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[PATCH] x86-64: reduce x86-64 bug frame by 4 bytes

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As mentioned before, the size of the bug frame can be further reduced while
continuing to use instructions to encode the information.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jan Beulich 2005-09-12 18:49:25 +02:00 committed by Linus Torvalds
parent c47a3167d0
commit 049cdefe19
2 changed files with 8 additions and 10 deletions
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8
arch/x86_64/kernel/traps.c
View file

@ -321,13 +321,13 @@ void handle_BUG(struct pt_regs *regs)
if (__copy_from_user(&f, (struct bug_frame *) regs->rip, if (__copy_from_user(&f, (struct bug_frame *) regs->rip,
sizeof(struct bug_frame))) sizeof(struct bug_frame)))
return; return;
if ((unsigned long)f.filename < __PAGE_OFFSET || if (f.filename >= 0 ||
f.ud2[0] != 0x0f || f.ud2[1] != 0x0b) f.ud2[0] != 0x0f || f.ud2[1] != 0x0b)
return; return;
if (__get_user(tmp, f.filename)) if (__get_user(tmp, (char *)(long)f.filename))
f.filename = "unmapped filename"; f.filename = (int)(long)"unmapped filename";
printk("----------- [cut here ] --------- [please bite here ] ---------\n"); printk("----------- [cut here ] --------- [please bite here ] ---------\n");
printk(KERN_ALERT "Kernel BUG at %.50s:%d\n", f.filename, f.line); printk(KERN_ALERT "Kernel BUG at %.50s:%d\n", (char *)(long)f.filename, f.line);
} }
#ifdef CONFIG_BUG #ifdef CONFIG_BUG

10
include/asm-x86_64/bug.h
View file

@ -9,10 +9,8 @@
*/ */
struct bug_frame { struct bug_frame {
unsigned char ud2[2]; unsigned char ud2[2];
unsigned char mov; unsigned char push;
/* should use 32bit offset instead, but the assembler doesn't signed int filename;
like it */
char *filename;
unsigned char ret; unsigned char ret;
unsigned short line; unsigned short line;
} __attribute__((packed)); } __attribute__((packed));
@ -25,8 +23,8 @@ struct bug_frame {
The magic numbers generate mov $64bitimm,%eax ; ret $offset. */ The magic numbers generate mov $64bitimm,%eax ; ret $offset. */
#define BUG() \ #define BUG() \
asm volatile( \ asm volatile( \
"ud2 ; .byte 0xa3 ; .quad %c1 ; .byte 0xc2 ; .short %c0" :: \ "ud2 ; pushq $%c1 ; ret $%c0" :: \
"i"(__LINE__), "i" (__stringify(__FILE__))) "i"(__LINE__), "i" (__FILE__))
void out_of_line_bug(void); void out_of_line_bug(void);
#else #else
static inline void out_of_line_bug(void) { } static inline void out_of_line_bug(void) { }