[msan] Make origin tracking fork-safe.

Chained origins make plain memory stores async-signal-unsafe.
We already disable it inside signal handlers.
This change grabs all origin-related locks before fork() and releases
them after fork() to avoid a deadlock in the child process.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@217140 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_stackdepotbase.h b/lib/sanitizer_common/sanitizer_stackdepotbase.h
index b4fa87509..d2d3d3498 100644
--- a/lib/sanitizer_common/sanitizer_stackdepotbase.h
+++ b/lib/sanitizer_common/sanitizer_stackdepotbase.h
@@ -32,6 +32,9 @@ class StackDepotBase {
 
   StackDepotStats *GetStats() { return &stats; }
 
+  void LockAll();
+  void UnlockAll();
+
  private:
   static Node *find(Node *s, args_type args, u32 hash);
   static Node *lock(atomic_uintptr_t *p);
@@ -153,5 +156,21 @@ StackDepotBase<Node, kReservedBits, kTabSizeLog>::Get(u32 id) {
   return args_type();
 }
 
+template <class Node, int kReservedBits, int kTabSizeLog>
+void StackDepotBase<Node, kReservedBits, kTabSizeLog>::LockAll() {
+  for (int i = 0; i < kTabSize; ++i) {
+    lock(&tab[i]);
+  }
+}
+
+template <class Node, int kReservedBits, int kTabSizeLog>
+void StackDepotBase<Node, kReservedBits, kTabSizeLog>::UnlockAll() {
+  for (int i = 0; i < kTabSize; ++i) {
+    atomic_uintptr_t *p = &tab[i];
+    uptr s = atomic_load(p, memory_order_relaxed);
+    unlock(p, (Node *)(s & ~1UL));
+  }
+}
+
 }  // namespace __sanitizer
 #endif  // SANITIZER_STACKDEPOTBASE_H