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

include/asm-x86_64/bug.h

+10 −3
Original line number Diff line number Diff line
@@ -9,16 +9,23 @@ 
 */

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 ; .quad %c1 ; .short %c0" :: \

	asm volatile(							\

	"ud2 ; .byte 0xa3 ; .quad %c1 ; .byte 0xc2 ; .short %c0" :: 	\

		     "i"(__LINE__), "i" (__stringify(__FILE__)))

void out_of_line_bug(void);

#else