[PATCH] compiler-intel: fix wrong compiler barrier() macro

From: Daniel Borkmann
Date: Wed Apr 29 2015 - 10:42:34 EST

Cleanup commit 23ebdedc67e ("compiler-intel.h: Remove duplicate
definition") removed the double definition of __memory_barrier()

However, in doing so, it also removed the preceding #undef barrier,
meaning, the actual barrier() macro from compiler-gcc.h with inline
asm is still in place when __GNUC__ is provided.

Subsequently, barrier() can never be defined as __memory_barrier()
from compiler.h since it already has a definition in place and if
we trust the comment in compiler-intel.h, ecc doesn't support gcc
specific asm statements. I don't have an ecc at hand, so a revert
of that cleanup would be the safest option, imho, as it has been
like this since pre-git times.

Fixes: 73679e508201 ("compiler-intel.h: Remove duplicate definition")
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Pranith Kumar <bobby.prani@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: mancha security <mancha1@xxxxxxxx>
include/linux/compiler-intel.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index ba147a1..5529c52 100644
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -13,9 +13,12 @@
/* Intel ECC compiler doesn't support gcc specific asm stmts.
* It uses intrinsics to do the equivalent things.
+#undef barrier

+#define barrier() __memory_barrier()
#define RELOC_HIDE(ptr, off) \
({ unsigned long __ptr; \
__ptr = (unsigned long) (ptr); \

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