From 8f324cdfc2c3843053b2d5914252390b67754045 Mon Sep 17 00:00:00 2001
From: Bernhard Urban <bernhard.urban@xamarin.com>
Date: Mon, 9 Oct 2017 16:56:11 +0200
Subject: [PATCH] [ASan] introduce MONO_NO_SANITIZE_ADDRESS macro and mark sgen
 pin object scanning function as such

ASan has very few false-positives, quoting the ASan documentation
(https://github.com/google/sanitizers/wiki/AddressSanitizer#turning-off-instrumentation):

> In some cases a particular function should be ignored (not instrumented)
> by AddressSanitizer:
>
>  [...]
>
> * Ignore a function that does some low-level magic (e.g. walking through
>   the thread's stack bypassing the frame boundaries).
>
>  [...]
---
 mono/sgen/sgen-gc.c        |  1 +
 mono/utils/mono-compiler.h | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/mono/sgen/sgen-gc.c b/mono/sgen/sgen-gc.c
index 4c3454823fd..d2b95115825 100644
--- a/mono/sgen/sgen-gc.c
+++ b/mono/sgen/sgen-gc.c
@@ -792,6 +792,7 @@ sgen_sort_addresses (void **array, size_t size)
  * to the area between start_nursery and end_nursery for later consideration.
  * Typically used for thread stacks.
  */
+MONO_NO_SANITIZE_ADDRESS
 void
 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
 {
diff --git a/mono/utils/mono-compiler.h b/mono/utils/mono-compiler.h
index f8481d004d1..b4509ef4c34 100644
--- a/mono/utils/mono-compiler.h
+++ b/mono/utils/mono-compiler.h
@@ -117,13 +117,22 @@ typedef SSIZE_T ssize_t;
 #endif
 
 #if defined(__has_feature)
+
 #if __has_feature(thread_sanitizer)
 #define MONO_HAS_CLANG_THREAD_SANITIZER 1
 #else
 #define MONO_HAS_CLANG_THREAD_SANITIZER 0
 #endif
+
+#if __has_feature(address_sanitizer)
+#define MONO_HAS_CLANG_ADDRESS_SANITIZER 1
+#else
+#define MONO_HAS_CLANG_ADDRESS_SANITIZER 0
+#endif
+
 #else
 #define MONO_HAS_CLANG_THREAD_SANITIZER 0
+#define MONO_HAS_CLANG_ADDRESS_SANITIZER 0
 #endif
 
 /* Used to tell Clang's ThreadSanitizer to not report data races that occur within a certain function */
@@ -133,6 +142,13 @@ typedef SSIZE_T ssize_t;
 #define MONO_NO_SANITIZE_THREAD
 #endif
 
+/* Used to tell Clang's AddressSanitizer to turn off instrumentation for a certain function */
+#if MONO_HAS_CLANG_ADDRESS_SANITIZER
+#define MONO_NO_SANITIZE_ADDRESS __attribute__ ((no_sanitize("address")))
+#else
+#define MONO_NO_SANITIZE_ADDRESS
+#endif
+
 /* Used when building with Android NDK's unified headers */
 #if defined(HOST_ANDROID) && defined (ANDROID_UNIFIED_HEADERS)
 #if __ANDROID_API__ < 21
-- 
2.11.4.GIT