path: root/include
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authorMikael Pettersson <mikpe@it.uu.se>2010-06-29 15:05:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-06-29 15:29:31 -0700
commit9c695203a7ddbe49dba5f22f4c941d24f47475df (patch)
tree0dcfa624ecb7c5810f7062fe950bf3f0de2e55b2 /include
parent2952095c6b2eefd068dda0dee6317cf95155a304 (diff)
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')
2 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 73dcf804bc9..0da5b187f12 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 */
diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 94dea3ffbfa..fcfa5b9a431 100644
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -48,6 +48,10 @@
* unreleased. Really, we need to have autoconf for the kernel.
#define unreachable() __builtin_unreachable()
+/* Mark a function definition as prohibited from being cloned. */
+#define __noclone __attribute__((__noclone__))