destination
>> + * @a0 - destination
>> + * @a1 - source
>> + */
>> +    .macro    copy_page a0, a1
>> +        lui    a2, 0x1
>> +        add    a2, a2, a0
>> +1 :
>> +        REG_L    t0, 0(a1)
>> +        REG_L    t1, SZREG(a1)
>> +
>> +        REG_S    t0, 0(a0)
>> +        REG_S    t1, SZREG(a0)
>> +
>> +        addi    a0, a0, 2 * SZREG
>> +        addi    a1, a1, 2 * SZREG
>> +        bne    a2, a0, 1b
>> +    .endm
>> +
>>   #endif    /* __ASM_ASSEMBLER_H */
>> diff --git a/arch/riscv/include/asm/suspend.h 
>> b/arch/riscv/include/asm/suspend.h
>> index 67e047445662..02f87867389a 100644
>> --- a/arch/riscv/include/asm/suspend.h
>> +++ b/arch/riscv/include/asm/suspend.h
>> @@ -21,6 +21,11 @@ struct suspend_context {
>>   #endif
>>   };
>>   +/*
>> + * Used by hibernation core and cleared during resume sequence
>> + */
>> +extern int in_suspend;
>> +
>>   /* Low-level CPU suspend entry function */
>>   int __cpu_suspend_enter(struct suspend_context *context);
>>   @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid, 
>> unsigned long context);
>>   /* Used to save and restore the CSRs */
>>   void suspend_save_csrs(struct suspend_context *context);
>>   void suspend_restore_csrs(struct suspend_context *context);
>> +
>> +/* Low-level API to support hibernation */
>> +int swsusp_arch_suspend(void);
>> +int swsusp_arch_resume(void);
>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
>> +int arch_hibernation_header_restore(void *addr);
>> +int __hibernate_cpu_resume(void);
>> +
>> +/* Used to resume on the CPU we hibernated on */
>> +int hibernate_resume_nonboot_cpu_disable(void);
>> +
>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp, 
>> unsigned long satp_temp,
>> +                    unsigned long cpu_resume);
>> +asmlinkage int hibernate_core_restore_code(void);
>>   #endif
>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>> index 4cf303a779ab..daab341d55e4 100644
>> --- a/arch/riscv/kernel/Makefile
>> +++ b/arch/riscv/kernel/Makefile
>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
>>   obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
>>     obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
>> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
>>     obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
>>   obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
>> diff --git a/arch/riscv/kernel/asm-offsets.c 
>> b/arch/riscv/kernel/asm-offsets.c
>> index df9444397908..d6a75aac1d27 100644
>> --- a/arch/riscv/kernel/asm-offsets.c
>> +++ b/arch/riscv/kernel/asm-offsets.c
>> @@ -9,6 +9,7 @@
>>   #include <linux/kbuild.h>
>>   #include <linux/mm.h>
>>   #include <linux/sched.h>
>> +#include <linux/suspend.h>
>>   #include <asm/kvm_host.h>
>>   #include <asm/thread_info.h>
>>   #include <asm/ptrace.h>
>> @@ -116,6 +117,10 @@ void asm_offsets(void)
>>         OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
>>   +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
>> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
>> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
>> +
>>       OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
>>       OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
>>       OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
>> diff --git a/arch/riscv/kernel/hibernate-asm.S 
>> b/arch/riscv/kernel/hibernate-asm.S
>> new file mode 100644
>> index 000000000000..effaf5ca5da0
>> --- /dev/null
>> +++ b/arch/riscv/kernel/hibernate-asm.S
>> @@ -0,0 +1,77 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Hibernation low level support for RISCV.
>> + *
>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>> + *
>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>> + */
>> +
>> +#include <asm/asm.h>
>> +#include <asm/asm-offsets.h>
>> +#include <asm/assembler.h>
>> +#include <asm/csr.h>
>> +
>> +#include <linux/linkage.h>
>> +
>> +/*
>> + * int __hibernate_cpu_resume(void)
>> + * Switch back to the hibernated image's page table prior to 
>> restoring the CPU
>> + * context.
>> + *
>> + * Always returns 0
>> + */
>> +ENTRY(__hibernate_cpu_resume)
>> +    /* switch to hibernated image's page table. */
>> +    csrw CSR_SATP, s0
>> +    sfence.vma
>> +
>> +    REG_L    a0, hibernate_cpu_context
>> +
>> +    suspend_restore_csrs
>> +    suspend_restore_regs
>> +
>> +    /* Return zero value. */
>> +    mv    a0, zero
>> +
>> +    ret
>> +END(__hibernate_cpu_resume)
>> +
>> +/*
>> + * Prepare to restore the image.
>> + * a0: satp of saved page tables.
>> + * a1: satp of temporary page tables.
>> + * a2: cpu_resume.
>> + */
>> +ENTRY(hibernate_restore_image)
>> +    mv    s0, a0
>> +    mv    s1, a1
>> +    mv    s2, a2
>> +    REG_L    s4, restore_pblist
>> +    REG_L    a1, relocated_restore_code
>> +
>> +    jalr    a1
>> +END(hibernate_restore_image)
>> +
>> +/*
>> + * The below code will be executed from a 'safe' page.
>> + * It first switches to the temporary page table, then starts to 
>> copy the pages
>> + * back to the original memory location. Finally, it jumps to 
>> __hibernate_cpu_resume()
>> + * to restore the CPU context.
>> + */
>> +ENTRY(hibernate_core_restore_code)
>> +    /* switch to temp page table. */
>> +    csrw satp, s1
>> +    sfence.vma
>> +.Lcopy:
>> +    /* The below code will restore the hibernated image. */
>> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
>> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
>> +
>> +    copy_page a0, a1
>> +
>> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
>> +    bnez    s4, .Lcopy
>> +
>> +    jalr    s2
>> +END(hibernate_core_restore_code)
>> diff --git a/arch/riscv/kernel/hibernate.c 
>> b/arch/riscv/kernel/hibernate.c
>> new file mode 100644
>> index 000000000000..8fab50122e54
>> --- /dev/null
>> +++ b/arch/riscv/kernel/hibernate.c
>> @@ -0,0 +1,424 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Hibernation support for RISCV
>> + *
>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>> + *
>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>> + */
>> +
>> +#include <asm/barrier.h>
>> +#include <asm/cacheflush.h>
>> +#include <asm/mmu_context.h>
>> +#include <asm/page.h>
>> +#include <asm/pgalloc.h>
>> +#include <asm/pgtable.h>
>> +#include <asm/sections.h>
>> +#include <asm/set_memory.h>
>> +#include <asm/smp.h>
>> +#include <asm/suspend.h>
>> +
>> +#include <linux/cpu.h>
>> +#include <linux/memblock.h>
>> +#include <linux/pm.h>
>> +#include <linux/sched.h>
>> +#include <linux/suspend.h>
>> +#include <linux/utsname.h>
>> +
>> +/* The logical cpu number we should resume on, initialised to a 
>> non-cpu number. */
>> +static int sleep_cpu = -EINVAL;
>> +
>> +/* Pointer to the temporary resume page table. */
>> +static pgd_t *resume_pg_dir;
>> +
>> +/* CPU context to be saved. */
>> +struct suspend_context *hibernate_cpu_context;
>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
>> +
>> +unsigned long relocated_restore_code;
>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
>> +
>> +/**
>> + * struct arch_hibernate_hdr_invariants - container to store kernel 
>> build version.
>> + * @uts_version: to save the build number and date so that the we do 
>> not resume with
>> + *        a different kernel.
>> + */
>> +struct arch_hibernate_hdr_invariants {
>> +    char        uts_version[__NEW_UTS_LEN + 1];
>> +};
>> +
>> +/**
>> + * struct arch_hibernate_hdr - helper parameters that help us to 
>> restore the image.
>> + * @invariants: container to store kernel build version.
>> + * @hartid: to make sure same boot_cpu executes the 
>> hibernate/restore code.
>> + * @saved_satp: original page table used by the hibernated image.
>> + * @restore_cpu_addr: the kernel's image address to restore the CPU 
>> context.
>> + */
>> +static struct arch_hibernate_hdr {
>> +    struct arch_hibernate_hdr_invariants invariants;
>> +    unsigned long    hartid;
>> +    unsigned long    saved_satp;
>> +    unsigned long    restore_cpu_addr;
>> +} resume_hdr;
>> +
>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants 
>> *i)
>> +{
>> +    memset(i, 0, sizeof(*i));
>> +    memcpy(i->uts_version, init_utsname()->version, 
>> sizeof(i->uts_version));
>> +}
>> +
>> +/*
>> + * Check if the given pfn is in the 'nosave' section.
>> + */
>> +int pfn_is_nosave(unsigned long pfn)
>> +{
>> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
>> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
>> +
>> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
>> +}
>> +
>> +void notrace save_processor_state(void)
>> +{
>> +    WARN_ON(num_online_cpus() != 1);
>> +}
>> +
>> +void notrace restore_processor_state(void)
>> +{
>> +}
>> +
>> +/*
>> + * Helper parameters need to be saved to the hibernation image header.
>> + */
>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
>> +{
>> +    struct arch_hibernate_hdr *hdr = addr;
>> +
>> +    if (max_size < sizeof(*hdr))
>> +        return -EOVERFLOW;
>> +
>> +    arch_hdr_invariants(&hdr->invariants);
>> +
>> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
>> +    hdr->saved_satp = csr_read(CSR_SATP);
>> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
>> +
>> +    return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
>> +
>> +/*
>> + * Retrieve the helper parameters from the hibernation image header.
>> + */
>> +int arch_hibernation_header_restore(void *addr)
>> +{
>> +    struct arch_hibernate_hdr_invariants invariants;
>> +    struct arch_hibernate_hdr *hdr = addr;
>> +    int ret = 0;
>> +
>> +    arch_hdr_invariants(&invariants);
>> +
>> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
>> +        pr_crit("Hibernate image not generated by this kernel!\n");
>> +        return -EINVAL;
>> +    }
>> +
>> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
>> +    if (sleep_cpu < 0) {
>> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
>> +        sleep_cpu = -EINVAL;
>> +        return -EINVAL;
>> +    }
>> +
>> +#ifdef CONFIG_SMP
>> +    ret = bringup_hibernate_cpu(sleep_cpu);
>> +    if (ret) {
>> +        sleep_cpu = -EINVAL;
>> +        return ret;
>> +    }
>> +#endif
>> +    resume_hdr = *hdr;
>> +
>> +    return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
>> +
>> +int swsusp_arch_suspend(void)
>> +{
>> +    int ret = 0;
>> +
>> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
>> +        sleep_cpu = smp_processor_id();
>> +        suspend_save_csrs(hibernate_cpu_context);
>> +        ret = swsusp_save();
>> +    } else {
>> +        suspend_restore_csrs(hibernate_cpu_context);
>> +        flush_tlb_all();
>> +        flush_icache_all();
>> +
>> +        /*
>> +         * Tell the hibernation core that we've just restored the 
>> memory.
>> +         */
>> +        in_suspend = 0;
>> +        sleep_cpu = -EINVAL;
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp, 
>> unsigned long start,
>> +                unsigned long end, pgprot_t prot)
>> +{
>> +    pte_t *src_ptep;
>> +    pte_t *dst_ptep;
>> +
>> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
>> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
>> +        if (!dst_ptep)
>> +            return -ENOMEM;
>> +
>> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
>> +    }
>> +
>> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
>> +    src_ptep = pte_offset_kernel(src_pmdp, start);
>> +
>> +    do {
>> +        pte_t pte = READ_ONCE(*src_ptep);
>> +
>> +        if (pte_present(pte))
>> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
>> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
>> +
>> +    return 0;
>> +}
>> +
>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp, 
>> unsigned long start,
>> +                unsigned long end, pgprot_t prot)
>> +{
>> +    unsigned long next;
>> +    unsigned long ret;
>> +    pmd_t *src_pmdp;
>> +    pmd_t *dst_pmdp;
>> +
>> +    if (pud_none(READ_ONCE(*dst_pudp))) {
>> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
>> +        if (!dst_pmdp)
>> +            return -ENOMEM;
>> +
>> +        pud_populate(NULL, dst_pudp, dst_pmdp);
>> +    }
>> +
>> +    dst_pmdp = pmd_offset(dst_pudp, start);
>> +    src_pmdp = pmd_offset(src_pudp, start);
>> +
>> +    do {
>> +        pmd_t pmd = READ_ONCE(*src_pmdp);
>> +
>> +        next = pmd_addr_end(start, end);
>> +
>> +        if (pmd_none(pmd))
>> +            continue;
>> +
>> +        if (pmd_leaf(pmd)) {
>> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
>> +        } else {
>> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start, 
>> next, prot);
>> +            if (ret)
>> +                return -ENOMEM;
>> +        }
>> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
>> +
>> +    return 0;
>> +}
>> +
>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp, 
>> unsigned long start,
>> +                unsigned long end, pgprot_t prot)
>> +{
>> +    unsigned long next;
>> +    unsigned long ret;
>> +    pud_t *dst_pudp;
>> +    pud_t *src_pudp;
>> +
>> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
>> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
>> +        if (!dst_pudp)
>> +            return -ENOMEM;
>> +
>> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
>> +    }
>> +
>> +    dst_pudp = pud_offset(dst_p4dp, start);
>> +    src_pudp = pud_offset(src_p4dp, start);
>> +
>> +    do {
>> +        pud_t pud = READ_ONCE(*src_pudp);
>> +
>> +        next = pud_addr_end(start, end);
>> +
>> +        if (pud_none(pud))
>> +            continue;
>> +
>> +        if (pud_leaf(pud)) {
>> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
>> +        } else {
>> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start, 
>> next, prot);
>> +            if (ret)
>> +                return -ENOMEM;
>> +        }
>> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
>> +
>> +    return 0;
>> +}
>> +
>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp, 
>> unsigned long start,
>> +                unsigned long end, pgprot_t prot)
>> +{
>> +    unsigned long next;
>> +    unsigned long ret;
>> +    p4d_t *dst_p4dp;
>> +    p4d_t *src_p4dp;
>> +
>> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
>> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
>> +        if (!dst_p4dp)
>> +            return -ENOMEM;
>> +
>> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
>> +    }
>> +
>> +    dst_p4dp = p4d_offset(dst_pgdp, start);
>> +    src_p4dp = p4d_offset(src_pgdp, start);
>> +
>> +    do {
>> +        p4d_t p4d = READ_ONCE(*src_p4dp);
>> +
>> +        next = p4d_addr_end(start, end);
>> +
>> +        if (p4d_none(p4d))
>> +            continue;
>> +
>> +        if (p4d_leaf(p4d)) {
>> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
>> +        } else {
>> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start, 
>> next, prot);
>> +            if (ret)
>> +                return -ENOMEM;
>> +        }
>> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
>> +
>> +    return 0;
>> +}
>> +
>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start, 
>> unsigned long end, pgprot_t prot)
>> +{
>> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
>> +    pgd_t *src_pgdp = pgd_offset_k(start);
>> +    unsigned long next;
>> +    unsigned long ret;
>> +
>> +    do {
>> +        pgd_t pgd = READ_ONCE(*src_pgdp);
>> +
>> +        next = pgd_addr_end(start, end);
>> +
>> +        if (pgd_none(pgd))
>> +            continue;
>> +
>> +        if (pgd_leaf(pgd)) {
>> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
>> +        } else {
>> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start, 
>> next, prot);
>> +            if (ret)
>> +                return -ENOMEM;
>> +        }
>> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
>> +
>> +    return 0;
>> +}
>> +
>> +static unsigned long relocate_restore_code(void)
>> +{
>> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
>> +
>> +    if (!page)
>> +        return -ENOMEM;
>> +
>> +    copy_page(page, hibernate_core_restore_code);
>> +
>> +    /* Make the page containing the relocated code executable. */
>> +    set_memory_x((unsigned long)page, 1);
>> +
>> +    return (unsigned long)page;
>> +}
>> +
>> +int swsusp_arch_resume(void)
>> +{
>> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
>> +    unsigned long start = PAGE_OFFSET;
>> +    int ret;
>> +
>> +    /*
>> +     * Memory allocated by get_safe_page() will be dealt with by the 
>> hibernation core,
>> +     * we don't need to free it here.
>> +     */
>> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
>> +    if (!resume_pg_dir)
>> +        return -ENOMEM;
>> +
>> +    /*
>> +     * Create a temporary page table and map the whole linear region 
>> as executable and
>> +     * writable.
>> +     */
>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end, 
>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>
>
> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set. 
> Shouldn't you use PAGE_KERNEL_EXEC instead?


