diff options
Diffstat (limited to 'test/sanitizer_common/TestCases/Linux/signal_segv_handler.cc')
-rw-r--r-- | test/sanitizer_common/TestCases/Linux/signal_segv_handler.cc | 48 |
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 |