[PATCH] x86-64: reduce x86-64 bug frame by 4 bytes
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>
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 1dfeb07..b5e09e6 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -321,13 +321,13 @@
if (__copy_from_user(&f, (struct bug_frame *) regs->rip,
sizeof(struct bug_frame)))
return;
- if ((unsigned long)f.filename < __PAGE_OFFSET ||
+ if (f.filename >= 0 ||
f.ud2[0] != 0x0f || f.ud2[1] != 0x0b)
return;
- if (__get_user(tmp, f.filename))
- f.filename = "unmapped filename";
+ if (__get_user(tmp, (char *)(long)f.filename))
+ f.filename = (int)(long)"unmapped filename";
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
diff --git a/include/asm-x86_64/bug.h b/include/asm-x86_64/bug.h
index eed7856..80ac1fe 100644
--- a/include/asm-x86_64/bug.h
+++ b/include/asm-x86_64/bug.h
@@ -9,10 +9,8 @@
*/
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 push;
+ signed int filename;
unsigned char ret;
unsigned short line;
} __attribute__((packed));
@@ -25,8 +23,8 @@
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__)))
+ "ud2 ; pushq $%c1 ; ret $%c0" :: \
+ "i"(__LINE__), "i" (__FILE__))
void out_of_line_bug(void);
#else
static inline void out_of_line_bug(void) { }