[X86] Control-Flow Enforcement Technology - Shadow Stack and Indirect Branch Tracking support (Clang side)

[oren_ben_simhon]

Summary

Control Flow Enforcement Technology (CET) provides HW capabilities to defend against Return Oriented Programming (ROP) attack and similarly Call/Jmp Oriented Programming (COP/JOP) attack.
Control flow subversion attacks are handled using two CET’s mechanisms:

1. Shadow Stack (SHSTK) – return address protection to defend against ROP.
2. Indirect Branch Tracking (IBT) – free branch protection to defend against JOP/COP.

Shadow stack solution introduces a new stack for return addresses only. The stack has a Shadow Stack Pointer (SSP) that points to the last address to which we expect to return. If we return to a different address an exception is triggered.
This patch includes shadow stack intrinsics as well as the corresponding CET header. It includes CET clang flags for shadow stack and Indirect Branch Tracking.

For more information, please see the following:
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

[erichkeane]

include/clang/Driver/Options.td

1803

Since CET is a union of the other two, how do we handle conflicting configurations? Is -mcet -mno-ibt an error, or the same as mno-shstk? Repeat question for all combinations.

[craig.topper]

include/clang/Basic/BuiltinsX86.def

642

Space after commas to match the rest of the file

include/clang/Driver/Options.td

1803

All the flags should go in the "X86 feature flags" section later in this file.

lib/Basic/Targets/X86.cpp

623

It looks like "cet" is meant to be a alias for two features? Should you avoid putting it in Features map at line 545 lke we do with "sse4"? Then it will never get sent to the backend and you can remove FeatureCET from X86.td

624

Is -mno-cet intended to disable both features? Cause that doesn't happen with the way this is written.

688

This shouldn't be needed. "+cet" implies +shstk and +ibt. Those should be added to feature map before we call this method

1224

I'm not sure what hasFeature is really used for, but I doubt "cet" needs to be in it.

test/CodeGen/builtins-x86.c

260

I don't think you need to update this test. The intrinsic header test should be enough. I don't know why this test exists.

test/Driver/x86-target-features.c

75

Should this check that +shstk and +ibt got added. That seems like the more important thing to check.

[oren_ben_simhon]

include/clang/Driver/Options.td

1803

Since 'mcet' flag (which was supposed to superset the other two) over complicates things, I prefer to remove it at the moment.

test/CodeGen/builtins-x86.c

260

I believe that it is for the case where someone is using the builtin directly instead of using the intrinsic (although this is not recommended). Builtin and intrinsic, although relate to each other, might not converge in the future. In that case it might be worth testing.

[oren_ben_simhon]

Implemented comments posted until 11/20 (Thanks Craig and Erich).

[craig.topper]

include/clang/Basic/BuiltinsX86_64.def

63

Space after commas here too.

test/Preprocessor/x86_target_features.c

336

Should this -mcet case be removed?

[oren_ben_simhon]

Implemented comments posted until 11/21 (Thanks Craig)

[craig.topper]

LGTM

include/clang/Basic/BuiltinsX86.def

 // XSAVE
 TARGET_BUILTIN(__builtin_ia32_xsave, "vv*ULLi", "", "xsave")
 TARGET_BUILTIN(__builtin_ia32_xrstor, "vv*ULLi", "", "xsave")
 TARGET_BUILTIN(__builtin_ia32_xsaveopt, "vv*ULLi", "", "xsaveopt")
 TARGET_BUILTIN(__builtin_ia32_xrstors, "vv*ULLi", "", "xsaves")
 TARGET_BUILTIN(__builtin_ia32_xsavec, "vv*ULLi", "", "xsavec")
 TARGET_BUILTIN(__builtin_ia32_xsaves, "vv*ULLi", "", "xsaves")
 
