[asan/coverage] change the way asan coverage instrumentation is done: instead of setting the guard to 1 in the generated code, pass the pointer to guard to __sanitizer_cov and set it there. No user-visible functionality change expected
llvm-svn: 222675
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
index bd98adb..af8f943 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
@@ -12,14 +12,14 @@
//
// Compiler instrumentation:
// For every interesting basic block the compiler injects the following code:
-// if (*Guard) {
-// __sanitizer_cov();
-// *Guard = 1;
+// if (Guard) {
+// __sanitizer_cov(&Guard);
// }
// It's fine to call __sanitizer_cov more than once for a given block.
//
// Run-time:
// - __sanitizer_cov(): record that we've executed the PC (GET_CALLER_PC).
+// and atomically set Guard to 1.
// - __sanitizer_cov_dump: dump the coverage data to disk.
// For every module of the current process that has coverage data
// this will create a file module_name.PID.sancov. The file format is simple:
@@ -65,7 +65,7 @@
void BeforeFork();
void AfterFork(int child_pid);
void Extend(uptr npcs);
- void Add(uptr pc);
+ void Add(uptr pc, u8 *guard);
void IndirCall(uptr caller, uptr callee, uptr callee_cache[],
uptr cache_size);
void DumpCallerCalleePairs();
@@ -230,15 +230,19 @@
atomic_store(&pc_array_size, size, memory_order_release);
}
-// Simply add the pc into the vector under lock. If the function is called more
-// than once for a given PC it will be inserted multiple times, which is fine.
-void CoverageData::Add(uptr pc) {
+// Atomically add the pc to the vector. The atomically set the guard to 1.
+// If the function is called more than once for a given PC it will
+// be inserted multiple times, which is fine.
+void CoverageData::Add(uptr pc, u8 *guard) {
if (!pc_array) return;
uptr idx = atomic_fetch_add(&pc_array_index, 1, memory_order_relaxed);
CHECK_LT(idx * sizeof(uptr),
atomic_load(&pc_array_size, memory_order_acquire));
pc_array[idx] = pc;
atomic_fetch_add(&coverage_counter, 1, memory_order_relaxed);
+ // Set the guard.
+ atomic_uint8_t *atomic_guard = reinterpret_cast<atomic_uint8_t*>(guard);
+ atomic_store(atomic_guard, 1, memory_order_relaxed);
}
// Registers a pair caller=>callee.
@@ -537,8 +541,9 @@
} // namespace __sanitizer
extern "C" {
-SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov() {
- coverage_data.Add(StackTrace::GetPreviousInstructionPc(GET_CALLER_PC()));
+SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov(u8 *guard) {
+ coverage_data.Add(StackTrace::GetPreviousInstructionPc(GET_CALLER_PC()),
+ guard);
}
SANITIZER_INTERFACE_ATTRIBUTE void
__sanitizer_cov_indir_call16(uptr callee, uptr callee_cache16[]) {