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author | Xi Ruoyao <xry111@xry111.site> | 2022-10-02 22:23:09 +0800 |
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committer | caiyinyu <caiyinyu@loongson.cn> | 2022-10-08 16:34:45 +0800 |
commit | 589eda82bb2ff210c33003beef239eedea1f9cac (patch) | |
tree | 9d017c1b81eb2efee3c490d065aabadeb2c3ef81 /sysdeps/nptl/Subdirs | |
parent | f9646d138f568ced95b29c20efdf902063c7ea96 (diff) | |
download | glibc-589eda82bb2ff210c33003beef239eedea1f9cac.tar.gz glibc-589eda82bb2ff210c33003beef239eedea1f9cac.tar.xz glibc-589eda82bb2ff210c33003beef239eedea1f9cac.zip |
LoongArch: Fix the condition to use PC-relative addressing in start.S
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.
Diffstat (limited to 'sysdeps/nptl/Subdirs')
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