[Bug other/26208] Serious problem with unwinding through signal frames

["uweigand at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #3 from uweigand at gcc dot gnu dot org  2006-02-10 20:00 -------
Yup.  See how this is handled in config/s390/linux-unwind.c:

  /* If we got a SIGSEGV or a SIGBUS, the PSW address points *to*
     the faulting instruction, not after it.  This causes the logic
     in unwind-dw2.c that decrements the RA to determine the correct
     CFI region to get confused.  To fix that, we *increment* the RA
     here in that case.  Note that we cannot modify the RA in place,
     and the frame state wants a *pointer*, not a value; thus we put
     the modified RA value into the unused register 33 slot of FS and
     have the register 32 save address point to that slot.

     Unfortunately, for regular signals on old kernels, we don't know
     the signal number.  We default to not fiddling with the RA;
     that can fail in rare cases.  Upgrade your kernel.  */

  if (signo && (*signo == 11 || *signo == 7))
    {
      fs->regs.reg[33].loc.exp =
        (unsigned char *)regs->psw_addr + 1;
      fs->regs.reg[32].loc.offset =
        (long)&fs->regs.reg[33].loc.exp - new_cfa;
    }


-- 

uweigand at gcc dot gnu dot org changed:

           What    |Removed                     |Added
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                 CC|                            |uweigand at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26208