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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-10-12 20:06:18 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-10-12 20:06:18 +0200 |
| commit | c786e90bb2540a6d992f609dc7322a001405cbc4 (patch) | |
| tree | 94cbae600664bae57dde6e148749770fc6078103 /include | |
| parent | Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/ker... (diff) | |
| parent | compiler/gcc4: Add quirk for 'asm goto' miscompilation bug (diff) | |
| download | linux-c786e90bb2540a6d992f609dc7322a001405cbc4.tar.xz linux-c786e90bb2540a6d992f609dc7322a001405cbc4.zip | |
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull gcc "asm goto" miscompilation workaround from Ingo Molnar:
"This is the fix for the GCC miscompilation discussed in the following
lkml thread:
[x86] BUG: unable to handle kernel paging request at 00740060
The bug in GCC has been fixed by Jakub and the fix will be part of the
GCC 4.8.2 release expected to be released next week - so the quirk's
version test checks for <= 4.8.1.
The quirk is only added to compiler-gcc4.h and not to the higher level
compiler.h because all asm goto uses are behind a feature check"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
compiler/gcc4: Add quirk for 'asm goto' miscompilation bug
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/compiler-gcc4.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index 842de225055f..ded429966c1f 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -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 |