Kewen Lin
15b83b69ca
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.
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.