https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108727
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Kewen Lin <li...@gcc.gnu.org>: https://gcc.gnu.org/g:15b83b69ca99d97643075776ba94f2dd1f05b46e commit r13-6545-g15b83b69ca99d97643075776ba94f2dd1f05b46e Author: Kewen Lin <li...@linux.ibm.com> Date: Wed Mar 8 00:57:21 2023 -0600 libgcc, rs6000: Fix bump size for powerpc64 elfv1 ABI [PR108727] As PR108727 shows, when cleanup code called by the stack unwinder calls function _Unwind_Resume, it goes via plt stub like: function 00000000.plt_call._Unwind_Resume: => 0x0000000010003580 <+0>: std r2,40(r1) 0x0000000010003584 <+4>: ld r12,-31760(r2) 0x0000000010003588 <+8>: mtctr r12 0x000000001000358c <+12>: ld r2,-31752(r2) 0x0000000010003590 <+16>: cmpldi r2,0 0x0000000010003594 <+20>: bnectr+ 0x0000000010003598 <+24>: b 0x100031a4 <_Unwind_Resume@plt> It wants to save TOC base (r2) to r1 + 40, but we only bump the stack segment by 32 bytes as follows: stdu %r29,-32(%r3) It means the access is out of the stack segment allocated by __generic_morestack, once the touch area isn't writable like this failure shows, it would cause segment fault. So fix the bump size with one reasonable value PARAMS. PR libgcc/108727 libgcc/ChangeLog: * config/rs6000/morestack.S (__morestack): Use PARAMS for new stack bump size.
