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Commit 16df4ff8 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
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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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hpe.com>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/6685a72ddbbd0ad3694337cca0af4b4ea09f5f40.1453405861.git.jpoimboe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5c1d5f28

arch/x86/include/asm/qspinlock_paravirt.h

+4 −0
Original line number Diff line number Diff line
@@ -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");