linux/include/asm-x86_64/bug.h
Andi Kleen b6a68a16dc [PATCH] x86_64: Turn BUG data into valid instruction
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>
2005-07-28 21:46:01 -07:00

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957 B
C

#ifndef __ASM_X8664_BUG_H
#define __ASM_X8664_BUG_H 1
#include <linux/stringify.h>
/*
* Tell the user there is some problem. The exception handler decodes
* this frame.
*/
struct bug_frame {
unsigned char ud2[2];
unsigned char mov;
/* should use 32bit offset instead, but the assembler doesn't
like it */
char *filename;
unsigned char ret;
unsigned short line;
} __attribute__((packed));
#ifdef CONFIG_BUG
#define HAVE_ARCH_BUG
/* We turn the bug frame into valid instructions to not confuse
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__)))
void out_of_line_bug(void);
#else
static inline void out_of_line_bug(void) { }
#endif
#include <asm-generic/bug.h>
#endif