Revert "[ASan] Removed ASAN_SHADOW_SCALE."

This reverts commit e4800fc099ad204f88c432276e6488772042bffc.

Reviewed By: kstoimenov

Differential Revision: https://reviews.llvm.org/D115286

4 files changed, 30 insertions, 2 deletions

diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
index bcab7e006108..a8c58069ce4e 100644
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -52,6 +52,25 @@ mark_as_advanced(COMPILER_RT_BUILD_ORC)
 option(COMPILER_RT_BUILD_GWP_ASAN "Build GWP-ASan, and link it into SCUDO" ON)
 mark_as_advanced(COMPILER_RT_BUILD_GWP_ASAN)
 
+set(COMPILER_RT_ASAN_SHADOW_SCALE ""
+    CACHE STRING "Override the shadow scale to be used in ASan runtime")
+
+if (NOT COMPILER_RT_ASAN_SHADOW_SCALE STREQUAL "")
+  # Check that the shadow scale value is valid.
+  if (NOT (COMPILER_RT_ASAN_SHADOW_SCALE GREATER -1 AND
+           COMPILER_RT_ASAN_SHADOW_SCALE LESS 8))
+    message(FATAL_ERROR "
+      Invalid ASan Shadow Scale '${COMPILER_RT_ASAN_SHADOW_SCALE}'.")
+  endif()
+
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_LLVM_FLAG
+      -mllvm -asan-mapping-scale=${COMPILER_RT_ASAN_SHADOW_SCALE})
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_DEFINITION
+      ASAN_SHADOW_SCALE=${COMPILER_RT_ASAN_SHADOW_SCALE})
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_FLAG
+      -D${COMPILER_RT_ASAN_SHADOW_SCALE_DEFINITION})
+endif()
+
 if(FUCHSIA)
   set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT OFF)
 else()
diff --git a/compiler-rt/lib/asan/asan_mapping.h b/compiler-rt/lib/asan/asan_mapping.h
index 42751390669d..5e73caa61bf9 100644
--- a/compiler-rt/lib/asan/asan_mapping.h
+++ b/compiler-rt/lib/asan/asan_mapping.h
@@ -151,10 +151,15 @@
 // || `[0x30000000, 0x35ffffff]` || LowShadow  ||
 // || `[0x00000000, 0x2fffffff]` || LowMem     ||
 
-#define SHADOW_SCALE 3
-
+#if defined(ASAN_SHADOW_SCALE)
+static const u64 kDefaultShadowScale = ASAN_SHADOW_SCALE;
+#else
+static const u64 kDefaultShadowScale = 3;
+#endif
 static const u64 kDefaultShadowSentinel = ~(uptr)0;
 
+#define SHADOW_SCALE kDefaultShadowScale
+
 #if SANITIZER_FUCHSIA
 #  define SHADOW_OFFSET_CONST (0)
 #elif SANITIZER_WORDSIZE == 32
diff --git a/compiler-rt/lib/asan/tests/CMakeLists.txt b/compiler-rt/lib/asan/tests/CMakeLists.txt
index cc375acf2dfb..1a77d89469b9 100644
--- a/compiler-rt/lib/asan/tests/CMakeLists.txt
+++ b/compiler-rt/lib/asan/tests/CMakeLists.txt
@@ -23,6 +23,7 @@ set(ASAN_UNITTEST_HEADERS
 set(ASAN_UNITTEST_COMMON_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
+  ${COMPILER_RT_ASAN_SHADOW_SCALE_LLVM_FLAG}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/asan
@@ -51,6 +52,7 @@ list(APPEND ASAN_UNITTEST_COMMON_LINK_FLAGS -g)
 
 # Use -D instead of definitions to please custom compile command.
 list(APPEND ASAN_UNITTEST_COMMON_CFLAGS
+  ${COMPILER_RT_ASAN_SHADOW_SCALE_FLAG}
   -DASAN_HAS_IGNORELIST=1
   -DASAN_HAS_EXCEPTIONS=1
   -DASAN_UAR=0
diff --git a/compiler-rt/lib/asan/tests/asan_interface_test.cpp b/compiler-rt/lib/asan/tests/asan_interface_test.cpp
index 6ea04191d789..47cbf0e8927f 100644
--- a/compiler-rt/lib/asan/tests/asan_interface_test.cpp
+++ b/compiler-rt/lib/asan/tests/asan_interface_test.cpp
@@ -160,6 +160,7 @@ TEST(AddressSanitizerInterface, DeathCallbackTest) {
 #define BAD_ACCESS(ptr, offset) \
     EXPECT_TRUE(__asan_address_is_poisoned(ptr + offset))
 
+#if !defined(ASAN_SHADOW_SCALE) || ASAN_SHADOW_SCALE == 3
 static const char* kUseAfterPoisonErrorMessage = "use-after-poison";
 
 TEST(AddressSanitizerInterface, SimplePoisonMemoryRegionTest) {
@@ -199,6 +200,7 @@ TEST(AddressSanitizerInterface, OverlappingPoisonMemoryRegionTest) {
   BAD_ACCESS(array, 96);
   free(array);
 }
+#endif  // !defined(ASAN_SHADOW_SCALE) || ASAN_SHADOW_SCALE == 3
 
 TEST(AddressSanitizerInterface, PushAndPopWithPoisoningTest) {
   // Vector of capacity 20