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| author | Mikael Pettersson <mikpe@it.uu.se> | 2010-06-29 15:05:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-06-29 15:29:31 -0700 |
| commit | 9c695203a7ddbe49dba5f22f4c941d24f47475df (patch) | |
| tree | 0dcfa624ecb7c5810f7062fe950bf3f0de2e55b2 /include/linux/compiler-gcc.h | |
| parent | 2952095c6b2eefd068dda0dee6317cf95155a304 (diff) | |
| download | lwn-9c695203a7ddbe49dba5f22f4c941d24f47475df.tar.gz lwn-9c695203a7ddbe49dba5f22f4c941d24f47475df.zip | |
compiler-gcc.h: gcc-4.5 needs noclone and noinline on __naked functions
A __naked function is defined in C but with a body completely implemented
by asm(), including any prologue and epilogue. These asm() bodies expect
standard calling conventions for parameter passing. Older GCCs implement
that correctly, but 4.[56] currently do not, see GCC PR44290. In the
Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c
modules to get miscompiled, resulting in kernel crashes during bootup.
Part of the kernel fix is to augment the __naked function attribute to
also imply noinline and noclone. This patch implements that, and has been
verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1
kernels. The patch is a no-op with older GCCs.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/compiler-gcc.h')
| -rw-r--r-- | include/linux/compiler-gcc.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 73dcf804bc94..0da5b187f124 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -58,8 +58,12 @@ * naked functions because then mcount is called without stack and frame pointer * being set up and there is no chance to restore the lr register to the value * before mcount was called. + * + * The asm() bodies of naked functions often depend on standard calling conventions, + * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce + * this, so we must do so ourselves. See GCC PR44290. */ -#define __naked __attribute__((naked)) notrace +#define __naked __attribute__((naked)) noinline __noclone notrace #define __noreturn __attribute__((noreturn)) @@ -85,3 +89,7 @@ #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) #define gcc_header(x) _gcc_header(x) #include gcc_header(__GNUC__) + +#if !defined(__noclone) +#define __noclone /* not needed */ +#endif |