[asan] when a fake stack is being unmapped also flush the corresponding shadow

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@197040 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/asan/asan_poisoning.cc b/lib/asan/asan_poisoning.cc
index 28b22751c..a4e6c0a23 100644
--- a/lib/asan/asan_poisoning.cc
+++ b/lib/asan/asan_poisoning.cc
@@ -50,6 +50,15 @@ struct ShadowSegmentEndpoint {
   }
 };
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+    // Since asan's mapping is compacting, the shadow chunk may be
+    // not page-aligned, so we only flush the page-aligned portion.
+    uptr page_size = GetPageSizeCached();
+    uptr shadow_beg = RoundUpTo(MemToShadow(p), page_size);
+    uptr shadow_end = RoundDownTo(MemToShadow(p + size), page_size);
+    FlushUnneededShadowMemory(shadow_beg, shadow_end - shadow_beg);
+}
+
 }  // namespace __asan
 
 // ---------------------- Interface ---------------- {{{1