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

Ard Biesheuvel
2026-01-09T07:59:27Z

On Fri, 9 Jan 2026 at 06:01, Brian Gerst <brgerst@gmail.com> wrote:
>
> 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.
>

Indeed, but I couldn't figure out how to do so without making objtool unhappy.