Forget this one, that's the protections you add, so that's good :)


>
>
>> +    if (ret)
>> +        return ret;
>> +
>> +    /* Move the restore code to a new page so that it doesn't get 
>> overwritten by itself. */
>> +    relocated_restore_code = relocate_restore_code();
>> +    if (relocated_restore_code == -ENOMEM)
>> +        return -ENOMEM;
>> +
>> +    /*
>> +     * Map the __hibernate_cpu_resume() address to the temporary 
>> page table so that the
>> +     * restore code can jumps to it after finished restore the 
>> image. The next execution
>> +     * code doesn't find itself in a different address space after 
>> switching over to the
>> +     * original page table used by the hibernated image.
>> +     *
>> +     */
>> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
>> +    end = start + PAGE_SIZE;
>> +
>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end, 
>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>> +    if (ret)
>> +        return ret;
>
>
> You set the linear mapping as executable so no need for this.
>
>
>> +
>> +    hibernate_restore_image(resume_hdr.saved_satp, 
>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
>> +                resume_hdr.restore_cpu_addr);
>> +
>> +    return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP_SMP
>> +int hibernate_resume_nonboot_cpu_disable(void)
>> +{
>> +    if (sleep_cpu < 0) {
>> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
>> +        return -ENODEV;
>> +    }
>> +
>> +    return freeze_secondary_cpus(sleep_cpu);
>> +}
>> +#endif
>> +
>> +static int __init riscv_hibernate_init(void)
>> +{
>> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context), 
>> GFP_KERNEL);
>> +
>> +    if (WARN_ON(!hibernate_cpu_context))
>> +        return -ENOMEM;
>> +
>> +    return 0;
>> +}
>> +
>> +early_initcall(riscv_hibernate_init);
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
  

> -----Original Message-----
> From: Alexandre Ghiti <alex@ghiti.fr>
> Sent: Wednesday, March 8, 2023 5:28 PM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> 
> 
> On 3/8/23 10:08, Alexandre Ghiti wrote:
> >
> > On 3/8/23 09:06, Sia Jee Heng wrote:
> >> Low level Arch functions were created to support hibernation.
> >> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
> >> cpu state onto the stack, then calling swsusp_save() to save the memory
> >> image.
> >>
> >> Arch specific hibernation header is implemented and is utilized by the
> >> arch_hibernation_header_restore() and arch_hibernation_header_save()
> >> functions. The arch specific hibernation header consists of satp,
> >> hartid,
> >> and the cpu_resume address. The kernel built version is also need to be
> >> saved into the hibernation image header to making sure only the same
> >> kernel is restore when resume.
> >>
> >> swsusp_arch_resume() creates a temporary page table that covering only
> >> the linear map. It copies the restore code to a 'safe' page, then start
> >> to restore the memory image. Once completed, it restores the original
> >> kernel's page table. It then calls into __hibernate_cpu_resume()
> >> to restore the CPU context. Finally, it follows the normal hibernation
> >> path back to the hibernation core.
> >>
> >> To enable hibernation/suspend to disk into RISCV, the below config
> >> need to be enabled:
> >> - CONFIG_ARCH_HIBERNATION_HEADER
> >> - CONFIG_ARCH_HIBERNATION_POSSIBLE
> >>
> >> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> >> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> >> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> >> ---
> >>   arch/riscv/Kconfig                 |   6 +
> >>   arch/riscv/include/asm/assembler.h |  20 ++
> >>   arch/riscv/include/asm/suspend.h   |  19 ++
> >>   arch/riscv/kernel/Makefile         |   1 +
> >>   arch/riscv/kernel/asm-offsets.c    |   5 +
> >>   arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
> >>   arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
> >>   7 files changed, 552 insertions(+)
> >>   create mode 100644 arch/riscv/kernel/hibernate-asm.S
> >>   create mode 100644 arch/riscv/kernel/hibernate.c
> >>
> >> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> index c5e42cc37604..473c2a1a6884 100644
> >> --- a/arch/riscv/Kconfig
> >> +++ b/arch/riscv/Kconfig
> >> @@ -707,6 +707,12 @@ menu "Power management options"
> >>     source "kernel/power/Kconfig"
> >>   +config ARCH_HIBERNATION_POSSIBLE
> >> +    def_bool y
> >> +
> >> +config ARCH_HIBERNATION_HEADER
> >> +    def_bool HIBERNATION
> >> +
> >>   endmenu # "Power management options"
> >>     menu "CPU Power Management"
> >> diff --git a/arch/riscv/include/asm/assembler.h
> >> b/arch/riscv/include/asm/assembler.h
> >> index ba59d38f8937..44b1457d3e95 100644
> >> --- a/arch/riscv/include/asm/assembler.h
> >> +++ b/arch/riscv/include/asm/assembler.h
> >> @@ -59,4 +59,24 @@
> >>           REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
> >>       .endm
> >>   +/*
> >> + * copy_page - copy 1 page (4KB) of data from source to destination
> >> + * @a0 - destination
> >> + * @a1 - source
> >> + */
> >> +    .macro    copy_page a0, a1
> >> +        lui    a2, 0x1
> >> +        add    a2, a2, a0
> >> +1 :
> >> +        REG_L    t0, 0(a1)
> >> +        REG_L    t1, SZREG(a1)
> >> +
> >> +        REG_S    t0, 0(a0)
> >> +        REG_S    t1, SZREG(a0)
> >> +
> >> +        addi    a0, a0, 2 * SZREG
> >> +        addi    a1, a1, 2 * SZREG
> >> +        bne    a2, a0, 1b
> >> +    .endm
> >> +
> >>   #endif    /* __ASM_ASSEMBLER_H */
> >> diff --git a/arch/riscv/include/asm/suspend.h
> >> b/arch/riscv/include/asm/suspend.h
> >> index 67e047445662..02f87867389a 100644
> >> --- a/arch/riscv/include/asm/suspend.h
> >> +++ b/arch/riscv/include/asm/suspend.h
> >> @@ -21,6 +21,11 @@ struct suspend_context {
> >>   #endif
> >>   };
> >>   +/*
> >> + * Used by hibernation core and cleared during resume sequence
> >> + */
> >> +extern int in_suspend;
> >> +
> >>   /* Low-level CPU suspend entry function */
> >>   int __cpu_suspend_enter(struct suspend_context *context);
> >>   @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
> >> unsigned long context);
> >>   /* Used to save and restore the CSRs */
> >>   void suspend_save_csrs(struct suspend_context *context);
> >>   void suspend_restore_csrs(struct suspend_context *context);
> >> +
> >> +/* Low-level API to support hibernation */
> >> +int swsusp_arch_suspend(void);
> >> +int swsusp_arch_resume(void);
> >> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
> >> +int arch_hibernation_header_restore(void *addr);
> >> +int __hibernate_cpu_resume(void);
> >> +
> >> +/* Used to resume on the CPU we hibernated on */
> >> +int hibernate_resume_nonboot_cpu_disable(void);
> >> +
> >> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
> >> unsigned long satp_temp,
> >> +                    unsigned long cpu_resume);
> >> +asmlinkage int hibernate_core_restore_code(void);
> >>   #endif
> >> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> >> index 4cf303a779ab..daab341d55e4 100644
> >> --- a/arch/riscv/kernel/Makefile
> >> +++ b/arch/riscv/kernel/Makefile
> >> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
> >>   obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
> >>     obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
> >> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
> >>     obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
> >>   obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
> >> diff --git a/arch/riscv/kernel/asm-offsets.c
> >> b/arch/riscv/kernel/asm-offsets.c
> >> index df9444397908..d6a75aac1d27 100644
> >> --- a/arch/riscv/kernel/asm-offsets.c
> >> +++ b/arch/riscv/kernel/asm-offsets.c
> >> @@ -9,6 +9,7 @@
> >>   #include <linux/kbuild.h>
> >>   #include <linux/mm.h>
> >>   #include <linux/sched.h>
> >> +#include <linux/suspend.h>
> >>   #include <asm/kvm_host.h>
> >>   #include <asm/thread_info.h>
> >>   #include <asm/ptrace.h>
> >> @@ -116,6 +117,10 @@ void asm_offsets(void)
> >>         OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
> >>   +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
> >> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
> >> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
> >> +
> >>       OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
> >>       OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
> >>       OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
> >> diff --git a/arch/riscv/kernel/hibernate-asm.S
> >> b/arch/riscv/kernel/hibernate-asm.S
> >> new file mode 100644
> >> index 000000000000..effaf5ca5da0
> >> --- /dev/null
> >> +++ b/arch/riscv/kernel/hibernate-asm.S
> >> @@ -0,0 +1,77 @@
> >> +/* SPDX-License-Identifier: GPL-2.0-only */
> >> +/*
> >> + * Hibernation low level support for RISCV.
> >> + *
> >> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >> + *
> >> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >> + */
> >> +
> >> +#include <asm/asm.h>
> >> +#include <asm/asm-offsets.h>
> >> +#include <asm/assembler.h>
> >> +#include <asm/csr.h>
> >> +
> >> +#include <linux/linkage.h>
> >> +
> >> +/*
> >> + * int __hibernate_cpu_resume(void)
> >> + * Switch back to the hibernated image's page table prior to
> >> restoring the CPU
> >> + * context.
> >> + *
> >> + * Always returns 0
> >> + */
> >> +ENTRY(__hibernate_cpu_resume)
> >> +    /* switch to hibernated image's page table. */
> >> +    csrw CSR_SATP, s0
> >> +    sfence.vma
> >> +
> >> +    REG_L    a0, hibernate_cpu_context
> >> +
> >> +    suspend_restore_csrs
> >> +    suspend_restore_regs
> >> +
> >> +    /* Return zero value. */
> >> +    mv    a0, zero
> >> +
> >> +    ret
> >> +END(__hibernate_cpu_resume)
> >> +
> >> +/*
> >> + * Prepare to restore the image.
> >> + * a0: satp of saved page tables.
> >> + * a1: satp of temporary page tables.
> >> + * a2: cpu_resume.
> >> + */
> >> +ENTRY(hibernate_restore_image)
> >> +    mv    s0, a0
> >> +    mv    s1, a1
> >> +    mv    s2, a2
> >> +    REG_L    s4, restore_pblist
> >> +    REG_L    a1, relocated_restore_code
> >> +
> >> +    jalr    a1
> >> +END(hibernate_restore_image)
> >> +
> >> +/*
> >> + * The below code will be executed from a 'safe' page.
> >> + * It first switches to the temporary page table, then starts to
> >> copy the pages
> >> + * back to the original memory location. Finally, it jumps to
> >> __hibernate_cpu_resume()
> >> + * to restore the CPU context.
> >> + */
> >> +ENTRY(hibernate_core_restore_code)
> >> +    /* switch to temp page table. */
> >> +    csrw satp, s1
> >> +    sfence.vma
> >> +.Lcopy:
> >> +    /* The below code will restore the hibernated image. */
> >> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
> >> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
> >> +
> >> +    copy_page a0, a1
> >> +
> >> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
> >> +    bnez    s4, .Lcopy
> >> +
> >> +    jalr    s2
> >> +END(hibernate_core_restore_code)
> >> diff --git a/arch/riscv/kernel/hibernate.c
> >> b/arch/riscv/kernel/hibernate.c
> >> new file mode 100644
> >> index 000000000000..8fab50122e54
> >> --- /dev/null
> >> +++ b/arch/riscv/kernel/hibernate.c
> >> @@ -0,0 +1,424 @@
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * Hibernation support for RISCV
> >> + *
> >> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >> + *
> >> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >> + */
> >> +
> >> +#include <asm/barrier.h>
> >> +#include <asm/cacheflush.h>
> >> +#include <asm/mmu_context.h>
> >> +#include <asm/page.h>
> >> +#include <asm/pgalloc.h>
> >> +#include <asm/pgtable.h>
> >> +#include <asm/sections.h>
> >> +#include <asm/set_memory.h>
> >> +#include <asm/smp.h>
> >> +#include <asm/suspend.h>
> >> +
> >> +#include <linux/cpu.h>
> >> +#include <linux/memblock.h>
> >> +#include <linux/pm.h>
> >> +#include <linux/sched.h>
> >> +#include <linux/suspend.h>
> >> +#include <linux/utsname.h>
> >> +
> >> +/* The logical cpu number we should resume on, initialised to a
> >> non-cpu number. */
> >> +static int sleep_cpu = -EINVAL;
> >> +
> >> +/* Pointer to the temporary resume page table. */
> >> +static pgd_t *resume_pg_dir;
> >> +
> >> +/* CPU context to be saved. */
> >> +struct suspend_context *hibernate_cpu_context;
> >> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
> >> +
> >> +unsigned long relocated_restore_code;
> >> +EXPORT_SYMBOL_GPL(relocated_restore_code);
> >> +
> >> +/**
> >> + * struct arch_hibernate_hdr_invariants - container to store kernel
> >> build version.
> >> + * @uts_version: to save the build number and date so that the we do
> >> not resume with
> >> + *        a different kernel.
> >> + */
> >> +struct arch_hibernate_hdr_invariants {
> >> +    char        uts_version[__NEW_UTS_LEN + 1];
> >> +};
> >> +
> >> +/**
> >> + * struct arch_hibernate_hdr - helper parameters that help us to
> >> restore the image.
> >> + * @invariants: container to store kernel build version.
> >> + * @hartid: to make sure same boot_cpu executes the
> >> hibernate/restore code.
> >> + * @saved_satp: original page table used by the hibernated image.
> >> + * @restore_cpu_addr: the kernel's image address to restore the CPU
> >> context.
> >> + */
> >> +static struct arch_hibernate_hdr {
> >> +    struct arch_hibernate_hdr_invariants invariants;
> >> +    unsigned long    hartid;
> >> +    unsigned long    saved_satp;
> >> +    unsigned long    restore_cpu_addr;
> >> +} resume_hdr;
> >> +
> >> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
> >> *i)
> >> +{
> >> +    memset(i, 0, sizeof(*i));
> >> +    memcpy(i->uts_version, init_utsname()->version,
> >> sizeof(i->uts_version));
> >> +}
> >> +
> >> +/*
> >> + * Check if the given pfn is in the 'nosave' section.
> >> + */
> >> +int pfn_is_nosave(unsigned long pfn)
> >> +{
> >> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
> >> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
> >> +
> >> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
> >> +}
> >> +
> >> +void notrace save_processor_state(void)
> >> +{
> >> +    WARN_ON(num_online_cpus() != 1);
> >> +}
> >> +
> >> +void notrace restore_processor_state(void)
> >> +{
> >> +}
> >> +
> >> +/*
> >> + * Helper parameters need to be saved to the hibernation image header.
> >> + */
> >> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
> >> +{
> >> +    struct arch_hibernate_hdr *hdr = addr;
> >> +
> >> +    if (max_size < sizeof(*hdr))
> >> +        return -EOVERFLOW;
> >> +
> >> +    arch_hdr_invariants(&hdr->invariants);
> >> +
> >> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
> >> +    hdr->saved_satp = csr_read(CSR_SATP);
> >> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
> >> +
> >> +    return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
> >> +
> >> +/*
> >> + * Retrieve the helper parameters from the hibernation image header.
> >> + */
> >> +int arch_hibernation_header_restore(void *addr)
> >> +{
> >> +    struct arch_hibernate_hdr_invariants invariants;
> >> +    struct arch_hibernate_hdr *hdr = addr;
> >> +    int ret = 0;
> >> +
> >> +    arch_hdr_invariants(&invariants);
> >> +
> >> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
> >> +        pr_crit("Hibernate image not generated by this kernel!\n");
> >> +        return -EINVAL;
> >> +    }
> >> +
> >> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
> >> +    if (sleep_cpu < 0) {
> >> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
> >> +        sleep_cpu = -EINVAL;
> >> +        return -EINVAL;
> >> +    }
> >> +
> >> +#ifdef CONFIG_SMP
> >> +    ret = bringup_hibernate_cpu(sleep_cpu);
> >> +    if (ret) {
> >> +        sleep_cpu = -EINVAL;
> >> +        return ret;
> >> +    }
> >> +#endif
> >> +    resume_hdr = *hdr;
> >> +
> >> +    return ret;
> >> +}
> >> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
> >> +
> >> +int swsusp_arch_suspend(void)
> >> +{
> >> +    int ret = 0;
> >> +
> >> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
> >> +        sleep_cpu = smp_processor_id();
> >> +        suspend_save_csrs(hibernate_cpu_context);
> >> +        ret = swsusp_save();
> >> +    } else {
> >> +        suspend_restore_csrs(hibernate_cpu_context);
> >> +        flush_tlb_all();
> >> +        flush_icache_all();
> >> +
> >> +        /*
> >> +         * Tell the hibernation core that we've just restored the
> >> memory.
> >> +         */
> >> +        in_suspend = 0;
> >> +        sleep_cpu = -EINVAL;
> >> +    }
> >> +
> >> +    return ret;
> >> +}
> >> +
> >> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
> >> unsigned long start,
> >> +                unsigned long end, pgprot_t prot)
> >> +{
> >> +    pte_t *src_ptep;
> >> +    pte_t *dst_ptep;
> >> +
> >> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
> >> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
> >> +        if (!dst_ptep)
> >> +            return -ENOMEM;
> >> +
> >> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
> >> +    }
> >> +
> >> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
> >> +    src_ptep = pte_offset_kernel(src_pmdp, start);
> >> +
> >> +    do {
> >> +        pte_t pte = READ_ONCE(*src_ptep);
> >> +
> >> +        if (pte_present(pte))
> >> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
> >> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
> >> unsigned long start,
> >> +                unsigned long end, pgprot_t prot)
> >> +{
> >> +    unsigned long next;
> >> +    unsigned long ret;
> >> +    pmd_t *src_pmdp;
> >> +    pmd_t *dst_pmdp;
> >> +
> >> +    if (pud_none(READ_ONCE(*dst_pudp))) {
> >> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
> >> +        if (!dst_pmdp)
> >> +            return -ENOMEM;
> >> +
> >> +        pud_populate(NULL, dst_pudp, dst_pmdp);
> >> +    }
> >> +
> >> +    dst_pmdp = pmd_offset(dst_pudp, start);
> >> +    src_pmdp = pmd_offset(src_pudp, start);
> >> +
> >> +    do {
> >> +        pmd_t pmd = READ_ONCE(*src_pmdp);
> >> +
> >> +        next = pmd_addr_end(start, end);
> >> +
> >> +        if (pmd_none(pmd))
> >> +            continue;
> >> +
> >> +        if (pmd_leaf(pmd)) {
> >> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
> >> +        } else {
> >> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
> >> next, prot);
> >> +            if (ret)
> >> +                return -ENOMEM;
> >> +        }
> >> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
> >> unsigned long start,
> >> +                unsigned long end, pgprot_t prot)
> >> +{
> >> +    unsigned long next;
> >> +    unsigned long ret;
> >> +    pud_t *dst_pudp;
> >> +    pud_t *src_pudp;
> >> +
> >> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
> >> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
> >> +        if (!dst_pudp)
> >> +            return -ENOMEM;
> >> +
> >> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
> >> +    }
> >> +
> >> +    dst_pudp = pud_offset(dst_p4dp, start);
> >> +    src_pudp = pud_offset(src_p4dp, start);
> >> +
> >> +    do {
> >> +        pud_t pud = READ_ONCE(*src_pudp);
> >> +
> >> +        next = pud_addr_end(start, end);
> >> +
> >> +        if (pud_none(pud))
> >> +            continue;
> >> +
> >> +        if (pud_leaf(pud)) {
> >> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
> >> +        } else {
> >> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
> >> next, prot);
> >> +            if (ret)
> >> +                return -ENOMEM;
> >> +        }
> >> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
> >> unsigned long start,
> >> +                unsigned long end, pgprot_t prot)
> >> +{
> >> +    unsigned long next;
> >> +    unsigned long ret;
> >> +    p4d_t *dst_p4dp;
> >> +    p4d_t *src_p4dp;
> >> +
> >> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
> >> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
> >> +        if (!dst_p4dp)
> >> +            return -ENOMEM;
> >> +
> >> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
> >> +    }
> >> +
> >> +    dst_p4dp = p4d_offset(dst_pgdp, start);
> >> +    src_p4dp = p4d_offset(src_pgdp, start);
> >> +
> >> +    do {
> >> +        p4d_t p4d = READ_ONCE(*src_p4dp);
> >> +
> >> +        next = p4d_addr_end(start, end);
> >> +
> >> +        if (p4d_none(p4d))
> >> +            continue;
> >> +
> >> +        if (p4d_leaf(p4d)) {
> >> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
> >> +        } else {
> >> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
> >> next, prot);
> >> +            if (ret)
> >> +                return -ENOMEM;
> >> +        }
> >> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
> >> unsigned long end, pgprot_t prot)
> >> +{
> >> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
> >> +    pgd_t *src_pgdp = pgd_offset_k(start);
> >> +    unsigned long next;
> >> +    unsigned long ret;
> >> +
> >> +    do {
> >> +        pgd_t pgd = READ_ONCE(*src_pgdp);
> >> +
> >> +        next = pgd_addr_end(start, end);
> >> +
> >> +        if (pgd_none(pgd))
> >> +            continue;
> >> +
> >> +        if (pgd_leaf(pgd)) {
> >> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
> >> +        } else {
> >> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
> >> next, prot);
> >> +            if (ret)
> >> +                return -ENOMEM;
> >> +        }
> >> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +static unsigned long relocate_restore_code(void)
> >> +{
> >> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
> >> +
> >> +    if (!page)
> >> +        return -ENOMEM;
> >> +
> >> +    copy_page(page, hibernate_core_restore_code);
> >> +
> >> +    /* Make the page containing the relocated code executable. */
> >> +    set_memory_x((unsigned long)page, 1);
> >> +
> >> +    return (unsigned long)page;
> >> +}
> >> +
> >> +int swsusp_arch_resume(void)
> >> +{
> >> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
> >> +    unsigned long start = PAGE_OFFSET;
> >> +    int ret;
> >> +
> >> +    /*
> >> +     * Memory allocated by get_safe_page() will be dealt with by the
> >> hibernation core,
> >> +     * we don't need to free it here.
> >> +     */
> >> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
> >> +    if (!resume_pg_dir)
> >> +        return -ENOMEM;
> >> +
> >> +    /*
> >> +     * Create a temporary page table and map the whole linear region
> >> as executable and
> >> +     * writable.
> >> +     */
> >> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >
> >
> > Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
> > Shouldn't you use PAGE_KERNEL_EXEC instead?
> 
> 
> Forget this one, that's the protections you add, so that's good :)
OK.
> 
> 
> >
> >
> >> +    if (ret)
> >> +        return ret;
> >> +
> >> +    /* Move the restore code to a new page so that it doesn't get
> >> overwritten by itself. */
> >> +    relocated_restore_code = relocate_restore_code();
> >> +    if (relocated_restore_code == -ENOMEM)
> >> +        return -ENOMEM;
> >> +
> >> +    /*
> >> +     * Map the __hibernate_cpu_resume() address to the temporary
> >> page table so that the
> >> +     * restore code can jumps to it after finished restore the
> >> image. The next execution
> >> +     * code doesn't find itself in a different address space after
> >> switching over to the
> >> +     * original page table used by the hibernated image.
> >> +     *
> >> +     */
> >> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
> >> +    end = start + PAGE_SIZE;
> >> +
> >> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >> +    if (ret)
> >> +        return ret;
> >
> >
> > You set the linear mapping as executable so no need for this.
We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For example:
Linear address start with 0xff60000000000000
Kernel address start with 0xffffffff80000000
> >
> >
> >> +
> >> +    hibernate_restore_image(resume_hdr.saved_satp,
> >> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> >> +                resume_hdr.restore_cpu_addr);
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +#ifdef CONFIG_PM_SLEEP_SMP
> >> +int hibernate_resume_nonboot_cpu_disable(void)
> >> +{
> >> +    if (sleep_cpu < 0) {
> >> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
> >> +        return -ENODEV;
> >> +    }
> >> +
> >> +    return freeze_secondary_cpus(sleep_cpu);
> >> +}
> >> +#endif
> >> +
> >> +static int __init riscv_hibernate_init(void)
> >> +{
> >> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
> >> GFP_KERNEL);
> >> +
> >> +    if (WARN_ON(!hibernate_cpu_context))
> >> +        return -ENOMEM;
> >> +
> >> +    return 0;
> >> +}
> >> +
> >> +early_initcall(riscv_hibernate_init);
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
  

