3.9.1's lld and powerpc64 for -pie use: can't create dynamic relocation R_PPC64_REL24 against readonly segment

[Mark Millard]

On 2017-Jan-21, at 2:16 PM, Mark Millard <markmi at dsl-only.net> wrote:

> For:
> 
> # more main.c                                                                                                                                                                                           static volatile char big_area[67001] = "This is a test";
> 
> int main ()
> {
>    big_area[67000] = '9';
> }
> 
> I get (the -fPIE is not required for the behavior):
> 
> # clang -fuse-ld=lld -Wl,-t -pie -fPIE main.c
> /usr/lib/Scrt1.o
> /usr/lib/crti.o
> /usr/lib/crtbeginS.o
> /tmp/main-c6f752.o
> /usr/lib/libgcc_s.so
> /lib/libc.so.7
> /usr/lib/libgcc_s.so
> /usr/lib/crtendS.o
> /usr/lib/crtn.o
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> can't create dynamic relocation R_PPC64_REL24 against readonly segment
> clang: error: linker command failed with exit code 1 (use -v to see invocation)
> 
> (This is difficult to study because it does not leave even a
> partial a.out and it does not report the specifics of what
> segment or what symbol or the like.)
> 
> Even an empty source produces that, but also including the
> expected:
> 
> undefined symbol: main in /usr/lib/Scrt1.o
> 
> It appears that the R_PPC64_REL24's are some subset of. . .
> 
> /usr/lib/Scrt1.o :
> 
> 00000000000000cc R_PPC64_REL24     atexit
> 00000000000000d8 R_PPC64_REL24     _init_tls
> 00000000000000f8 R_PPC64_REL24     atexit
> 00000000000001b4 R_PPC64_REL24     _init
> 0000000000000240 R_PPC64_REL24     main
> 0000000000000248 R_PPC64_REL24     exit
> 00000000000002fc R_PPC64_REL24     _fini
> 
> (That would be 6 by ignoring main, matching
> the message count.)
> 
> /usr/lib/crtbeginS.o :
> 
> 0000000000000040 R_PPC64_REL24     __cxa_finalize
> 0000000000000000 R_PPC64_REL24     .opd
> 0000000000000000 R_PPC64_REL24     .opd+0x0000000000000018
> 
> /usr/lib/crtendS.o :
> 
> 0000000000000000 R_PPC64_REL24     .opd
> 
> main.o , if I have it produced, does not have R_PPC64_REL24
> in it.

I have submitted this as llvm bugzilla 31762 and added
it to llvm bugzilla 25780's Depends On list (the meta
submittal for using clang and [its toolchain] as the
FreeBSD powerpc and powerpc64 system compiler [and
toolchain]).

===
Mark Millard
markmi at dsl-only.net