Adding nocf_check attribute for cf-protection fine tuning

The patch adds nocf_check target independent attribute for disabling checks that were enabled by cf-protection flag.
The attribute can be appertained to functions and function pointers.
Attribute name follows GCC's similar attribute name.

Differential Revision: https://reviews.llvm.org/D41880

llvm-svn: 327768

diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 4dd67f7..0a5c086 100644 (file)
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -1511,7 +1511,7 @@ protected:
 
     /// Extra information which affects how the function is called, like
     /// regparm and the calling convention.
-    unsigned ExtInfo : 11;
+    unsigned ExtInfo : 12;
 
     /// Used only by FunctionProtoType, put here to pack with the
     /// other bitfields.
@@ -3147,24 +3147,24 @@ public:
   class ExtInfo {
     friend class FunctionType;
 
-    // Feel free to rearrange or add bits, but if you go over 11,
+    // Feel free to rearrange or add bits, but if you go over 12,
     // you'll need to adjust both the Bits field below and
     // Type::FunctionTypeBitfields.
 
-    //   |  CC  |noreturn|produces|nocallersavedregs|regparm|
-    //   |0 .. 4|   5    |    6   |       7         |8 .. 10|
+    //   |  CC  |noreturn|produces|nocallersavedregs|regparm|nocfcheck|
+    //   |0 .. 4|   5    |    6   |       7         |8 .. 10|    11   |
     //
     // regparm is either 0 (no regparm attribute) or the regparm value+1.
     enum { CallConvMask = 0x1F };
     enum { NoReturnMask = 0x20 };
     enum { ProducesResultMask = 0x40 };
     enum { NoCallerSavedRegsMask = 0x80 };
+    enum { NoCfCheckMask = 0x800 };
     enum {
       RegParmMask = ~(CallConvMask | NoReturnMask | ProducesResultMask |
-                      NoCallerSavedRegsMask),
+                      NoCallerSavedRegsMask | NoCfCheckMask),
       RegParmOffset = 8
     }; // Assumed to be the last field
-
     uint16_t Bits = CC_C;
 
     ExtInfo(unsigned Bits) : Bits(static_cast<uint16_t>(Bits)) {}
@@ -3173,12 +3173,13 @@ public:
      // Constructor with no defaults. Use this when you know that you
      // have all the elements (when reading an AST file for example).
      ExtInfo(bool noReturn, bool hasRegParm, unsigned regParm, CallingConv cc,
-             bool producesResult, bool noCallerSavedRegs) {
+             bool producesResult, bool noCallerSavedRegs, bool NoCfCheck) {
        assert((!hasRegParm || regParm < 7) && "Invalid regparm value");
        Bits = ((unsigned)cc) | (noReturn ? NoReturnMask : 0) |
               (producesResult ? ProducesResultMask : 0) |
               (noCallerSavedRegs ? NoCallerSavedRegsMask : 0) |
-              (hasRegParm ? ((regParm + 1) << RegParmOffset) : 0);
+              (hasRegParm ? ((regParm + 1) << RegParmOffset) : 0) | 
+              (NoCfCheck ? NoCfCheckMask : 0);
     }
 
     // Constructor with all defaults. Use when for example creating a
@@ -3192,10 +3193,11 @@ public:
     bool getNoReturn() const { return Bits & NoReturnMask; }
     bool getProducesResult() const { return Bits & ProducesResultMask; }
     bool getNoCallerSavedRegs() const { return Bits & NoCallerSavedRegsMask; }
+    bool getNoCfCheck() const { return Bits & NoCfCheckMask; }
     bool getHasRegParm() const { return (Bits >> RegParmOffset) != 0; }
 
     unsigned getRegParm() const {
-      unsigned RegParm = Bits >> RegParmOffset;
+      unsigned RegParm = (Bits & RegParmMask) >> RegParmOffset;
       if (RegParm > 0)
         --RegParm;
       return RegParm;
@@ -3234,6 +3236,13 @@ public:
         return ExtInfo(Bits & ~NoCallerSavedRegsMask);
     }
 
+    ExtInfo withNoCfCheck(bool noCfCheck) const {
+      if (noCfCheck)
+        return ExtInfo(Bits | NoCfCheckMask);
+      else
+        return ExtInfo(Bits & ~NoCfCheckMask);
+    }
+
     ExtInfo withRegParm(unsigned RegParm) const {
       assert(RegParm < 7 && "Invalid regparm value");
       return ExtInfo((Bits & ~RegParmMask) |
@@ -4120,6 +4129,7 @@ public:
 
