1 files changed, 52 insertions, 0 deletions
diff --git a/lib/hwasan/hwasan_poisoning.cpp b/lib/hwasan/hwasan_poisoning.cpp
new file mode 100644
index 000000000000..2a0816428e75
--- /dev/null
+++ b/lib/hwasan/hwasan_poisoning.cpp
@@ -0,0 +1,52 @@
+//===-- hwasan_poisoning.cpp ------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of HWAddressSanitizer.
+//
+//===----------------------------------------------------------------------===//
+
+#include "hwasan_poisoning.h"
+
+#include "hwasan_mapping.h"
+#include "interception/interception.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_linux.h"
+
+namespace __hwasan {
+
+uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
+  CHECK(IsAligned(p, kShadowAlignment));
+  CHECK(IsAligned(size, kShadowAlignment));
+  uptr shadow_start = MemToShadow(p);
+  uptr shadow_size = MemToShadowSize(size);
+
+  uptr page_size = GetPageSizeCached();
+  uptr page_start = RoundUpTo(shadow_start, page_size);
+  uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size);
+  uptr threshold = common_flags()->clear_shadow_mmap_threshold;
+  if (SANITIZER_LINUX &&
+      UNLIKELY(page_end >= page_start + threshold && tag == 0)) {
+    internal_memset((void *)shadow_start, tag, page_start - shadow_start);
+    internal_memset((void *)page_end, tag,
+                    shadow_start + shadow_size - page_end);
+    // For an anonymous private mapping MADV_DONTNEED will return a zero page on
+    // Linux.
+    ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end);
+  } else {
+    internal_memset((void *)shadow_start, tag, shadow_size);
+  }
+  return AddTagToPointer(p, tag);
+}
+
+uptr TagMemory(uptr p, uptr size, tag_t tag) {
+  uptr start = RoundDownTo(p, kShadowAlignment);
+  uptr end = RoundUpTo(p + size, kShadowAlignment);
+  return TagMemoryAligned(start, end - start, tag);
+}
+
+}  // namespace __hwasan