[Crash-utility] [PATCH] bug on get_be_long() and improvement of bt

[Dave Anderson]

----- "Hu Tao" <hutao at cn.fujitsu.com> wrote:

> Hi Dave,
> 
>    There is a bug on get_be_long() that causes high 32 bits truncated.
>    As a result, we get wrong registers values from dump file. Patch 1
>    fixes this.

Good catch!
 
>    Once we can get right cpu registers values, it's better to use the
>    sp/ip for backtracing the active task. This can show a more accurate
>    backtrace, not including those invalid frames beyond sp. pathes 2 and
>    3 do this on kvmdump case(virsh dump).
> 
>    To verify: run that km_probe.c test module on a x86_64 system, then
>    `echo q > /proc/sysrq-trigger' to trigger the kprobe which does
>    looping in post_handler. Then vrish dump then crash. 

However, I'm wondering whether you actually tested this with a 
*crashed* system's dumpfile, and not just with a *live* system dump with
a contrived set of circumstances.  And if so, what differences, if any,
did you see with the backtraces of the task that either oops'd or called
panic(), as well as those of the other active tasks that were brought down
by IP interrupt?

Anyway, I'll give this a thorough testing with a set of sample
dumpfiles that I have on hand.

Thanks,
  Dave