Add top-level Clang flag -f(no-)sanitize-address-zero-base-shadow that makes AddressSanitizer use bottom of the address space for the shadow memory. On Linux it can be used with -fPIE/-pie to improve performance.

llvm-svn: 172974

4 files changed, 38 insertions, 11 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 8a3ee398cd1..b938aacf1fc 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -164,12 +164,16 @@ static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
       static_cast<const PassManagerBuilderWrapper&>(Builder);
   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
-  PM.add(createAddressSanitizerFunctionPass(LangOpts.Sanitize.InitOrder,
-                                            LangOpts.Sanitize.UseAfterReturn,
-                                            LangOpts.Sanitize.UseAfterScope,
-                                            CGOpts.SanitizerBlacklistFile));
-  PM.add(createAddressSanitizerModulePass(LangOpts.Sanitize.InitOrder,
-                                          CGOpts.SanitizerBlacklistFile));
+  PM.add(createAddressSanitizerFunctionPass(
+      LangOpts.Sanitize.InitOrder,
+      LangOpts.Sanitize.UseAfterReturn,
+      LangOpts.Sanitize.UseAfterScope,
+      CGOpts.SanitizerBlacklistFile,
+      CGOpts.SanitizeAddressZeroBaseShadow));
+  PM.add(createAddressSanitizerModulePass(
+      LangOpts.Sanitize.InitOrder,
+      CGOpts.SanitizerBlacklistFile,
+      CGOpts.SanitizeAddressZeroBaseShadow));
 }
 
 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
@@ -177,7 +181,7 @@ static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
   const PassManagerBuilderWrapper &BuilderWrapper =
       static_cast<const PassManagerBuilderWrapper&>(Builder);
   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  PM.add(createMemorySanitizerPass(CGOpts.MemorySanitizerTrackOrigins,
+  PM.add(createMemorySanitizerPass(CGOpts.SanitizeMemoryTrackOrigins,
                                    CGOpts.SanitizerBlacklistFile));
 }
 
diff --git a/clang/lib/Driver/SanitizerArgs.h b/clang/lib/Driver/SanitizerArgs.h
index 09558890045..ea89904e584 100644
--- a/clang/lib/Driver/SanitizerArgs.h
+++ b/clang/lib/Driver/SanitizerArgs.h
@@ -41,9 +41,11 @@ class SanitizerArgs {
   unsigned Kind;
   std::string BlacklistFile;
   bool MsanTrackOrigins;
+  bool AsanZeroBaseShadow;
 
  public:
-  SanitizerArgs() : Kind(0), BlacklistFile(""), MsanTrackOrigins(false) {}
+  SanitizerArgs() : Kind(0), BlacklistFile(""), MsanTrackOrigins(false),
+                    AsanZeroBaseShadow(false) {}
   /// Parses the sanitizer arguments from an argument list.
   SanitizerArgs(const Driver &D, const ArgList &Args);
 
@@ -72,6 +74,10 @@ class SanitizerArgs {
 
     if (MsanTrackOrigins)
       CmdArgs.push_back(Args.MakeArgString("-fsanitize-memory-track-origins"));
+
+    if (AsanZeroBaseShadow)
+      CmdArgs.push_back(Args.MakeArgString(
+          "-fsanitize-address-zero-base-shadow"));
   }
 
  private:
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 3132e75000d..0cc9ea25373 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1444,7 +1444,8 @@ static bool UseRelaxAll(Compilation &C, const ArgList &Args) {
 }
 
 SanitizerArgs::SanitizerArgs(const Driver &D, const ArgList &Args)
-    : Kind(0), BlacklistFile(""), MsanTrackOrigins(false) {
+    : Kind(0), BlacklistFile(""), MsanTrackOrigins(false),
+      AsanZeroBaseShadow(false) {
 
   for (ArgList::const_iterator I = Args.begin(), E = Args.end(); I != E; ++I) {
     unsigned Add, Remove;
@@ -1493,11 +1494,18 @@ SanitizerArgs::SanitizerArgs(const Driver &D, const ArgList &Args)
   }
 
   // Parse -f(no-)sanitize-memory-track-origins options.
-  if (Kind & Memory)
+  if (NeedsMsan)
     MsanTrackOrigins =
       Args.hasFlag(options::OPT_fsanitize_memory_track_origins,
                    options::OPT_fno_sanitize_memory_track_origins,
                    /* Default */false);
+
+  // Parse -f(no-)sanitize-address-zero-base-shadow options.
+  if (NeedsAsan)
+    AsanZeroBaseShadow =
+      Args.hasFlag(options::OPT_fsanitize_address_zero_base_shadow,
+                   options::OPT_fno_sanitize_address_zero_base_shadow,
+                   /* Default */false);
 }
 
 /// If AddressSanitizer is enabled, add appropriate linker flags (Linux).
@@ -1517,6 +1525,13 @@ static void addAsanRTLinux(const ToolChain &TC, const ArgList &Args,
     CmdArgs.insert(CmdArgs.begin(), Args.MakeArgString(LibAsan));
   } else {
     if (!Args.hasArg(options::OPT_shared)) {
+      bool ZeroBaseShadow = Args.hasFlag(
+          options::OPT_fsanitize_address_zero_base_shadow,
+          options::OPT_fno_sanitize_address_zero_base_shadow, false);
+      if (ZeroBaseShadow && !Args.hasArg(options::OPT_pie)) {
+        TC.getDriver().Diag(diag::err_drv_argument_only_allowed_with) <<
+            "-fsanitize-address-zero-base-shadow" << "-pie";
+      }
       // LibAsan is "libclang_rt.asan-<ArchName>.a" in the Linux library
       // resource directory.
       SmallString<128> LibAsan(TC.getDriver().ResourceDir);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 9329b3bc1b0..a16b822d235 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -404,8 +404,10 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
   Opts.LinkBitcodeFile = Args.getLastArgValue(OPT_mlink_bitcode_file);
   Opts.SanitizerBlacklistFile = Args.getLastArgValue(OPT_fsanitize_blacklist);
-  Opts.MemorySanitizerTrackOrigins =
+  Opts.SanitizeMemoryTrackOrigins =
     Args.hasArg(OPT_fsanitize_memory_track_origins);
+  Opts.SanitizeAddressZeroBaseShadow =
+    Args.hasArg(OPT_fsanitize_address_zero_base_shadow);
   Opts.SSPBufferSize =
     Args.getLastArgIntValue(OPT_stack_protector_buffer_size, 8, Diags);
   Opts.StackRealignment = Args.hasArg(OPT_mstackrealign);