diff mbox series

[v2,5/5] riscv: kvm: use ".L" local labels in assembly when applicable

Message ID 20231024132655.730417-6-cleger@rivosinc.com
State New
Headers
Series riscv: cleanup assembly usage of ENTRY()/END() and use local labels |

Commit Message

Clément Léger Oct. 24, 2023, 1:26 p.m. UTC 
  For the sake of coherency, use local labels in assembly when
applicable. This also avoid kprobes being confused when applying a
kprobe since the size of function is computed by checking where the
next visible symbol is located. This might end up in computing some
function size to be way shorter than expected and thus failing to apply
kprobes to the specified offset.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/kvm/vcpu_switch.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Palmer Dabbelt Nov. 6, 2023, 5:47 p.m. UTC | #1 
On Tue, 24 Oct 2023 06:26:55 PDT (-0700), cleger@rivosinc.com wrote:
> For the sake of coherency, use local labels in assembly when
> applicable. This also avoid kprobes being confused when applying a
> kprobe since the size of function is computed by checking where the
> next visible symbol is located. This might end up in computing some
> function size to be way shorter than expected and thus failing to apply
> kprobes to the specified offset.
>
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
>  arch/riscv/kvm/vcpu_switch.S | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
> index 8b18473780ac..0c26189aa01c 100644
> --- a/arch/riscv/kvm/vcpu_switch.S
> +++ b/arch/riscv/kvm/vcpu_switch.S
> @@ -45,7 +45,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
>  	REG_L	t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
>  	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
>  	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
> -	la	t4, __kvm_switch_return
> +	la	t4, .Lkvm_switch_return
>  	REG_L	t5, (KVM_ARCH_GUEST_SEPC)(a0)
>
>  	/* Save Host and Restore Guest SSTATUS */
> @@ -113,7 +113,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
>
>  	/* Back to Host */
>  	.align 2
> -__kvm_switch_return:
> +.Lkvm_switch_return:
>  	/* Swap Guest A0 with SSCRATCH */
>  	csrrw	a0, CSR_SSCRATCH, a0

Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Anup Patel Dec. 13, 2023, 6:16 a.m. UTC | #2 
On Tue, Oct 24, 2023 at 6:58 PM Clément Léger <cleger@rivosinc.com> wrote:
>
> For the sake of coherency, use local labels in assembly when
> applicable. This also avoid kprobes being confused when applying a
> kprobe since the size of function is computed by checking where the
> next visible symbol is located. This might end up in computing some
> function size to be way shorter than expected and thus failing to apply
> kprobes to the specified offset.
>
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Queued this patch for Linux-6.8

Thanks,
Anup


> ---
>  arch/riscv/kvm/vcpu_switch.S | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
> index 8b18473780ac..0c26189aa01c 100644
> --- a/arch/riscv/kvm/vcpu_switch.S
> +++ b/arch/riscv/kvm/vcpu_switch.S
> @@ -45,7 +45,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
>         REG_L   t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
>         REG_L   t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
>         REG_L   t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
> -       la      t4, __kvm_switch_return
> +       la      t4, .Lkvm_switch_return
>         REG_L   t5, (KVM_ARCH_GUEST_SEPC)(a0)
>
>         /* Save Host and Restore Guest SSTATUS */
> @@ -113,7 +113,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
>
>         /* Back to Host */
>         .align 2
> -__kvm_switch_return:
> +.Lkvm_switch_return:
>         /* Swap Guest A0 with SSCRATCH */
>         csrrw   a0, CSR_SSCRATCH, a0
>
> --
> 2.42.0
>
>
> --
> kvm-riscv mailing list
> kvm-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv
diff mbox series

Patch

diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index 8b18473780ac..0c26189aa01c 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -45,7 +45,7 @@  SYM_FUNC_START(__kvm_riscv_switch_to)
 	REG_L	t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
 	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
 	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
-	la	t4, __kvm_switch_return
+	la	t4, .Lkvm_switch_return
 	REG_L	t5, (KVM_ARCH_GUEST_SEPC)(a0)
 
 	/* Save Host and Restore Guest SSTATUS */
@@ -113,7 +113,7 @@  SYM_FUNC_START(__kvm_riscv_switch_to)
 
 	/* Back to Host */
 	.align 2
-__kvm_switch_return:
+.Lkvm_switch_return:
 	/* Swap Guest A0 with SSCRATCH */
 	csrrw	a0, CSR_SSCRATCH, a0