[ASan] Allow to atomically modify malloc_context_size at runtime.

Summary:
Introduce __asan::malloc_context_size atomic that is used to determine
required malloc/free stack trace size. It is initialized with
common_flags()->malloc_context_size flag, but can later be overwritten
at runtime (e.g. when ASan is activated / deactivated).

Test Plan: regression test suite

Reviewers: kcc, eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6645

llvm-svn: 224305

1 files changed, 15 insertions, 0 deletions

diff --git a/compiler-rt/lib/asan/asan_stack.cc b/compiler-rt/lib/asan/asan_stack.cc
index 8188f3b5b6e..cf7a587fa65 100644
--- a/compiler-rt/lib/asan/asan_stack.cc
+++ b/compiler-rt/lib/asan/asan_stack.cc
@@ -13,6 +13,21 @@
 //===----------------------------------------------------------------------===//
 #include "asan_internal.h"
 #include "asan_stack.h"
+#include "sanitizer_common/sanitizer_atomic.h"
+
+namespace __asan {
+
+static atomic_uint32_t malloc_context_size;
+
+void SetMallocContextSize(u32 size) {
+  atomic_store(&malloc_context_size, size, memory_order_release);
+}
+
+u32 GetMallocContextSize() {
+  return atomic_load(&malloc_context_size, memory_order_acquire);
+}
+
+}  // namespace __asan
 
 // ------------------ Interface -------------- {{{1