On 06/26/2018 02:53 PM, Dave Love wrote:
What has changed in the last month to affect building shared libraries
in rawhide?
I tried to rebuild libxsmm in rawhide, after changing the spec to use
python2 explicitly, and it failed with
/usr/bin/ld: build/intel64/libxsmm_main.o: relocation R_X86_64_PC32 against symbol `libxsmm_crc32_u64' can not be used when making a shared object; recompile with -fPIC
The sources are compiled with -fpic and it's x86_64 only, so -fPIC
v. -fpic shouldn't matter as I understand it.
It's related to annobin. libxsmm_crc32_u64 is a static function with a
target attribute, and the sources are compiled with -ffunction-sections.
GCC emits calls to the function using:
call libxsmm_crc32_u64
This is a direct call, not through the PLT, and is allowed under the
default x86-64 memory model for local (static) functions because all
code fits into 2 GiB.
But annobin generates this:
.pushsection .text.libxsmm_crc32_u64
libxsmm_crc32_u64_end:
.popsection
.pushsection .gnu.build.attributes
.weak libxsmm_crc32_u64
.weak libxsmm_crc32_u64_end
.popsection
The .weak directive makes the symbol global, so it can be interposed
from other modules, and the direct call shown above is no longer permitted.
Nick, this looks like an annobin bug. This is really, really
problematic from an ABI perspective.
Thanks,
Florian
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