[PATCH] x86-32: Fix alignment of alternative instruction entries

From: Ben Hutchings
Date: Wed Sep 21 2011 - 00:45:41 EST


The altinstruction_entry macro was originally used only on x86-64,
and assumed 64-bit pointers and alignment.

Commit b4ca46e4e82a0a5976fe5eab85be585d75f8202f ("x86-32: Fix boot
with CONFIG_X86_INVD_BUG") introduced a use of the macro on x86-32.
Before this, the 64-bit pointers had been replaced by 32-bit offsets,
so it worked - in at least one case. However, the alignment is still
wrong for x86-32, which can result in zero-padding between entries and
a BUG in apply_alternatives.

Reported-by: Andres Salomon <dilinger@xxxxxxxxxx>
References: http://bugs.debian.org/640964
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/alternative-asm.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index 4554cc6..d00dc2a 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -16,7 +16,7 @@
#endif

.macro altinstruction_entry orig alt feature orig_len alt_len
- .align 8
+ _ASM_ALIGN
.long \orig - .
.long \alt - .
.word \feature
--
1.7.5.4


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/