     // No operand.
     attr_noreturn,
+    attr_nocf_check,
     attr_cdecl,
     attr_fastcall,
     attr_stdcall,

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 92d1dd6..14fa0ee 100644 (file)
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2122,6 +2122,12 @@ def AnyX86NoCallerSavedRegisters : InheritableAttr,
   let Documentation = [AnyX86NoCallerSavedRegistersDocs];
 }
 
+def AnyX86NoCfCheck : InheritableAttr, TargetSpecificAttr<TargetAnyX86>{
+  let Spellings = [GCC<"nocf_check">];
+  let Subjects = SubjectList<[FunctionLike]>;
+  let Documentation = [AnyX86NoCfCheckDocs];
+}
+
 def X86ForceAlignArgPointer : InheritableAttr, TargetSpecificAttr<TargetAnyX86> {
   let Spellings = [GCC<"force_align_arg_pointer">];
   // Technically, this appertains to a FunctionDecl, but the target-specific

diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 35c0cb3..d30dbcb 100644 (file)
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -2913,6 +2913,24 @@ jumps from i386 arch code).
   }];
 }
 
+def AnyX86NoCfCheckDocs : Documentation{
+  let Category = DocCatFunction;
+  let Content = [{
+Jump Oriented Programming attacks rely on tampering with addresses used by
+indirect call / jmp, e.g. redirect control-flow to non-programmer
+intended bytes in the binary.
+X86 Supports Indirect Branch Tracking (IBT) as part of Control-Flow
+Enforcement Technology (CET). IBT instruments ENDBR instructions used to
+specify valid targets of indirect call / jmp.
+The ``nocf_check`` attribute has two roles:
+1. Appertains to a function - do not add ENDBR instruction at the
+    beginning of the function.
+2. Appertains to a function pointer - do not track the target
+    function of this pointer (by adding nocf_check prefix to the
+    indirect-call instruction).
+}];
+}
+
 def SwiftCallDocs : Documentation {
   let Category = DocCatVariable;
   let Content = [{

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 809d37e..e58d1c7 100644 (file)
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2691,6 +2691,9 @@ def warn_attribute_ignored : Warning<"%0 attribute ignored">,
 def warn_attribute_ignored_on_inline :
   Warning<"%0 attribute ignored on inline function">,
   InGroup<IgnoredAttributes>;
+def warn_nocf_check_attribute_ignored :
+  Warning<"'nocf_check' attribute ignored; use -fcf-protection to enable the attribute">,
+  InGroup<IgnoredAttributes>;
 def warn_attribute_after_definition_ignored : Warning<
   "attribute %0 after definition is ignored">,
    InGroup<IgnoredAttributes>;

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 68edee2..69f67a9 100644 (file)
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -236,6 +236,7 @@ LANGOPT(ObjCAutoRefCount , 1, 0, "Objective-C automated reference counting")
 LANGOPT(ObjCWeakRuntime     , 1, 0, "__weak support in the ARC runtime")
 LANGOPT(ObjCWeak            , 1, 0, "Objective-C __weak in ARC and MRC files")
 LANGOPT(ObjCSubscriptingLegacyRuntime         , 1, 0, "Subscripting support in legacy ObjectiveC runtime")
+LANGOPT(CFProtectionBranch , 1, 0, "Control-Flow Branch Protection enabled")
 LANGOPT(FakeAddressSpaceMap , 1, 0, "OpenCL fake address space map")
 ENUM_LANGOPT(AddressSpaceMapMangling , AddrSpaceMapMangling, 2, ASMM_Target, "OpenCL address space map mangling mode")
 LANGOPT(IncludeDefaultHeader, 1, 0, "Include default header file for OpenCL")

diff --git a/clang/include/clang/CodeGen/CGFunctionInfo.h b/clang/include/clang/CodeGen/CGFunctionInfo.h
index 42f963b..d6f9908 100644 (file)
--- a/clang/include/clang/CodeGen/CGFunctionInfo.h
+++ b/clang/include/clang/CodeGen/CGFunctionInfo.h
@@ -494,7 +494,7 @@ class CGFunctionInfo final
   unsigned EffectiveCallingConvention : 8;
 
   /// The clang::CallingConv that this was originally created with.
-  unsigned ASTCallingConvention : 7;
+  unsigned ASTCallingConvention : 6;
 
