If the thread receives a signal concurrently with PTRACE_ATTACH,
we can get notification about the signal before notification about stop.
In such case we need to forward the signal to the thread, otherwise
the signal will be missed (as we do PTRACE_DETACH with arg=0) and
any logic relying on signals will break. After forwarding we need to
continue to wait for stopping, because the thread is not stopped yet.
We do ignore delivery of SIGSTOP, because we want to make stop-the-world
as invisible as possible.
http://reviews.llvm.org/D7723
--This line, and those below, will be ignored--
M lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
M test/tsan/signal_segv_handler.cc
llvm-svn: 229832
Long story short: stop-the-world briefly resets SIGSEGV handler to SIG_DFL.
This breaks programs that handle and continue after SIGSEGV (namely JVM).
See the test and comments for details.
http://reviews.llvm.org/D7722
llvm-svn: 229678
Also rename internal_sigaction() into internal_sigaction_norestorer(), as this function doesn't fully
implement the sigaction() functionality on Linux.
This change is a part of refactoring intended to have common signal handling behavior in all tools.
llvm-svn: 200535
Summary:
Fix race on report_fd/report_fd_pid between the parent process and the
tracer task.
Reviewers: samsonov
Reviewed By: samsonov
CC: llvm-commits, kcc, dvyukov
Differential Revision: http://llvm-reviews.chandlerc.com/D2306
llvm-svn: 196385
Comparing the parent PID with 1 isn't sufficient to ensure the parent is alive,
because of prctl(PR_SET_CHILD_SUBREAPER, ...). Compare with the real parent's
recorded PID instead.
llvm-svn: 192295
The tracer thread in StopTheWorld could wait on a mutex forever if the parent
process died before unlocking it. Use PR_SET_PDEATHSIG so that the parent would
kill the child in this scenario.
llvm-svn: 192210
Add a wrapper for the clone syscall for use in StopTheWorld. We
implement it only for x86_64, so stop building StopTheWorld for other platforms
(no one uses it outside x86_64 anyway).
See https://code.google.com/p/address-sanitizer/issues/detail?id=214 for why we
can't use the glibc clone() wrapper.
llvm-svn: 189753
Handle calls to Die() from the tracer thread. Fixes a bug where a CHECK
could fail in the tracer thread, resulting in a call to AsanDie. The tracer
thread then exited and the parent process continued execution despite its
address space being in an unusable state.
llvm-svn: 189216
Hans Wennborg