Hi JeeHeng,

On 3/8/23 12:07, JeeHeng Sia wrote:
>
>> -----Original Message-----
>> From: Alexandre Ghiti <alex@ghiti.fr>
>> Sent: Wednesday, March 8, 2023 5:28 PM
>> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
>> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
>> <mason.huo@starfivetech.com>
>> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
>>
>>
>> On 3/8/23 10:08, Alexandre Ghiti wrote:
>>> On 3/8/23 09:06, Sia Jee Heng wrote:
>>>> Low level Arch functions were created to support hibernation.
>>>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
>>>> cpu state onto the stack, then calling swsusp_save() to save the memory
>>>> image.
>>>>
>>>> Arch specific hibernation header is implemented and is utilized by the
>>>> arch_hibernation_header_restore() and arch_hibernation_header_save()
>>>> functions. The arch specific hibernation header consists of satp,
>>>> hartid,
>>>> and the cpu_resume address. The kernel built version is also need to be
>>>> saved into the hibernation image header to making sure only the same
>>>> kernel is restore when resume.
>>>>
>>>> swsusp_arch_resume() creates a temporary page table that covering only
>>>> the linear map. It copies the restore code to a 'safe' page, then start
>>>> to restore the memory image. Once completed, it restores the original
>>>> kernel's page table. It then calls into __hibernate_cpu_resume()
>>>> to restore the CPU context. Finally, it follows the normal hibernation
>>>> path back to the hibernation core.
>>>>
>>>> To enable hibernation/suspend to disk into RISCV, the below config
>>>> need to be enabled:
>>>> - CONFIG_ARCH_HIBERNATION_HEADER
>>>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
>>>>
>>>> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
>>>> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
>>>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
>>>> ---
>>>>    arch/riscv/Kconfig                 |   6 +
>>>>    arch/riscv/include/asm/assembler.h |  20 ++
>>>>    arch/riscv/include/asm/suspend.h   |  19 ++
>>>>    arch/riscv/kernel/Makefile         |   1 +
>>>>    arch/riscv/kernel/asm-offsets.c    |   5 +
>>>>    arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
>>>>    arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
>>>>    7 files changed, 552 insertions(+)
>>>>    create mode 100644 arch/riscv/kernel/hibernate-asm.S
>>>>    create mode 100644 arch/riscv/kernel/hibernate.c
>>>>
>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>> index c5e42cc37604..473c2a1a6884 100644
>>>> --- a/arch/riscv/Kconfig
>>>> +++ b/arch/riscv/Kconfig
>>>> @@ -707,6 +707,12 @@ menu "Power management options"
>>>>      source "kernel/power/Kconfig"
>>>>    +config ARCH_HIBERNATION_POSSIBLE
>>>> +    def_bool y
>>>> +
>>>> +config ARCH_HIBERNATION_HEADER
>>>> +    def_bool HIBERNATION
>>>> +
>>>>    endmenu # "Power management options"
>>>>      menu "CPU Power Management"
>>>> diff --git a/arch/riscv/include/asm/assembler.h
>>>> b/arch/riscv/include/asm/assembler.h
>>>> index ba59d38f8937..44b1457d3e95 100644
>>>> --- a/arch/riscv/include/asm/assembler.h
>>>> +++ b/arch/riscv/include/asm/assembler.h
>>>> @@ -59,4 +59,24 @@
>>>>            REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
>>>>        .endm
>>>>    +/*
>>>> + * copy_page - copy 1 page (4KB) of data from source to destination
>>>> + * @a0 - destination
>>>> + * @a1 - source
>>>> + */
>>>> +    .macro    copy_page a0, a1
>>>> +        lui    a2, 0x1
>>>> +        add    a2, a2, a0
>>>> +1 :
>>>> +        REG_L    t0, 0(a1)
>>>> +        REG_L    t1, SZREG(a1)
>>>> +
>>>> +        REG_S    t0, 0(a0)
>>>> +        REG_S    t1, SZREG(a0)
>>>> +
>>>> +        addi    a0, a0, 2 * SZREG
>>>> +        addi    a1, a1, 2 * SZREG
>>>> +        bne    a2, a0, 1b
>>>> +    .endm
>>>> +
>>>>    #endif    /* __ASM_ASSEMBLER_H */
>>>> diff --git a/arch/riscv/include/asm/suspend.h
>>>> b/arch/riscv/include/asm/suspend.h
>>>> index 67e047445662..02f87867389a 100644
>>>> --- a/arch/riscv/include/asm/suspend.h
>>>> +++ b/arch/riscv/include/asm/suspend.h
>>>> @@ -21,6 +21,11 @@ struct suspend_context {
>>>>    #endif
>>>>    };
>>>>    +/*
>>>> + * Used by hibernation core and cleared during resume sequence
>>>> + */
>>>> +extern int in_suspend;
>>>> +
>>>>    /* Low-level CPU suspend entry function */
>>>>    int __cpu_suspend_enter(struct suspend_context *context);
>>>>    @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
>>>> unsigned long context);
>>>>    /* Used to save and restore the CSRs */
>>>>    void suspend_save_csrs(struct suspend_context *context);
>>>>    void suspend_restore_csrs(struct suspend_context *context);
>>>> +
>>>> +/* Low-level API to support hibernation */
>>>> +int swsusp_arch_suspend(void);
>>>> +int swsusp_arch_resume(void);
>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
>>>> +int arch_hibernation_header_restore(void *addr);
>>>> +int __hibernate_cpu_resume(void);
>>>> +
>>>> +/* Used to resume on the CPU we hibernated on */
>>>> +int hibernate_resume_nonboot_cpu_disable(void);
>>>> +
>>>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
>>>> unsigned long satp_temp,
>>>> +                    unsigned long cpu_resume);
>>>> +asmlinkage int hibernate_core_restore_code(void);
>>>>    #endif
>>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>>>> index 4cf303a779ab..daab341d55e4 100644
>>>> --- a/arch/riscv/kernel/Makefile
>>>> +++ b/arch/riscv/kernel/Makefile
>>>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
>>>>    obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
>>>>      obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
>>>> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
>>>>      obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
>>>>    obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
>>>> diff --git a/arch/riscv/kernel/asm-offsets.c
>>>> b/arch/riscv/kernel/asm-offsets.c
>>>> index df9444397908..d6a75aac1d27 100644
>>>> --- a/arch/riscv/kernel/asm-offsets.c
>>>> +++ b/arch/riscv/kernel/asm-offsets.c
>>>> @@ -9,6 +9,7 @@
>>>>    #include <linux/kbuild.h>
>>>>    #include <linux/mm.h>
>>>>    #include <linux/sched.h>
>>>> +#include <linux/suspend.h>
>>>>    #include <asm/kvm_host.h>
>>>>    #include <asm/thread_info.h>
>>>>    #include <asm/ptrace.h>
>>>> @@ -116,6 +117,10 @@ void asm_offsets(void)
>>>>          OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
>>>>    +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
>>>> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
>>>> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
>>>> +
>>>>        OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
>>>>        OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
>>>>        OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
>>>> diff --git a/arch/riscv/kernel/hibernate-asm.S
>>>> b/arch/riscv/kernel/hibernate-asm.S
>>>> new file mode 100644
>>>> index 000000000000..effaf5ca5da0
>>>> --- /dev/null
>>>> +++ b/arch/riscv/kernel/hibernate-asm.S
>>>> @@ -0,0 +1,77 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>>> +/*
>>>> + * Hibernation low level support for RISCV.
>>>> + *
>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>> + *
>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>>>> + */
>>>> +
>>>> +#include <asm/asm.h>
>>>> +#include <asm/asm-offsets.h>
>>>> +#include <asm/assembler.h>
>>>> +#include <asm/csr.h>
>>>> +
>>>> +#include <linux/linkage.h>
>>>> +
>>>> +/*
>>>> + * int __hibernate_cpu_resume(void)
>>>> + * Switch back to the hibernated image's page table prior to
>>>> restoring the CPU
>>>> + * context.
>>>> + *
>>>> + * Always returns 0
>>>> + */
>>>> +ENTRY(__hibernate_cpu_resume)
>>>> +    /* switch to hibernated image's page table. */
>>>> +    csrw CSR_SATP, s0
>>>> +    sfence.vma
>>>> +
>>>> +    REG_L    a0, hibernate_cpu_context
>>>> +
>>>> +    suspend_restore_csrs
>>>> +    suspend_restore_regs
>>>> +
>>>> +    /* Return zero value. */
>>>> +    mv    a0, zero
>>>> +
>>>> +    ret
>>>> +END(__hibernate_cpu_resume)
>>>> +
>>>> +/*
>>>> + * Prepare to restore the image.
>>>> + * a0: satp of saved page tables.
>>>> + * a1: satp of temporary page tables.
>>>> + * a2: cpu_resume.
>>>> + */
>>>> +ENTRY(hibernate_restore_image)
>>>> +    mv    s0, a0
>>>> +    mv    s1, a1
>>>> +    mv    s2, a2
>>>> +    REG_L    s4, restore_pblist
>>>> +    REG_L    a1, relocated_restore_code
>>>> +
>>>> +    jalr    a1
>>>> +END(hibernate_restore_image)
>>>> +
>>>> +/*
>>>> + * The below code will be executed from a 'safe' page.
>>>> + * It first switches to the temporary page table, then starts to
>>>> copy the pages
>>>> + * back to the original memory location. Finally, it jumps to
>>>> __hibernate_cpu_resume()
>>>> + * to restore the CPU context.
>>>> + */
>>>> +ENTRY(hibernate_core_restore_code)
>>>> +    /* switch to temp page table. */
>>>> +    csrw satp, s1
>>>> +    sfence.vma
>>>> +.Lcopy:
>>>> +    /* The below code will restore the hibernated image. */
>>>> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
>>>> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
>>>> +
>>>> +    copy_page a0, a1
>>>> +
>>>> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
>>>> +    bnez    s4, .Lcopy
>>>> +
>>>> +    jalr    s2
>>>> +END(hibernate_core_restore_code)
>>>> diff --git a/arch/riscv/kernel/hibernate.c
>>>> b/arch/riscv/kernel/hibernate.c
>>>> new file mode 100644
>>>> index 000000000000..8fab50122e54
>>>> --- /dev/null
>>>> +++ b/arch/riscv/kernel/hibernate.c
>>>> @@ -0,0 +1,424 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Hibernation support for RISCV
>>>> + *
>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>> + *
>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>>>> + */
>>>> +
>>>> +#include <asm/barrier.h>
>>>> +#include <asm/cacheflush.h>
>>>> +#include <asm/mmu_context.h>
>>>> +#include <asm/page.h>
>>>> +#include <asm/pgalloc.h>
>>>> +#include <asm/pgtable.h>
>>>> +#include <asm/sections.h>
>>>> +#include <asm/set_memory.h>
>>>> +#include <asm/smp.h>
>>>> +#include <asm/suspend.h>
>>>> +
>>>> +#include <linux/cpu.h>
>>>> +#include <linux/memblock.h>
>>>> +#include <linux/pm.h>
>>>> +#include <linux/sched.h>
>>>> +#include <linux/suspend.h>
>>>> +#include <linux/utsname.h>
>>>> +
>>>> +/* The logical cpu number we should resume on, initialised to a
>>>> non-cpu number. */
>>>> +static int sleep_cpu = -EINVAL;
>>>> +
>>>> +/* Pointer to the temporary resume page table. */
>>>> +static pgd_t *resume_pg_dir;
>>>> +
>>>> +/* CPU context to be saved. */
>>>> +struct suspend_context *hibernate_cpu_context;
>>>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
>>>> +
>>>> +unsigned long relocated_restore_code;
>>>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
>>>> +
>>>> +/**
>>>> + * struct arch_hibernate_hdr_invariants - container to store kernel
>>>> build version.
>>>> + * @uts_version: to save the build number and date so that the we do
>>>> not resume with
>>>> + *        a different kernel.
>>>> + */
>>>> +struct arch_hibernate_hdr_invariants {
>>>> +    char        uts_version[__NEW_UTS_LEN + 1];
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct arch_hibernate_hdr - helper parameters that help us to
>>>> restore the image.
>>>> + * @invariants: container to store kernel build version.
>>>> + * @hartid: to make sure same boot_cpu executes the
>>>> hibernate/restore code.
>>>> + * @saved_satp: original page table used by the hibernated image.
>>>> + * @restore_cpu_addr: the kernel's image address to restore the CPU
>>>> context.
>>>> + */
>>>> +static struct arch_hibernate_hdr {
>>>> +    struct arch_hibernate_hdr_invariants invariants;
>>>> +    unsigned long    hartid;
>>>> +    unsigned long    saved_satp;
>>>> +    unsigned long    restore_cpu_addr;
>>>> +} resume_hdr;
>>>> +
>>>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
>>>> *i)
>>>> +{
>>>> +    memset(i, 0, sizeof(*i));
>>>> +    memcpy(i->uts_version, init_utsname()->version,
>>>> sizeof(i->uts_version));
>>>> +}
>>>> +
>>>> +/*
>>>> + * Check if the given pfn is in the 'nosave' section.
>>>> + */
>>>> +int pfn_is_nosave(unsigned long pfn)
>>>> +{
>>>> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
>>>> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
>>>> +
>>>> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
>>>> +}
>>>> +
>>>> +void notrace save_processor_state(void)
>>>> +{
>>>> +    WARN_ON(num_online_cpus() != 1);
>>>> +}
>>>> +
>>>> +void notrace restore_processor_state(void)
>>>> +{
>>>> +}
>>>> +
>>>> +/*
>>>> + * Helper parameters need to be saved to the hibernation image header.
>>>> + */
>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
>>>> +{
>>>> +    struct arch_hibernate_hdr *hdr = addr;
>>>> +
>>>> +    if (max_size < sizeof(*hdr))
>>>> +        return -EOVERFLOW;
>>>> +
>>>> +    arch_hdr_invariants(&hdr->invariants);
>>>> +
>>>> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
>>>> +    hdr->saved_satp = csr_read(CSR_SATP);
>>>> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
>>>> +
>>>> +/*
>>>> + * Retrieve the helper parameters from the hibernation image header.
>>>> + */
>>>> +int arch_hibernation_header_restore(void *addr)
>>>> +{
>>>> +    struct arch_hibernate_hdr_invariants invariants;
>>>> +    struct arch_hibernate_hdr *hdr = addr;
>>>> +    int ret = 0;
>>>> +
>>>> +    arch_hdr_invariants(&invariants);
>>>> +
>>>> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
>>>> +        pr_crit("Hibernate image not generated by this kernel!\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
>>>> +    if (sleep_cpu < 0) {
>>>> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
>>>> +        sleep_cpu = -EINVAL;
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +#ifdef CONFIG_SMP
>>>> +    ret = bringup_hibernate_cpu(sleep_cpu);
>>>> +    if (ret) {
>>>> +        sleep_cpu = -EINVAL;
>>>> +        return ret;
>>>> +    }
>>>> +#endif
>>>> +    resume_hdr = *hdr;
>>>> +
>>>> +    return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
>>>> +
>>>> +int swsusp_arch_suspend(void)
>>>> +{
>>>> +    int ret = 0;
>>>> +
>>>> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
>>>> +        sleep_cpu = smp_processor_id();
>>>> +        suspend_save_csrs(hibernate_cpu_context);
>>>> +        ret = swsusp_save();
>>>> +    } else {
>>>> +        suspend_restore_csrs(hibernate_cpu_context);
>>>> +        flush_tlb_all();
>>>> +        flush_icache_all();
>>>> +
>>>> +        /*
>>>> +         * Tell the hibernation core that we've just restored the
>>>> memory.
>>>> +         */
>>>> +        in_suspend = 0;
>>>> +        sleep_cpu = -EINVAL;
>>>> +    }
>>>> +
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
>>>> unsigned long start,
>>>> +                unsigned long end, pgprot_t prot)
>>>> +{
>>>> +    pte_t *src_ptep;
>>>> +    pte_t *dst_ptep;
>>>> +
>>>> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
>>>> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
>>>> +        if (!dst_ptep)
>>>> +            return -ENOMEM;
>>>> +
>>>> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
>>>> +    }
>>>> +
>>>> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
>>>> +    src_ptep = pte_offset_kernel(src_pmdp, start);
>>>> +
>>>> +    do {
>>>> +        pte_t pte = READ_ONCE(*src_ptep);
>>>> +
>>>> +        if (pte_present(pte))
>>>> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
>>>> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
>>>> unsigned long start,
>>>> +                unsigned long end, pgprot_t prot)
>>>> +{
>>>> +    unsigned long next;
>>>> +    unsigned long ret;
>>>> +    pmd_t *src_pmdp;
>>>> +    pmd_t *dst_pmdp;
>>>> +
>>>> +    if (pud_none(READ_ONCE(*dst_pudp))) {
>>>> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
>>>> +        if (!dst_pmdp)
>>>> +            return -ENOMEM;
>>>> +
>>>> +        pud_populate(NULL, dst_pudp, dst_pmdp);
>>>> +    }
>>>> +
>>>> +    dst_pmdp = pmd_offset(dst_pudp, start);
>>>> +    src_pmdp = pmd_offset(src_pudp, start);
>>>> +
>>>> +    do {
>>>> +        pmd_t pmd = READ_ONCE(*src_pmdp);
>>>> +
>>>> +        next = pmd_addr_end(start, end);
>>>> +
>>>> +        if (pmd_none(pmd))
>>>> +            continue;
>>>> +
>>>> +        if (pmd_leaf(pmd)) {
>>>> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
>>>> +        } else {
>>>> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
>>>> next, prot);
>>>> +            if (ret)
>>>> +                return -ENOMEM;
>>>> +        }
>>>> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
>>>> unsigned long start,
>>>> +                unsigned long end, pgprot_t prot)
>>>> +{
>>>> +    unsigned long next;
>>>> +    unsigned long ret;
>>>> +    pud_t *dst_pudp;
>>>> +    pud_t *src_pudp;
>>>> +
>>>> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
>>>> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
>>>> +        if (!dst_pudp)
>>>> +            return -ENOMEM;
>>>> +
>>>> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
>>>> +    }
>>>> +
>>>> +    dst_pudp = pud_offset(dst_p4dp, start);
>>>> +    src_pudp = pud_offset(src_p4dp, start);
>>>> +
>>>> +    do {
>>>> +        pud_t pud = READ_ONCE(*src_pudp);
>>>> +
>>>> +        next = pud_addr_end(start, end);
>>>> +
>>>> +        if (pud_none(pud))
>>>> +            continue;
>>>> +
>>>> +        if (pud_leaf(pud)) {
>>>> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
>>>> +        } else {
>>>> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
>>>> next, prot);
>>>> +            if (ret)
>>>> +                return -ENOMEM;
>>>> +        }
>>>> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
>>>> unsigned long start,
>>>> +                unsigned long end, pgprot_t prot)
>>>> +{
>>>> +    unsigned long next;
>>>> +    unsigned long ret;
>>>> +    p4d_t *dst_p4dp;
>>>> +    p4d_t *src_p4dp;
>>>> +
>>>> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
>>>> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
>>>> +        if (!dst_p4dp)
>>>> +            return -ENOMEM;
>>>> +
>>>> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
>>>> +    }
>>>> +
>>>> +    dst_p4dp = p4d_offset(dst_pgdp, start);
>>>> +    src_p4dp = p4d_offset(src_pgdp, start);
>>>> +
>>>> +    do {
>>>> +        p4d_t p4d = READ_ONCE(*src_p4dp);
>>>> +
>>>> +        next = p4d_addr_end(start, end);
>>>> +
>>>> +        if (p4d_none(p4d))
>>>> +            continue;
>>>> +
>>>> +        if (p4d_leaf(p4d)) {
>>>> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
>>>> +        } else {
>>>> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
>>>> next, prot);
>>>> +            if (ret)
>>>> +                return -ENOMEM;
>>>> +        }
>>>> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
>>>> unsigned long end, pgprot_t prot)
>>>> +{
>>>> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
>>>> +    pgd_t *src_pgdp = pgd_offset_k(start);
>>>> +    unsigned long next;
>>>> +    unsigned long ret;
>>>> +
>>>> +    do {
>>>> +        pgd_t pgd = READ_ONCE(*src_pgdp);
>>>> +
>>>> +        next = pgd_addr_end(start, end);
>>>> +
>>>> +        if (pgd_none(pgd))
>>>> +            continue;
>>>> +
>>>> +        if (pgd_leaf(pgd)) {
>>>> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
>>>> +        } else {
>>>> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
>>>> next, prot);
>>>> +            if (ret)
>>>> +                return -ENOMEM;
>>>> +        }
>>>> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static unsigned long relocate_restore_code(void)
>>>> +{
>>>> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
>>>> +
>>>> +    if (!page)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    copy_page(page, hibernate_core_restore_code);
>>>> +
>>>> +    /* Make the page containing the relocated code executable. */
>>>> +    set_memory_x((unsigned long)page, 1);
>>>> +
>>>> +    return (unsigned long)page;
>>>> +}
>>>> +
>>>> +int swsusp_arch_resume(void)
>>>> +{
>>>> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
>>>> +    unsigned long start = PAGE_OFFSET;
>>>> +    int ret;
>>>> +
>>>> +    /*
>>>> +     * Memory allocated by get_safe_page() will be dealt with by the
>>>> hibernation core,
>>>> +     * we don't need to free it here.
>>>> +     */
>>>> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
>>>> +    if (!resume_pg_dir)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    /*
>>>> +     * Create a temporary page table and map the whole linear region
>>>> as executable and
>>>> +     * writable.
>>>> +     */
>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>
>>> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
>>> Shouldn't you use PAGE_KERNEL_EXEC instead?
>>
>> Forget this one, that's the protections you add, so that's good :)
> OK.
>>
>>>
>>>> +    if (ret)
>>>> +        return ret;
>>>> +
>>>> +    /* Move the restore code to a new page so that it doesn't get
>>>> overwritten by itself. */
>>>> +    relocated_restore_code = relocate_restore_code();
>>>> +    if (relocated_restore_code == -ENOMEM)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    /*
>>>> +     * Map the __hibernate_cpu_resume() address to the temporary
>>>> page table so that the
>>>> +     * restore code can jumps to it after finished restore the
>>>> image. The next execution
>>>> +     * code doesn't find itself in a different address space after
>>>> switching over to the
>>>> +     * original page table used by the hibernated image.
>>>> +     *
>>>> +     */
>>>> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
>>>> +    end = start + PAGE_SIZE;
>>>> +
>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>> +    if (ret)
>>>> +        return ret;
>>>
>>> You set the linear mapping as executable so no need for this.
> We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For example:
> Linear address start with 0xff60000000000000
> Kernel address start with 0xffffffff80000000


