[all-commits] [llvm/llvm-project] 0a6436: Sanitizer/MIPS: Use $t9 for preemptible function c...

[YunQiang Su via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0a64367a72f1634321f5051221f05f2f364bd882
      https://github.com/llvm/llvm-project/commit/0a64367a72f1634321f5051221f05f2f364bd882
  Author: YunQiang Su <wzssyqa at gmail.com>
  Date:   2024-01-16 (Tue, 16 Jan 2024)

  Changed paths:
    M compiler-rt/lib/interception/interception.h
    M compiler-rt/lib/sanitizer_common/sanitizer_asm.h

  Log Message:
  -----------
  Sanitizer/MIPS: Use $t9 for preemptible function call (#76894)

Currently, almost all of the shared libraries of MIPS, rely on $t9
to get the address of current function, instead of PCREL instructions,
even on MIPSr6. So we have to set $t9 properly.

To get the address of preemptible function, we need the help of GOT.
MIPS/O32 has .cpload, which can help to generate 3 instructions to get GOT.
For __mips64, we can get GOT by:

lui $t8, %hi(%neg(%gp_rel(SANITIZER_STRINGIFY(TRAMPOLINE(func)))))
daddu $t8, $t8, $t9
daddiu $t8, $t8, %hi(%neg(%gp_rel(SANITIZER_STRINGIFY(TRAMPOLINE(func)))))

And then get the address of __interceptor_func, and jump to it

ld $t9, %got_disp(_interceptor" SANITIZER_STRINGIFY(func) ")($t8)
jr $t9

Fixes #74047

Co-authored-by: YunQiang Su <yunqiang.su at cipunited.com>