1 files changed, 48 insertions, 0 deletions
diff --git a/test/sanitizer_common/TestCases/Linux/signal_segv_handler.cc b/test/sanitizer_common/TestCases/Linux/signal_segv_handler.cc
new file mode 100644
index 000000000000..643fb48ae773
--- /dev/null
+++ b/test/sanitizer_common/TestCases/Linux/signal_segv_handler.cc
@@ -0,0 +1,48 @@
+// RUN: %clangxx -O1 %s -o %t && TSAN_OPTIONS="flush_memory_ms=1 memory_limit_mb=1" ASAN_OPTIONS="handle_segv=0 allow_user_segv_handler=1" %run %t 2>&1 | FileCheck %s
+
+// JVM uses SEGV to preempt threads. All threads do a load from a known address
+// periodically. When runtime needs to preempt threads, it unmaps the page.
+// Threads start triggering SEGV one by one. The signal handler blocks
+// threads while runtime does its thing. Then runtime maps the page again
+// and resumes the threads.
+// Previously this pattern conflicted with stop-the-world machinery,
+// because it briefly reset SEGV handler to SIG_DFL.
+// As the consequence JVM just silently died.
+
+// This test sets memory flushing rate to maximum, then does series of
+// "benign" SEGVs that are handled by signal handler, and ensures that
+// the process survive.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <unistd.h>
+
+unsigned long page_size;
+void *guard;
+
+void handler(int signo, siginfo_t *info, void *uctx) {
+  mprotect(guard, page_size, PROT_READ | PROT_WRITE);
+}
+
+int main() {
+  page_size = sysconf(_SC_PAGESIZE);
+  struct sigaction a, old;
+  memset(&a, 0, sizeof(a));
+  memset(&old, 0, sizeof(old));
+  a.sa_sigaction = handler;
+  a.sa_flags = SA_SIGINFO;
+  sigaction(SIGSEGV, &a, &old);
+  guard = mmap(0, 3 * page_size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+  guard = (char*)guard + page_size;  // work around a kernel bug 
+  for (int i = 0; i < 1000000; i++) {
+    mprotect(guard, page_size, PROT_NONE);
+    *(int*)guard = 1;
+  }
+  sigaction(SIGSEGV, &old, 0);
+  fprintf(stderr, "DONE\n");
+}
+
+// CHECK: DONE