linux-kernel - [PATCH] i386: add unwind directives to syscall ptregs stubs

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Date:	Thu, 02 Sep 2010 14:04:16 +0100
From:	"Jan Beulich" <JBeulich@...ell.com>
To:	<mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: [PATCH] i386: add unwind directives to syscall ptregs stubs

When these stubs are actual functions (i.e. having a return
instruction) and have stack manipulation instructions in them, they
should also be annotated to allow unwinding through them.

Signed-off-by: Jan Beulich <jbeulich@...ell.com>

---
 arch/x86/kernel/entry_32.S    |  16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

--- linux-2.6.36-rc3/arch/x86/kernel/entry_32.S
+++ 2.6.36-rc3-x86-push-pop-cfi/arch/x86/kernel/entry_32.S
@@ -750,14 +710,18 @@ ptregs_##name: \
 #define PTREGSCALL3(name) \
 	ALIGN; \
 ptregs_##name: \
+	CFI_STARTPROC; \
 	leal 4(%esp),%eax; \
-	pushl %eax; \
+	pushl_cfi %eax; \
 	movl PT_EDX(%eax),%ecx; \
 	movl PT_ECX(%eax),%edx; \
 	movl PT_EBX(%eax),%eax; \
 	call sys_##name; \
 	addl $4,%esp; \
-	ret
+	CFI_ADJUST_CFA_OFFSET -4; \
+	ret; \
+	CFI_ENDPROC; \
+ENDPROC(ptregs_##name)
 
 PTREGSCALL1(iopl)
 PTREGSCALL0(fork)
@@ -772,15 +736,19 @@ PTREGSCALL1(vm86old)
 /* Clone is an oddball.  The 4th arg is in %edi */
 	ALIGN;
 ptregs_clone:
+	CFI_STARTPROC
 	leal 4(%esp),%eax
-	pushl %eax
-	pushl PT_EDI(%eax)
+	pushl_cfi %eax
+	pushl_cfi PT_EDI(%eax)
 	movl PT_EDX(%eax),%ecx
 	movl PT_ECX(%eax),%edx
 	movl PT_EBX(%eax),%eax
 	call sys_clone
 	addl $8,%esp
+	CFI_ADJUST_CFA_OFFSET -8
 	ret
+	CFI_ENDPROC
+ENDPROC(ptregs_clone)
 
 .macro FIXUP_ESPFIX_STACK
 /*



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