+// SHSTK
+TARGET_BUILTIN(__builtin_ia32_incsspd, "vUi", "u", "shstk")
+TARGET_BUILTIN(__builtin_ia32_rdsspd, "UiUi", "Un", "shstk")
+TARGET_BUILTIN(__builtin_ia32_saveprevssp, "v", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_rstorssp, "vv*", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_wrssd, "vUiv*", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_wrussd, "vUiv*", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_setssbsy, "v", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_clrssbsy, "vv*", "", "shstk")
+
 //CLFLUSHOPT
 TARGET_BUILTIN(__builtin_ia32_clflushopt, "vvC*", "", "clflushopt")
 
 //CLWB
 TARGET_BUILTIN(__builtin_ia32_clwb, "vvC*", "", "clwb")
 
 // ADX
 TARGET_BUILTIN(__builtin_ia32_addcarryx_u32, "UcUcUiUiUi*", "", "adx")

include/clang/Basic/BuiltinsX86_64.def

 TARGET_BUILTIN(__builtin_ia32_fxrstor64, "vv*", "", "fxsr")
 TARGET_BUILTIN(__builtin_ia32_fxsave64, "vv*", "", "fxsr")
 TARGET_BUILTIN(__builtin_ia32_xsave64, "vv*ULLi", "", "xsave")
 TARGET_BUILTIN(__builtin_ia32_xrstor64, "vv*ULLi", "", "xsave")
 TARGET_BUILTIN(__builtin_ia32_xsaveopt64, "vv*ULLi", "", "xsaveopt")
 TARGET_BUILTIN(__builtin_ia32_xrstors64, "vv*ULLi", "", "xsaves")
 TARGET_BUILTIN(__builtin_ia32_xsavec64, "vv*ULLi", "", "xsavec")
 TARGET_BUILTIN(__builtin_ia32_xsaves64, "vv*ULLi", "", "xsaves")
+TARGET_BUILTIN(__builtin_ia32_incsspq, "vULLi", "u", "shstk")
+TARGET_BUILTIN(__builtin_ia32_rdsspq, "ULLiULLi", "Un", "shstk")
+TARGET_BUILTIN(__builtin_ia32_wrssq, "vULLiv*", "", "shstk")
+TARGET_BUILTIN(__builtin_ia32_wrussq, "vULLiv*", "", "shstk")
 TARGET_BUILTIN(__builtin_ia32_addcarryx_u64, "UcUcULLiULLiULLi*", "", "adx")
 TARGET_BUILTIN(__builtin_ia32_addcarry_u64, "UcUcULLiULLiULLi*", "", "")
 TARGET_BUILTIN(__builtin_ia32_subborrow_u64, "UcUcULLiULLiULLi*", "", "")
 TARGET_BUILTIN(__builtin_ia32_rdseed64_step, "UiULLi*", "", "rdseed")
 TARGET_BUILTIN(__builtin_ia32_bextr_u64, "ULLiULLiULLi", "", "bmi")
 TARGET_BUILTIN(__builtin_ia32_bzhi_di, "ULLiULLiULLi", "", "bmi2")
 TARGET_BUILTIN(__builtin_ia32_pdep_di, "ULLiULLiULLi", "", "bmi2")
 TARGET_BUILTIN(__builtin_ia32_pext_di, "ULLiULLiULLi", "", "bmi2")

include/clang/Driver/Options.td

def mno_global_merge : Flag<["-"], "mno-global-merge">, Group<m_Group>, Flags<[CC1Option]>,
   HelpText<"Disable merging of globals">;
 def mno_pascal_strings : Flag<["-"], "mno-pascal-strings">,
   Alias<fno_pascal_strings>;
 def mno_red_zone : Flag<["-"], "mno-red-zone">, Group<m_Group>;
 def mno_relax_all : Flag<["-"], "mno-relax-all">, Group<m_Group>;
 def mno_rtd: Flag<["-"], "mno-rtd">, Group<m_Group>;
 def mno_soft_float : Flag<["-"], "mno-soft-float">, Group<m_Group>;
 def mno_stackrealign : Flag<["-"], "mno-stackrealign">, Group<m_Group>;
 