Ok I understand now that you need to map this into the temporary page 
table: one nit though, since you copy the kernel mapping, no need to use 
PAGE_WRITE | PAGE_EXEC, the protections are already correct.

Thanks,

Alex


>>>
>>>> +
>>>> +    hibernate_restore_image(resume_hdr.saved_satp,
>>>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
>>>> +                resume_hdr.restore_cpu_addr);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_PM_SLEEP_SMP
>>>> +int hibernate_resume_nonboot_cpu_disable(void)
>>>> +{
>>>> +    if (sleep_cpu < 0) {
>>>> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
>>>> +        return -ENODEV;
>>>> +    }
>>>> +
>>>> +    return freeze_secondary_cpus(sleep_cpu);
>>>> +}
>>>> +#endif
>>>> +
>>>> +static int __init riscv_hibernate_init(void)
>>>> +{
>>>> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
>>>> GFP_KERNEL);
>>>> +
>>>> +    if (WARN_ON(!hibernate_cpu_context))
>>>> +        return -ENOMEM;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +early_initcall(riscv_hibernate_init);
>>> _______________________________________________
>>> linux-riscv mailing list
>>> linux-riscv@lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
  

Hi Alex,

> -----Original Message-----
> From: Alexandre Ghiti <alex@ghiti.fr>
> Sent: Friday, March 10, 2023 5:59 PM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> 
> Hi JeeHeng,
> 
> On 3/8/23 12:07, JeeHeng Sia wrote:
> >
> >> -----Original Message-----
> >> From: Alexandre Ghiti <alex@ghiti.fr>
> >> Sent: Wednesday, March 8, 2023 5:28 PM
> >> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> >> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> >> <mason.huo@starfivetech.com>
> >> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> >>
> >>
> >> On 3/8/23 10:08, Alexandre Ghiti wrote:
> >>> On 3/8/23 09:06, Sia Jee Heng wrote:
> >>>> Low level Arch functions were created to support hibernation.
> >>>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
> >>>> cpu state onto the stack, then calling swsusp_save() to save the memory
> >>>> image.
> >>>>
> >>>> Arch specific hibernation header is implemented and is utilized by the
> >>>> arch_hibernation_header_restore() and arch_hibernation_header_save()
> >>>> functions. The arch specific hibernation header consists of satp,
> >>>> hartid,
> >>>> and the cpu_resume address. The kernel built version is also need to be
> >>>> saved into the hibernation image header to making sure only the same
> >>>> kernel is restore when resume.
> >>>>
> >>>> swsusp_arch_resume() creates a temporary page table that covering only
> >>>> the linear map. It copies the restore code to a 'safe' page, then start
> >>>> to restore the memory image. Once completed, it restores the original
> >>>> kernel's page table. It then calls into __hibernate_cpu_resume()
> >>>> to restore the CPU context. Finally, it follows the normal hibernation
> >>>> path back to the hibernation core.
> >>>>
> >>>> To enable hibernation/suspend to disk into RISCV, the below config
> >>>> need to be enabled:
> >>>> - CONFIG_ARCH_HIBERNATION_HEADER
> >>>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
> >>>>
> >>>> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> >>>> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> >>>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> >>>> ---
> >>>>    arch/riscv/Kconfig                 |   6 +
> >>>>    arch/riscv/include/asm/assembler.h |  20 ++
> >>>>    arch/riscv/include/asm/suspend.h   |  19 ++
> >>>>    arch/riscv/kernel/Makefile         |   1 +
> >>>>    arch/riscv/kernel/asm-offsets.c    |   5 +
> >>>>    arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
> >>>>    arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
> >>>>    7 files changed, 552 insertions(+)
> >>>>    create mode 100644 arch/riscv/kernel/hibernate-asm.S
> >>>>    create mode 100644 arch/riscv/kernel/hibernate.c
> >>>>
> >>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >>>> index c5e42cc37604..473c2a1a6884 100644
> >>>> --- a/arch/riscv/Kconfig
> >>>> +++ b/arch/riscv/Kconfig
> >>>> @@ -707,6 +707,12 @@ menu "Power management options"
> >>>>      source "kernel/power/Kconfig"
> >>>>    +config ARCH_HIBERNATION_POSSIBLE
> >>>> +    def_bool y
> >>>> +
> >>>> +config ARCH_HIBERNATION_HEADER
> >>>> +    def_bool HIBERNATION
> >>>> +
> >>>>    endmenu # "Power management options"
> >>>>      menu "CPU Power Management"
> >>>> diff --git a/arch/riscv/include/asm/assembler.h
> >>>> b/arch/riscv/include/asm/assembler.h
> >>>> index ba59d38f8937..44b1457d3e95 100644
> >>>> --- a/arch/riscv/include/asm/assembler.h
> >>>> +++ b/arch/riscv/include/asm/assembler.h
> >>>> @@ -59,4 +59,24 @@
> >>>>            REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
> >>>>        .endm
> >>>>    +/*
> >>>> + * copy_page - copy 1 page (4KB) of data from source to destination
> >>>> + * @a0 - destination
> >>>> + * @a1 - source
> >>>> + */
> >>>> +    .macro    copy_page a0, a1
> >>>> +        lui    a2, 0x1
> >>>> +        add    a2, a2, a0
> >>>> +1 :
> >>>> +        REG_L    t0, 0(a1)
> >>>> +        REG_L    t1, SZREG(a1)
> >>>> +
> >>>> +        REG_S    t0, 0(a0)
> >>>> +        REG_S    t1, SZREG(a0)
> >>>> +
> >>>> +        addi    a0, a0, 2 * SZREG
> >>>> +        addi    a1, a1, 2 * SZREG
> >>>> +        bne    a2, a0, 1b
> >>>> +    .endm
> >>>> +
> >>>>    #endif    /* __ASM_ASSEMBLER_H */
> >>>> diff --git a/arch/riscv/include/asm/suspend.h
> >>>> b/arch/riscv/include/asm/suspend.h
> >>>> index 67e047445662..02f87867389a 100644
> >>>> --- a/arch/riscv/include/asm/suspend.h
> >>>> +++ b/arch/riscv/include/asm/suspend.h
> >>>> @@ -21,6 +21,11 @@ struct suspend_context {
> >>>>    #endif
> >>>>    };
> >>>>    +/*
> >>>> + * Used by hibernation core and cleared during resume sequence
> >>>> + */
> >>>> +extern int in_suspend;
> >>>> +
> >>>>    /* Low-level CPU suspend entry function */
> >>>>    int __cpu_suspend_enter(struct suspend_context *context);
> >>>>    @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
> >>>> unsigned long context);
> >>>>    /* Used to save and restore the CSRs */
> >>>>    void suspend_save_csrs(struct suspend_context *context);
> >>>>    void suspend_restore_csrs(struct suspend_context *context);
> >>>> +
> >>>> +/* Low-level API to support hibernation */
> >>>> +int swsusp_arch_suspend(void);
> >>>> +int swsusp_arch_resume(void);
> >>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
> >>>> +int arch_hibernation_header_restore(void *addr);
> >>>> +int __hibernate_cpu_resume(void);
> >>>> +
> >>>> +/* Used to resume on the CPU we hibernated on */
> >>>> +int hibernate_resume_nonboot_cpu_disable(void);
> >>>> +
> >>>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
> >>>> unsigned long satp_temp,
> >>>> +                    unsigned long cpu_resume);
> >>>> +asmlinkage int hibernate_core_restore_code(void);
> >>>>    #endif
> >>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> >>>> index 4cf303a779ab..daab341d55e4 100644
> >>>> --- a/arch/riscv/kernel/Makefile
> >>>> +++ b/arch/riscv/kernel/Makefile
> >>>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
> >>>>    obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
> >>>>      obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
> >>>> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
> >>>>      obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
> >>>>    obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
> >>>> diff --git a/arch/riscv/kernel/asm-offsets.c
> >>>> b/arch/riscv/kernel/asm-offsets.c
> >>>> index df9444397908..d6a75aac1d27 100644
> >>>> --- a/arch/riscv/kernel/asm-offsets.c
> >>>> +++ b/arch/riscv/kernel/asm-offsets.c
> >>>> @@ -9,6 +9,7 @@
> >>>>    #include <linux/kbuild.h>
> >>>>    #include <linux/mm.h>
> >>>>    #include <linux/sched.h>
> >>>> +#include <linux/suspend.h>
> >>>>    #include <asm/kvm_host.h>
> >>>>    #include <asm/thread_info.h>
> >>>>    #include <asm/ptrace.h>
> >>>> @@ -116,6 +117,10 @@ void asm_offsets(void)
> >>>>          OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
> >>>>    +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
> >>>> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
> >>>> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
> >>>> +
> >>>>        OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
> >>>>        OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
> >>>>        OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
> >>>> diff --git a/arch/riscv/kernel/hibernate-asm.S
> >>>> b/arch/riscv/kernel/hibernate-asm.S
> >>>> new file mode 100644
> >>>> index 000000000000..effaf5ca5da0
> >>>> --- /dev/null
> >>>> +++ b/arch/riscv/kernel/hibernate-asm.S
> >>>> @@ -0,0 +1,77 @@
> >>>> +/* SPDX-License-Identifier: GPL-2.0-only */
> >>>> +/*
> >>>> + * Hibernation low level support for RISCV.
> >>>> + *
> >>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >>>> + *
> >>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >>>> + */
> >>>> +
> >>>> +#include <asm/asm.h>
> >>>> +#include <asm/asm-offsets.h>
> >>>> +#include <asm/assembler.h>
> >>>> +#include <asm/csr.h>
> >>>> +
> >>>> +#include <linux/linkage.h>
> >>>> +
> >>>> +/*
> >>>> + * int __hibernate_cpu_resume(void)
> >>>> + * Switch back to the hibernated image's page table prior to
> >>>> restoring the CPU
> >>>> + * context.
> >>>> + *
> >>>> + * Always returns 0
> >>>> + */
> >>>> +ENTRY(__hibernate_cpu_resume)
> >>>> +    /* switch to hibernated image's page table. */
> >>>> +    csrw CSR_SATP, s0
> >>>> +    sfence.vma
> >>>> +
> >>>> +    REG_L    a0, hibernate_cpu_context
> >>>> +
> >>>> +    suspend_restore_csrs
> >>>> +    suspend_restore_regs
> >>>> +
> >>>> +    /* Return zero value. */
> >>>> +    mv    a0, zero
> >>>> +
> >>>> +    ret
> >>>> +END(__hibernate_cpu_resume)
> >>>> +
> >>>> +/*
> >>>> + * Prepare to restore the image.
> >>>> + * a0: satp of saved page tables.
> >>>> + * a1: satp of temporary page tables.
> >>>> + * a2: cpu_resume.
> >>>> + */
> >>>> +ENTRY(hibernate_restore_image)
> >>>> +    mv    s0, a0
> >>>> +    mv    s1, a1
> >>>> +    mv    s2, a2
> >>>> +    REG_L    s4, restore_pblist
> >>>> +    REG_L    a1, relocated_restore_code
> >>>> +
> >>>> +    jalr    a1
> >>>> +END(hibernate_restore_image)
> >>>> +
> >>>> +/*
> >>>> + * The below code will be executed from a 'safe' page.
> >>>> + * It first switches to the temporary page table, then starts to
> >>>> copy the pages
> >>>> + * back to the original memory location. Finally, it jumps to
> >>>> __hibernate_cpu_resume()
> >>>> + * to restore the CPU context.
> >>>> + */
> >>>> +ENTRY(hibernate_core_restore_code)
> >>>> +    /* switch to temp page table. */
> >>>> +    csrw satp, s1
> >>>> +    sfence.vma
> >>>> +.Lcopy:
> >>>> +    /* The below code will restore the hibernated image. */
> >>>> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
> >>>> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
> >>>> +
> >>>> +    copy_page a0, a1
> >>>> +
> >>>> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
> >>>> +    bnez    s4, .Lcopy
> >>>> +
> >>>> +    jalr    s2
> >>>> +END(hibernate_core_restore_code)
> >>>> diff --git a/arch/riscv/kernel/hibernate.c
> >>>> b/arch/riscv/kernel/hibernate.c
> >>>> new file mode 100644
> >>>> index 000000000000..8fab50122e54
> >>>> --- /dev/null
> >>>> +++ b/arch/riscv/kernel/hibernate.c
> >>>> @@ -0,0 +1,424 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0-only
> >>>> +/*
> >>>> + * Hibernation support for RISCV
> >>>> + *
> >>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >>>> + *
> >>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >>>> + */
> >>>> +
> >>>> +#include <asm/barrier.h>
> >>>> +#include <asm/cacheflush.h>
> >>>> +#include <asm/mmu_context.h>
> >>>> +#include <asm/page.h>
> >>>> +#include <asm/pgalloc.h>
> >>>> +#include <asm/pgtable.h>
> >>>> +#include <asm/sections.h>
> >>>> +#include <asm/set_memory.h>
> >>>> +#include <asm/smp.h>
> >>>> +#include <asm/suspend.h>
> >>>> +
> >>>> +#include <linux/cpu.h>
> >>>> +#include <linux/memblock.h>
> >>>> +#include <linux/pm.h>
> >>>> +#include <linux/sched.h>
> >>>> +#include <linux/suspend.h>
> >>>> +#include <linux/utsname.h>
> >>>> +
> >>>> +/* The logical cpu number we should resume on, initialised to a
> >>>> non-cpu number. */
> >>>> +static int sleep_cpu = -EINVAL;
> >>>> +
> >>>> +/* Pointer to the temporary resume page table. */
> >>>> +static pgd_t *resume_pg_dir;
> >>>> +
> >>>> +/* CPU context to be saved. */
> >>>> +struct suspend_context *hibernate_cpu_context;
> >>>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
> >>>> +
> >>>> +unsigned long relocated_restore_code;
> >>>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
> >>>> +
> >>>> +/**
> >>>> + * struct arch_hibernate_hdr_invariants - container to store kernel
> >>>> build version.
> >>>> + * @uts_version: to save the build number and date so that the we do
> >>>> not resume with
> >>>> + *        a different kernel.
> >>>> + */
> >>>> +struct arch_hibernate_hdr_invariants {
> >>>> +    char        uts_version[__NEW_UTS_LEN + 1];
> >>>> +};
> >>>> +
> >>>> +/**
> >>>> + * struct arch_hibernate_hdr - helper parameters that help us to
> >>>> restore the image.
> >>>> + * @invariants: container to store kernel build version.
> >>>> + * @hartid: to make sure same boot_cpu executes the
> >>>> hibernate/restore code.
> >>>> + * @saved_satp: original page table used by the hibernated image.
> >>>> + * @restore_cpu_addr: the kernel's image address to restore the CPU
> >>>> context.
> >>>> + */
> >>>> +static struct arch_hibernate_hdr {
> >>>> +    struct arch_hibernate_hdr_invariants invariants;
> >>>> +    unsigned long    hartid;
> >>>> +    unsigned long    saved_satp;
> >>>> +    unsigned long    restore_cpu_addr;
> >>>> +} resume_hdr;
> >>>> +
> >>>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
> >>>> *i)
> >>>> +{
> >>>> +    memset(i, 0, sizeof(*i));
> >>>> +    memcpy(i->uts_version, init_utsname()->version,
> >>>> sizeof(i->uts_version));
> >>>> +}
> >>>> +
> >>>> +/*
> >>>> + * Check if the given pfn is in the 'nosave' section.
> >>>> + */
> >>>> +int pfn_is_nosave(unsigned long pfn)
> >>>> +{
> >>>> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
> >>>> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
> >>>> +
> >>>> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
> >>>> +}
> >>>> +
> >>>> +void notrace save_processor_state(void)
> >>>> +{
> >>>> +    WARN_ON(num_online_cpus() != 1);
> >>>> +}
> >>>> +
> >>>> +void notrace restore_processor_state(void)
> >>>> +{
> >>>> +}
> >>>> +
> >>>> +/*
> >>>> + * Helper parameters need to be saved to the hibernation image header.
> >>>> + */
> >>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
> >>>> +{
> >>>> +    struct arch_hibernate_hdr *hdr = addr;
> >>>> +
> >>>> +    if (max_size < sizeof(*hdr))
> >>>> +        return -EOVERFLOW;
> >>>> +
> >>>> +    arch_hdr_invariants(&hdr->invariants);
> >>>> +
> >>>> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
> >>>> +    hdr->saved_satp = csr_read(CSR_SATP);
> >>>> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
> >>>> +
> >>>> +/*
> >>>> + * Retrieve the helper parameters from the hibernation image header.
> >>>> + */
> >>>> +int arch_hibernation_header_restore(void *addr)
> >>>> +{
> >>>> +    struct arch_hibernate_hdr_invariants invariants;
> >>>> +    struct arch_hibernate_hdr *hdr = addr;
> >>>> +    int ret = 0;
> >>>> +
> >>>> +    arch_hdr_invariants(&invariants);
> >>>> +
> >>>> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
> >>>> +        pr_crit("Hibernate image not generated by this kernel!\n");
> >>>> +        return -EINVAL;
> >>>> +    }
> >>>> +
> >>>> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
> >>>> +    if (sleep_cpu < 0) {
> >>>> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
> >>>> +        sleep_cpu = -EINVAL;
> >>>> +        return -EINVAL;
> >>>> +    }
> >>>> +
> >>>> +#ifdef CONFIG_SMP
> >>>> +    ret = bringup_hibernate_cpu(sleep_cpu);
> >>>> +    if (ret) {
> >>>> +        sleep_cpu = -EINVAL;
> >>>> +        return ret;
> >>>> +    }
> >>>> +#endif
> >>>> +    resume_hdr = *hdr;
> >>>> +
> >>>> +    return ret;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
> >>>> +
> >>>> +int swsusp_arch_suspend(void)
> >>>> +{
> >>>> +    int ret = 0;
> >>>> +
> >>>> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
> >>>> +        sleep_cpu = smp_processor_id();
> >>>> +        suspend_save_csrs(hibernate_cpu_context);
> >>>> +        ret = swsusp_save();
> >>>> +    } else {
> >>>> +        suspend_restore_csrs(hibernate_cpu_context);
> >>>> +        flush_tlb_all();
> >>>> +        flush_icache_all();
> >>>> +
> >>>> +        /*
> >>>> +         * Tell the hibernation core that we've just restored the
> >>>> memory.
> >>>> +         */
> >>>> +        in_suspend = 0;
> >>>> +        sleep_cpu = -EINVAL;
> >>>> +    }
> >>>> +
> >>>> +    return ret;
> >>>> +}
> >>>> +
> >>>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
> >>>> unsigned long start,
> >>>> +                unsigned long end, pgprot_t prot)
> >>>> +{
> >>>> +    pte_t *src_ptep;
> >>>> +    pte_t *dst_ptep;
> >>>> +
> >>>> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
> >>>> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
> >>>> +        if (!dst_ptep)
> >>>> +            return -ENOMEM;
> >>>> +
> >>>> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
> >>>> +    }
> >>>> +
> >>>> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
> >>>> +    src_ptep = pte_offset_kernel(src_pmdp, start);
> >>>> +
> >>>> +    do {
> >>>> +        pte_t pte = READ_ONCE(*src_ptep);
> >>>> +
> >>>> +        if (pte_present(pte))
> >>>> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
> >>>> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
> >>>> unsigned long start,
> >>>> +                unsigned long end, pgprot_t prot)
> >>>> +{
> >>>> +    unsigned long next;
> >>>> +    unsigned long ret;
> >>>> +    pmd_t *src_pmdp;
> >>>> +    pmd_t *dst_pmdp;
> >>>> +
> >>>> +    if (pud_none(READ_ONCE(*dst_pudp))) {
> >>>> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
> >>>> +        if (!dst_pmdp)
> >>>> +            return -ENOMEM;
> >>>> +
> >>>> +        pud_populate(NULL, dst_pudp, dst_pmdp);
> >>>> +    }
> >>>> +
> >>>> +    dst_pmdp = pmd_offset(dst_pudp, start);
> >>>> +    src_pmdp = pmd_offset(src_pudp, start);
> >>>> +
> >>>> +    do {
> >>>> +        pmd_t pmd = READ_ONCE(*src_pmdp);
> >>>> +
> >>>> +        next = pmd_addr_end(start, end);
> >>>> +
> >>>> +        if (pmd_none(pmd))
> >>>> +            continue;
> >>>> +
> >>>> +        if (pmd_leaf(pmd)) {
> >>>> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
> >>>> +        } else {
> >>>> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
> >>>> next, prot);
> >>>> +            if (ret)
> >>>> +                return -ENOMEM;
> >>>> +        }
> >>>> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
> >>>> unsigned long start,
> >>>> +                unsigned long end, pgprot_t prot)
> >>>> +{
> >>>> +    unsigned long next;
> >>>> +    unsigned long ret;
> >>>> +    pud_t *dst_pudp;
> >>>> +    pud_t *src_pudp;
> >>>> +
> >>>> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
> >>>> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
> >>>> +        if (!dst_pudp)
> >>>> +            return -ENOMEM;
> >>>> +
> >>>> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
> >>>> +    }
> >>>> +
> >>>> +    dst_pudp = pud_offset(dst_p4dp, start);
> >>>> +    src_pudp = pud_offset(src_p4dp, start);
> >>>> +
> >>>> +    do {
> >>>> +        pud_t pud = READ_ONCE(*src_pudp);
> >>>> +
> >>>> +        next = pud_addr_end(start, end);
> >>>> +
> >>>> +        if (pud_none(pud))
> >>>> +            continue;
> >>>> +
> >>>> +        if (pud_leaf(pud)) {
> >>>> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
> >>>> +        } else {
> >>>> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
> >>>> next, prot);
> >>>> +            if (ret)
> >>>> +                return -ENOMEM;
> >>>> +        }
> >>>> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
> >>>> unsigned long start,
> >>>> +                unsigned long end, pgprot_t prot)
> >>>> +{
> >>>> +    unsigned long next;
> >>>> +    unsigned long ret;
> >>>> +    p4d_t *dst_p4dp;
> >>>> +    p4d_t *src_p4dp;
> >>>> +
> >>>> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
> >>>> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
> >>>> +        if (!dst_p4dp)
> >>>> +            return -ENOMEM;
> >>>> +
> >>>> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
> >>>> +    }
> >>>> +
> >>>> +    dst_p4dp = p4d_offset(dst_pgdp, start);
> >>>> +    src_p4dp = p4d_offset(src_pgdp, start);
> >>>> +
> >>>> +    do {
> >>>> +        p4d_t p4d = READ_ONCE(*src_p4dp);
> >>>> +
> >>>> +        next = p4d_addr_end(start, end);
> >>>> +
> >>>> +        if (p4d_none(p4d))
> >>>> +            continue;
> >>>> +
> >>>> +        if (p4d_leaf(p4d)) {
> >>>> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
> >>>> +        } else {
> >>>> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
> >>>> next, prot);
> >>>> +            if (ret)
> >>>> +                return -ENOMEM;
> >>>> +        }
> >>>> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
> >>>> unsigned long end, pgprot_t prot)
> >>>> +{
> >>>> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
> >>>> +    pgd_t *src_pgdp = pgd_offset_k(start);
> >>>> +    unsigned long next;
> >>>> +    unsigned long ret;
> >>>> +
> >>>> +    do {
> >>>> +        pgd_t pgd = READ_ONCE(*src_pgdp);
> >>>> +
> >>>> +        next = pgd_addr_end(start, end);
> >>>> +
> >>>> +        if (pgd_none(pgd))
> >>>> +            continue;
> >>>> +
> >>>> +        if (pgd_leaf(pgd)) {
> >>>> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
> >>>> +        } else {
> >>>> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
> >>>> next, prot);
> >>>> +            if (ret)
> >>>> +                return -ENOMEM;
> >>>> +        }
> >>>> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static unsigned long relocate_restore_code(void)
> >>>> +{
> >>>> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
> >>>> +
> >>>> +    if (!page)
> >>>> +        return -ENOMEM;
> >>>> +
> >>>> +    copy_page(page, hibernate_core_restore_code);
> >>>> +
> >>>> +    /* Make the page containing the relocated code executable. */
> >>>> +    set_memory_x((unsigned long)page, 1);
> >>>> +
> >>>> +    return (unsigned long)page;
> >>>> +}
> >>>> +
> >>>> +int swsusp_arch_resume(void)
> >>>> +{
> >>>> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
> >>>> +    unsigned long start = PAGE_OFFSET;
> >>>> +    int ret;
> >>>> +
> >>>> +    /*
> >>>> +     * Memory allocated by get_safe_page() will be dealt with by the
> >>>> hibernation core,
> >>>> +     * we don't need to free it here.
> >>>> +     */
> >>>> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
> >>>> +    if (!resume_pg_dir)
> >>>> +        return -ENOMEM;
> >>>> +
> >>>> +    /*
> >>>> +     * Create a temporary page table and map the whole linear region
> >>>> as executable and
> >>>> +     * writable.
> >>>> +     */
> >>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >>>
> >>> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
> >>> Shouldn't you use PAGE_KERNEL_EXEC instead?
> >>
> >> Forget this one, that's the protections you add, so that's good :)
> > OK.
> >>
> >>>
> >>>> +    if (ret)
> >>>> +        return ret;
> >>>> +
> >>>> +    /* Move the restore code to a new page so that it doesn't get
> >>>> overwritten by itself. */
> >>>> +    relocated_restore_code = relocate_restore_code();
> >>>> +    if (relocated_restore_code == -ENOMEM)
> >>>> +        return -ENOMEM;
> >>>> +
> >>>> +    /*
> >>>> +     * Map the __hibernate_cpu_resume() address to the temporary
> >>>> page table so that the
> >>>> +     * restore code can jumps to it after finished restore the
> >>>> image. The next execution
> >>>> +     * code doesn't find itself in a different address space after
> >>>> switching over to the
> >>>> +     * original page table used by the hibernated image.
> >>>> +     *
> >>>> +     */
> >>>> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
> >>>> +    end = start + PAGE_SIZE;
> >>>> +
> >>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >>>> +    if (ret)
> >>>> +        return ret;
> >>>
> >>> You set the linear mapping as executable so no need for this.
> > We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For example:
> > Linear address start with 0xff60000000000000
> > Kernel address start with 0xffffffff80000000
> 
> 
> Ok I understand now that you need to map this into the temporary page
> table: one nit though, since you copy the kernel mapping, no need to use
> PAGE_WRITE | PAGE_EXEC, the protections are already correct.
Here is the thing. For riscv_64bit, I am agreed with you that we don’t need to use PAGE_WRITE | PAGE_EXEC.
However, we need to use PAGE_WRITE | PAGE_EXEC for riscv_32bit because the linear addresses and kernel addresses are similar. The attribute becomes not writable if following the "original" page table. I am thinking to use #ifdef config_32bit to split the path for 64bit and 32bit but I just afraid the linear addresses and kernel addresses might change again in the future. To be on the safe side, I let both riscv_32bit & riscv_64bit to use the PAGE_WRITE | PAGE_EXEC.
For example:
Linear address and kernel address for 32bit started with 0xc0000000
Linear address for 64bit start with 0xff60000000000000
Kernel address for 64bit start with 0xffffffff80000000

Please let me know your thoughts.

> 
> Thanks,
> 
> Alex
> 
> 
> >>>
> >>>> +
> >>>> +    hibernate_restore_image(resume_hdr.saved_satp,
> >>>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> >>>> +                resume_hdr.restore_cpu_addr);
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +#ifdef CONFIG_PM_SLEEP_SMP
> >>>> +int hibernate_resume_nonboot_cpu_disable(void)
> >>>> +{
> >>>> +    if (sleep_cpu < 0) {
> >>>> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
> >>>> +        return -ENODEV;
> >>>> +    }
> >>>> +
> >>>> +    return freeze_secondary_cpus(sleep_cpu);
> >>>> +}
> >>>> +#endif
> >>>> +
> >>>> +static int __init riscv_hibernate_init(void)
> >>>> +{
> >>>> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
> >>>> GFP_KERNEL);
> >>>> +
> >>>> +    if (WARN_ON(!hibernate_cpu_context))
> >>>> +        return -ENOMEM;
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +early_initcall(riscv_hibernate_init);
> >>> _______________________________________________
> >>> linux-riscv mailing list
> >>> linux-riscv@lists.infradead.org
> >>> http://lists.infradead.org/mailman/listinfo/linux-riscv
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
  

