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compiler/gcc4: Add quirk for 'asm goto' miscompilation bug

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Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down
a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto'
constructs, as outlined here:

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670

Implement a workaround suggested by Jakub Jelinek.

Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2013-10-10 10:16:30 +02:00
parent 2fe80d3bbf
commit 3f0116c323
9 changed files with 26 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

15
include/linux/compiler-gcc4.h
View file

@ -65,6 +65,21 @@
#define __visible __attribute__((externally_visible))
#endif
/*
* GCC 'asm goto' miscompiles certain code sequences:
*
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
* Fixed in GCC 4.8.2 and later versions.
*
* (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
#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
#if GCC_VERSION >= 40400