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A start.o compiled from start.S with -DPIC and no -DSHARED is used by
both crt1.o and rcrt1.o. So the LoongArch static PIE patch
unintentionally introduced PC-relative addressing for main and
__libc_start_main into crt1.o.
While the latest Binutils (trunk, which will be released as 2.40)
supports the PC-relative relocs against an external function by creating
a PLT entry, the 2.39 release branch doesn't (and won't) support this.
An error is raised:
"PLT stub does not represent and symbol not defined."
So, we need the following changes:
1. Check if ld supports the PC-relative relocs against an external
function. If it's not supported, we deem static PIE unsupported.
2. Change start.S. If static PIE is supported, use PC-relative
addressing for main and __libc_start_main and rely on the linker to
create PLT entries. Otherwise, restore the old behavior (using GOT
to address these functions).
An alternative would be adding a new "static-pie-start.S", and some
custom logic into Makefile to build rcrt1.o with it. And, restore
start.S to the state before static PIE change so crt1.o won't contain
PC-relative relocs against external symbols. But I can't see any
benefit of this alternative, so I'd just keep it simple.
Tested by building glibc with the following configurations:
1. Binutils trunk + GCC trunk. Static PIE enabled. All tests
passed.
2. Binutils 2.39 branch + GCC trunk. Static PIE disabled. Tests
related to ifunc failed (it's a known issue). All other tests
passed.
3. Binutils 2.39 branch + GCC 12 branch, cross compilation with
build-many-glibcs.py from x86_64-linux-gnu. Static PIE disabled.
Build succeeded.
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|---|---|---|
| .. | ||
| bits | ||
| fpu | ||
| lp64 | ||
| nofpu | ||
| nptl | ||
| sys | ||
| __longjmp.S | ||
| abort-instr.h | ||
| bsd-_setjmp.c | ||
| bsd-setjmp.c | ||
| configure | ||
| configure.ac | ||
| dl-irel.h | ||
| dl-machine.h | ||
| dl-tls.h | ||
| dl-trampoline.S | ||
| e_sqrtl.c | ||
| fpu_control.h | ||
| hp-timing.h | ||
| Implies | ||
| jmpbuf-offsets.h | ||
| jmpbuf-unwind.h | ||
| ldsodefs.h | ||
| libc-tls.c | ||
| linkmap.h | ||
| machine-gmon.h | ||
| Makefile | ||
| math_private.h | ||
| preconfigure | ||
| preconfigure.ac | ||
| setjmp.S | ||
| sfp-machine.h | ||
| sotruss-lib.c | ||
| stackinfo.h | ||
| start.S | ||
| tininess.h | ||
| tst-audit.h | ||