linux-kernel - [PATCH v14 03/24] x86/asm: Frame pointer macro cleanup

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Message-Id: <b193a5aaa518c2bbf9b22db08349613619de0486.1445443144.git.jpoimboe@redhat.com>
Date:	Wed, 21 Oct 2015 11:11:42 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	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>,
	Chris J Arges <chris.j.arges@...onical.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH v14 03/24] x86/asm: Frame pointer macro cleanup

The 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 stacktool.

Rename FRAME/ENDFRAME to FRAME_BEGIN/FRAME_END for more symmetry.  Also
make the code more readable and improve the comments.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/include/asm/frame.h | 43 +++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/frame.h b/arch/x86/include/asm/frame.h
index 793179c..cec213b 100644
--- a/arch/x86/include/asm/frame.h
+++ b/arch/x86/include/asm/frame.h
@@ -1,23 +1,34 @@
+#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.
+ */
 #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
-#endif
+
+.macro FRAME_BEGIN
+	push %_ASM_BP
+	_ASM_MOV %_ASM_SP, %_ASM_BP
+.endm
+
+.macro FRAME_END
+	pop %_ASM_BP
+.endm
+
+#define FRAME_OFFSET __ASM_SEL(4, 8)
+
+#else /* !CONFIG_FRAME_POINTER */
+
+#define FRAME_BEGIN
+#define FRAME_END
+#define FRAME_OFFSET 0
+
+#endif /* CONFIG_FRAME_POINTER */
 
 #endif  /*  __ASSEMBLY__  */
+#endif /* _ASM_X86_FRAME_H */
-- 
2.4.3

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