Hi Segher, > On Wed, Sep 24, 2014 at 12:33:07PM +1000, Anton Blanchard wrote: > > We are scratching our heads trying to remember details of the issue > > right now. In retrospect we should have linked the gcc bugzilla or > > gcc commit details in the kernel commit message :) > > There have been many GCC bugs in this area. > > 30282 (for 32-bit) > 44199 (for 64-bit) > 52828 (for everything, and this one should finally handle things for > good) Also a bunch of duplicates, and I'm sure I've missed some more. > > The original issue as far as I remember: when using a frame pointer, > GCC would sometimes schedule the epilogue to do the stack adjust > before restoring all regs from the stack. Then an interrupt comes > in, those saved regs are clobbered, kaboom. We cannot disable the > frame pointer because -pg forces it (although PowerPC does not need > it). The -mno-sched-epilog flag is a workaround: the epilogue (and > prologue) will not be reordered by instruction scheduling. Slow code > is better than blowing up fast ;-)
Thanks for explaining it! It does look like the last issue wasn't fixed until gcc 4.8. We'll drop that patch. Anton _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
