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x86/acpi: Use %rip-relative addressing in wakeup_64.S

PATCH Applied Uros Bizjak 3 participants 5 messages Nov 3, 2023 – Nov 30, 2023

Subsystems (3)
x86 ACPI Suspend to RAM
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Uros Bizjak

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#0 lore raw

PATCH 1/1 x86/acpi: Use %rip-relative addressing in wakeup_64.S

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.

Cc "Rafael J. Wysocki" <[email protected]>
Cc Len Brown <[email protected]>
Cc Pavel Machek <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Dave Hansen <[email protected]>
Cc "H. Peter Anvin" <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
arch/x86/kernel/acpi/wakeup_64.S +12 -12
index d5d8a352eafa..94ff83f3d3fe 100644
@@ -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
Signature · 1 line
2.41.0
maintainer
#1 lore raw
Quoted 6 lines · Uros Bizjak

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.

Quoted 65 lines
Cc "Rafael J. Wysocki" <[email protected]>
Cc Len Brown <[email protected]>
Cc Pavel Machek <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Dave Hansen <[email protected]>
Cc "H. Peter Anvin" <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
arch/x86/kernel/acpi/wakeup_64.S +12 -13
index d5d8a352eafa..94ff83f3d3fe 100644
@@ -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
--
author
#2 lore raw
Quoted 10 lines · Rafael J. Wysocki
Quoted 6 lines · Uros Bizjak

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.

Mainly to be consistent with what the compiler emits by default when a symbol is accessed. As said in the commit message, the %rip-relative access is also one byte shorter, and results in a position independent code.

Quoted 1 line

Any urgent need for it doesn't seem to be there.

True. It's mostly a nice-to-have change.

Thanks,
Uros.

Quoted 65 lines
Quoted 65 lines
Cc "Rafael J. Wysocki" <[email protected]>
Cc Len Brown <[email protected]>
Cc Pavel Machek <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Dave Hansen <[email protected]>
Cc "H. Peter Anvin" <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
arch/x86/kernel/acpi/wakeup_64.S +12 -13
index d5d8a352eafa..94ff83f3d3fe 100644
@@ -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
--
maintainer Acked-by
#3 lore raw
Quoted 13 lines · Uros Bizjak
Quoted 10 lines · Rafael J. Wysocki
Quoted 6 lines · Uros Bizjak

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.

Quoted 8 lines

Mainly to be consistent with what the compiler emits by default when a symbol is accessed. As said in the commit message, the %rip-relative access is also one byte shorter, and results in a position independent code.

Quoted 1 line

Any urgent need for it doesn't seem to be there.

True. It's mostly a nice-to-have change.

OK, so

Acked-by Rafael J. Wysocki <[email protected]>

and the decision what to do with it is up to the x86 folks.

Quoted 65 lines
Quoted 65 lines
Quoted 65 lines
Cc "Rafael J. Wysocki" <[email protected]>
Cc Len Brown <[email protected]>
Cc Pavel Machek <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Dave Hansen <[email protected]>
Cc "H. Peter Anvin" <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
arch/x86/kernel/acpi/wakeup_64.S +12 -13
index d5d8a352eafa..94ff83f3d3fe 100644
@@ -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
--
merge bot Applied
#4 lore raw
In reply to Uros Bizjak
The following commit has been merged into the x86/percpu branch of tip:

The following commit has been merged into the x86/percpu branch of tip:

Commit-ID:     0978d64f9406122c369d5f46e1eb855646f6c32c
Gitweb:        https://git.kernel.org/tip/0978d64f9406122c369d5f46e1eb855646f6c32c
Author:        Uros Bizjak <[email protected]>
AuthorDate:    Fri, 03 Nov 2023 11:48:22 +01:00
Committer:     Ingo Molnar <[email protected]>
CommitterDate: Thu, 30 Nov 2023 20:09:49 +01:00

x86/acpi: Use %rip-relative addressing in wakeup_64.S

This is a "nice-to-have" change with minor code generation benefits:

- Instruction with %rip-relative address operand is one byte shorter than its absolute address counterpart,

- it is also compatible with position independent executable (-fpie) builds,

- it is also consistent with what the compiler emits by default when a symbol is accessed.

No functional changes intended.

Signed-off-by Uros Bizjak <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
Acked-by Rafael J. Wysocki <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
---
 arch/x86/kernel/acpi/wakeup_64.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
arch/x86/kernel/acpi/wakeup_64.S +12 -12
index d5d8a35..94ff83f 100644
@@ -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