dwarf info in modules.

[Tigran Aivazian]

On Mon, 12 Sep 2005, Frank Ch. Eigler wrote:

> Tigran Aivazian <tigran_aivazian@symantec.com> writes:
>
>> upgrading elfutils to 0.115 solved the "no dwarf info found" but now I
>> get an oops:
>> [...]
>> 0x100497fbdc8 0xffffffff801229da arch_copy_kprobe+0x16
>> (0xffffffffa01cdc20, 0x7fbffff314, 0x100497fbe84, 0x4, 0x100497fbf48)
>> [...]
>
> I wonder if this is because the init function is in a special section
> (.init.text) of the .ko binary, which is unloaded/unmapped after
> initialization (in sys_init_module).  By the time systemtap asks to
> insert a kprobe, there would be no "there" there.

I am not sure that this analysis is correct, because if I simply do 
modprobe microcode and place a probe at microcode_open then I get exactly 
the same oops (same backtrace). And microcode driver wasn't going 
anywhere, i.e. not unloaded.

Note that I didn't try to open the microcode device or do anything else 
other than stap microcode.stp which contained two lines pointing directly 
to microcode_open and NOT *@microcode.c

Also I forgot to mention that the problem with the trivial module occurs 
even if I point directly to a function in it (not ->init or ->exit 
functions) and not *@tmod.c globally.

Kind regards
Tigran