[libcxx-commits] [libcxxabi] f326df3 - [libunwind][AArch64] Fix _Unwind_ForcedUnwind via sigreturn.

[Daniel Kiss via libcxx-commits]

Author: Daniel Kiss
Date: 2022-04-28T18:41:38+02:00
New Revision: f326df34bc179e41ea17d31e1ffba4a479e45589

URL: https://github.com/llvm/llvm-project/commit/f326df34bc179e41ea17d31e1ffba4a479e45589
DIFF: https://github.com/llvm/llvm-project/commit/f326df34bc179e41ea17d31e1ffba4a479e45589.diff

LOG: [libunwind][AArch64] Fix _Unwind_ForcedUnwind via sigreturn.

When the sigreturn trampoline is found the unw_proc_info_t.end_ip need to be set to
indicate a stack frame is found.

Reviewed By: cjdb, #libunwind, MaskRay

Differential Revision: https://reviews.llvm.org/D124522

Added: 
    libcxxabi/test/forced_unwind4.pass.cpp

Modified: 
    libunwind/src/UnwindCursor.hpp

Removed: 
    


################################################################################
diff  --git a/libcxxabi/test/forced_unwind4.pass.cpp b/libcxxabi/test/forced_unwind4.pass.cpp
new file mode 100644
index 0000000000000..53a0121da92e4
--- /dev/null
+++ b/libcxxabi/test/forced_unwind4.pass.cpp
@@ -0,0 +1,50 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: linux && target={{aarch64-.+}}
+
+// pthread_cancel in case of glibc calls _Unwind_ForcedUnwind from a signal on
+// the child_thread. This test ensures sigretrun is handled correctly (see:
+// UnwindCursor<A, R>::setInfoForSigReturn).
+
+#include <chrono>
+#include <condition_variable>
+#include <pthread.h>
+#include <unistd.h>
+
+using namespace std::chrono_literals;
+
+std::condition_variable cv;
+std::mutex cv_m;
+bool thread_ready = false;
+
+static void* test(void* arg) {
+  (void)arg;
+  thread_ready = true;
+  cv.notify_all();
+
+  // This must be a pthread cancellation point.
+  while (1)
+    sleep(100);
+
+  return (void*)1;
+}
+
+int main() {
+  pthread_t child_thread;
+  std::unique_lock<std::mutex> lk(cv_m);
+  pthread_create(&child_thread, 0, test, (void*)0);
+
+  if (!cv.wait_for(lk, 100ms, [] { return thread_ready; }))
+    return -1;
+
+  pthread_cancel(child_thread);
+  pthread_join(child_thread, NULL);
+  return 0;
+}

diff  --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index dd849b781753e..29ded5c4e78ed 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -2606,6 +2606,8 @@ bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
   if (_addressSpace.get32(pc) == 0xd2801168 &&
       _addressSpace.get32(pc + 4) == 0xd4000001) {
     _info = {};
+    _info.start_ip = pc;
+    _info.end_ip = pc + 4;
     _isSigReturn = true;
     return true;
   }