On 3/10/23 11:43, JeeHeng Sia wrote:
> Hi Alex,
>
>> -----Original Message-----
>> From: Alexandre Ghiti <alex@ghiti.fr>
>> Sent: Friday, March 10, 2023 5:59 PM
>> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
>> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
>> <mason.huo@starfivetech.com>
>> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
>>
>> Hi JeeHeng,
>>
>> On 3/8/23 12:07, JeeHeng Sia wrote:
>>>> -----Original Message-----
>>>> From: Alexandre Ghiti <alex@ghiti.fr>
>>>> Sent: Wednesday, March 8, 2023 5:28 PM
>>>> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
>>>> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
>>>> <mason.huo@starfivetech.com>
>>>> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
>>>>
>>>>
>>>> On 3/8/23 10:08, Alexandre Ghiti wrote:
>>>>> On 3/8/23 09:06, Sia Jee Heng wrote:
>>>>>> Low level Arch functions were created to support hibernation.
>>>>>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
>>>>>> cpu state onto the stack, then calling swsusp_save() to save the memory
>>>>>> image.
>>>>>>
>>>>>> Arch specific hibernation header is implemented and is utilized by the
>>>>>> arch_hibernation_header_restore() and arch_hibernation_header_save()
>>>>>> functions. The arch specific hibernation header consists of satp,
>>>>>> hartid,
>>>>>> and the cpu_resume address. The kernel built version is also need to be
>>>>>> saved into the hibernation image header to making sure only the same
>>>>>> kernel is restore when resume.
>>>>>>
>>>>>> swsusp_arch_resume() creates a temporary page table that covering only
>>>>>> the linear map. It copies the restore code to a 'safe' page, then start
>>>>>> to restore the memory image. Once completed, it restores the original
>>>>>> kernel's page table. It then calls into __hibernate_cpu_resume()
>>>>>> to restore the CPU context. Finally, it follows the normal hibernation
>>>>>> path back to the hibernation core.
>>>>>>
>>>>>> To enable hibernation/suspend to disk into RISCV, the below config
>>>>>> need to be enabled:
>>>>>> - CONFIG_ARCH_HIBERNATION_HEADER
>>>>>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
>>>>>>
>>>>>> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
>>>>>> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
>>>>>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
>>>>>> ---
>>>>>>     arch/riscv/Kconfig                 |   6 +
>>>>>>     arch/riscv/include/asm/assembler.h |  20 ++
>>>>>>     arch/riscv/include/asm/suspend.h   |  19 ++
>>>>>>     arch/riscv/kernel/Makefile         |   1 +
>>>>>>     arch/riscv/kernel/asm-offsets.c    |   5 +
>>>>>>     arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
>>>>>>     arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
>>>>>>     7 files changed, 552 insertions(+)
>>>>>>     create mode 100644 arch/riscv/kernel/hibernate-asm.S
>>>>>>     create mode 100644 arch/riscv/kernel/hibernate.c
>>>>>>
>>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>>>> index c5e42cc37604..473c2a1a6884 100644
>>>>>> --- a/arch/riscv/Kconfig
>>>>>> +++ b/arch/riscv/Kconfig
>>>>>> @@ -707,6 +707,12 @@ menu "Power management options"
>>>>>>       source "kernel/power/Kconfig"
>>>>>>     +config ARCH_HIBERNATION_POSSIBLE
>>>>>> +    def_bool y
>>>>>> +
>>>>>> +config ARCH_HIBERNATION_HEADER
>>>>>> +    def_bool HIBERNATION
>>>>>> +
>>>>>>     endmenu # "Power management options"
>>>>>>       menu "CPU Power Management"
>>>>>> diff --git a/arch/riscv/include/asm/assembler.h
>>>>>> b/arch/riscv/include/asm/assembler.h
>>>>>> index ba59d38f8937..44b1457d3e95 100644
>>>>>> --- a/arch/riscv/include/asm/assembler.h
>>>>>> +++ b/arch/riscv/include/asm/assembler.h
>>>>>> @@ -59,4 +59,24 @@
>>>>>>             REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
>>>>>>         .endm
>>>>>>     +/*
>>>>>> + * copy_page - copy 1 page (4KB) of data from source to destination
>>>>>> + * @a0 - destination
>>>>>> + * @a1 - source
>>>>>> + */
>>>>>> +    .macro    copy_page a0, a1
>>>>>> +        lui    a2, 0x1
>>>>>> +        add    a2, a2, a0
>>>>>> +1 :
>>>>>> +        REG_L    t0, 0(a1)
>>>>>> +        REG_L    t1, SZREG(a1)
>>>>>> +
>>>>>> +        REG_S    t0, 0(a0)
>>>>>> +        REG_S    t1, SZREG(a0)
>>>>>> +
>>>>>> +        addi    a0, a0, 2 * SZREG
>>>>>> +        addi    a1, a1, 2 * SZREG
>>>>>> +        bne    a2, a0, 1b
>>>>>> +    .endm
>>>>>> +
>>>>>>     #endif    /* __ASM_ASSEMBLER_H */
>>>>>> diff --git a/arch/riscv/include/asm/suspend.h
>>>>>> b/arch/riscv/include/asm/suspend.h
>>>>>> index 67e047445662..02f87867389a 100644
>>>>>> --- a/arch/riscv/include/asm/suspend.h
>>>>>> +++ b/arch/riscv/include/asm/suspend.h
>>>>>> @@ -21,6 +21,11 @@ struct suspend_context {
>>>>>>     #endif
>>>>>>     };
>>>>>>     +/*
>>>>>> + * Used by hibernation core and cleared during resume sequence
>>>>>> + */
>>>>>> +extern int in_suspend;
>>>>>> +
>>>>>>     /* Low-level CPU suspend entry function */
>>>>>>     int __cpu_suspend_enter(struct suspend_context *context);
>>>>>>     @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
>>>>>> unsigned long context);
>>>>>>     /* Used to save and restore the CSRs */
>>>>>>     void suspend_save_csrs(struct suspend_context *context);
>>>>>>     void suspend_restore_csrs(struct suspend_context *context);
>>>>>> +
>>>>>> +/* Low-level API to support hibernation */
>>>>>> +int swsusp_arch_suspend(void);
>>>>>> +int swsusp_arch_resume(void);
>>>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
>>>>>> +int arch_hibernation_header_restore(void *addr);
>>>>>> +int __hibernate_cpu_resume(void);
>>>>>> +
>>>>>> +/* Used to resume on the CPU we hibernated on */
>>>>>> +int hibernate_resume_nonboot_cpu_disable(void);
>>>>>> +
>>>>>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
>>>>>> unsigned long satp_temp,
>>>>>> +                    unsigned long cpu_resume);
>>>>>> +asmlinkage int hibernate_core_restore_code(void);
>>>>>>     #endif
>>>>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>>>>>> index 4cf303a779ab..daab341d55e4 100644
>>>>>> --- a/arch/riscv/kernel/Makefile
>>>>>> +++ b/arch/riscv/kernel/Makefile
>>>>>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
>>>>>>     obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
>>>>>>       obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
>>>>>> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
>>>>>>       obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
>>>>>>     obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
>>>>>> diff --git a/arch/riscv/kernel/asm-offsets.c
>>>>>> b/arch/riscv/kernel/asm-offsets.c
>>>>>> index df9444397908..d6a75aac1d27 100644
>>>>>> --- a/arch/riscv/kernel/asm-offsets.c
>>>>>> +++ b/arch/riscv/kernel/asm-offsets.c
>>>>>> @@ -9,6 +9,7 @@
>>>>>>     #include <linux/kbuild.h>
>>>>>>     #include <linux/mm.h>
>>>>>>     #include <linux/sched.h>
>>>>>> +#include <linux/suspend.h>
>>>>>>     #include <asm/kvm_host.h>
>>>>>>     #include <asm/thread_info.h>
>>>>>>     #include <asm/ptrace.h>
>>>>>> @@ -116,6 +117,10 @@ void asm_offsets(void)
>>>>>>           OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
>>>>>>     +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
>>>>>> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
>>>>>> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
>>>>>> +
>>>>>>         OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
>>>>>>         OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
>>>>>>         OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
>>>>>> diff --git a/arch/riscv/kernel/hibernate-asm.S
>>>>>> b/arch/riscv/kernel/hibernate-asm.S
>>>>>> new file mode 100644
>>>>>> index 000000000000..effaf5ca5da0
>>>>>> --- /dev/null
>>>>>> +++ b/arch/riscv/kernel/hibernate-asm.S
>>>>>> @@ -0,0 +1,77 @@
>>>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>>>>> +/*
>>>>>> + * Hibernation low level support for RISCV.
>>>>>> + *
>>>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>>>> + *
>>>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>>>>>> + */
>>>>>> +
>>>>>> +#include <asm/asm.h>
>>>>>> +#include <asm/asm-offsets.h>
>>>>>> +#include <asm/assembler.h>
>>>>>> +#include <asm/csr.h>
>>>>>> +
>>>>>> +#include <linux/linkage.h>
>>>>>> +
>>>>>> +/*
>>>>>> + * int __hibernate_cpu_resume(void)
>>>>>> + * Switch back to the hibernated image's page table prior to
>>>>>> restoring the CPU
>>>>>> + * context.
>>>>>> + *
>>>>>> + * Always returns 0
>>>>>> + */
>>>>>> +ENTRY(__hibernate_cpu_resume)
>>>>>> +    /* switch to hibernated image's page table. */
>>>>>> +    csrw CSR_SATP, s0
>>>>>> +    sfence.vma
>>>>>> +
>>>>>> +    REG_L    a0, hibernate_cpu_context
>>>>>> +
>>>>>> +    suspend_restore_csrs
>>>>>> +    suspend_restore_regs
>>>>>> +
>>>>>> +    /* Return zero value. */
>>>>>> +    mv    a0, zero
>>>>>> +
>>>>>> +    ret
>>>>>> +END(__hibernate_cpu_resume)
>>>>>> +
>>>>>> +/*
>>>>>> + * Prepare to restore the image.
>>>>>> + * a0: satp of saved page tables.
>>>>>> + * a1: satp of temporary page tables.
>>>>>> + * a2: cpu_resume.
>>>>>> + */
>>>>>> +ENTRY(hibernate_restore_image)
>>>>>> +    mv    s0, a0
>>>>>> +    mv    s1, a1
>>>>>> +    mv    s2, a2
>>>>>> +    REG_L    s4, restore_pblist
>>>>>> +    REG_L    a1, relocated_restore_code
>>>>>> +
>>>>>> +    jalr    a1
>>>>>> +END(hibernate_restore_image)
>>>>>> +
>>>>>> +/*
>>>>>> + * The below code will be executed from a 'safe' page.
>>>>>> + * It first switches to the temporary page table, then starts to
>>>>>> copy the pages
>>>>>> + * back to the original memory location. Finally, it jumps to
>>>>>> __hibernate_cpu_resume()
>>>>>> + * to restore the CPU context.
>>>>>> + */
>>>>>> +ENTRY(hibernate_core_restore_code)
>>>>>> +    /* switch to temp page table. */
>>>>>> +    csrw satp, s1
>>>>>> +    sfence.vma
>>>>>> +.Lcopy:
>>>>>> +    /* The below code will restore the hibernated image. */
>>>>>> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
>>>>>> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
>>>>>> +
>>>>>> +    copy_page a0, a1
>>>>>> +
>>>>>> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
>>>>>> +    bnez    s4, .Lcopy
>>>>>> +
>>>>>> +    jalr    s2
>>>>>> +END(hibernate_core_restore_code)
>>>>>> diff --git a/arch/riscv/kernel/hibernate.c
>>>>>> b/arch/riscv/kernel/hibernate.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..8fab50122e54
>>>>>> --- /dev/null
>>>>>> +++ b/arch/riscv/kernel/hibernate.c
>>>>>> @@ -0,0 +1,424 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>>>> +/*
>>>>>> + * Hibernation support for RISCV
>>>>>> + *
>>>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>>>> + *
>>>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
>>>>>> + */
>>>>>> +
>>>>>> +#include <asm/barrier.h>
>>>>>> +#include <asm/cacheflush.h>
>>>>>> +#include <asm/mmu_context.h>
>>>>>> +#include <asm/page.h>
>>>>>> +#include <asm/pgalloc.h>
>>>>>> +#include <asm/pgtable.h>
>>>>>> +#include <asm/sections.h>
>>>>>> +#include <asm/set_memory.h>
>>>>>> +#include <asm/smp.h>
>>>>>> +#include <asm/suspend.h>
>>>>>> +
>>>>>> +#include <linux/cpu.h>
>>>>>> +#include <linux/memblock.h>
>>>>>> +#include <linux/pm.h>
>>>>>> +#include <linux/sched.h>
>>>>>> +#include <linux/suspend.h>
>>>>>> +#include <linux/utsname.h>
>>>>>> +
>>>>>> +/* The logical cpu number we should resume on, initialised to a
>>>>>> non-cpu number. */
>>>>>> +static int sleep_cpu = -EINVAL;
>>>>>> +
>>>>>> +/* Pointer to the temporary resume page table. */
>>>>>> +static pgd_t *resume_pg_dir;
>>>>>> +
>>>>>> +/* CPU context to be saved. */
>>>>>> +struct suspend_context *hibernate_cpu_context;
>>>>>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
>>>>>> +
>>>>>> +unsigned long relocated_restore_code;
>>>>>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
>>>>>> +
>>>>>> +/**
>>>>>> + * struct arch_hibernate_hdr_invariants - container to store kernel
>>>>>> build version.
>>>>>> + * @uts_version: to save the build number and date so that the we do
>>>>>> not resume with
>>>>>> + *        a different kernel.
>>>>>> + */
>>>>>> +struct arch_hibernate_hdr_invariants {
>>>>>> +    char        uts_version[__NEW_UTS_LEN + 1];
>>>>>> +};
>>>>>> +
>>>>>> +/**
>>>>>> + * struct arch_hibernate_hdr - helper parameters that help us to
>>>>>> restore the image.
>>>>>> + * @invariants: container to store kernel build version.
>>>>>> + * @hartid: to make sure same boot_cpu executes the
>>>>>> hibernate/restore code.
>>>>>> + * @saved_satp: original page table used by the hibernated image.
>>>>>> + * @restore_cpu_addr: the kernel's image address to restore the CPU
>>>>>> context.
>>>>>> + */
>>>>>> +static struct arch_hibernate_hdr {
>>>>>> +    struct arch_hibernate_hdr_invariants invariants;
>>>>>> +    unsigned long    hartid;
>>>>>> +    unsigned long    saved_satp;
>>>>>> +    unsigned long    restore_cpu_addr;
>>>>>> +} resume_hdr;
>>>>>> +
>>>>>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
>>>>>> *i)
>>>>>> +{
>>>>>> +    memset(i, 0, sizeof(*i));
>>>>>> +    memcpy(i->uts_version, init_utsname()->version,
>>>>>> sizeof(i->uts_version));
>>>>>> +}
>>>>>> +
>>>>>> +/*
>>>>>> + * Check if the given pfn is in the 'nosave' section.
>>>>>> + */
>>>>>> +int pfn_is_nosave(unsigned long pfn)
>>>>>> +{
>>>>>> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
>>>>>> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
>>>>>> +
>>>>>> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
>>>>>> +}
>>>>>> +
>>>>>> +void notrace save_processor_state(void)
>>>>>> +{
>>>>>> +    WARN_ON(num_online_cpus() != 1);
>>>>>> +}
>>>>>> +
>>>>>> +void notrace restore_processor_state(void)
>>>>>> +{
>>>>>> +}
>>>>>> +
>>>>>> +/*
>>>>>> + * Helper parameters need to be saved to the hibernation image header.
>>>>>> + */
>>>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
>>>>>> +{
>>>>>> +    struct arch_hibernate_hdr *hdr = addr;
>>>>>> +
>>>>>> +    if (max_size < sizeof(*hdr))
>>>>>> +        return -EOVERFLOW;
>>>>>> +
>>>>>> +    arch_hdr_invariants(&hdr->invariants);
>>>>>> +
>>>>>> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
>>>>>> +    hdr->saved_satp = csr_read(CSR_SATP);
>>>>>> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
>>>>>> +
>>>>>> +/*
>>>>>> + * Retrieve the helper parameters from the hibernation image header.
>>>>>> + */
>>>>>> +int arch_hibernation_header_restore(void *addr)
>>>>>> +{
>>>>>> +    struct arch_hibernate_hdr_invariants invariants;
>>>>>> +    struct arch_hibernate_hdr *hdr = addr;
>>>>>> +    int ret = 0;
>>>>>> +
>>>>>> +    arch_hdr_invariants(&invariants);
>>>>>> +
>>>>>> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
>>>>>> +        pr_crit("Hibernate image not generated by this kernel!\n");
>>>>>> +        return -EINVAL;
>>>>>> +    }
>>>>>> +
>>>>>> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
>>>>>> +    if (sleep_cpu < 0) {
>>>>>> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
>>>>>> +        sleep_cpu = -EINVAL;
>>>>>> +        return -EINVAL;
>>>>>> +    }
>>>>>> +
>>>>>> +#ifdef CONFIG_SMP
>>>>>> +    ret = bringup_hibernate_cpu(sleep_cpu);
>>>>>> +    if (ret) {
>>>>>> +        sleep_cpu = -EINVAL;
>>>>>> +        return ret;
>>>>>> +    }
>>>>>> +#endif
>>>>>> +    resume_hdr = *hdr;
>>>>>> +
>>>>>> +    return ret;
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
>>>>>> +
>>>>>> +int swsusp_arch_suspend(void)
>>>>>> +{
>>>>>> +    int ret = 0;
>>>>>> +
>>>>>> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
>>>>>> +        sleep_cpu = smp_processor_id();
>>>>>> +        suspend_save_csrs(hibernate_cpu_context);
>>>>>> +        ret = swsusp_save();
>>>>>> +    } else {
>>>>>> +        suspend_restore_csrs(hibernate_cpu_context);
>>>>>> +        flush_tlb_all();
>>>>>> +        flush_icache_all();
>>>>>> +
>>>>>> +        /*
>>>>>> +         * Tell the hibernation core that we've just restored the
>>>>>> memory.
>>>>>> +         */
>>>>>> +        in_suspend = 0;
>>>>>> +        sleep_cpu = -EINVAL;
>>>>>> +    }
>>>>>> +
>>>>>> +    return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
>>>>>> unsigned long start,
>>>>>> +                unsigned long end, pgprot_t prot)
>>>>>> +{
>>>>>> +    pte_t *src_ptep;
>>>>>> +    pte_t *dst_ptep;
>>>>>> +
>>>>>> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
>>>>>> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
>>>>>> +        if (!dst_ptep)
>>>>>> +            return -ENOMEM;
>>>>>> +
>>>>>> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
>>>>>> +    }
>>>>>> +
>>>>>> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
>>>>>> +    src_ptep = pte_offset_kernel(src_pmdp, start);
>>>>>> +
>>>>>> +    do {
>>>>>> +        pte_t pte = READ_ONCE(*src_ptep);
>>>>>> +
>>>>>> +        if (pte_present(pte))
>>>>>> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
>>>>>> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
>>>>>> unsigned long start,
>>>>>> +                unsigned long end, pgprot_t prot)
>>>>>> +{
>>>>>> +    unsigned long next;
>>>>>> +    unsigned long ret;
>>>>>> +    pmd_t *src_pmdp;
>>>>>> +    pmd_t *dst_pmdp;
>>>>>> +
>>>>>> +    if (pud_none(READ_ONCE(*dst_pudp))) {
>>>>>> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
>>>>>> +        if (!dst_pmdp)
>>>>>> +            return -ENOMEM;
>>>>>> +
>>>>>> +        pud_populate(NULL, dst_pudp, dst_pmdp);
>>>>>> +    }
>>>>>> +
>>>>>> +    dst_pmdp = pmd_offset(dst_pudp, start);
>>>>>> +    src_pmdp = pmd_offset(src_pudp, start);
>>>>>> +
>>>>>> +    do {
>>>>>> +        pmd_t pmd = READ_ONCE(*src_pmdp);
>>>>>> +
>>>>>> +        next = pmd_addr_end(start, end);
>>>>>> +
>>>>>> +        if (pmd_none(pmd))
>>>>>> +            continue;
>>>>>> +
>>>>>> +        if (pmd_leaf(pmd)) {
>>>>>> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
>>>>>> +        } else {
>>>>>> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
>>>>>> next, prot);
>>>>>> +            if (ret)
>>>>>> +                return -ENOMEM;
>>>>>> +        }
>>>>>> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
>>>>>> unsigned long start,
>>>>>> +                unsigned long end, pgprot_t prot)
>>>>>> +{
>>>>>> +    unsigned long next;
>>>>>> +    unsigned long ret;
>>>>>> +    pud_t *dst_pudp;
>>>>>> +    pud_t *src_pudp;
>>>>>> +
>>>>>> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
>>>>>> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
>>>>>> +        if (!dst_pudp)
>>>>>> +            return -ENOMEM;
>>>>>> +
>>>>>> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
>>>>>> +    }
>>>>>> +
>>>>>> +    dst_pudp = pud_offset(dst_p4dp, start);
>>>>>> +    src_pudp = pud_offset(src_p4dp, start);
>>>>>> +
>>>>>> +    do {
>>>>>> +        pud_t pud = READ_ONCE(*src_pudp);
>>>>>> +
>>>>>> +        next = pud_addr_end(start, end);
>>>>>> +
>>>>>> +        if (pud_none(pud))
>>>>>> +            continue;
>>>>>> +
>>>>>> +        if (pud_leaf(pud)) {
>>>>>> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
>>>>>> +        } else {
>>>>>> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
>>>>>> next, prot);
>>>>>> +            if (ret)
>>>>>> +                return -ENOMEM;
>>>>>> +        }
>>>>>> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
>>>>>> unsigned long start,
>>>>>> +                unsigned long end, pgprot_t prot)
>>>>>> +{
>>>>>> +    unsigned long next;
>>>>>> +    unsigned long ret;
>>>>>> +    p4d_t *dst_p4dp;
>>>>>> +    p4d_t *src_p4dp;
>>>>>> +
>>>>>> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
>>>>>> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
>>>>>> +        if (!dst_p4dp)
>>>>>> +            return -ENOMEM;
>>>>>> +
>>>>>> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
>>>>>> +    }
>>>>>> +
>>>>>> +    dst_p4dp = p4d_offset(dst_pgdp, start);
>>>>>> +    src_p4dp = p4d_offset(src_pgdp, start);
>>>>>> +
>>>>>> +    do {
>>>>>> +        p4d_t p4d = READ_ONCE(*src_p4dp);
>>>>>> +
>>>>>> +        next = p4d_addr_end(start, end);
>>>>>> +
>>>>>> +        if (p4d_none(p4d))
>>>>>> +            continue;
>>>>>> +
>>>>>> +        if (p4d_leaf(p4d)) {
>>>>>> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
>>>>>> +        } else {
>>>>>> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
>>>>>> next, prot);
>>>>>> +            if (ret)
>>>>>> +                return -ENOMEM;
>>>>>> +        }
>>>>>> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
>>>>>> unsigned long end, pgprot_t prot)
>>>>>> +{
>>>>>> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
>>>>>> +    pgd_t *src_pgdp = pgd_offset_k(start);
>>>>>> +    unsigned long next;
>>>>>> +    unsigned long ret;
>>>>>> +
>>>>>> +    do {
>>>>>> +        pgd_t pgd = READ_ONCE(*src_pgdp);
>>>>>> +
>>>>>> +        next = pgd_addr_end(start, end);
>>>>>> +
>>>>>> +        if (pgd_none(pgd))
>>>>>> +            continue;
>>>>>> +
>>>>>> +        if (pgd_leaf(pgd)) {
>>>>>> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
>>>>>> +        } else {
>>>>>> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
>>>>>> next, prot);
>>>>>> +            if (ret)
>>>>>> +                return -ENOMEM;
>>>>>> +        }
>>>>>> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static unsigned long relocate_restore_code(void)
>>>>>> +{
>>>>>> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
>>>>>> +
>>>>>> +    if (!page)
>>>>>> +        return -ENOMEM;
>>>>>> +
>>>>>> +    copy_page(page, hibernate_core_restore_code);
>>>>>> +
>>>>>> +    /* Make the page containing the relocated code executable. */
>>>>>> +    set_memory_x((unsigned long)page, 1);
>>>>>> +
>>>>>> +    return (unsigned long)page;
>>>>>> +}
>>>>>> +
>>>>>> +int swsusp_arch_resume(void)
>>>>>> +{
>>>>>> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
>>>>>> +    unsigned long start = PAGE_OFFSET;
>>>>>> +    int ret;
>>>>>> +
>>>>>> +    /*
>>>>>> +     * Memory allocated by get_safe_page() will be dealt with by the
>>>>>> hibernation core,
>>>>>> +     * we don't need to free it here.
>>>>>> +     */
>>>>>> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
>>>>>> +    if (!resume_pg_dir)
>>>>>> +        return -ENOMEM;
>>>>>> +
>>>>>> +    /*
>>>>>> +     * Create a temporary page table and map the whole linear region
>>>>>> as executable and
>>>>>> +     * writable.
>>>>>> +     */
>>>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>>> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
>>>>> Shouldn't you use PAGE_KERNEL_EXEC instead?
>>>> Forget this one, that's the protections you add, so that's good :)
>>> OK.
>>>>>> +    if (ret)
>>>>>> +        return ret;
>>>>>> +
>>>>>> +    /* Move the restore code to a new page so that it doesn't get
>>>>>> overwritten by itself. */
>>>>>> +    relocated_restore_code = relocate_restore_code();
>>>>>> +    if (relocated_restore_code == -ENOMEM)
>>>>>> +        return -ENOMEM;
>>>>>> +
>>>>>> +    /*
>>>>>> +     * Map the __hibernate_cpu_resume() address to the temporary
>>>>>> page table so that the
>>>>>> +     * restore code can jumps to it after finished restore the
>>>>>> image. The next execution
>>>>>> +     * code doesn't find itself in a different address space after
>>>>>> switching over to the
>>>>>> +     * original page table used by the hibernated image.
>>>>>> +     *
>>>>>> +     */
>>>>>> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
>>>>>> +    end = start + PAGE_SIZE;
>>>>>> +
>>>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>>>> +    if (ret)
>>>>>> +        return ret;
>>>>> You set the linear mapping as executable so no need for this.
>>> We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For example:
>>> Linear address start with 0xff60000000000000
>>> Kernel address start with 0xffffffff80000000
>>
>> Ok I understand now that you need to map this into the temporary page
>> table: one nit though, since you copy the kernel mapping, no need to use
>> PAGE_WRITE | PAGE_EXEC, the protections are already correct.
> Here is the thing. For riscv_64bit, I am agreed with you that we don’t need to use PAGE_WRITE | PAGE_EXEC.
> However, we need to use PAGE_WRITE | PAGE_EXEC for riscv_32bit because the linear addresses and kernel addresses are similar. The attribute becomes not writable if following the "original" page table. I am thinking to use #ifdef config_32bit to split the path for 64bit and 32bit but I just afraid the linear addresses and kernel addresses might change again in the future. To be on the safe side, I let both riscv_32bit & riscv_64bit to use the PAGE_WRITE | PAGE_EXEC.