 def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>,
   HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64 only)">;
 def mno_unaligned_access : Flag<["-"], "mno-unaligned-access">, Group<m_arm_Features_Group>,
   HelpText<"Force all memory accesses to be aligned (AArch32/AArch64 only)">;
 def mstrict_align : Flag<["-"], "mstrict-align">, Alias<mno_unaligned_access>, Flags<[CC1Option,HelpHidden]>,
   HelpText<"Force all memory accesses to be aligned (same as mno-unaligned-access)">;
 def mno_thumb : Flag<["-"], "mno-thumb">, Group<m_arm_Features_Group>;
 def mrestrict_it: Flag<["-"], "mrestrict-it">, Group<m_arm_Features_Group>,

 def mxsave : Flag<["-"], "mxsave">, Group<m_x86_Features_Group>;
 def mno_xsave : Flag<["-"], "mno-xsave">, Group<m_x86_Features_Group>;
 def mxsavec : Flag<["-"], "mxsavec">, Group<m_x86_Features_Group>;
 def mno_xsavec : Flag<["-"], "mno-xsavec">, Group<m_x86_Features_Group>;
 def mxsaveopt : Flag<["-"], "mxsaveopt">, Group<m_x86_Features_Group>;
 def mno_xsaveopt : Flag<["-"], "mno-xsaveopt">, Group<m_x86_Features_Group>;
 def mxsaves : Flag<["-"], "mxsaves">, Group<m_x86_Features_Group>;
 def mno_xsaves : Flag<["-"], "mno-xsaves">, Group<m_x86_Features_Group>;
-
+def mshstk : Flag<["-"], "mshstk">, Group<m_x86_Features_Group>;
+def mno_shstk : Flag<["-"], "mno-shstk">, Group<m_x86_Features_Group>;
+def mibt : Flag<["-"], "mibt">, Group<m_x86_Features_Group>;
+def mno_ibt : Flag<["-"], "mno-ibt">, Group<m_x86_Features_Group>;
 
 // These are legacy user-facing driver-level option spellings. They are always
 // aliases for options that are spelled using the more common Unix / GNU flag
 // style of double-dash and equals-joined flags.
 def gcc_toolchain_legacy_spelling : Separate<["-"], "gcc-toolchain">, Alias<gcc_toolchain>;
 def target_legacy_spelling : Separate<["-"], "target">, Alias<target>;
 
 // Special internal option to handle -Xlinker --no-demangle.

lib/Basic/Targets/X86.h

class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
   bool HasAVX512PF = false;
   bool HasAVX512DQ = false;
   bool HasAVX512BW = false;
   bool HasAVX512VL = false;
   bool HasAVX512VBMI = false;
   bool HasAVX512IFMA = false;
   bool HasSHA = false;
   bool HasMPX = false;
+  bool HasSHSTK = false;
+  bool HasIBT = false;
   bool HasSGX = false;
   bool HasCX16 = false;
   bool HasFXSR = false;
   bool HasXSAVE = false;
   bool HasXSAVEOPT = false;
   bool HasXSAVEC = false;
   bool HasXSAVES = false;
   bool HasMWAITX = false;

lib/Basic/Targets/X86.cpp

if (Name == "mmx") {
     else
       setSSELevel(Features, SSE41, Enabled);
   } else if (Name == "xsave") {
     if (!Enabled)
       Features["xsaveopt"] = false;
   } else if (Name == "xsaveopt" || Name == "xsavec" || Name == "xsaves") {
     if (Enabled)
       Features["xsave"] = true;
   }
 }
 
