Commit b6a68a16 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds

[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: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2275cfa8
......@@ -8,17 +8,24 @@
* this 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
like it */
char *filename;
unsigned char ret;
unsigned short line;
} __attribute__((packed));
#ifdef CONFIG_BUG
#define HAVE_ARCH_BUG
#define BUG() \
asm volatile("ud2 ; .quad %c1 ; .short %c0" :: \
/* 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
......
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