On 1/17/07, Curran, Dominic <dcurran@xxxxxx> wrote:
I used to write kernel modules for the 2.4 series kernel.
When my driver Oops'ed it would print out the eip line
e.g.
EIP is at my_func+0xf9/0x3ee [mod_abc]
I could then use objdump to output the assembler interleaved with the C
src code. e.g.
$ objdump -DS mod_abc.o > mod_abc.txt
I could then search through mod_abc.txt to find the start address of
my_func() and add on the offset (0xf9) to find the address of the fault.
Because the C source was interleaved with the assembler then I could
easily pinpoint the offending line of C code.
This made 80% of my kernel debugging much simpler ! :)
PROBLEM:
When I try this with modules built for the 2.6 kernel, objdump doesn't
interleave the C source with the assembler.
$ objdump -DS mod_abc.ko > mod_abc.txt
This makes it MUCH more difficult to relate the offending assembler line
back to C code. ><
Is there anyway to get an interleaved output of assembler and C code for
a 2.6 kernel module ?
I'm using kernel 2.6.18. I tried the same command ($ objdump -DS
mod_abc.ko > mod_abc.txt) and am getting intermixed C code and
assembly as output:
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
474: 8b 4c 24 04 mov 0x4(%esp),%ecx
if (!list_empty(&active_list)) {
478: 8d 44 24 04 lea 0x4(%esp),%eax
47c: 39 c1 cmp %eax,%ecx
47e: 74 4b je 4cb <scsi_device_cancel+0xdb>
list_for_each_safe(lh, lh_sf, &active_list) {
480: 8b 31 mov (%ecx),%esi
* @entry: the element to delete from the list.
*/
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
482: 8b 11 mov (%ecx),%edx
484: 8b 41 04 mov 0x4(%ecx),%eax
487: 89 42 04 mov %eax,0x4(%edx)
48a: 89 10 mov %edx,(%eax)
48c: 89 49 04 mov %ecx,0x4(%ecx)
48f: 89 09 mov %ecx,(%ecx)
scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
Perhaps you forgot to add debug information to the kernel (-g)? You
can also try to turn off all optimizations (-O0) while compiling the
kernel.
Regards,
Rajat
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