trap and frame address

[Beesdeckar <beesdeckar%softinengines.com@localhost>]

Hello,
I am trying to analyze crash in kernel module. I already know C code 
line which is reason of crash but I am not able to find how to switch to 
stack which made trap like it is displayed in /var/log/message 
(mutex_enter()...) for investigating it's local argument.

If I understand good I need to load trap frame into gdb with "frame 
address <address>" to see stack before trap  happens, but I don't know 
how to find frame address even I am not sure if my assumption is proper.

What should I try or what to look on ?


gdb with loaded crash dump shows:

(gdb) bt
#0  0xffffffff80239985 in cpu_reboot (howto=howto@entry=260, 
bootstr=bootstr@entry=0x0) at /usr/src/sys/arch/amd64/amd64/machdep.c:717
#1  0xffffffff80cfd6db in kern_reboot (howto=howto@entry=260, 
bootstr=bootstr@entry=0x0) at /usr/src/sys/kern/kern_reboot.c:73
#2  0xffffffff80d345b5 in vpanic (fmt=fmt@entry=0xffffffff813a8010 
"trap", ap=ap@entry=0xffffb80384d5ad48) at /usr/src/sys/kern/subr_prf.c:291
#3  0xffffffff80d3468a in panic (fmt=fmt@entry=0xffffffff813a8010 
"trap") at /usr/src/sys/kern/subr_prf.c:208
#4  0xffffffff8023c185 in trap (frame=0xffffb80384d5ae90) at 
/usr/src/sys/arch/amd64/amd64/trap.c:326
#5  0xffffffff80234a7b in alltraps ()
#6  0x000000000000001a in ?? ()
#7  0x0000000000000002 in ?? ()
...

and /var/log/message shows:

Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] fatal page fault in 
supervisor mode
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] trap type 6 code 0x2 rip 
0xffffffff8023fb0c cs 0x8 rflags 0x10246 cr2 0x1a ilevel 0x8 rsp 
0xffffb80384d5af88
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] curlwp 0xffffb266fc5b52c0 
pid 0.97 lowest kstack 0xffffb80384d562c0
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] panic: trap
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] cpu2: Begin traceback...
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] vpanic() at netbsd:vpanic+0x188
Mar 28 21:10:17 bsd /netbsd: [ 463.7723403] panic() at netbsd:panic+0x3c
Mar 28 21:10:17 bsd /netbsd: [ 463.7823380] trap() at netbsd:trap+0xbaf
Mar 28 21:10:17 bsd /netbsd: [ 463.7823380] --- trap (number 6) ---
Mar 28 21:10:17 bsd /netbsd: [ 463.7823380] mutex_enter() at 
netbsd:mutex_enter+0xc
Mar 28 21:10:17 bsd /netbsd: [ 463.7923369] itimer_callout() at 
netbsd:itimer_callout+0x2e
Mar 28 21:10:17 bsd /netbsd: [ 463.7923369] callout_softclock() at 
netbsd:callout_softclock+0xac
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] softint_dispatch() at 
netbsd:softint_dispatch+0x95
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] DDB lost frame for 
netbsd:Xsoftintr+0x4c, trying 0xffffb80384d5b0f0
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] Xsoftintr() at 
netbsd:Xsoftintr+0x4c
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] --- interrupt ---
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] bd199e21ddf6cd01:
Mar 28 21:10:17 bsd /netbsd: [ 463.8023378] cpu2: End traceback...

Peter