Indeed, you really thought about everything, well done! I would add a 
comment that explains just that above, no need for other ifdefs IMO.


> For example:
> Linear address and kernel address for 32bit started with 0xc0000000
> Linear address for 64bit start with 0xff60000000000000
> Kernel address for 64bit start with 0xffffffff80000000
>
> Please let me know your thoughts.
>
>> Thanks,
>>
>> Alex
>>
>>
>>>>>> +
>>>>>> +    hibernate_restore_image(resume_hdr.saved_satp,
>>>>>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
>>>>>> +                resume_hdr.restore_cpu_addr);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +#ifdef CONFIG_PM_SLEEP_SMP
>>>>>> +int hibernate_resume_nonboot_cpu_disable(void)
>>>>>> +{
>>>>>> +    if (sleep_cpu < 0) {
>>>>>> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
>>>>>> +        return -ENODEV;
>>>>>> +    }
>>>>>> +
>>>>>> +    return freeze_secondary_cpus(sleep_cpu);
>>>>>> +}
>>>>>> +#endif
>>>>>> +
>>>>>> +static int __init riscv_hibernate_init(void)
>>>>>> +{
>>>>>> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
>>>>>> GFP_KERNEL);
>>>>>> +
>>>>>> +    if (WARN_ON(!hibernate_cpu_context))
>>>>>> +        return -ENOMEM;
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +early_initcall(riscv_hibernate_init);
>>>>> _______________________________________________
>>>>> linux-riscv mailing list
>>>>> linux-riscv@lists.infradead.org
>>>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>>> _______________________________________________
>>> linux-riscv mailing list
>>> linux-riscv@lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
  

