[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAJZ5v0iOY3u_jBmf=_3AnqEWHb+eTA6DtTfoU3tb=0RB0O+szw@mail.gmail.com>
Date: Mon, 6 Nov 2023 15:14:27 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Uros Bizjak <ubizjak@...il.com>
Cc: x86@...nel.org, linux-pm@...r.kernel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86/acpi: Use %rip-relative addressing in wakeup_64.S
On Fri, Nov 3, 2023 at 11:49 AM Uros Bizjak <ubizjak@...il.com> wrote:
>
> Instruction with %rip-relative address operand is one byte shorter than
> its absolute address counterpart and is also compatible with position
> independent executable (-fpie) build.
>
> No functional changes intended.
I'm wondering what's the exact motivation for making this change.
Any urgent need for it doesn't seem to be there.
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Len Brown <len.brown@...el.com>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Signed-off-by: Uros Bizjak <ubizjak@...il.com>
> ---
> arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index d5d8a352eafa..94ff83f3d3fe 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -17,7 +17,7 @@
> * Hooray, we are in Long 64-bit mode (but still running in low memory)
> */
> SYM_FUNC_START(wakeup_long64)
> - movq saved_magic, %rax
> + movq saved_magic(%rip), %rax
> movq $0x123456789abcdef0, %rdx
> cmpq %rdx, %rax
> je 2f
> @@ -33,14 +33,14 @@ SYM_FUNC_START(wakeup_long64)
> movw %ax, %es
> movw %ax, %fs
> movw %ax, %gs
> - movq saved_rsp, %rsp
> + movq saved_rsp(%rip), %rsp
>
> - movq saved_rbx, %rbx
> - movq saved_rdi, %rdi
> - movq saved_rsi, %rsi
> - movq saved_rbp, %rbp
> + movq saved_rbx(%rip), %rbx
> + movq saved_rdi(%rip), %rdi
> + movq saved_rsi(%rip), %rsi
> + movq saved_rbp(%rip), %rbp
>
> - movq saved_rip, %rax
> + movq saved_rip(%rip), %rax
> ANNOTATE_RETPOLINE_SAFE
> jmp *%rax
> SYM_FUNC_END(wakeup_long64)
> @@ -72,11 +72,11 @@ SYM_FUNC_START(do_suspend_lowlevel)
>
> movq $.Lresume_point, saved_rip(%rip)
>
> - movq %rsp, saved_rsp
> - movq %rbp, saved_rbp
> - movq %rbx, saved_rbx
> - movq %rdi, saved_rdi
> - movq %rsi, saved_rsi
> + movq %rsp, saved_rsp(%rip)
> + movq %rbp, saved_rbp(%rip)
> + movq %rbx, saved_rbx(%rip)
> + movq %rdi, saved_rdi(%rip)
> + movq %rsi, saved_rsi(%rip)
>
> addq $8, %rsp
> movl $3, %edi
> --
Powered by blists - more mailing lists