[AArch64] Add support for pointer authentication relocations#801
[AArch64] Add support for pointer authentication relocations#801nezetic wants to merge 1 commit intoqualcomm:mainfrom
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Implements basic PAuth support for AArch64 following the PAuth ABI Extension specification (2025Q1): https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst **Adds:** - R_AARCH64_AUTH_ABS64 (0x244): authenticated absolute relocations - R_AARCH64_AUTH_RELATIVE (0x411): authenticated relative relocations **Testing:** Covers PIE/non-PIE/static executables, as well as various corner cases from the spec like undefined weak references, COPY relocations and non-allocating sections. **Not included:** GOT/PLT signing, additional AUTH relocation types (future work). **Notes:** I changed the way *GNULDBackend::recordRelativeReloc* store relative relocations. The original map is only iterated once (in a linear way), but reversing the key / values allows to implement an efficient *GNULDBackend::findRelativeReloc*. No changes to existing non-AUTH relocation behavior. Signed-off-by: Cedric Tessier <ctessier@qti.qualcomm.com>
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quic-seaswara
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apazos,
quic-areg,
quic-seaswara and
svs-quic
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@pzhengqc might be a better suited to review this. |
| uint32_t relaCount = 0; | ||
| for (auto &R : m_Backend.getRelaDyn()->getRelocations()) { | ||
| if (R->type() == llvm::ELF::R_AARCH64_RELATIVE) | ||
| if (R->type() == llvm::ELF::R_AARCH64_RELATIVE || |
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I think this may lead to a potentially wrong DT_RELACOUNT value with eld (lld does not count AARCH64_AUTH_RELATIVE here).
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My understanding if that DT_RELACOUNT represents the number of relative relocations in .rela.dyn. AARCH64_AUTH_RELATIVE relocations will end up in this section, so they must be counted.
Relocation section '.rela.dyn' at offset 0x1e8 contains 11 entries:
Offset Info Type Symbol's Value Symbol's Name + Addend
0000000000001130 0000000000000411 R_AARCH64_AUTH_RELATIVE 341
0000000000001138 0000000000000411 R_AARCH64_AUTH_RELATIVE 1132
It's important to note LLD implement a very tedious (and optional) Relocation Compression (section 11) , that is not in the scope of this PR.
I did not perform a 1:1 comparaison with LLD, but made sure ELD is passing similar tests.
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Implements basic PAuth support for AArch64 following the PAuth ABI Extension specification (2025Q1):
https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst
Adds:
Testing:
Covers PIE/non-PIE/static executables, as well as various corner cases from the spec like undefined weak references, COPY relocations and non-allocating sections.
Not included:
GOT/PLT signing, additional AUTH relocation types (future work).
Notes:
I changed the way GNULDBackend::recordRelativeReloc store relative relocations. The original map is only iterated once (in a linear way), but reversing the key / values allows to implement an efficient GNULDBackend::findRelativeReloc.
No changes to existing non-AUTH relocation behavior.