> -----Original Message-----
> From: Alexandre Ghiti <alex@ghiti.fr>
> Sent: Friday, March 10, 2023 6:50 PM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> 
> 
> On 3/10/23 11:43, JeeHeng Sia wrote:
> > Hi Alex,
> >
> >> -----Original Message-----
> >> From: Alexandre Ghiti <alex@ghiti.fr>
> >> Sent: Friday, March 10, 2023 5:59 PM
> >> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> >> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> >> <mason.huo@starfivetech.com>
> >> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> >>
> >> Hi JeeHeng,
> >>
> >> On 3/8/23 12:07, JeeHeng Sia wrote:
> >>>> -----Original Message-----
> >>>> From: Alexandre Ghiti <alex@ghiti.fr>
> >>>> Sent: Wednesday, March 8, 2023 5:28 PM
> >>>> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu
> >>>> Cc: linux-riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> >>>> <mason.huo@starfivetech.com>
> >>>> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> >>>>
> >>>>
> >>>> On 3/8/23 10:08, Alexandre Ghiti wrote:
> >>>>> On 3/8/23 09:06, Sia Jee Heng wrote:
> >>>>>> Low level Arch functions were created to support hibernation.
> >>>>>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
> >>>>>> cpu state onto the stack, then calling swsusp_save() to save the memory
> >>>>>> image.
> >>>>>>
> >>>>>> Arch specific hibernation header is implemented and is utilized by the
> >>>>>> arch_hibernation_header_restore() and arch_hibernation_header_save()
> >>>>>> functions. The arch specific hibernation header consists of satp,
> >>>>>> hartid,
> >>>>>> and the cpu_resume address. The kernel built version is also need to be
> >>>>>> saved into the hibernation image header to making sure only the same
> >>>>>> kernel is restore when resume.
> >>>>>>
> >>>>>> swsusp_arch_resume() creates a temporary page table that covering only
> >>>>>> the linear map. It copies the restore code to a 'safe' page, then start
> >>>>>> to restore the memory image. Once completed, it restores the original
> >>>>>> kernel's page table. It then calls into __hibernate_cpu_resume()
> >>>>>> to restore the CPU context. Finally, it follows the normal hibernation
> >>>>>> path back to the hibernation core.
> >>>>>>
> >>>>>> To enable hibernation/suspend to disk into RISCV, the below config
> >>>>>> need to be enabled:
> >>>>>> - CONFIG_ARCH_HIBERNATION_HEADER
> >>>>>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
> >>>>>>
> >>>>>> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> >>>>>> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> >>>>>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> >>>>>> ---
> >>>>>>     arch/riscv/Kconfig                 |   6 +
> >>>>>>     arch/riscv/include/asm/assembler.h |  20 ++
> >>>>>>     arch/riscv/include/asm/suspend.h   |  19 ++
> >>>>>>     arch/riscv/kernel/Makefile         |   1 +
> >>>>>>     arch/riscv/kernel/asm-offsets.c    |   5 +
> >>>>>>     arch/riscv/kernel/hibernate-asm.S  |  77 ++++++
> >>>>>>     arch/riscv/kernel/hibernate.c      | 424 +++++++++++++++++++++++++++++
> >>>>>>     7 files changed, 552 insertions(+)
> >>>>>>     create mode 100644 arch/riscv/kernel/hibernate-asm.S
> >>>>>>     create mode 100644 arch/riscv/kernel/hibernate.c
> >>>>>>
> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >>>>>> index c5e42cc37604..473c2a1a6884 100644
> >>>>>> --- a/arch/riscv/Kconfig
> >>>>>> +++ b/arch/riscv/Kconfig
> >>>>>> @@ -707,6 +707,12 @@ menu "Power management options"
> >>>>>>       source "kernel/power/Kconfig"
> >>>>>>     +config ARCH_HIBERNATION_POSSIBLE
> >>>>>> +    def_bool y
> >>>>>> +
> >>>>>> +config ARCH_HIBERNATION_HEADER
> >>>>>> +    def_bool HIBERNATION
> >>>>>> +
> >>>>>>     endmenu # "Power management options"
> >>>>>>       menu "CPU Power Management"
> >>>>>> diff --git a/arch/riscv/include/asm/assembler.h
> >>>>>> b/arch/riscv/include/asm/assembler.h
> >>>>>> index ba59d38f8937..44b1457d3e95 100644
> >>>>>> --- a/arch/riscv/include/asm/assembler.h
> >>>>>> +++ b/arch/riscv/include/asm/assembler.h
> >>>>>> @@ -59,4 +59,24 @@
> >>>>>>             REG_L    s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
> >>>>>>         .endm
> >>>>>>     +/*
> >>>>>> + * copy_page - copy 1 page (4KB) of data from source to destination
> >>>>>> + * @a0 - destination
> >>>>>> + * @a1 - source
> >>>>>> + */
> >>>>>> +    .macro    copy_page a0, a1
> >>>>>> +        lui    a2, 0x1
> >>>>>> +        add    a2, a2, a0
> >>>>>> +1 :
> >>>>>> +        REG_L    t0, 0(a1)
> >>>>>> +        REG_L    t1, SZREG(a1)
> >>>>>> +
> >>>>>> +        REG_S    t0, 0(a0)
> >>>>>> +        REG_S    t1, SZREG(a0)
> >>>>>> +
> >>>>>> +        addi    a0, a0, 2 * SZREG
> >>>>>> +        addi    a1, a1, 2 * SZREG
> >>>>>> +        bne    a2, a0, 1b
> >>>>>> +    .endm
> >>>>>> +
> >>>>>>     #endif    /* __ASM_ASSEMBLER_H */
> >>>>>> diff --git a/arch/riscv/include/asm/suspend.h
> >>>>>> b/arch/riscv/include/asm/suspend.h
> >>>>>> index 67e047445662..02f87867389a 100644
> >>>>>> --- a/arch/riscv/include/asm/suspend.h
> >>>>>> +++ b/arch/riscv/include/asm/suspend.h
> >>>>>> @@ -21,6 +21,11 @@ struct suspend_context {
> >>>>>>     #endif
> >>>>>>     };
> >>>>>>     +/*
> >>>>>> + * Used by hibernation core and cleared during resume sequence
> >>>>>> + */
> >>>>>> +extern int in_suspend;
> >>>>>> +
> >>>>>>     /* Low-level CPU suspend entry function */
> >>>>>>     int __cpu_suspend_enter(struct suspend_context *context);
> >>>>>>     @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
> >>>>>> unsigned long context);
> >>>>>>     /* Used to save and restore the CSRs */
> >>>>>>     void suspend_save_csrs(struct suspend_context *context);
> >>>>>>     void suspend_restore_csrs(struct suspend_context *context);
> >>>>>> +
> >>>>>> +/* Low-level API to support hibernation */
> >>>>>> +int swsusp_arch_suspend(void);
> >>>>>> +int swsusp_arch_resume(void);
> >>>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
> >>>>>> +int arch_hibernation_header_restore(void *addr);
> >>>>>> +int __hibernate_cpu_resume(void);
> >>>>>> +
> >>>>>> +/* Used to resume on the CPU we hibernated on */
> >>>>>> +int hibernate_resume_nonboot_cpu_disable(void);
> >>>>>> +
> >>>>>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
> >>>>>> unsigned long satp_temp,
> >>>>>> +                    unsigned long cpu_resume);
> >>>>>> +asmlinkage int hibernate_core_restore_code(void);
> >>>>>>     #endif
> >>>>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> >>>>>> index 4cf303a779ab..daab341d55e4 100644
> >>>>>> --- a/arch/riscv/kernel/Makefile
> >>>>>> +++ b/arch/riscv/kernel/Makefile
> >>>>>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES)        += module.o
> >>>>>>     obj-$(CONFIG_MODULE_SECTIONS)    += module-sections.o
> >>>>>>       obj-$(CONFIG_CPU_PM)        += suspend_entry.o suspend.o
> >>>>>> +obj-$(CONFIG_HIBERNATION)    += hibernate.o hibernate-asm.o
> >>>>>>       obj-$(CONFIG_FUNCTION_TRACER)    += mcount.o ftrace.o
> >>>>>>     obj-$(CONFIG_DYNAMIC_FTRACE)    += mcount-dyn.o
> >>>>>> diff --git a/arch/riscv/kernel/asm-offsets.c
> >>>>>> b/arch/riscv/kernel/asm-offsets.c
> >>>>>> index df9444397908..d6a75aac1d27 100644
> >>>>>> --- a/arch/riscv/kernel/asm-offsets.c
> >>>>>> +++ b/arch/riscv/kernel/asm-offsets.c
> >>>>>> @@ -9,6 +9,7 @@
> >>>>>>     #include <linux/kbuild.h>
> >>>>>>     #include <linux/mm.h>
> >>>>>>     #include <linux/sched.h>
> >>>>>> +#include <linux/suspend.h>
> >>>>>>     #include <asm/kvm_host.h>
> >>>>>>     #include <asm/thread_info.h>
> >>>>>>     #include <asm/ptrace.h>
> >>>>>> @@ -116,6 +117,10 @@ void asm_offsets(void)
> >>>>>>           OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
> >>>>>>     +    OFFSET(HIBERN_PBE_ADDR, pbe, address);
> >>>>>> +    OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
> >>>>>> +    OFFSET(HIBERN_PBE_NEXT, pbe, next);
> >>>>>> +
> >>>>>>         OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
> >>>>>>         OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
> >>>>>>         OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
> >>>>>> diff --git a/arch/riscv/kernel/hibernate-asm.S
> >>>>>> b/arch/riscv/kernel/hibernate-asm.S
> >>>>>> new file mode 100644
> >>>>>> index 000000000000..effaf5ca5da0
> >>>>>> --- /dev/null
> >>>>>> +++ b/arch/riscv/kernel/hibernate-asm.S
> >>>>>> @@ -0,0 +1,77 @@
> >>>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
> >>>>>> +/*
> >>>>>> + * Hibernation low level support for RISCV.
> >>>>>> + *
> >>>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >>>>>> + *
> >>>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >>>>>> + */
> >>>>>> +
> >>>>>> +#include <asm/asm.h>
> >>>>>> +#include <asm/asm-offsets.h>
> >>>>>> +#include <asm/assembler.h>
> >>>>>> +#include <asm/csr.h>
> >>>>>> +
> >>>>>> +#include <linux/linkage.h>
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * int __hibernate_cpu_resume(void)
> >>>>>> + * Switch back to the hibernated image's page table prior to
> >>>>>> restoring the CPU
> >>>>>> + * context.
> >>>>>> + *
> >>>>>> + * Always returns 0
> >>>>>> + */
> >>>>>> +ENTRY(__hibernate_cpu_resume)
> >>>>>> +    /* switch to hibernated image's page table. */
> >>>>>> +    csrw CSR_SATP, s0
> >>>>>> +    sfence.vma
> >>>>>> +
> >>>>>> +    REG_L    a0, hibernate_cpu_context
> >>>>>> +
> >>>>>> +    suspend_restore_csrs
> >>>>>> +    suspend_restore_regs
> >>>>>> +
> >>>>>> +    /* Return zero value. */
> >>>>>> +    mv    a0, zero
> >>>>>> +
> >>>>>> +    ret
> >>>>>> +END(__hibernate_cpu_resume)
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * Prepare to restore the image.
> >>>>>> + * a0: satp of saved page tables.
> >>>>>> + * a1: satp of temporary page tables.
> >>>>>> + * a2: cpu_resume.
> >>>>>> + */
> >>>>>> +ENTRY(hibernate_restore_image)
> >>>>>> +    mv    s0, a0
> >>>>>> +    mv    s1, a1
> >>>>>> +    mv    s2, a2
> >>>>>> +    REG_L    s4, restore_pblist
> >>>>>> +    REG_L    a1, relocated_restore_code
> >>>>>> +
> >>>>>> +    jalr    a1
> >>>>>> +END(hibernate_restore_image)
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * The below code will be executed from a 'safe' page.
> >>>>>> + * It first switches to the temporary page table, then starts to
> >>>>>> copy the pages
> >>>>>> + * back to the original memory location. Finally, it jumps to
> >>>>>> __hibernate_cpu_resume()
> >>>>>> + * to restore the CPU context.
> >>>>>> + */
> >>>>>> +ENTRY(hibernate_core_restore_code)
> >>>>>> +    /* switch to temp page table. */
> >>>>>> +    csrw satp, s1
> >>>>>> +    sfence.vma
> >>>>>> +.Lcopy:
> >>>>>> +    /* The below code will restore the hibernated image. */
> >>>>>> +    REG_L    a1, HIBERN_PBE_ADDR(s4)
> >>>>>> +    REG_L    a0, HIBERN_PBE_ORIG(s4)
> >>>>>> +
> >>>>>> +    copy_page a0, a1
> >>>>>> +
> >>>>>> +    REG_L    s4, HIBERN_PBE_NEXT(s4)
> >>>>>> +    bnez    s4, .Lcopy
> >>>>>> +
> >>>>>> +    jalr    s2
> >>>>>> +END(hibernate_core_restore_code)
> >>>>>> diff --git a/arch/riscv/kernel/hibernate.c
> >>>>>> b/arch/riscv/kernel/hibernate.c
> >>>>>> new file mode 100644
> >>>>>> index 000000000000..8fab50122e54
> >>>>>> --- /dev/null
> >>>>>> +++ b/arch/riscv/kernel/hibernate.c
> >>>>>> @@ -0,0 +1,424 @@
> >>>>>> +// SPDX-License-Identifier: GPL-2.0-only
> >>>>>> +/*
> >>>>>> + * Hibernation support for RISCV
> >>>>>> + *
> >>>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> >>>>>> + *
> >>>>>> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> >>>>>> + */
> >>>>>> +
> >>>>>> +#include <asm/barrier.h>
> >>>>>> +#include <asm/cacheflush.h>
> >>>>>> +#include <asm/mmu_context.h>
> >>>>>> +#include <asm/page.h>
> >>>>>> +#include <asm/pgalloc.h>
> >>>>>> +#include <asm/pgtable.h>
> >>>>>> +#include <asm/sections.h>
> >>>>>> +#include <asm/set_memory.h>
> >>>>>> +#include <asm/smp.h>
> >>>>>> +#include <asm/suspend.h>
> >>>>>> +
> >>>>>> +#include <linux/cpu.h>
> >>>>>> +#include <linux/memblock.h>
> >>>>>> +#include <linux/pm.h>
> >>>>>> +#include <linux/sched.h>
> >>>>>> +#include <linux/suspend.h>
> >>>>>> +#include <linux/utsname.h>
> >>>>>> +
> >>>>>> +/* The logical cpu number we should resume on, initialised to a
> >>>>>> non-cpu number. */
> >>>>>> +static int sleep_cpu = -EINVAL;
> >>>>>> +
> >>>>>> +/* Pointer to the temporary resume page table. */
> >>>>>> +static pgd_t *resume_pg_dir;
> >>>>>> +
> >>>>>> +/* CPU context to be saved. */
> >>>>>> +struct suspend_context *hibernate_cpu_context;
> >>>>>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
> >>>>>> +
> >>>>>> +unsigned long relocated_restore_code;
> >>>>>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
> >>>>>> +
> >>>>>> +/**
> >>>>>> + * struct arch_hibernate_hdr_invariants - container to store kernel
> >>>>>> build version.
> >>>>>> + * @uts_version: to save the build number and date so that the we do
> >>>>>> not resume with
> >>>>>> + *        a different kernel.
> >>>>>> + */
> >>>>>> +struct arch_hibernate_hdr_invariants {
> >>>>>> +    char        uts_version[__NEW_UTS_LEN + 1];
> >>>>>> +};
> >>>>>> +
> >>>>>> +/**
> >>>>>> + * struct arch_hibernate_hdr - helper parameters that help us to
> >>>>>> restore the image.
> >>>>>> + * @invariants: container to store kernel build version.
> >>>>>> + * @hartid: to make sure same boot_cpu executes the
> >>>>>> hibernate/restore code.
> >>>>>> + * @saved_satp: original page table used by the hibernated image.
> >>>>>> + * @restore_cpu_addr: the kernel's image address to restore the CPU
> >>>>>> context.
> >>>>>> + */
> >>>>>> +static struct arch_hibernate_hdr {
> >>>>>> +    struct arch_hibernate_hdr_invariants invariants;
> >>>>>> +    unsigned long    hartid;
> >>>>>> +    unsigned long    saved_satp;
> >>>>>> +    unsigned long    restore_cpu_addr;
> >>>>>> +} resume_hdr;
> >>>>>> +
> >>>>>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
> >>>>>> *i)
> >>>>>> +{
> >>>>>> +    memset(i, 0, sizeof(*i));
> >>>>>> +    memcpy(i->uts_version, init_utsname()->version,
> >>>>>> sizeof(i->uts_version));
> >>>>>> +}
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * Check if the given pfn is in the 'nosave' section.
> >>>>>> + */
> >>>>>> +int pfn_is_nosave(unsigned long pfn)
> >>>>>> +{
> >>>>>> +    unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
