From 08da675c9421b1a7df9aadee84640908390aeb3c Mon Sep 17 00:00:00 2001
From: Paul Lawrence <paullawrence@google.com>
Date: Tue, 6 Feb 2018 15:36:03 -0800
Subject: [PATCH] BACKPORT: kasan: add compiler support for clang

Patch series "kasan: support alloca, LLVM", v4.

This patch (of 5):

For now we can hard-code ASAN ABI level 5, since historical clang builds
can't build the kernel anyway.  We also need to emulate gcc's
__SANITIZE_ADDRESS__ flag, or memset() calls won't be instrumented.

Link: http://lkml.kernel.org/r/20171204191735.132544-2-paullawrence@google.com
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry-picked from 53a98ed73b848432a51631346b02049bb7fa039d)
Change-Id: I4f694d1c06ad286e165d68938ff0f4348dc5fedf
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 include/linux/compiler-clang.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index eeb2331e9fa3..026517d882c0 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -24,3 +24,11 @@
 
 #define __nocfi		__attribute__((no_sanitize("cfi")))
 #endif
+
+/* all clang versions usable with the kernel support KASAN ABI version 5 */
+#define KASAN_ABI_VERSION 5
+
+/* emulate gcc's __SANITIZE_ADDRESS__ flag */
+#if __has_feature(address_sanitizer)
+#define __SANITIZE_ADDRESS__
+#endif