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| author | Kito Cheng <kito.cheng@sifive.com> | 2022-06-28 21:52:19 +0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2022-06-30 08:04:52 -0700 |
| commit | c22d2021a9f9bdea62398976eea4f0e6ef668b7d (patch) | |
| tree | 31c84de370e090ad007b11e4d679a5eff94ab717 | |
| parent | e9dd3682963a7038d699430e3ece68045b6caafc (diff) | |
| download | glibc-c22d2021a9f9bdea62398976eea4f0e6ef668b7d.zip glibc-c22d2021a9f9bdea62398976eea4f0e6ef668b7d.tar.gz glibc-c22d2021a9f9bdea62398976eea4f0e6ef668b7d.tar.bz2 | |
riscv: Use memcpy to handle unaligned access when fixing R_RISCV_RELATIVE
Although RISC-V Linux will enable the unaligned memory access handler by
default, that is quite expensive in general, using memcpy will be much cheaper
- just break down that into several load/store byte instructions.
ARM and MIPS has similar issue:
ARM: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51456
MIPS: https://gcc.gnu.org/legacy-ml/gcc-help/2005-07/msg00325.html
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
| -rw-r--r-- | sysdeps/riscv/dl-machine.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h index 4bb858a..dfedc98 100644 --- a/sysdeps/riscv/dl-machine.h +++ b/sysdeps/riscv/dl-machine.h @@ -157,7 +157,10 @@ __attribute__ ((always_inline)) elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc, void *const reloc_addr) { - *(ElfW(Addr) *) reloc_addr = l_addr + reloc->r_addend; + /* R_RISCV_RELATIVE might located in debug info section which might not + aligned to XLEN bytes. Also support relocations on unaligned offsets. */ + ElfW(Addr) value = l_addr + reloc->r_addend; + memcpy (reloc_addr, &value, sizeof value); } /* Perform a relocation described by R_INFO at the location pointed to |