   /// Whether this is an instance method.
   unsigned InstanceMethod : 1;
@@ -515,6 +515,9 @@ class CGFunctionInfo final
   unsigned HasRegParm : 1;
   unsigned RegParm : 3;
 
+  /// Whether this function has nocf_check attribute.
+  unsigned NoCfCheck : 1;
+
   RequiredArgs Required;
 
   /// The struct representing all arguments passed in memory.  Only used when
@@ -599,6 +602,9 @@ public:
   /// Whether this function no longer saves caller registers.
   bool isNoCallerSavedRegs() const { return NoCallerSavedRegs; }
 
+  /// Whether this function has nocf_check attribute.
+  bool isNoCfCheck() const { return NoCfCheck; }
+
   /// getASTCallingConvention() - Return the AST-specified calling
   /// convention.
   CallingConv getASTCallingConvention() const {
@@ -624,7 +630,7 @@ public:
   FunctionType::ExtInfo getExtInfo() const {
     return FunctionType::ExtInfo(isNoReturn(), getHasRegParm(), getRegParm(),
                                  getASTCallingConvention(), isReturnsRetained(),
-                                 isNoCallerSavedRegs());
+                                 isNoCallerSavedRegs(), isNoCfCheck());
   }
 
   CanQualType getReturnType() const { return getArgsBuffer()[0].type; }
@@ -664,6 +670,7 @@ public:
     ID.AddBoolean(NoCallerSavedRegs);
     ID.AddBoolean(HasRegParm);
     ID.AddInteger(RegParm);
+    ID.AddBoolean(NoCfCheck);
     ID.AddInteger(Required.getOpaqueData());
     ID.AddBoolean(HasExtParameterInfos);
     if (HasExtParameterInfos) {
@@ -690,6 +697,7 @@ public:
     ID.AddBoolean(info.getNoCallerSavedRegs());
     ID.AddBoolean(info.getHasRegParm());
     ID.AddInteger(info.getRegParm());
+    ID.AddBoolean(info.getNoCfCheck());
     ID.AddInteger(required.getOpaqueData());
     ID.AddBoolean(!paramInfos.empty());
     if (!paramInfos.empty()) {

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 70c9494..a107b25 100644 (file)
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -3323,8 +3323,8 @@ public:
   bool CheckRegparmAttr(const AttributeList &attr, unsigned &value);
   bool CheckCallingConvAttr(const AttributeList &attr, CallingConv &CC,
                             const FunctionDecl *FD = nullptr);
-  bool CheckNoReturnAttr(const AttributeList &attr);
-  bool CheckNoCallerSavedRegsAttr(const AttributeList &attr);
+  bool CheckAttrTarget(const AttributeList &CurrAttr);
+  bool CheckAttrNoArgs(const AttributeList &CurrAttr);
   bool checkStringLiteralArgumentAttr(const AttributeList &Attr,
                                       unsigned ArgNum, StringRef &Str,
                                       SourceLocation *ArgLocation = nullptr);

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 49ac8c1..619af9a 100644 (file)
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -8241,6 +8241,8 @@ QualType ASTContext::mergeFunctionTypes(QualType lhs, QualType rhs,
     return QualType();
   if (lbaseInfo.getNoCallerSavedRegs() != rbaseInfo.getNoCallerSavedRegs())
     return QualType();
+  if (lbaseInfo.getNoCfCheck() != rbaseInfo.getNoCfCheck())
+    return QualType();
 
   // FIXME: some uses, e.g. conditional exprs, really want this to be 'both'.
   bool NoReturn = lbaseInfo.getNoReturn() || rbaseInfo.getNoReturn();

diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index da7fdb0..99f5b13 100644 (file)
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -3129,6 +3129,7 @@ bool AttributedType::isQualifier() const {
   case AttributedType::attr_uptr:
   case AttributedType::attr_objc_kindof:
   case AttributedType::attr_ns_returns_retained:
+  case AttributedType::attr_nocf_check:
     return false;
   }
   llvm_unreachable("bad attributed type kind");
@@ -3166,6 +3167,7 @@ bool AttributedType::isCallingConv() const {
   case attr_nullable:
   case attr_null_unspecified:
   case attr_objc_kindof:
+  case attr_nocf_check:
     return false;
 
   case attr_pcs:

diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index c28ada7..d46f8d3 100644 (file)
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -801,6 +801,8 @@ void TypePrinter::printFunctionAfter(const FunctionType::ExtInfo &Info,
        << Info.getRegParm() << ")))";
   if (Info.getNoCallerSavedRegs())
     OS << " __attribute__((no_caller_saved_registers))";
+  if (Info.getNoCfCheck())
+    OS << " __attribute__((nocf_check))";
 }
 
