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Date:	Mon, 31 Mar 2014 00:23:35 +0100
From:	Ben Hutchings <>
CC:, "Jakub Jelinek" <>,
	"Ingo Molnar" <>,
	"Richard Henderson" <>,
	"Linus Torvalds" <>,
	"Steven Noonan" <>,
	"Peter Zijlstra" <>,
	"Oleg Nesterov" <>,
	"Steven Rostedt" <>
Subject: [PATCH 3.2 109/200] compiler/gcc4: Make quirk for asm_volatile_goto()

3.2.56-rc1 review patch.  If anyone has any objections, please let me know.


From: Steven Noonan <>

commit a9f180345f5378ac87d80ed0bea55ba421d83859 upstream.

I started noticing problems with KVM guest destruction on Linux
3.12+, where guest memory wasn't being cleaned up. I bisected it
down to the commit introducing the new 'asm goto'-based atomics,
and found this quirk was later applied to those.

Unfortunately, even with GCC 4.8.2 (which ostensibly fixed the
known 'asm goto' bug) I am still getting some kind of
miscompilation. If I enable the asm_volatile_goto quirk for my
compiler, KVM guests are destroyed correctly and the memory is
cleaned up.

So make the quirk unconditional for now, until bug is found
and fixed.

Suggested-by: Linus Torvalds <>
Signed-off-by: Steven Noonan <>
Cc: Peter Zijlstra <>
Cc: Steven Rostedt <>
Cc: Jakub Jelinek <>
Cc: Richard Henderson <>
Cc: Andrew Morton <>
Cc: Oleg Nesterov <>
Signed-off-by: Ingo Molnar <>
Signed-off-by: Ben Hutchings <>
 include/linux/compiler-gcc4.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -39,11 +39,7 @@
  * (asm goto is automatically volatile - the naming reflects this.)
-#if GCC_VERSION <= 40801
-# define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
-# define asm_volatile_goto(x...)	do { asm goto(x); } while (0)
+#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
 #if __GNUC_MINOR__ >= 5

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