 /// handleTargetFeatures - Perform initialization based on the user
 /// configured set of features.
 bool X86TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
                                          DiagnosticsEngine &Diags) {
   for (const auto &Feature : Features) {
     if (Feature[0] != '+')
       continue;
for (const auto &Feature : Features) {
     } else if (Feature == "+avx512vbmi") {
       HasAVX512VBMI = true;
     } else if (Feature == "+avx512ifma") {
       HasAVX512IFMA = true;
     } else if (Feature == "+sha") {
       HasSHA = true;
     } else if (Feature == "+mpx") {
       HasMPX = true;
+    } else if (Feature == "+shstk") {
+      HasSHSTK = true;
+    } else if (Feature == "+ibt") {
+      HasIBT = true;
     } else if (Feature == "+movbe") {
       HasMOVBE = true;
     } else if (Feature == "+sgx") {
       HasSGX = true;
     } else if (Feature == "+cx16") {
       HasCX16 = true;
     } else if (Feature == "+fxsr") {
       HasFXSR = true;
void X86TargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasCX16)
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_16");
   if (HasCLFLUSHOPT)
     Builder.defineMacro("__CLFLUSHOPT__");
   if (HasCLWB)
     Builder.defineMacro("__CLWB__");
   if (HasMPX)
     Builder.defineMacro("__MPX__");
+  if (HasSHSTK)
+    Builder.defineMacro("__SHSTK__");
   if (HasSGX)
     Builder.defineMacro("__SGX__");
   if (HasPREFETCHWT1)
     Builder.defineMacro("__PREFETCHWT1__");
   if (HasCLZERO)
     Builder.defineMacro("__CLZERO__");
 
   // Each case falls through to the previous one here.
return llvm::StringSwitch<bool>(Feature)
       .Case("fxsr", HasFXSR)
       .Case("lwp", HasLWP)
       .Case("lzcnt", HasLZCNT)
       .Case("mm3dnow", MMX3DNowLevel >= AMD3DNow)
       .Case("mm3dnowa", MMX3DNowLevel >= AMD3DNowAthlon)
       .Case("mmx", MMX3DNowLevel >= MMX)
       .Case("movbe", HasMOVBE)
       .Case("mpx", HasMPX)
+      .Case("shstk", HasSHSTK)
+      .Case("ibt", HasIBT)
       .Case("pclmul", HasPCLMUL)
       .Case("pku", HasPKU)
       .Case("popcnt", HasPOPCNT)
       .Case("prefetchwt1", HasPREFETCHWT1)
       .Case("prfchw", HasPRFCHW)
       .Case("rdrnd", HasRDRND)
       .Case("rdseed", HasRDSEED)
       .Case("rtm", HasRTM)

lib/Headers/CMakeLists.txt

set(files
   bmi2intrin.h
   bmiintrin.h
   __clang_cuda_builtin_vars.h
   __clang_cuda_cmath.h
   __clang_cuda_complex_builtins.h
   __clang_cuda_intrinsics.h
   __clang_cuda_math_forward_declares.h
   __clang_cuda_runtime_wrapper.h
+  cetintrin.h
   clzerointrin.h
   cpuid.h
   clflushoptintrin.h
   clwbintrin.h
   emmintrin.h
   f16cintrin.h
   float.h
   fma4intrin.h

