On Wed, 20 Aug 2008, Steven Rostedt wrote: > > On Wed, 20 Aug 2008, Benjamin Herrenschmidt wrote: > > > Found the problem (or at least -a- problem), it's a gcc bug. > > > > Well, first I must say the code generated by -pg is just plain > > horrible :-) > > > > Appart from that, look at the exit of, for example, __d_lookup, as > > generated by gcc when ftrace is enabled: > > > > c00c0498: 38 60 00 00 li r3,0 > > c00c049c: 81 61 00 00 lwz r11,0(r1) > > c00c04a0: 80 0b 00 04 lwz r0,4(r11) > > c00c04a4: 7d 61 5b 78 mr r1,r11 > > c00c04a8: bb 0b ff e0 lmw r24,-32(r11) > > c00c04ac: 7c 08 03 a6 mtlr r0 > > c00c04b0: 4e 80 00 20 blr > > > > As you can see, it restores r1 -before- it pops r24..r31 off > > the stack ! I let you imagine what happens if an interrupt happens > > just in between those two instructions (mr and lmw). We don't do > > redzones on our ABI, so basically, the registers end up corrupted > > by the interrupt. > > Ouch! You've disassembled this without -pg too, and it does not have this > bug? What version of gcc do you have? >
I have: gcc (Debian 4.3.1-2) 4.3.1 c00c64c8: 81 61 00 00 lwz r11,0(r1) c00c64cc: 7f 83 e3 78 mr r3,r28 c00c64d0: 80 0b 00 04 lwz r0,4(r11) c00c64d4: ba eb ff dc lmw r23,-36(r11) c00c64d8: 7d 61 5b 78 mr r1,r11 c00c64dc: 7c 08 03 a6 mtlr r0 c00c64e0: 4e 80 00 20 blr My version looks fine. I'm thinking that this is a separate issue than what Eran is seeing. Eran, can you do an "objdump -dr vmlinux" and search for __d_lookup, and print out the end of the function dump. Thanks, -- Steve _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev