[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, 15 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 30e9ebffa28..f5edea7810a 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -201,8 +201,14 @@ static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
 
 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
                                       legacy::PassManagerBase &PM) {
-  PM.add(createAddressSanitizerFunctionPass());
-  PM.add(createAddressSanitizerModulePass());
+  PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/false));
+  PM.add(createAddressSanitizerModulePass(/*CompileKernel*/false));
+}
+
+static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
+                                            legacy::PassManagerBase &PM) {
+  PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/true));
+  PM.add(createAddressSanitizerModulePass(/*CompileKernel*/true));
 }
 
 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
@@ -328,6 +334,13 @@ void EmitAssemblyHelper::CreatePasses() {
                            addAddressSanitizerPasses);
   }
 
+  if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
+    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
+                           addKernelAddressSanitizerPasses);
+    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
+                           addKernelAddressSanitizerPasses);
+  }
+
   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                            addMemorySanitizerPass);