linux-kernel - Re: [PATCH v2 5/5] riscv: kvm: use ".L" local labels in assembly when applicable

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Date:   Mon, 06 Nov 2023 09:47:31 -0800 (PST)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     cleger@...osinc.com
CC:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        anup@...infault.org, atishp@...shpatra.org,
        ajones@...tanamicro.com, cleger@...osinc.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org
Subject:     Re: [PATCH v2 5/5] riscv: kvm: use ".L" local labels in assembly when applicable

On Tue, 24 Oct 2023 06:26:55 PDT (-0700), cleger@...osinc.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@...osinc.com>
> Reviewed-by: Andrew Jones <ajones@...tanamicro.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@...osinc.com>