Import compiler-rt trunk r224034.vendor/compiler-rt/compiler-rt-r224034

https://llvm.org/svn/llvm-project/compiler-rt/trunk@224034

1 files changed, 31 insertions, 1 deletions

diff --git a/lib/asan/asan_poisoning.h b/lib/asan/asan_poisoning.h
index fbac21196b8f..feda1a984544 100644
--- a/lib/asan/asan_poisoning.h
+++ b/lib/asan/asan_poisoning.h
@@ -15,6 +15,7 @@
 #include "asan_interceptors.h"
 #include "asan_internal.h"
 #include "asan_mapping.h"
+#include "sanitizer_common/sanitizer_flags.h"
 
 namespace __asan {
 
@@ -37,7 +38,32 @@ ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
   uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
   uptr shadow_end = MEM_TO_SHADOW(
       aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1;
-  REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
+  // FIXME: Page states are different on Windows, so using the same interface
+  // for mapping shadow and zeroing out pages doesn't "just work", so we should
+  // probably provide higher-level interface for these operations.
+  // For now, just memset on Windows.
+  if (value ||
+      SANITIZER_WINDOWS == 1 ||
+      shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
+    REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
+  } else {
+    uptr page_size = GetPageSizeCached();
+    uptr page_beg = RoundUpTo(shadow_beg, page_size);
+    uptr page_end = RoundDownTo(shadow_end, page_size);
+
+    if (page_beg >= page_end) {
+      REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
+    } else {
+      if (page_beg != shadow_beg) {
+        REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
+      }
+      if (page_end != shadow_end) {
+        REAL(memset)((void *)page_end, 0, shadow_end - page_end);
+      }
+      void *res = MmapFixedNoReserve(page_beg, page_end - page_beg);
+      CHECK_EQ(page_beg, res);
+    }
+  }
 }
 
 ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
@@ -57,4 +83,8 @@ ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
   }
 }
 
+// Calls __sanitizer::FlushUnneededShadowMemory() on
+// [MemToShadow(p), MemToShadow(p+size)] with proper rounding.
+void FlushUnneededASanShadowMemory(uptr p, uptr size);
+
 }  // namespace __asan