> >>>>>> +    unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
> >>>>>> +
> >>>>>> +    return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
> >>>>>> +}
> >>>>>> +
> >>>>>> +void notrace save_processor_state(void)
> >>>>>> +{
> >>>>>> +    WARN_ON(num_online_cpus() != 1);
> >>>>>> +}
> >>>>>> +
> >>>>>> +void notrace restore_processor_state(void)
> >>>>>> +{
> >>>>>> +}
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * Helper parameters need to be saved to the hibernation image header.
> >>>>>> + */
> >>>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
> >>>>>> +{
> >>>>>> +    struct arch_hibernate_hdr *hdr = addr;
> >>>>>> +
> >>>>>> +    if (max_size < sizeof(*hdr))
> >>>>>> +        return -EOVERFLOW;
> >>>>>> +
> >>>>>> +    arch_hdr_invariants(&hdr->invariants);
> >>>>>> +
> >>>>>> +    hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
> >>>>>> +    hdr->saved_satp = csr_read(CSR_SATP);
> >>>>>> +    hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * Retrieve the helper parameters from the hibernation image header.
> >>>>>> + */
> >>>>>> +int arch_hibernation_header_restore(void *addr)
> >>>>>> +{
> >>>>>> +    struct arch_hibernate_hdr_invariants invariants;
> >>>>>> +    struct arch_hibernate_hdr *hdr = addr;
> >>>>>> +    int ret = 0;
> >>>>>> +
> >>>>>> +    arch_hdr_invariants(&invariants);
> >>>>>> +
> >>>>>> +    if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
> >>>>>> +        pr_crit("Hibernate image not generated by this kernel!\n");
> >>>>>> +        return -EINVAL;
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
> >>>>>> +    if (sleep_cpu < 0) {
> >>>>>> +        pr_crit("Hibernated on a CPU not known to this kernel!\n");
> >>>>>> +        sleep_cpu = -EINVAL;
> >>>>>> +        return -EINVAL;
> >>>>>> +    }
> >>>>>> +
> >>>>>> +#ifdef CONFIG_SMP
> >>>>>> +    ret = bringup_hibernate_cpu(sleep_cpu);
> >>>>>> +    if (ret) {
> >>>>>> +        sleep_cpu = -EINVAL;
> >>>>>> +        return ret;
> >>>>>> +    }
> >>>>>> +#endif
> >>>>>> +    resume_hdr = *hdr;
> >>>>>> +
> >>>>>> +    return ret;
> >>>>>> +}
> >>>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
> >>>>>> +
> >>>>>> +int swsusp_arch_suspend(void)
> >>>>>> +{
> >>>>>> +    int ret = 0;
> >>>>>> +
> >>>>>> +    if (__cpu_suspend_enter(hibernate_cpu_context)) {
> >>>>>> +        sleep_cpu = smp_processor_id();
> >>>>>> +        suspend_save_csrs(hibernate_cpu_context);
> >>>>>> +        ret = swsusp_save();
> >>>>>> +    } else {
> >>>>>> +        suspend_restore_csrs(hibernate_cpu_context);
> >>>>>> +        flush_tlb_all();
> >>>>>> +        flush_icache_all();
> >>>>>> +
> >>>>>> +        /*
> >>>>>> +         * Tell the hibernation core that we've just restored the
> >>>>>> memory.
> >>>>>> +         */
> >>>>>> +        in_suspend = 0;
> >>>>>> +        sleep_cpu = -EINVAL;
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    return ret;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
> >>>>>> unsigned long start,
> >>>>>> +                unsigned long end, pgprot_t prot)
> >>>>>> +{
> >>>>>> +    pte_t *src_ptep;
> >>>>>> +    pte_t *dst_ptep;
> >>>>>> +
> >>>>>> +    if (pmd_none(READ_ONCE(*dst_pmdp))) {
> >>>>>> +        dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
> >>>>>> +        if (!dst_ptep)
> >>>>>> +            return -ENOMEM;
> >>>>>> +
> >>>>>> +        pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    dst_ptep = pte_offset_kernel(dst_pmdp, start);
> >>>>>> +    src_ptep = pte_offset_kernel(src_pmdp, start);
> >>>>>> +
> >>>>>> +    do {
> >>>>>> +        pte_t pte = READ_ONCE(*src_ptep);
> >>>>>> +
> >>>>>> +        if (pte_present(pte))
> >>>>>> +            set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
> >>>>>> +    } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
> >>>>>> unsigned long start,
> >>>>>> +                unsigned long end, pgprot_t prot)
> >>>>>> +{
> >>>>>> +    unsigned long next;
> >>>>>> +    unsigned long ret;
> >>>>>> +    pmd_t *src_pmdp;
> >>>>>> +    pmd_t *dst_pmdp;
> >>>>>> +
> >>>>>> +    if (pud_none(READ_ONCE(*dst_pudp))) {
> >>>>>> +        dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
> >>>>>> +        if (!dst_pmdp)
> >>>>>> +            return -ENOMEM;
> >>>>>> +
> >>>>>> +        pud_populate(NULL, dst_pudp, dst_pmdp);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    dst_pmdp = pmd_offset(dst_pudp, start);
> >>>>>> +    src_pmdp = pmd_offset(src_pudp, start);
> >>>>>> +
> >>>>>> +    do {
> >>>>>> +        pmd_t pmd = READ_ONCE(*src_pmdp);
> >>>>>> +
> >>>>>> +        next = pmd_addr_end(start, end);
> >>>>>> +
> >>>>>> +        if (pmd_none(pmd))
> >>>>>> +            continue;
> >>>>>> +
> >>>>>> +        if (pmd_leaf(pmd)) {
> >>>>>> +            set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
> >>>>>> +        } else {
> >>>>>> +            ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
> >>>>>> next, prot);
> >>>>>> +            if (ret)
> >>>>>> +                return -ENOMEM;
> >>>>>> +        }
> >>>>>> +    } while (dst_pmdp++, src_pmdp++, start = next, start != end);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
> >>>>>> unsigned long start,
> >>>>>> +                unsigned long end, pgprot_t prot)
> >>>>>> +{
> >>>>>> +    unsigned long next;
> >>>>>> +    unsigned long ret;
> >>>>>> +    pud_t *dst_pudp;
> >>>>>> +    pud_t *src_pudp;
> >>>>>> +
> >>>>>> +    if (p4d_none(READ_ONCE(*dst_p4dp))) {
> >>>>>> +        dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
> >>>>>> +        if (!dst_pudp)
> >>>>>> +            return -ENOMEM;
> >>>>>> +
> >>>>>> +        p4d_populate(NULL, dst_p4dp, dst_pudp);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    dst_pudp = pud_offset(dst_p4dp, start);
> >>>>>> +    src_pudp = pud_offset(src_p4dp, start);
> >>>>>> +
> >>>>>> +    do {
> >>>>>> +        pud_t pud = READ_ONCE(*src_pudp);
> >>>>>> +
> >>>>>> +        next = pud_addr_end(start, end);
> >>>>>> +
> >>>>>> +        if (pud_none(pud))
> >>>>>> +            continue;
> >>>>>> +
> >>>>>> +        if (pud_leaf(pud)) {
> >>>>>> +            set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
> >>>>>> +        } else {
> >>>>>> +            ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
> >>>>>> next, prot);
> >>>>>> +            if (ret)
> >>>>>> +                return -ENOMEM;
> >>>>>> +        }
> >>>>>> +    } while (dst_pudp++, src_pudp++, start = next, start != end);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
> >>>>>> unsigned long start,
> >>>>>> +                unsigned long end, pgprot_t prot)
> >>>>>> +{
> >>>>>> +    unsigned long next;
> >>>>>> +    unsigned long ret;
> >>>>>> +    p4d_t *dst_p4dp;
> >>>>>> +    p4d_t *src_p4dp;
> >>>>>> +
> >>>>>> +    if (pgd_none(READ_ONCE(*dst_pgdp))) {
> >>>>>> +        dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
> >>>>>> +        if (!dst_p4dp)
> >>>>>> +            return -ENOMEM;
> >>>>>> +
> >>>>>> +        pgd_populate(NULL, dst_pgdp, dst_p4dp);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    dst_p4dp = p4d_offset(dst_pgdp, start);
> >>>>>> +    src_p4dp = p4d_offset(src_pgdp, start);
> >>>>>> +
> >>>>>> +    do {
> >>>>>> +        p4d_t p4d = READ_ONCE(*src_p4dp);
> >>>>>> +
> >>>>>> +        next = p4d_addr_end(start, end);
> >>>>>> +
> >>>>>> +        if (p4d_none(p4d))
> >>>>>> +            continue;
> >>>>>> +
> >>>>>> +        if (p4d_leaf(p4d)) {
> >>>>>> +            set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
> >>>>>> +        } else {
> >>>>>> +            ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
> >>>>>> next, prot);
> >>>>>> +            if (ret)
> >>>>>> +                return -ENOMEM;
> >>>>>> +        }
> >>>>>> +    } while (dst_p4dp++, src_p4dp++, start = next, start != end);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
> >>>>>> unsigned long end, pgprot_t prot)
> >>>>>> +{
> >>>>>> +    pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
> >>>>>> +    pgd_t *src_pgdp = pgd_offset_k(start);
> >>>>>> +    unsigned long next;
> >>>>>> +    unsigned long ret;
> >>>>>> +
> >>>>>> +    do {
> >>>>>> +        pgd_t pgd = READ_ONCE(*src_pgdp);
> >>>>>> +
> >>>>>> +        next = pgd_addr_end(start, end);
> >>>>>> +
> >>>>>> +        if (pgd_none(pgd))
> >>>>>> +            continue;
> >>>>>> +
> >>>>>> +        if (pgd_leaf(pgd)) {
> >>>>>> +            set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
> >>>>>> +        } else {
> >>>>>> +            ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
> >>>>>> next, prot);
> >>>>>> +            if (ret)
> >>>>>> +                return -ENOMEM;
> >>>>>> +        }
> >>>>>> +    } while (dst_pgdp++, src_pgdp++, start = next, start != end);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static unsigned long relocate_restore_code(void)
> >>>>>> +{
> >>>>>> +    void *page = (void *)get_safe_page(GFP_ATOMIC);
> >>>>>> +
> >>>>>> +    if (!page)
> >>>>>> +        return -ENOMEM;
> >>>>>> +
> >>>>>> +    copy_page(page, hibernate_core_restore_code);
> >>>>>> +
> >>>>>> +    /* Make the page containing the relocated code executable. */
> >>>>>> +    set_memory_x((unsigned long)page, 1);
> >>>>>> +
> >>>>>> +    return (unsigned long)page;
> >>>>>> +}
> >>>>>> +
> >>>>>> +int swsusp_arch_resume(void)
> >>>>>> +{
> >>>>>> +    unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
> >>>>>> +    unsigned long start = PAGE_OFFSET;
> >>>>>> +    int ret;
> >>>>>> +
> >>>>>> +    /*
> >>>>>> +     * Memory allocated by get_safe_page() will be dealt with by the
> >>>>>> hibernation core,
> >>>>>> +     * we don't need to free it here.
> >>>>>> +     */
> >>>>>> +    resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
> >>>>>> +    if (!resume_pg_dir)
> >>>>>> +        return -ENOMEM;
> >>>>>> +
> >>>>>> +    /*
> >>>>>> +     * Create a temporary page table and map the whole linear region
> >>>>>> as executable and
> >>>>>> +     * writable.
> >>>>>> +     */
> >>>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >>>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >>>>> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
> >>>>> Shouldn't you use PAGE_KERNEL_EXEC instead?
> >>>> Forget this one, that's the protections you add, so that's good :)
> >>> OK.
> >>>>>> +    if (ret)
> >>>>>> +        return ret;
> >>>>>> +
> >>>>>> +    /* Move the restore code to a new page so that it doesn't get
> >>>>>> overwritten by itself. */
> >>>>>> +    relocated_restore_code = relocate_restore_code();
> >>>>>> +    if (relocated_restore_code == -ENOMEM)
> >>>>>> +        return -ENOMEM;
> >>>>>> +
> >>>>>> +    /*
> >>>>>> +     * Map the __hibernate_cpu_resume() address to the temporary
> >>>>>> page table so that the
> >>>>>> +     * restore code can jumps to it after finished restore the
> >>>>>> image. The next execution
> >>>>>> +     * code doesn't find itself in a different address space after
> >>>>>> switching over to the
> >>>>>> +     * original page table used by the hibernated image.
> >>>>>> +     *
> >>>>>> +     */
> >>>>>> +    start = (unsigned long)resume_hdr.restore_cpu_addr;
> >>>>>> +    end = start + PAGE_SIZE;
> >>>>>> +
> >>>>>> +    ret = temp_pgtable_mapping(resume_pg_dir, start, end,
> >>>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
> >>>>>> +    if (ret)
> >>>>>> +        return ret;
> >>>>> You set the linear mapping as executable so no need for this.
> >>> We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For
> example:
> >>> Linear address start with 0xff60000000000000
> >>> Kernel address start with 0xffffffff80000000
> >>
> >> Ok I understand now that you need to map this into the temporary page
> >> table: one nit though, since you copy the kernel mapping, no need to use
> >> PAGE_WRITE | PAGE_EXEC, the protections are already correct.
> > Here is the thing. For riscv_64bit, I am agreed with you that we don’t need to use PAGE_WRITE | PAGE_EXEC.
> > However, we need to use PAGE_WRITE | PAGE_EXEC for riscv_32bit because the linear addresses and kernel addresses are similar.
> The attribute becomes not writable if following the "original" page table. I am thinking to use #ifdef config_32bit to split the path for
> 64bit and 32bit but I just afraid the linear addresses and kernel addresses might change again in the future. To be on the safe side, I
> let both riscv_32bit & riscv_64bit to use the PAGE_WRITE | PAGE_EXEC.
> 
> 
> Indeed, you really thought about everything, well done! I would add a
> comment that explains just that above, no need for other ifdefs IMO.
Sure, can add comment to explain the above situation.
> 
> 
> > For example:
> > Linear address and kernel address for 32bit started with 0xc0000000
> > Linear address for 64bit start with 0xff60000000000000
> > Kernel address for 64bit start with 0xffffffff80000000
> >
> > Please let me know your thoughts.
> >
> >> Thanks,
> >>
> >> Alex
> >>
> >>
> >>>>>> +
> >>>>>> +    hibernate_restore_image(resume_hdr.saved_satp,
> >>>>>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> >>>>>> +                resume_hdr.restore_cpu_addr);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +#ifdef CONFIG_PM_SLEEP_SMP
> >>>>>> +int hibernate_resume_nonboot_cpu_disable(void)
> >>>>>> +{
> >>>>>> +    if (sleep_cpu < 0) {
> >>>>>> +        pr_err("Failing to resume from hibernate on an unknown CPU\n");
> >>>>>> +        return -ENODEV;
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    return freeze_secondary_cpus(sleep_cpu);
> >>>>>> +}
> >>>>>> +#endif
> >>>>>> +
> >>>>>> +static int __init riscv_hibernate_init(void)
> >>>>>> +{
> >>>>>> +    hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
> >>>>>> GFP_KERNEL);
> >>>>>> +
> >>>>>> +    if (WARN_ON(!hibernate_cpu_context))
> >>>>>> +        return -ENOMEM;
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +early_initcall(riscv_hibernate_init);
> >>>>> _______________________________________________
> >>>>> linux-riscv mailing list
> >>>>> linux-riscv@lists.infradead.org
> >>>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
> >>> _______________________________________________
> >>> linux-riscv mailing list
> >>> linux-riscv@lists.infradead.org
> >>> http://lists.infradead.org/mailman/listinfo/linux-riscv