| From | Ben Hutchings <> | Date | Mon, 31 Mar 2014 00:23:35 +0100 | Subject | [PATCH 3.2 109/200] compiler/gcc4: Make quirk for asm_volatile_goto() unconditional |
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3.2.56-rc1 review patch. If anyone has any objections, please let me know.
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From: Steven Noonan <steven@uplinklabs.net>
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 <torvalds@linux-foundation.org> Signed-off-by: Steven Noonan <steven@uplinklabs.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jakub Jelinek <jakub@redhat.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: http://lkml.kernel.org/r/1392274867-15236-1-git-send-email-steven@uplinklabs.net Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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) -#else -# define asm_volatile_goto(x...) do { asm goto(x); } while (0) -#endif +#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) #if __GNUC_MINOR__ >= 5 /*
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