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? -- Steve _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
