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Peter Anvin" , Peter Zijlstra , Uros Bizjak , Brian Gerst Subject: [PATCH 4/9] x86/percpu/64: Remove fixed_percpu_data Date: Mon, 23 Oct 2023 17:17:25 -0400 Message-ID: <20231023211730.40566-5-brgerst@gmail.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231023211730.40566-1-brgerst@gmail.com> References: <20231023211730.40566-1-brgerst@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Mon, 23 Oct 2023 14:17:58 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780582585027976439 X-GMAIL-MSGID: 1780582585027976439 Now that the stack protector canary value is a normal percpu variable, fixed_percpu_data is unused and can be removed. Signed-off-by: Brian Gerst --- arch/x86/include/asm/processor.h | 13 +++++-------- arch/x86/kernel/cpu/common.c | 4 ---- arch/x86/kernel/head_64.S | 12 ++++++------ arch/x86/kernel/vmlinux.lds.S | 6 ------ arch/x86/tools/relocs.c | 1 - arch/x86/xen/xen-head.S | 12 ++++++++---- 6 files changed, 19 insertions(+), 29 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 04371f60e3c6..48c31b8e3e72 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -393,16 +393,13 @@ struct irq_stack { } __aligned(IRQ_STACK_SIZE); #ifdef CONFIG_X86_64 -struct fixed_percpu_data { - char gs_base[40]; -}; - -DECLARE_PER_CPU_FIRST(struct fixed_percpu_data, fixed_percpu_data) __visible; -DECLARE_INIT_PER_CPU(fixed_percpu_data); - static inline unsigned long cpu_kernelmode_gs_base(int cpu) { - return (unsigned long)per_cpu(fixed_percpu_data.gs_base, cpu); +#ifdef CONFIG_SMP + return per_cpu_offset(cpu); +#else + return 0; +#endif } extern asmlinkage void entry_SYSCALL32_ignore(void); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f9c8bd27b642..a44fd3ad460e 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2051,10 +2051,6 @@ DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) = { EXPORT_PER_CPU_SYMBOL(pcpu_hot); #ifdef CONFIG_X86_64 -DEFINE_PER_CPU_FIRST(struct fixed_percpu_data, - fixed_percpu_data) __aligned(PAGE_SIZE) __visible; -EXPORT_PER_CPU_SYMBOL_GPL(fixed_percpu_data); - static void wrmsrl_cstar(unsigned long val) { /* diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 3dcabbc49149..f2453eb38417 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -72,9 +72,14 @@ SYM_CODE_START_NOALIGN(startup_64) /* Setup GSBASE to allow stack canary access for C code */ movl $MSR_GS_BASE, %ecx - leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx +#ifdef CONFIG_SMP + leaq __per_cpu_load(%rip), %rdx movl %edx, %eax shrq $32, %rdx +#else + xorl %eax, %eax + xorl %edx, %edx +#endif wrmsr call startup_64_setup_env @@ -345,15 +350,10 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) /* Set up %gs. * - * The base of %gs always points to fixed_percpu_data. If the - * stack protector canary is enabled, it is located at %gs:40. * Note that, on SMP, the boot cpu uses init data section until * the per cpu areas are set up. */ movl $MSR_GS_BASE,%ecx -#ifndef CONFIG_SMP - leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx -#endif movl %edx, %eax shrq $32, %rdx wrmsr diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 54a5596adaa6..c87dc8de2084 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -509,14 +509,8 @@ SECTIONS */ #define INIT_PER_CPU(x) init_per_cpu__##x = ABSOLUTE(x) + __per_cpu_load INIT_PER_CPU(gdt_page); -INIT_PER_CPU(fixed_percpu_data); INIT_PER_CPU(irq_stack_backing_store); -#ifdef CONFIG_SMP -. = ASSERT((fixed_percpu_data == 0), - "fixed_percpu_data is not at start of per-cpu area"); -#endif - #ifdef CONFIG_CPU_UNRET_ENTRY . = ASSERT((retbleed_return_thunk & 0x3f) == 0, "retbleed_return_thunk not cacheline-aligned"); #endif diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index d30949e25ebd..3ccd9d4fcf9c 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -811,7 +811,6 @@ static void percpu_init(void) * __per_cpu_load * * The "gold" linker incorrectly associates: - * init_per_cpu__fixed_percpu_data * init_per_cpu__gdt_page */ static int is_percpu_sym(ElfW(Sym) *sym, const char *symname) diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index a0ea285878db..9ce0d9d268bb 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -53,14 +53,18 @@ SYM_CODE_START(startup_xen) /* Set up %gs. * - * The base of %gs always points to fixed_percpu_data. If the - * stack protector canary is enabled, it is located at %gs:40. * Note that, on SMP, the boot cpu uses init data section until * the per cpu areas are set up. */ movl $MSR_GS_BASE,%ecx - movq $INIT_PER_CPU_VAR(fixed_percpu_data),%rax - cdq +#ifdef CONFIG_SMP + leaq __per_cpu_load(%rip), %rdx + movl %edx, %eax + shrq $32, %rdx +#else + xorl %eax, %eax + xorl %edx, %edx +#endif wrmsr mov %rsi, %rdi