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Commit 5f1d189f authored by Jan Beulich's avatar Jan Beulich Committed by Linus Torvalds
Browse files

[PATCH] x86_64: Display meaningful part of filename during BUG() 



When building in a separate objtree, file names produced by BUG() & Co. can
get fairly long; printing only the first 50 characters may thus result in
(almost) no useful information. The following change makes it so that rather
the last 50 characters of the filename get printed.

Signed-Off-By: default avatarJan Beulich <jbeulich@novell.com>

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 1b2f6304

arch/x86_64/kernel/traps.c

+9 −3
Original line number Diff line number Diff line
@@ -340,7 +340,8 @@ bad: 
void handle_BUG(struct pt_regs *regs)

{ 

	struct bug_frame f;

	char tmp;

	long len;

	const char *prefix = "";



	if (user_mode(regs))

		return;
@@ -350,10 +351,15 @@ void handle_BUG(struct pt_regs *regs) 
	if (f.filename >= 0 ||

	    f.ud2[0] != 0x0f || f.ud2[1] != 0x0b) 

		return;

	if (__get_user(tmp, (char *)(long)f.filename))

	len = __strnlen_user((char *)(long)f.filename, PATH_MAX) - 1;

	if (len < 0 || len >= PATH_MAX)

		f.filename = (int)(long)"unmapped filename";

	else if (len > 50) {

		f.filename += len - 50;

		prefix = "...";

	}

	printk("----------- [cut here ] --------- [please bite here ] ---------\n");

	printk(KERN_ALERT "Kernel BUG at %.50s:%d\n", (char *)(long)f.filename, f.line);

	printk(KERN_ALERT "Kernel BUG at %s%.50s:%d\n", prefix, (char *)(long)f.filename, f.line);

} 



#ifdef CONFIG_BUG

arch/x86_64/lib/usercopy.c

+8 −4
Original line number Diff line number Diff line
@@ -109,14 +109,11 @@ unsigned long clear_user(void __user *to, unsigned long n) 
 * Return 0 on exception, a value greater than N if too long

 */



long strnlen_user(const char __user *s, long n)

long __strnlen_user(const char __user *s, long n)

{

	long res = 0;

	char c;



	if (!access_ok(VERIFY_READ, s, n))

		return 0;



	while (1) {

		if (res>n)

			return n+1;
@@ -129,6 +126,13 @@ long strnlen_user(const char __user *s, long n) 
	}

}



long strnlen_user(const char __user *s, long n)

{

	if (!access_ok(VERIFY_READ, s, n))

		return 0;

	return __strnlen_user(s, n);

}



long strlen_user(const char __user *s)

{

	long res = 0;

include/asm-x86_64/uaccess.h

+1 −0
Original line number Diff line number Diff line
@@ -348,6 +348,7 @@ static inline int __copy_in_user(void __user *dst, const void __user *src, unsig 
long strncpy_from_user(char *dst, const char __user *src, long count);

long __strncpy_from_user(char *dst, const char __user *src, long count);

long strnlen_user(const char __user *str, long n);

long __strnlen_user(const char __user *str, long n);

long strlen_user(const char __user *str);

unsigned long clear_user(void __user *mem, unsigned long len);

unsigned long __clear_user(void __user *mem, unsigned long len);