linux-kernel - Re: [RFC/RFT PATCH 15/19] x64/acpi: Use PIC-compatible references in wakeup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMzpN2jZDEh2r1UwV2JOqUD+JH65TZo+RQxFOx5Hwd1GC0p+hA@mail.gmail.com>
Date: Fri, 9 Jan 2026 00:01:20 -0500
From: Brian Gerst <brgerst@...il.com>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Kees Cook <kees@...nel.org>, 
	Uros Bizjak <ubizjak@...il.com>, linux-hardening@...r.kernel.org
Subject: Re: [RFC/RFT PATCH 15/19] x64/acpi: Use PIC-compatible references in wakeup_64.S

On Thu, Jan 8, 2026 at 4:28 AM Ard Biesheuvel <ardb@...nel.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@...nel.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