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[PATCH] x86_64: Turn BUG data into valid instruction

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This avoids confusing the disassembler. Costs 2 bytes per BUG.

Thanks to Suresh Siddha and Jan Beulich for suggesting suitable instructions.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen
2005-07-28 21:15:45 -07:00
committed by Linus Torvalds
parent 2275cfa8bc
commit b6a68a16dc
1 changed files with 10 additions and 3 deletions
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13
include/asm-x86_64/bug.h
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@@ -8,17 +8,24 @@
* this frame. * this frame.
*/ */
struct bug_frame { struct bug_frame {
unsigned char ud2[2]; unsigned char ud2[2];
unsigned char mov;
/* should use 32bit offset instead, but the assembler doesn't /* should use 32bit offset instead, but the assembler doesn't
like it */ like it */
char *filename; char *filename;
unsigned char ret;
unsigned short line; unsigned short line;
} __attribute__((packed)); } __attribute__((packed));
#ifdef CONFIG_BUG #ifdef CONFIG_BUG
#define HAVE_ARCH_BUG #define HAVE_ARCH_BUG
#define BUG() \ /* We turn the bug frame into valid instructions to not confuse
asm volatile("ud2 ; .quad %c1 ; .short %c0" :: \ the disassembler. Thanks to Jan Beulich & Suresh Siddha
for nice instruction selection.
The magic numbers generate mov $64bitimm,%eax ; ret $offset. */
#define BUG() \
asm volatile( \
"ud2 ; .byte 0xa3 ; .quad %c1 ; .byte 0xc2 ; .short %c0" :: \
"i"(__LINE__), "i" (__stringify(__FILE__))) "i"(__LINE__), "i" (__stringify(__FILE__)))
void out_of_line_bug(void); void out_of_line_bug(void);
#else #else