lib/Headers/cetintrin.h

+/*===---- cetintrin.h - CET intrinsic ------------------------------------===
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#ifndef __IMMINTRIN_H
+#error "Never use <cetintrin.h> directly; include <immintrin.h> instead."
+#endif
+
+#ifndef __CETINTRIN_H
+#define __CETINTRIN_H
+
+/* Define the default attributes for the functions in this file. */
+#define __DEFAULT_FN_ATTRS                                                     \
+  __attribute__((__always_inline__, __nodebug__, __target__("shstk")))
+
+static __inline__ void __DEFAULT_FN_ATTRS _incsspd(int __a) {
+  __builtin_ia32_incsspd(__a);
+}
+
+#ifdef __x86_64__
+static __inline__ void __DEFAULT_FN_ATTRS _incsspq(unsigned long long __a) {
+  __builtin_ia32_incsspq(__a);
+}
+#endif /* __x86_64__ */
+
+static __inline__ unsigned int __DEFAULT_FN_ATTRS _rdsspd(unsigned int __a) {
+  return __builtin_ia32_rdsspd(__a);
+}
+
+#ifdef __x86_64__
+static __inline__ unsigned long long __DEFAULT_FN_ATTRS _rdsspq(unsigned long long __a) {
+  return __builtin_ia32_rdsspq(__a);
+}
+#endif /* __x86_64__ */
+
+static __inline__ void __DEFAULT_FN_ATTRS _saveprevssp() {
+  __builtin_ia32_saveprevssp();
+}
+
+static __inline__ void __DEFAULT_FN_ATTRS _rstorssp(void * __p) {
+  __builtin_ia32_rstorssp(__p);
+}
+
+static __inline__ void __DEFAULT_FN_ATTRS _wrssd(unsigned int __a, void * __p) {
+  __builtin_ia32_wrssd(__a, __p);
+}
+
+#ifdef __x86_64__
+static __inline__ void __DEFAULT_FN_ATTRS _wrssq(unsigned long long __a, void * __p) {
+  __builtin_ia32_wrssq(__a, __p);
+}
+#endif /* __x86_64__ */
+
+static __inline__ void __DEFAULT_FN_ATTRS _wrussd(unsigned int __a, void * __p) {
+  __builtin_ia32_wrussd(__a, __p);
+}
+
+#ifdef __x86_64__
+static __inline__ void __DEFAULT_FN_ATTRS _wrussq(unsigned long long __a, void * __p) {
+  __builtin_ia32_wrussq(__a, __p);
+}
+#endif /* __x86_64__ */
+
+static __inline__ void __DEFAULT_FN_ATTRS _setssbsy() {
+  __builtin_ia32_setssbsy();
+}
+
+static __inline__ void __DEFAULT_FN_ATTRS _clrssbsy(void * __p) {
+  __builtin_ia32_clrssbsy(__p);
+}
+
+#undef __DEFAULT_FN_ATTRS
+
+#endif /* __CETINTRIN_H */

lib/Headers/immintrin.h

 #if !defined(_MSC_VER) || __has_feature(modules) || defined(__XSAVEC__)
 #include <xsavecintrin.h>
 #endif
 
 #if !defined(_MSC_VER) || __has_feature(modules) || defined(__XSAVES__)
 #include <xsavesintrin.h>
 #endif
 
+#if !defined(_MSC_VER) || __has_feature(modules) || defined(__SHSTK__)
+#include <cetintrin.h>
+#endif
+
 /* Some intrinsics inside adxintrin.h are available only on processors with ADX,
  * whereas others are also available at all times. */
 #include <adxintrin.h>
 
 #endif /* __IMMINTRIN_H */

test/CodeGen/builtins-x86.c

-// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +clzero -emit-llvm -o %t %s
-// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +clzero -fsyntax-only -o %t %s
+// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +clzero -target-feature +ibt -target-feature +shstk -emit-llvm -o %t %s
+// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +ibt -target-feature +shstk -target-feature +clzero -fsyntax-only -o %t %s
 
 #ifdef USE_ALL
 #define USE_3DNOW
 #define USE_64
 #define USE_SSE4
 #endif
 
 // 64-bit
#endif
   tmp_V4s = __builtin_ia32_psraw(tmp_V4s, tmp_V1LLi);
   tmp_V2i = __builtin_ia32_psrad(tmp_V2i, tmp_V1LLi);
   tmp_V2i = __builtin_ia32_pmaddwd(tmp_V4s, tmp_V4s);
   tmp_V8c = __builtin_ia32_packsswb(tmp_V4s, tmp_V4s);
   tmp_V4s = __builtin_ia32_packssdw(tmp_V2i, tmp_V2i);
   tmp_V8c = __builtin_ia32_packuswb(tmp_V4s, tmp_V4s);
   tmp_i = __builtin_ia32_vec_ext_v2si(tmp_V2i, 0);
 