 void TypePrinter::printFunctionNoProtoBefore(const FunctionNoProtoType *T, 
@@ -1396,7 +1398,7 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
   // FIXME: When Sema learns to form this AttributedType, avoid printing the
   // attribute again in printFunctionProtoAfter.
   case AttributedType::attr_noreturn: OS << "noreturn"; break;
-
+  case AttributedType::attr_nocf_check: OS << "nocf_check"; break;
   case AttributedType::attr_cdecl: OS << "cdecl"; break;
   case AttributedType::attr_fastcall: OS << "fastcall"; break;
   case AttributedType::attr_stdcall: OS << "stdcall"; break;

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3a5505f..41ed22e 100644 (file)
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -803,6 +803,7 @@ CGFunctionInfo *CGFunctionInfo::create(unsigned llvmCC,
   FI->NoReturn = info.getNoReturn();
   FI->ReturnsRetained = info.getProducesResult();
   FI->NoCallerSavedRegs = info.getNoCallerSavedRegs();
+  FI->NoCfCheck = info.getNoCfCheck();
   FI->Required = required;
   FI->HasRegParm = info.getHasRegParm();
   FI->RegParm = info.getRegParm();
@@ -1850,6 +1851,8 @@ void CodeGenModule::ConstructAttributeList(
       RetAttrs.addAttribute(llvm::Attribute::NonNull);
     if (TargetDecl->hasAttr<AnyX86NoCallerSavedRegistersAttr>())
       FuncAttrs.addAttribute("no_caller_saved_registers");
+    if (TargetDecl->hasAttr<AnyX86NoCfCheckAttr>())
+      FuncAttrs.addAttribute(llvm::Attribute::NoCfCheck);
 
     HasOptnone = TargetDecl->hasAttr<OptimizeNoneAttr>();
     if (auto *AllocSize = TargetDecl->getAttr<AllocSizeAttr>()) {

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index ff8db47..330212a 100644 (file)
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2042,6 +2042,12 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
     }
   }
 
+  if (const Arg *A = Args.getLastArg(OPT_fcf_protection_EQ)) {
+    StringRef Name = A->getValue();
+    if (Name == "full" || Name == "branch") {
+      Opts.CFProtectionBranch = 1;
+    }
+  }
   // -cl-std only applies for OpenCL language standards.
   // Override the -std option in this case.
   if (const Arg *A = Args.getLastArg(OPT_cl_std_EQ)) {

diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 6df1324..260dfa5 100644 (file)
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1908,9 +1908,6 @@ static void handleNakedAttr(Sema &S, Decl *D, const AttributeList &AL) {
 static void handleNoReturnAttr(Sema &S, Decl *D, const AttributeList &Attrs) {
   if (hasDeclarator(D)) return;
 
-  if (S.CheckNoReturnAttr(Attrs))
-    return;
-
   if (!isa<ObjCMethodDecl>(D)) {
     S.Diag(Attrs.getLoc(), diag::warn_attribute_wrong_decl_type)
         << Attrs.getName() << ExpectedFunctionOrMethod;
@@ -1921,16 +1918,14 @@ static void handleNoReturnAttr(Sema &S, Decl *D, const AttributeList &Attrs) {
       Attrs.getRange(), S.Context, Attrs.getAttributeSpellingListIndex()));
 }
 
-static void handleNoCallerSavedRegsAttr(Sema &S, Decl *D,
-                                        const AttributeList &AL) {
-  if (S.CheckNoCallerSavedRegsAttr(AL))
-    return;
-
-  D->addAttr(::new (S.Context) AnyX86NoCallerSavedRegistersAttr(
-      AL.getRange(), S.Context, AL.getAttributeSpellingListIndex()));
+static void handleNoCfCheckAttr(Sema &S, Decl *D, const AttributeList &Attrs) {
+  if (!S.getLangOpts().CFProtectionBranch)
+    S.Diag(Attrs.getLoc(), diag::warn_nocf_check_attribute_ignored);
+  else
+    handleSimpleAttribute<AnyX86NoCfCheckAttr>(S, D, Attrs);
 }
 
