Reraise signals via rt_tgsigqueueinfo(2) on Linux (try 2).

Previously we would rely on implicit re-raising to deliver signals to
the underlying handler on POSIX systems if the signal is detected as
being re-raisable via WillSignalReraiseAutonomously(). This detection
mechanism is imperfect, as it will misclassify signals delivered as
a result of kill(2) when passing a signal number usually used for
synchronous signals, but now also asynchronous MTE tag check faults,
which are delivered as SIGSEGV signals on Linux. As a result, these
signals would not be re-raised and therefore would be discarded.

Although we could, for example, teach WillSignalReraiseAutonomously()
about MTE faults, the signal would still be re-raised via raise(3)
and therefore we would lose the information in siginfo.

We can avoid discarding these signals on Linux while at the
same time preserving the siginfo by making use of the syscall
rt_tgsigqueueinfo(2) which delivers a signal together with a
user-provided siginfo. The problem still exists on non-Linux POSIX
systems because this syscall is Linux-specific.

With kernel versions prior to 3.9, the kernel will reject the
rt_tgsigqueueinfo() syscall with EPERM. If that happens, follow
the non-Linux code path.

Change-Id: Ia410fbd651a756945c9402e361edfd5c520453d6
Reviewed-by: Mark Mentovai <>
Commit-Queue: Peter Collingbourne <>
2 files changed
tree: c0f72ea94724a08779cb8b80e12ef1c73cf04348
  1. .clang-format
  2. .gitattributes
  3. .gitignore
  4. .gn
  5. .style.yapf
  6. .vpython
  10. DEPS
  13. build/
  14. client/
  15. codereview.settings
  16. compat/
  17. doc/
  18. handler/
  19. infra/
  20. minidump/
  22. package.h
  23. snapshot/
  24. test/
  25. third_party/
  26. tools/
  27. util/


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