+  __builtin_ia32_incsspd(tmp_Ui);
+  __builtin_ia32_incsspq(tmp_ULLi);
+  tmp_Ui = __builtin_ia32_rdsspd(tmp_Ui);
+  tmp_ULLi = __builtin_ia32_rdsspq(tmp_ULLi);
+  __builtin_ia32_saveprevssp();
+  __builtin_ia32_rstorssp(tmp_vp);
+  __builtin_ia32_wrssd(tmp_Ui, tmp_vp);
+  __builtin_ia32_wrssq(tmp_ULLi, tmp_vp);
+  __builtin_ia32_wrussd(tmp_Ui, tmp_vp);
+  __builtin_ia32_wrussq(tmp_ULLi, tmp_vp);
+  __builtin_ia32_setssbsy();
+  __builtin_ia32_clrssbsy(tmp_vp);
+
   (void) __builtin_ia32_ldmxcsr(tmp_Ui);
   (void) _mm_setcsr(tmp_Ui);
   tmp_Ui = __builtin_ia32_stmxcsr();
   tmp_Ui = _mm_getcsr();
   (void)__builtin_ia32_fxsave(tmp_vp);
   (void)__builtin_ia32_fxsave64(tmp_vp);
   (void)__builtin_ia32_fxrstor(tmp_vp);
   (void)__builtin_ia32_fxrstor64(tmp_vp);

test/CodeGen/cetintrin.c

+// RUN: %clang_cc1 -ffreestanding %s -triple=i386-apple-darwin -target-feature +shstk -emit-llvm -o - -Wall -Werror | FileCheck %s
+// RUN: %clang_cc1 -ffreestanding %s -triple=x86_64-apple-darwin -target-feature +shstk  -emit-llvm -o - -Wall -Werror | FileCheck %s --check-prefix=X86_64
+
+#include <immintrin.h>
+
+void test_incsspd(int a) {
+  // CHECK-LABEL: @test_incsspd
+  // CHECK:       call void @llvm.x86.incsspd(i32 %{{[0-9]+}})
+  _incsspd(a);
+}
+
+#ifdef __x86_64__
+void test_incsspq(int a) {
+  // X86_64-LABEL: @test_incsspq
+  // X86_64:       call void @llvm.x86.incsspq(i64 %{{[a-z0-9.]+}})
+  _incsspq(a);
+}
+#endif
+
+unsigned int test_rdsspd(unsigned int a) {
+  // CHECK-LABEL: @test_rdsspd
+  // CHECK:       call i32 @llvm.x86.rdsspd(i32 %{{[a-z0-9.]+}})
+  return _rdsspd(a);
+}
+
+#ifdef __x86_64__
+unsigned long long test_rdsspq(unsigned long long a) {
+  // X86_64-LABEL: @test_rdsspq
+  // X86_64:       call i64 @llvm.x86.rdsspq(i64 %{{[a-z0-9.]+}})
+  return _rdsspq(a);
+}
+#endif
+
+void  test_saveprevssp() {
+  // CHECK-LABEL: @test_saveprevssp
+  // CHECK:       call void @llvm.x86.saveprevssp()
+  _saveprevssp();
+}
+
+void test_rstorssp(void * __p) {
+  // CHECK-LABEL: @test_rstorssp
+  // CHECK:       call void @llvm.x86.rstorssp(i8* %{{[a-z0-9.]+}})
+  _rstorssp(__p);
+}
+
+void test_wrssd(unsigned int __a, void * __p) {
+  // CHECK-LABEL: @test_wrssd
+  // CHECK:       call void @llvm.x86.wrssd(i32 %{{[a-z0-9.]+}}, i8* %{{[a-z0-9.]+}})
+  _wrssd(__a, __p);
+}
+
+#ifdef __x86_64__
+void test_wrssq(unsigned long long __a, void * __p) {
+  // X86_64-LABEL: @test_wrssq
+  // X86_64:       call void @llvm.x86.wrssq(i64 %{{[a-z0-9.]+}}, i8* %{{[a-z0-9.]+}})
+  _wrssq(__a, __p);
+}
+#endif
+
+void test_wrussd(unsigned int __a, void * __p) {
+  // CHECK-LABEL: @test_wrussd
+  // CHECK:       call void @llvm.x86.wrussd(i32 %{{[a-z0-9.]+}}, i8* %{{[a-z0-9.]+}})
+  _wrussd(__a, __p);
+}
+
+#ifdef __x86_64__
+void test_wrussq(unsigned long long __a, void * __p) {
+  // X86_64-LABEL: @test_wrussq
+  // X86_64:       call void @llvm.x86.wrussq(i64 %{{[a-z0-9.]+}}, i8* %{{[a-z0-9.]+}})
+  _wrussq(__a, __p);
+}
+#endif
+
+void test_setssbsy() {
+  // CHECK-LABEL: @test_setssbsy
+  // CHECK:       call void @llvm.x86.setssbsy()
+  _setssbsy();
+}
+
+void test_clrssbsy(void * __p) {
+  // CHECK-LABEL: @test_clrssbsy
+  // CHECK:       call void @llvm.x86.clrssbsy(i8* %{{[a-z0-9.]+}})
+  _clrssbsy(__p);
+}

