[ASan] Initial support for Kernel AddressSanitizer

This patch adds initial support for the -fsanitize=kernel-address flag to Clang.
Right now it's quite restricted: only out-of-line instrumentation is supported, globals are not instrumented, some GCC kasan flags are not supported.
Using this patch I am able to build and boot the KASan tree with LLVMLinux patches from github.com/ramosian-glider/kasan/tree/kasan_llvmlinux.
To disable KASan instrumentation for a certain function attribute((no_sanitize("kernel-address"))) can be used.

llvm-svn: 240131

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index c63cafb6d79..ccfb30240b0 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1049,7 +1049,9 @@ static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
     Feature = Feature.substr(2, Feature.size() - 4);
 
   return llvm::StringSwitch<bool>(Feature)
-      .Case("address_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Address))
+      .Case("address_sanitizer",
+            LangOpts.Sanitize.hasOneOf(SanitizerKind::Address |
+                                       SanitizerKind::KernelAddress))
       .Case("attribute_analyzer_noreturn", true)
       .Case("attribute_availability", true)
       .Case("attribute_availability_with_message", true)