[all-commits] [llvm/llvm-project] 493565: [HWASan] Run LAM tests with -hwasan-generate-tags-...

[Matt Morehouse via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 493565a4aa7cc3b48e2b5c51b541a438fc449217
      https://github.com/llvm/llvm-project/commit/493565a4aa7cc3b48e2b5c51b541a438fc449217
  Author: Matt Morehouse <mascasa at google.com>
  Date:   2021-06-18 (Fri, 18 Jun 2021)

  Changed paths:
    M compiler-rt/lib/hwasan/hwasan.cpp
    M compiler-rt/test/hwasan/lit.cfg.py

  Log Message:
  -----------
  [HWASan] Run LAM tests with -hwasan-generate-tags-with-calls.

The default callback instrumentation in x86 LAM mode uses ASLR bits
to randomly choose a tag, and thus has a 1/64 chance of choosing a
stack tag of 0, causing stack tests to fail intermittently.  By using
__hwasan_generate_tag to pick tags, we guarantee non-zero tags and
eliminate the test flakiness.

aarch64 doesn't seem to have this problem using thread-local addresses
to pick tags, so perhaps we can remove this workaround once we implement
a similar mechanism for LAM.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D104470