Re: [RFC/RFT PATCH 15/19] x64/acpi: Use PIC-compatible references in wakeup_64.S

Brian Gerst
2026-01-09T05:01:33Z

On Thu, Jan 8, 2026 at 4:28 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> Use ordinary RIP-relative references to make the code compatible with
> running the linker in PIE mode.
>
> Note that wakeup_long64() runs in the kernel's ordinary virtual mapping
> so there is no need to record the address of .Lresume_point in a global
> variable. And fix the comment while at it.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/x86/kernel/acpi/wakeup_64.S | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 04f561f75e99..15233a4e1c95 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -14,7 +14,7 @@
>
> .code64
> /*
> - * Hooray, we are in Long 64-bit mode (but still running in low memory)
> + * Hooray, we are in Long 64-bit mode
> */
> SYM_FUNC_START(wakeup_long64)
> ANNOTATE_NOENDBR
> @@ -41,7 +41,7 @@ SYM_FUNC_START(wakeup_long64)
> movq saved_rsi(%rip), %rsi
> movq saved_rbp(%rip), %rbp
>
> - movq saved_rip(%rip), %rax
> + leaq .Lresume_point(%rip), %rax
> ANNOTATE_RETPOLINE_SAFE
> jmp *%rax

If this is already running on the virtual mapping, this can simply be
changed to a direct jump.

Brian Gerst