[Driver] Default Android toolchains to noexecstack.

Android does not support executable stacks.

Reviewers: srhines, pirama

Reviewed By: pirama

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D53343

llvm-svn: 357197

clang/include/clang/Driver/ToolChain.h

@@ -412,6 +412,9 @@ class ToolChain {
   /// Test whether this toolchain defaults to PIE.
   virtual bool isPIEDefault() const = 0;
 
+  /// Test whether this toolchaind defaults to non-executable stacks.
+  virtual bool isNoExecStackDefault() const;
+
   /// Tests whether this toolchain forces its default for PIC, PIE or
   /// non-PIC.  If this returns true, any PIC related flags should be ignored
   /// and instead the results of \c isPICDefault() and \c isPIEDefault() are

clang/lib/Driver/ToolChain.cpp

@@ -112,6 +112,10 @@ bool ToolChain::useRelaxRelocations() const {
   return ENABLE_X86_RELAX_RELOCATIONS;
 }
 
+bool ToolChain::isNoExecStackDefault() const {
+    return false;
+}
+
 const SanitizerArgs& ToolChain::getSanitizerArgs() const {
   if (!SanitizerArguments.get())
     SanitizerArguments.reset(new SanitizerArgs(*this, Args));

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2053,6 +2053,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
   bool TakeNextArg = false;
 
   bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations();
+  bool UseNoExecStack = C.getDefaultToolChain().isNoExecStackDefault();
   const char *MipsTargetFeature = nullptr;
   for (const Arg *A :
        Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
@@ -2134,7 +2135,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
       } else if (Value == "--fatal-warnings") {
         CmdArgs.push_back("-massembler-fatal-warnings");
       } else if (Value == "--noexecstack") {
-        CmdArgs.push_back("-mnoexecstack");
+        UseNoExecStack = true;
       } else if (Value.startswith("-compress-debug-sections") ||
                  Value.startswith("--compress-debug-sections") ||
                  Value == "-nocompress-debug-sections" ||
@@ -2197,6 +2198,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
   }
   if (UseRelaxRelocations)
     CmdArgs.push_back("--mrelax-relocations");
+  if (UseNoExecStack)
+    CmdArgs.push_back("-mnoexecstack");
   if (MipsTargetFeature != nullptr) {
     CmdArgs.push_back("-target-feature");
     CmdArgs.push_back(MipsTargetFeature);

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -360,6 +360,11 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("--no-dynamic-linker");
   }
 
+  if (ToolChain.isNoExecStackDefault()) {
+    CmdArgs.push_back("-z");
+    CmdArgs.push_back("noexecstack");
+  }
+
   if (Args.hasArg(options::OPT_rdynamic))
     CmdArgs.push_back("-export-dynamic");
 
@@ -609,6 +614,10 @@ void tools::gnutools::Assembler::ConstructJob(Compilation &C,
     }
   }
 
+  if (getToolChain().isNoExecStackDefault()) {
+      CmdArgs.push_back("--noexecstack");
+  }
+
   switch (getToolChain().getArch()) {
   default:
     break;

clang/lib/Driver/ToolChains/Linux.cpp

@@ -971,6 +971,10 @@ bool Linux::isPIEDefault() const {
           getTriple().isMusl() || getSanitizerArgs().requiresPIE();
 }
 
+bool Linux::isNoExecStackDefault() const {
+    return getTriple().isAndroid();
+}
+
 bool Linux::IsMathErrnoDefault() const {
   if (getTriple().isAndroid())
     return false;

clang/lib/Driver/ToolChains/Linux.h

@@ -38,6 +38,7 @@ class LLVM_LIBRARY_VISIBILITY Linux : public Generic_ELF {
                            llvm::opt::ArgStringList &CC1Args) const override;
   CXXStdlibType GetDefaultCXXStdlibType() const override;
   bool isPIEDefault() const override;
+  bool isNoExecStackDefault() const override;
   bool IsMathErrnoDefault() const override;
   SanitizerMask getSupportedSanitizers() const override;
   void addProfileRTLibs(const llvm::opt::ArgList &Args,

clang/test/Driver/integrated-as.c

@@ -13,3 +13,8 @@
 // NOFIAS-NOT: cc1as
 // NOFIAS: -cc1
 // NOFIAS: -no-integrated-as
+
+// RUN: %clang -target arm-linux-androideabi -### \
+// RUN:   -integrated-as -c %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-ARM-ANDROID %s
+// CHECK-ARM-ANDROID: "-mnoexecstack"

clang/test/Driver/linux-as.c

@@ -108,12 +108,12 @@
 // RUN: %clang -target arm-linux-androideabi -### \
 // RUN:   -no-integrated-as -c %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-ARM-ANDROID %s
-// CHECK-ARM-ANDROID: as{{(.exe)?}}" "-EL" "-mfloat-abi=soft"
+// CHECK-ARM-ANDROID: as{{(.exe)?}}" "--noexecstack" "-EL" "-mfloat-abi=soft"
 //
 // RUN: %clang -target arm-linux-androideabi -march=armv7-a -### \
 // RUN:   -no-integrated-as -c %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-ARM-ANDROID-SOFTFP %s
-// CHECK-ARM-ANDROID-SOFTFP: as{{(.exe)?}}" "-EL" "-mfloat-abi=softfp" "-march=armv7-a"
+// CHECK-ARM-ANDROID-SOFTFP: as{{(.exe)?}}" "--noexecstack" "-EL" "-mfloat-abi=softfp" "-march=armv7-a"
 //
 // RUN: %clang -target arm-linux-eabi -mhard-float -### \
 // RUN:   -no-integrated-as -c %s 2>&1 \

clang/test/Driver/linux-ld.c

@@ -997,6 +997,15 @@
 // RUN:   | FileCheck --check-prefix=CHECK-ANDROID-HASH-STYLE-M %s
 // CHECK-ANDROID-HASH-STYLE-M: "{{.*}}ld{{(.exe)?}}"
 // CHECK-ANDROID-HASH-STYLE-M: "--hash-style=gnu"
+
+// RUN: %clang %s -### -o %t.o 2>&1 \
+// RUN:     --target=armv7-linux-android21 \
+// RUN:   | FileCheck --check-prefix=CHECK-ANDROID-NOEXECSTACK %s
+// CHECK-ANDROID-NOEXECSTACK: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-NOEXECSTACK: "-z" "noexecstack"
+// CHECK-ANDROID-NOEXECSTACK-NOT: "-z" "execstack"
+// CHECK-ANDROID-NOEXECSTACK-NOT: "-z,execstack"
+// CHECK-ANDROID-NOEXECSTACK-NOT: "-zexecstack"
 //
 // RUN: %clang %s -### -o %t.o 2>&1 --target=mips64-linux-gnuabin32 \
 // RUN:   | FileCheck --check-prefix=CHECK-MIPS64EL-GNUABIN32 %s