[PATCH 28/33] x86/locking: Create stack frame in PV unlock

[Josh Poimboeuf]

The assembly PV_UNLOCK function is a callable non-leaf function which
doesn't honor CONFIG_FRAME_POINTER, which can result in bad stack
traces.

Create a stack frame when CONFIG_FRAME_POINTER is enabled.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Waiman Long <Waiman.Long@xxxxxxx>
---
 arch/x86/include/asm/qspinlock_paravirt.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h
index 9f92c18..9d55f9b 100644
--- a/arch/x86/include/asm/qspinlock_paravirt.h
+++ b/arch/x86/include/asm/qspinlock_paravirt.h
@@ -36,8 +36,10 @@ PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath);
  */
 asm    (".pushsection .text;"
 	".globl " PV_UNLOCK ";"
+	".type " PV_UNLOCK ", @function;"
 	".align 4,0x90;"
 	PV_UNLOCK ": "
+	FRAME_BEGIN
 	"push  %rdx;"
 	"mov   $0x1,%eax;"
 	"xor   %edx,%edx;"
@@ -45,6 +47,7 @@ asm    (".pushsection .text;"
 	"cmp   $0x1,%al;"
 	"jne   .slowpath;"
 	"pop   %rdx;"
+	FRAME_END
 	"ret;"
 	".slowpath: "
 	"push   %rsi;"
@@ -52,6 +55,7 @@ asm    (".pushsection .text;"
 	"call " PV_UNLOCK_SLOWPATH ";"
 	"pop    %rsi;"
 	"pop    %rdx;"
+	FRAME_END
 	"ret;"
 	".size " PV_UNLOCK ", .-" PV_UNLOCK ";"
 	".popsection");
-- 
2.4.3