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

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Message-Id: <6685a72ddbbd0ad3694337cca0af4b4ea09f5f40.1453405861.git.jpoimboe@redhat.com>
Date:	Thu, 21 Jan 2016 16:49:32 -0600
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>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Waiman Long <Waiman.Long@....com>
Subject: [PATCH 28/33] x86/locking: Create stack frame in PV unlock

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@...hat.com>
Cc: Waiman Long <Waiman.Long@....com>
---
 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