-bool Sema::CheckNoReturnAttr(const AttributeList &Attrs) {
+bool Sema::CheckAttrNoArgs(const AttributeList &Attrs) {
   if (!checkAttributeNumArgs(*this, Attrs, 0)) {
     Attrs.setInvalid();
     return true;
@@ -1939,7 +1934,7 @@ bool Sema::CheckNoReturnAttr(const AttributeList &Attrs) {
   return false;
 }
 
-bool Sema::CheckNoCallerSavedRegsAttr(const AttributeList &AL) {
+bool Sema::CheckAttrTarget(const AttributeList &AL) {
   // Check whether the attribute is valid on the current target.
   if (!AL.existsInTarget(Context.getTargetInfo())) {
     Diag(AL.getLoc(), diag::warn_unknown_attribute_ignored) << AL.getName();
@@ -1947,11 +1942,6 @@ bool Sema::CheckNoCallerSavedRegsAttr(const AttributeList &AL) {
     return true;
   }
 
-  if (!checkAttributeNumArgs(*this, AL, 0)) {
-    AL.setInvalid();
-    return true;
-  }
-
   return false;
 }
 
@@ -5756,6 +5746,9 @@ static bool handleCommonAttributeFeatures(Sema &S, Decl *D,
       return true;
   }
 
+  if (S.CheckAttrTarget(AL))
+    return true;
+
   return false;
 }
 
@@ -6052,6 +6045,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_NoReturn:
     handleNoReturnAttr(S, D, AL);
     break;
+  case AttributeList::AT_AnyX86NoCfCheck:
+    handleNoCfCheckAttr(S, D, AL);
+    break;
   case AttributeList::AT_NoThrow:
     handleSimpleAttribute<NoThrowAttr>(S, D, AL);
     break;
@@ -6427,7 +6423,7 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleTypeTagForDatatypeAttr(S, D, AL);
     break;
   case AttributeList::AT_AnyX86NoCallerSavedRegisters:
-    handleNoCallerSavedRegsAttr(S, D, AL);
+    handleSimpleAttribute<AnyX86NoCallerSavedRegistersAttr>(S, D, AL);
     break;
   case AttributeList::AT_RenderScriptKernel:
     handleSimpleAttribute<RenderScriptKernelAttr>(S, D, AL);

diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 9791003..acf22cd 100644 (file)
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -125,6 +125,7 @@ static void diagnoseBadTypeAttribute(Sema &S, const AttributeList &attr,
   case AttributeList::AT_NoReturn: \
   case AttributeList::AT_Regparm: \
   case AttributeList::AT_AnyX86NoCallerSavedRegisters: \
+  case AttributeList::AT_AnyX86NoCfCheck: \
     CALLING_CONV_ATTRS_CASELIST
 
 // Microsoft-specific type qualifiers.
@@ -5144,6 +5145,8 @@ static AttributeList::Kind getAttrListKind(AttributedType::Kind kind) {
     return AttributeList::AT_ObjCOwnership;
   case AttributedType::attr_noreturn:
     return AttributeList::AT_NoReturn;
+  case AttributedType::attr_nocf_check:
+    return AttributeList::AT_AnyX86NoCfCheck;
   case AttributedType::attr_cdecl:
     return AttributeList::AT_CDecl;
   case AttributedType::attr_fastcall:
@@ -6609,7 +6612,7 @@ static bool handleFunctionTypeAttr(TypeProcessingState &state,
   FunctionTypeUnwrapper unwrapped(S, type);
 
   if (attr.getKind() == AttributeList::AT_NoReturn) {
-    if (S.CheckNoReturnAttr(attr))
+    if (S.CheckAttrNoArgs(attr))
       return true;
 
     // Delay if this is not a function type.
@@ -6649,7 +6652,7 @@ static bool handleFunctionTypeAttr(TypeProcessingState &state,
   }
 
   if (attr.getKind() == AttributeList::AT_AnyX86NoCallerSavedRegisters) {
-    if (S.CheckNoCallerSavedRegsAttr(attr))
+    if (S.CheckAttrTarget(attr) || S.CheckAttrNoArgs(attr))
       return true;
 
     // Delay if this is not a function type.
@@ -6662,6 +6665,27 @@ static bool handleFunctionTypeAttr(TypeProcessingState &state,
     return true;
   }
 
