Commit 926b2898 authored by Pekka Enberg's avatar Pekka Enberg Committed by Linus Torvalds

Documentation: How to use GDB to decode OOPSes

Adds instructions how to use GDB to figure out the exact location of
an OOPS to Documentation/BUG-HUNTING.
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0a920b5b
...@@ -191,6 +191,30 @@ e.g. crash dump output as shown by Dave Miller. ...@@ -191,6 +191,30 @@ e.g. crash dump output as shown by Dave Miller.
> mov 0x8(%ebp), %ebx ! %ebx = skb->sk > mov 0x8(%ebp), %ebx ! %ebx = skb->sk
> mov 0x13c(%ebx), %eax ! %eax = inet_sk(sk)->opt > mov 0x13c(%ebx), %eax ! %eax = inet_sk(sk)->opt
In addition, you can use GDB to figure out the exact file and line
number of the OOPS from the vmlinux file. If you have
CONFIG_DEBUG_INFO enabled, you can simply copy the EIP value from the
OOPS:
EIP: 0060:[<c021e50e>] Not tainted VLI
And use GDB to translate that to human-readable form:
gdb vmlinux
(gdb) l *0xc021e50e
If you don't have CONFIG_DEBUG_INFO enabled, you use the function
offset from the OOPS:
EIP is at vt_ioctl+0xda8/0x1482
And recompile the kernel with CONFIG_DEBUG_INFO enabled:
make vmlinux
gdb vmlinux
(gdb) p vt_ioctl
(gdb) l *(0x<address of vt_ioctl> + 0xda8)
Another very useful option of the Kernel Hacking section in menuconfig is Another very useful option of the Kernel Hacking section in menuconfig is
Debug memory allocations. This will help you see whether data has been Debug memory allocations. This will help you see whether data has been
initialised and not set before use etc. To see the values that get assigned initialised and not set before use etc. To see the values that get assigned
......
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