On Mon, 2012-09-03 at 23:18 -0700, Christian Kujau wrote: > On Mon, 30 Jul 2012 at 22:46, Christian Kujau wrote: > > when trying to upgrade from 3.5 (final) to today's git checkout from > > Linus' tree, yaboot cannot boot and the following is printed: > > > > [...] > > returning from prom_init > > Invalid memory access at %SRR0: 00c62fd4 %SRR1: 00003030 > > Finally got around to do a bisection: > > ----------------------------- > b6e3796834faefe4b6e9a2aedfe12665cd51fbc5 is the first bad commit > commit b6e3796834faefe4b6e9a2aedfe12665cd51fbc5 > Author: Steven Rostedt <srost...@redhat.com> > Date: Thu Apr 26 08:31:18 2012 +0000 > > powerpc: Have patch_instruction detect faults > > For ftrace to use the patch_instruction code, it needs to check for > faults on write. Ftrace updates code all over the kernel, and we need > to know if code is updated or not due to protections that are placed > on some portions of the kernel. If ftrace does not detect a fault, it > will error later on, and it will be much more difficult to find the > problem. > > By changing patch_instruction() to detect faults, then ftrace will be > able to make use of it too. > > Signed-off-by: Steven Rostedt <rost...@goodmis.org> > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org> > > :040000 040000 83fb0e420524db452c07425e4dc402041428e696 > 0d1a01acd863237cf388045946ad4446a28df50c M arch > ----------------------------- > > The changeset looked pretty harmless to me but I tested with a current > 3.6+ git checkout and the kernel would only boot when this changeset was > reverted. > > Thoughts?
My guess would be we're calling that quite early and the __put_user() check is getting confused and failing. That means we'll have left some code unpatched, which then fails. Can you try with the patch applied, but instead of returning if the __put_user() fails, just continue on anyway. That will isolate if it's something in the __put_user() (I doubt it), or just that the __put_user() is failing and leaving the code unpatched. cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
