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| author | Fangrui Song <maskray@google.com> | 2020-04-17 23:08:11 -0700 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2020-04-28 12:13:27 -0700 |
| commit | 03ffe5860549e97a0f2d8262b100e8910f61c528 (patch) | |
| tree | 553d9819a5d455b756932bb7eeb1652c0d6fb1bf /llvm/lib/Support/ThreadPool.cpp | |
| parent | 2a3cf5e5834302a9525a721627c17902399b8d62 (diff) | |
| download | llvm-03ffe5860549e97a0f2d8262b100e8910f61c528.zip llvm-03ffe5860549e97a0f2d8262b100e8910f61c528.tar.gz llvm-03ffe5860549e97a0f2d8262b100e8910f61c528.tar.bz2 | |
[ELF][PPC64] Don't perform toc-indirect to toc-relative relaxation for R_PPC64_TOC16_HA not followed by R_PPC64_TOC16_LO_DS
The current implementation assumes that R_PPC64_TOC16_HA is always followed
by R_PPC64_TOC16_LO_DS. This can break with:
// Load the address of the TOC entry, instead of the value stored at that address
addis 3, 2, .LC0@tloc@ha # R_PPC64_TOC16_HA
addi 3, 3, .LC0@tloc@l # R_PPC64_TOC16_LO
blr
which is used by boringssl's util/fipstools/delocate/delocate.go
https://github.com/google/boringssl/blob/master/crypto/fipsmodule/FIPS.md has some documentation.
In short, this tool converts an assembly file to avoid any potential relocations.
The distance to an input .toc is not a constant after linking, so the assembly cannot use an `addis;ld` pair.
Instead, delocate changes the code to jump to a stub (`addis;addi`) which loads the TOC entry address.
Reviewed By: sfertile
Differential Revision: https://reviews.llvm.org/D78431
Diffstat (limited to 'llvm/lib/Support/ThreadPool.cpp')
0 files changed, 0 insertions, 0 deletions