+  if (attr.getKind() == AttributeList::AT_AnyX86NoCfCheck) {
+    if (!S.getLangOpts().CFProtectionBranch) {
+      S.Diag(attr.getLoc(), diag::warn_nocf_check_attribute_ignored);
+      attr.setInvalid();
+      return true;
+    }
+
+    if (S.CheckAttrTarget(attr) || S.CheckAttrNoArgs(attr))
+      return true;
+
+    // If this is not a function type, warning will be asserted by subject 
+    // check.
+    if (!unwrapped.isFunctionType())
+      return true;
+
+    FunctionType::ExtInfo EI =
+      unwrapped.get()->getExtInfo().withNoCfCheck(true);
+    type = unwrapped.wrap(S, S.Context.adjustFunctionType(unwrapped.get(), EI));
+    return true;
+  }
+
   if (attr.getKind() == AttributeList::AT_Regparm) {
     unsigned value;
     if (S.CheckRegparmAttr(attr, value))

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index b6fc4b2..4cc3f9c 100644 (file)
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -6005,13 +6005,14 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
   }
 
   case TYPE_FUNCTION_NO_PROTO: {
-    if (Record.size() != 7) {
+    if (Record.size() != 8) {
       Error("incorrect encoding of no-proto function type");
       return QualType();
     }
     QualType ResultType = readType(*Loc.F, Record, Idx);
     FunctionType::ExtInfo Info(Record[1], Record[2], Record[3],
-                               (CallingConv)Record[4], Record[5], Record[6]);
+                               (CallingConv)Record[4], Record[5], Record[6], 
+                               Record[7]);
     return Context.getFunctionNoProtoType(ResultType, Info);
   }
 
@@ -6024,9 +6025,10 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
                                         /*regparm*/ Record[3],
                                         static_cast<CallingConv>(Record[4]),
                                         /*produces*/ Record[5],
-                                        /*nocallersavedregs*/ Record[6]);
+                                        /*nocallersavedregs*/ Record[6],
+                                        /*nocfcheck*/ Record[7]);
 
-    unsigned Idx = 7;
+    unsigned Idx = 8;
 
     EPI.Variadic = Record[Idx++];
     EPI.HasTrailingReturn = Record[Idx++];

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 53e09b3..e63000c 100644 (file)
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -276,6 +276,7 @@ void ASTTypeWriter::VisitFunctionType(const FunctionType *T) {
   Record.push_back(C.getCC());
   Record.push_back(C.getProducesResult());
   Record.push_back(C.getNoCallerSavedRegs());
+  Record.push_back(C.getNoCfCheck());
 
   if (C.getHasRegParm() || C.getRegParm() || C.getProducesResult())
     AbbrevToUse = 0;
@@ -884,6 +885,7 @@ void ASTWriter::WriteTypeAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // CC
   Abv->Add(BitCodeAbbrevOp(0));                         // ProducesResult
   Abv->Add(BitCodeAbbrevOp(0));                         // NoCallerSavedRegs
+  Abv->Add(BitCodeAbbrevOp(0));                         // NoCfCheck
   // FunctionProtoType
   Abv->Add(BitCodeAbbrevOp(0));                         // IsVariadic
   Abv->Add(BitCodeAbbrevOp(0));                         // HasTrailingReturn

diff --git a/clang/test/CodeGen/attributes.c b/clang/test/CodeGen/attributes.c
index 34833a2..e7fd076 100644 (file)
--- a/clang/test/CodeGen/attributes.c
+++ b/clang/test/CodeGen/attributes.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -triple i386-linux-gnu -o %t %s
+// RUN: %clang_cc1 -emit-llvm -fcf-protection=branch -target-feature +ibt -triple i386-linux-gnu -o %t %s
 // RUN: FileCheck --input-file=%t %s
 
 // CHECK: @t5 = weak global i32 2
@@ -97,8 +97,20 @@ void __attribute__((section(".bar"))) t22(void) {}
 
 // CHECK: define void @t22() [[NUW]] section ".bar"
 
+// CHECK: define void @t23() [[NOCF_CHECK_FUNC:#[0-9]+]]
+void __attribute__((nocf_check)) t23(void) {}
+
+// CHECK: call void %{{[a-z0-9]+}}() [[NOCF_CHECK_CALL:#[0-9]+]]
+typedef void (*f_t)(void);
+void t24(f_t f1) {
+  __attribute__((nocf_check)) f_t p = f1;
+  (*p)();
+}
+
 // CHECK: attributes [[NUW]] = { noinline nounwind{{.*}} }
 // CHECK: attributes [[NR]] = { noinline noreturn nounwind{{.*}} }
 // CHECK: attributes [[COLDDEF]] = { cold {{.*}}}
 // CHECK: attributes [[COLDDECL]] = { cold {{.*}}}
+// CHECK: attributes [[NOCF_CHECK_FUNC]] = { nocf_check {{.*}}}
 // CHECK: attributes [[COLDSITE]] = { cold {{.*}}}
+// CHECK: attributes [[NOCF_CHECK_CALL]] = { nocf_check }

