Commit-ID: 01be50a308be466e122c3a8b3d535f1b673ecbd2
Gitweb: http://git.kernel.org/tip/01be50a308be466e122c3a8b3d535f1b673ecbd2
Author: Jan Beulich <JBeulich@xxxxxxxxxx>
AuthorDate: Fri, 27 Nov 2009 15:04:58 +0000
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 2 Dec 2009 11:39:45 +0100
x86/alternatives: Check replacementlen <= instrlen at build time
Having run into the run-(boot-)time check a couple of times lately,
I finally took time to find a build-time check so that one doesn't
need to analyze the register/stack dump and resolve this (through
manual lookup in vmlinux) to the offending construct.
The assembler will emit a message like "Error: value of <num> too
large for field of 1 bytes at <offset>", which while not pointing
out the source location still makes analysis quite a bit easier.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
LKML-Reference: <4B0FF8AA0200007800022703@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/include/asm/alternative.h | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index c240efc..69b74a7 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -84,6 +84,7 @@ static inline void alternatives_smp_switch(int smp) {}
" .byte " __stringify(feature) "\n" /* feature bit */ \
" .byte 662b-661b\n" /* sourcelen */ \
" .byte 664f-663f\n" /* replacementlen */ \
+ " .byte 0xff + (664f-663f) - (662b-661b)\n" /* rlen <= slen */ \
".previous\n" \
".section .altinstr_replacement, \"ax\"\n" \
"663:\n\t" newinstr "\n664:\n" /* replacement */ \
--
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