Re: Stap is translating to functions in __exit sections...and later module load fails

[Keshavamurthy Anil S <anil dot s dot keshavamurthy at intel dot com>]

On Fri, Oct 13, 2006 at 02:02:39PM -0700, Stone, Joshua I wrote:
> On Friday, October 13, 2006 1:26 PM, Keshavamurthy, Anil S wrote:
> > stap -e 'probe kernel.function("*") { log("."); }'
> > results in
> > ERROR: dwarf probe
> > kernel.function("exit_pfm_fs@arch/ia64/kernel/perfmon.c:1507")
> > registration failed, rc=1
> > 
> > Looks like on Ia64, stap is translating to functions which are in
> > __exit sections, as in the above failure case exit_pfm_fs() function
> > is prefixed with __exit and when the module is loaded the
> > kprobe registration fails as the functions in exit sections no longer
> > exist.
> 
> The translator blacklist tries to avoid such functions by checking the
> section name -- anything within a section beginning with '.exit.' (e.g.,
> .exit.text) is blacklisted, and thus won't match a function("*").
Exactly, I expected that the translator blacklists' and does not 
elaborate such functions. But looks like this is not happening.

See here....
#stap -p2 -e 'probe kernel.function("*") {}' | sort | uniq |grep exit_pfm_fs
kernel.function("exit_pfm_fs@arch/ia64/kernel/perfmon.c:1507"),

# cat /proc/kallsyms |grep exit_pfm_fs
#
#

> 
> Does IA64 do something different with the __exit sections?
> 
Everything in __exit sections will be discarded just after boot.

-thanks,
Anil