S390x Weekly testing

[David Wilder]

Some bad luck this week.  I am hitting what looks like a kprobes bug on 
the 2.6.21-rc3.
The system is crashing in the stap prologue test.

 illegal operation: 0001 Ý#29¨
CPU:    3    Not tainted
Process find (pid: 1571, task: 000000003fc28718, ksp: 000000003a357c70)
Krnl PSW : 0704200180000000 000000000018d844 (sys_write+0x24/0x80)
Krnl GPRS: 0000000000000000 000002000018fd38 0000000000000001 
0000020000020000
           0000000000000048 000002000018a8a8 0000000000000048 
0000000000000010
           000000000018d820 000000003a356000 0000020000020000 
fffffffffffffff7
           0000000000000048 000000000010e408 000000003a357eb8 
000000003a357e70
Krnl Code: f0 98 00 24 41 30 f0 ac c0 e5 00 00 03 94 b9 04 00 4c b9 02
Call Trace:
(Ý<040000003a357e78>¨ 0x40000003a357e78)

The crashing PSW (ip) is in the middle of the probed instruction.
Digging into it..
---

000000000018d820 <sys_write>:
  18d820:       eb af f0 68 00 24       stmg    %r10,%r15,104(%r15)
  18d826:       a7 f1 1f 00             tml     %r15,7936
  18d82a:       b9 04 00 ef             lgr     %r14,%r15
  18d82e:       a7 84 00 01             je      18d830 <sys_write+0x10>
  18d832:       a7 fb ff b8             aghi    %r15,-72
  18d836:       b9 04 00 a3             lgr     %r10,%r3
  18d83a:       b9 04 00 c4             lgr     %r12,%r4
  18d83e:       a7 b9 ff f7             lghi    %r11,-9
 >>  18d842:       e3 e0 f0 98 00 24       stg     %r14,152(%r15)      
<<   this is the probe point
  18d848:       41 30 f0 ac             la      %r3,172(%r15)
  18d84c:       c0 e5 00 00 03 94       brasl   %r14,18df74 <fget_light>
  18d852:       b9 04 00 4c             lgr     %r4,%r12

-- 
David Wilder
IBM Linux Technology Center
Beaverton, Oregon, USA 
dwilder@us.ibm.com
(503)578-3789