diff --git a/clang/test/CodeGen/cetintrin.c b/clang/test/CodeGen/cetintrin.c
index 4d2f87a..f70d1c8 100644 (file)
--- a/clang/test/CodeGen/cetintrin.c
+++ b/clang/test/CodeGen/cetintrin.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -ffreestanding %s -triple=i386-apple-darwin -target-feature +shstk -emit-llvm -o - -Wall -Werror | FileCheck %s --check-prefix=I386 --check-prefix=CHECK
-// RUN: %clang_cc1 -ffreestanding %s -triple=x86_64-apple-darwin -target-feature +shstk  -emit-llvm -o - -Wall -Werror | FileCheck %s --check-prefix=X86_64  --check-prefix=CHECK
+// RUN: %clang_cc1 -ffreestanding %s -triple=i386-unknown-unknown -target-feature +shstk -emit-llvm -o - -Wall -Werror | FileCheck %s --check-prefix=I386 --check-prefix=CHECK
+// RUN: %clang_cc1 -ffreestanding %s -triple=x86_64-unknown-unknown -target-feature +shstk  -emit-llvm -o - -Wall -Werror | FileCheck %s --check-prefix=X86_64  --check-prefix=CHECK
 
 #include <immintrin.h>
 

diff --git a/clang/test/CodeGen/x86-cf-protection.c b/clang/test/CodeGen/x86-cf-protection.c
index c853791..044f839 100644 (file)
--- a/clang/test/CodeGen/x86-cf-protection.c
+++ b/clang/test/CodeGen/x86-cf-protection.c
@@ -1,5 +1,5 @@
-// RUN: not %clang_cc1 -fsyntax-only -S -emit-llvm -o %t -triple i386-unknown-unknown -fcf-protection=return %s 2>&1 | FileCheck %s --check-prefix=RETURN
-// RUN: not %clang_cc1 -fsyntax-only -S -emit-llvm -o %t -triple i386-unknown-unknown -fcf-protection=branch %s 2>&1 | FileCheck %s --check-prefix=BRANCH
+// RUN: not %clang_cc1 -fsyntax-only -S -o %t -triple i386-unknown-unknown -fcf-protection=return %s 2>&1 | FileCheck %s --check-prefix=RETURN
+// RUN: not %clang_cc1 -fsyntax-only -S -o %t -triple i386-unknown-unknown -fcf-protection=branch %s 2>&1 | FileCheck %s --check-prefix=BRANCH
 
 // RETURN: error: option 'cf-protection=return' cannot be specified without '-mshstk'
 // BRANCH: error: option 'cf-protection=branch' cannot be specified without '-mibt'

diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 1004459..c911c50 100644 (file)
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -2,7 +2,7 @@
 
 // The number of supported attributes should never go down!
 
-// CHECK: #pragma clang attribute supports 67 attributes:
+// CHECK: #pragma clang attribute supports 68 attributes:
 // CHECK-NEXT: AMDGPUFlatWorkGroupSize (SubjectMatchRule_function)
 // CHECK-NEXT: AMDGPUNumSGPR (SubjectMatchRule_function)
 // CHECK-NEXT: AMDGPUNumVGPR (SubjectMatchRule_function)
@@ -12,6 +12,7 @@
 // CHECK-NEXT: AlignValue (SubjectMatchRule_variable, SubjectMatchRule_type_alias)
 // CHECK-NEXT: AllocSize (SubjectMatchRule_function)
 // CHECK-NEXT: Annotate ()
+// CHECK-NEXT: AnyX86NoCfCheck (SubjectMatchRule_hasType_functionType)
 // CHECK-NEXT: AssumeAligned (SubjectMatchRule_objc_method, SubjectMatchRule_function)
 // CHECK-NEXT: Availability ((SubjectMatchRule_record, SubjectMatchRule_enum, SubjectMatchRule_enum_constant, SubjectMatchRule_field, SubjectMatchRule_function, SubjectMatchRule_namespace, SubjectMatchRule_objc_category, SubjectMatchRule_objc_interface, SubjectMatchRule_objc_method, SubjectMatchRule_objc_property, SubjectMatchRule_objc_protocol, SubjectMatchRule_record, SubjectMatchRule_type_alias, SubjectMatchRule_variable))
 // CHECK-NEXT: CXX11NoReturn (SubjectMatchRule_function)

