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authorJan Beulich <JBeulich@novell.com>2009-11-27 15:04:58 +0000
committerIngo Molnar <mingo@elte.hu>2009-12-02 11:39:45 +0100
commit01be50a308be466e122c3a8b3d535f1b673ecbd2 (patch)
tree051a50e00ba89d113569379dfc6510090d719583
parent8ec6993d9f7d961014af970ded57542961fe9ad9 (diff)
downloadop-kernel-dev-01be50a308be466e122c3a8b3d535f1b673ecbd2.zip
op-kernel-dev-01be50a308be466e122c3a8b3d535f1b673ecbd2.tar.gz
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@novell.com> LKML-Reference: <4B0FF8AA0200007800022703@vpn.id2.novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/include/asm/alternative.h1
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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