* [PATCH] x86-32: Fix alignment of alternative instruction entries
@ 2011-09-21 4:45 Ben Hutchings
2011-09-21 10:06 ` Thomas Gleixner
0 siblings, 1 reply; 2+ messages in thread
From: Ben Hutchings @ 2011-09-21 4:45 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin
Cc: LKML, Andres Salomon, Andy Lutomirski, Arnaud Lacombe
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Before this, the 64-bit pointers had been replaced by 32-bit offsets,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@queued.net>
References: http://bugs.debian.org/640964
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] x86-32: Fix alignment of alternative instruction entries
2011-09-21 4:45 [PATCH] x86-32: Fix alignment of alternative instruction entries Ben Hutchings
@ 2011-09-21 10:06 ` Thomas Gleixner
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Gleixner @ 2011-09-21 10:06 UTC (permalink / raw)
To: Ben Hutchings
Cc: Ingo Molnar, H. Peter Anvin, LKML, Andres Salomon,
Andy Lutomirski, Arnaud Lacombe
On Wed, 21 Sep 2011, Ben Hutchings wrote:
> 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 Before this, the 64-bit pointers had been replaced by 32-bit offsets,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.
Fixed in Linus tree already: commit a7f934d4f16144cb
Thanks,
tglx
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