linux-kernel - [PATCH v8 01/21] x86/asm: Frame pointer macro cleanup

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Message-Id: <10b6e02189ff44d2a24994127d34d916aeb1a448.1438093915.git.jpoimboe@redhat.com>
Date:	Tue, 28 Jul 2015 09:46:52 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc:	Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Pedro Alves <palves@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Bernd Petrovitsch <bernd@...rovitsch.priv.at>, x86@...nel.org,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v8 01/21] x86/asm: Frame pointer macro cleanup

The FRAME/ENDFRAME asm macros for setting up and restoring the frame
pointer aren't currently being used.  However, they will be needed soon
to help asm functions to comply with stackvalidate.

Make the code more readable and improve the comments.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/include/asm/frame.h | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/frame.h b/arch/x86/include/asm/frame.h
index 793179c..a4ac454 100644
--- a/arch/x86/include/asm/frame.h
+++ b/arch/x86/include/asm/frame.h
@@ -1,23 +1,26 @@
+#ifndef _ASM_X86_FRAME_H
+#define _ASM_X86_FRAME_H
+
 #ifdef __ASSEMBLY__
 
 #include <asm/asm.h>
 
-/* The annotation hides the frame from the unwinder and makes it look
-   like a ordinary ebp save/restore. This avoids some special cases for
-   frame pointer later */
+/*
+ * These are stack frame creation macros.  They should be used by every
+ * callable non-leaf asm function to make kernel stack traces more reliable.
+ */
+.macro FRAME
+#ifdef CONFIG_FRAME_POINTER
+	push %_ASM_BP
+	_ASM_MOV %_ASM_SP, %_ASM_BP
+#endif
+.endm
+
+.macro ENDFRAME
 #ifdef CONFIG_FRAME_POINTER
-	.macro FRAME
-	__ASM_SIZE(push,)	%__ASM_REG(bp)
-	__ASM_SIZE(mov)		%__ASM_REG(sp), %__ASM_REG(bp)
-	.endm
-	.macro ENDFRAME
-	__ASM_SIZE(pop,)	%__ASM_REG(bp)
-	.endm
-#else
-	.macro FRAME
-	.endm
-	.macro ENDFRAME
-	.endm
+	pop %_ASM_BP
 #endif
+.endm
 
 #endif  /*  __ASSEMBLY__  */
+#endif /* _ASM_X86_FRAME_H */
-- 
2.1.0

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