diff --git a/clang/test/Sema/attr-nocf_check.c b/clang/test/Sema/attr-nocf_check.c
new file mode 100644 (file)
index 0000000..aab4eac
--- /dev/null
+++ b/clang/test/Sema/attr-nocf_check.c
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -verify -fcf-protection=branch -target-feature +ibt -fsyntax-only %s
+
+// Function pointer definition.
+typedef void (*FuncPointerWithNoCfCheck)(void) __attribute__((nocf_check)); // no-warning
+typedef void (*FuncPointer)(void);
+
+// Dont allow function declaration and definition mismatch.
+void __attribute__((nocf_check)) testNoCfCheck();   // expected-note {{previous declaration is here}}
+void testNoCfCheck(){}; //  expected-error {{conflicting types for 'testNoCfCheck'}}
+
+// No variable or parameter declaration
+__attribute__((nocf_check)) int i;                              // expected-warning {{'nocf_check' attribute only applies to function}}
+void testNoCfCheckImpl(double __attribute__((nocf_check)) i) {} // expected-warning {{'nocf_check' attribute only applies to function}}
+
+// Allow attributed function pointers as well as casting between attributed
+// and non-attributed function pointers.
+void testNoCfCheckMismatch(FuncPointer f) {
+  FuncPointerWithNoCfCheck fNoCfCheck = f; // expected-warning {{incompatible function pointer types}}
+  (*fNoCfCheck)();                         // no-warning
+}
+
+// 'nocf_check' Attribute has no parameters.
+int testNoCfCheckParams() __attribute__((nocf_check(1))); // expected-error {{'nocf_check' attribute takes no arguments}}

diff --git a/clang/test/Sema/attr-nocf_check.cpp b/clang/test/Sema/attr-nocf_check.cpp
new file mode 100644 (file)
index 0000000..b785f98
--- /dev/null
+++ b/clang/test/Sema/attr-nocf_check.cpp
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple=i386-unknown-unknown -verify -fcf-protection=branch -target-feature +ibt -std=c++11 -fsyntax-only %s
+
+// Function pointer definition.
+[[gnu::nocf_check]] typedef void (*FuncPointerWithNoCfCheck)(void); // no-warning
+typedef void (*FuncPointer)(void);
+
+// Dont allow function declaration and definition mismatch.
+[[gnu::nocf_check]] void testNoCfCheck();   // expected-note {{previous declaration is here}}
+void testNoCfCheck(){}; //  expected-error {{conflicting types for 'testNoCfCheck'}}
+
+// No variable or parameter declaration
+int [[gnu::nocf_check]] i;                              // expected-error {{'nocf_check' attribute cannot be applied to types}}
+void testNoCfCheckImpl(double i [[gnu::nocf_check]]) {} // expected-warning {{'nocf_check' attribute only applies to functions and function pointers}}
+
+// Allow attributed function pointers as well as casting between attributed
+// and non-attributed function pointers.
+void testNoCfCheckMismatch(FuncPointer f) {
+  FuncPointerWithNoCfCheck fNoCfCheck = f; // expected-error {{cannot initialize a variable of type}}
+  (*fNoCfCheck)();                         // no-warning
+}
+
+// 'nocf_check' Attribute has no parameters.
+[[gnu::nocf_check(1)]] int testNoCfCheckParams(); // expected-error {{'nocf_check' attribute takes no arguments}}

diff --git a/clang/test/Sema/nocf_check_attr_not_allowed.c b/clang/test/Sema/nocf_check_attr_not_allowed.c
new file mode 100644 (file)
index 0000000..2ba71d4
--- /dev/null
+++ b/clang/test/Sema/nocf_check_attr_not_allowed.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -triple powerpc-unknown-linux-gnu -fsyntax-only -verify -fcf-protection=branch %s
+// RUN: %clang_cc1 -triple arm-unknown-linux-gnu -fsyntax-only -verify -fcf-protection=branch %s
+// RUN: %clang_cc1 -triple arm-unknown-linux-gnu -fsyntax-only -verify %s
+
+void __attribute__((nocf_check)) foo(); // expected-warning-re{{{{((unknown attribute 'nocf_check' ignored)|('nocf_check' attribute ignored; use -fcf-protection to enable the attribute))}}}}