test/Driver/x86-target-features.c

 // MOVBE: "-target-feature" "+movbe"
 // NO-MOVBE: "-target-feature" "-movbe"
 
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mmpx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=MPX %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-mpx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-MPX %s
 // MPX: "-target-feature" "+mpx"
 // NO-MPX: "-target-feature" "-mpx"
 
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mshstk %s -### -o %t.o 2>&1 | FileCheck -check-prefix=CETSS %s
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-shstk %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-CETSS %s
+// CETSS: "-target-feature" "+shstk"
+// NO-CETSS: "-target-feature" "-shstk"
+
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mibt %s -### -o %t.o 2>&1 | FileCheck -check-prefix=CETIBT %s
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-ibt %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-CETIBT %s
+// CETIBT: "-target-feature" "+ibt"
+// NO-CETIBT: "-target-feature" "-ibt"
+
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -msgx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=SGX %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-sgx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-SGX %s
 // SGX: "-target-feature" "+sgx"
 // NO-SGX: "-target-feature" "-sgx"
 
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mprefetchwt1 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=PREFETCHWT1 %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-prefetchwt1 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-PREFETCHWT1 %s
 // PREFETCHWT1: "-target-feature" "+prefetchwt1"
 // NO-PREFETCHWT1: "-target-feature" "-prefetchwt1"
 
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mclzero %s -### -o %t.o 2>&1 | FileCheck -check-prefix=CLZERO %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-clzero %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-CLZERO %s
 // CLZERO: "-target-feature" "+clzero"
 // NO-CLZERO: "-target-feature" "-clzero"

test/Preprocessor/x86_target_features.c

 // RUN: %clang -target i386-unknown-unknown -march=atom -mprfchw -mno-3dnow -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=NO3DNOWPRFCHW %s
 
 // NO3DNOWPRFCHW: #define __PRFCHW__ 1
 
 // RUN: %clang -target i386-unknown-unknown -march=atom -madx -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=ADX %s
 
 // ADX: #define __ADX__ 1
 
+// RUN: %clang -target i386-unknown-unknown -mshstk -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=CETSS %s
+
+// CETSS: #define __SHSTK__ 1
+
 // RUN: %clang -target i386-unknown-unknown -march=atom -mrdseed -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=RDSEED %s
 
 // RDSEED: #define __RDSEED__ 1
 
 // RUN: %clang -target i386-unknown-unknown -march=atom -mxsave -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=XSAVE %s
 
 // XSAVE: #define __XSAVE__ 1