Tag CFI-generated data structures with "#pragma clang section" attributes.

[dmikulin]

Summary

Data structured generated by type checkers need to be tagged with "#pragma clang section" attributes if those are being used.

[dmikulin]

Updated after recent commits.

clang/lib/CodeGen/CGExpr.cpp

llvm::Constant *Components[] = {
     llvm::ConstantDataArray::getString(getLLVMContext(), Buffer)
   };
   llvm::Constant *Descriptor = llvm::ConstantStruct::getAnon(Components);
 
   auto *GV = new llvm::GlobalVariable(
       CGM.getModule(), Descriptor->getType(),
       /*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, Descriptor);
   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+  CGM.setPragmaSectionAttributes(CurFuncDecl, GV);
   CGM.getSanitizerMetadata()->disableSanitizerForGlobal(GV);
 
   // Remember the descriptor for this type.
   CGM.setTypeDescriptorInMap(T, GV);
 
   return GV;
 }
 
if (PathComponentsToStrip < 0) {
       if (I != E)
         FilenameString =
             FilenameString.substr(I - llvm::sys::path::begin(FilenameString));
       else
         FilenameString = llvm::sys::path::filename(FilenameString);
     }
 
     auto FilenameGV = CGM.GetAddrOfConstantCString(FilenameString, ".src");
+    CGM.setPragmaSectionAttributes(CurFuncDecl, cast<llvm::GlobalVariable>(FilenameGV.getPointer()));
     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(
                           cast<llvm::GlobalVariable>(FilenameGV.getPointer()));
     Filename = FilenameGV.getPointer();
     Line = PLoc.getLine();
     Column = PLoc.getColumn();
   } else {
     Filename = llvm::Constant::getNullValue(Int8PtrTy);
     Line = Column = 0;
if (!CGM.getCodeGenOpts().SanitizeMinimalRuntime) {
 
     // Emit handler arguments and create handler function type.
     if (!StaticArgs.empty()) {
       llvm::Constant *Info = llvm::ConstantStruct::getAnon(StaticArgs);
       auto *InfoPtr =
           new llvm::GlobalVariable(CGM.getModule(), Info->getType(), false,
                                    llvm::GlobalVariable::PrivateLinkage, Info);
       InfoPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+      CGM.setPragmaSectionAttributes(CurFuncDecl, InfoPtr);
       CGM.getSanitizerMetadata()->disableSanitizerForGlobal(InfoPtr);
       Args.push_back(Builder.CreateBitCast(InfoPtr, Int8PtrTy));
       ArgTypes.push_back(Int8PtrTy);
     }
 
     for (size_t i = 0, n = DynamicArgs.size(); i != n; ++i) {
       Args.push_back(EmitCheckValue(DynamicArgs[i]));
       ArgTypes.push_back(IntPtrTy);

clang/lib/CodeGen/CodeGenModule.h

void GenOpenCLArgMetadata(llvm::Function *FN,
                             const FunctionDecl *FD = nullptr,
                             CodeGenFunction *CGF = nullptr);
 
   /// Get target specific null pointer.
   /// \param T is the LLVM type of the null pointer.
   /// \param QT is the clang QualType of the null pointer.
   llvm::Constant *getNullPointer(llvm::PointerType *T, QualType QT);
 
+  /// Set section attributes requested by "#pragma clang section"
+  ///  \param D is the declaration to read semantic attributes from.
+  ///  \param GO is the global object to set section attributes.
+  void setPragmaSectionAttributes(const Decl *D, llvm::GlobalObject *GO);
+
 private:
   llvm::Constant *GetOrCreateLLVMFunction(
       StringRef MangledName, llvm::Type *Ty, GlobalDecl D, bool ForVTable,
       bool DontDefer = false, bool IsThunk = false,
       llvm::AttributeList ExtraAttrs = llvm::AttributeList(),
       ForDefinition_t IsForDefinition = NotForDefinition);
 
   llvm::Constant *GetOrCreateMultiVersionResolver(GlobalDecl GD,

clang/lib/CodeGen/CodeGenModule.cpp

if (!Features.empty()) {
     llvm::sort(Features);
     Attrs.addAttribute("target-features", llvm::join(Features, ","));
     AddedAttr = true;
   }
 
   return AddedAttr;
 }
 
-void CodeGenModule::setNonAliasAttributes(GlobalDecl GD,
-                                          llvm::GlobalObject *GO) {
-  const Decl *D = GD.getDecl();
-  SetCommonAttributes(GD, GO);
-
+void CodeGenModule::setPragmaSectionAttributes(const Decl *D,
+                 llvm::GlobalObject *GO) {
   if (D) {
     if (auto *GV = dyn_cast<llvm::GlobalVariable>(GO)) {
       if (auto *SA = D->getAttr<PragmaClangBSSSectionAttr>())
         GV->addAttribute("bss-section", SA->getName());
       if (auto *SA = D->getAttr<PragmaClangDataSectionAttr>())
         GV->addAttribute("data-section", SA->getName());
       if (auto *SA = D->getAttr<PragmaClangRodataSectionAttr>())
         GV->addAttribute("rodata-section", SA->getName());
       if (auto *SA = D->getAttr<PragmaClangRelroSectionAttr>())
         GV->addAttribute("relro-section", SA->getName());
     }
 
     if (auto *F = dyn_cast<llvm::Function>(GO)) {
       if (auto *SA = D->getAttr<PragmaClangTextSectionAttr>())
         if (!D->getAttr<SectionAttr>())
           F->addFnAttr("implicit-section-name", SA->getName());
 
+      if (auto *SA = D->getAttr<PragmaClangBSSSectionAttr>())
+        F->addFnAttr("bss-section", SA->getName());
+      if (auto *SA = D->getAttr<PragmaClangDataSectionAttr>())
+        F->addFnAttr("data-section", SA->getName());
+      if (auto *SA = D->getAttr<PragmaClangRodataSectionAttr>())
+        F->addFnAttr("rodata-section", SA->getName());
+      if (auto *SA = D->getAttr<PragmaClangRelroSectionAttr>())
+        F->addFnAttr("relro-section", SA->getName());
+    }
+  }
+}
+
+void CodeGenModule::setNonAliasAttributes(GlobalDecl GD,
+                                          llvm::GlobalObject *GO) {
+  const Decl *D = GD.getDecl();
+  SetCommonAttributes(GD, GO);
+  setPragmaSectionAttributes(D, GO);
+
+  if (D) {
+    if (auto *F = dyn_cast<llvm::Function>(GO)) {
       llvm::AttrBuilder Attrs;
       if (GetCPUAndFeaturesAttributes(GD, Attrs)) {
         // We know that GetCPUAndFeaturesAttributes will always have the
         // newest set, since it has the newest possible FunctionDecl, so the
         // new ones should replace the old.
         F->removeFnAttr("target-cpu");
         F->removeFnAttr("target-features");
         F->addAttributes(llvm::AttributeList::FunctionIndex, Attrs);

clang/lib/Sema/SemaDecl.cpp

Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
 
   // Apply an implicit SectionAttr if '#pragma clang section text' is active
   if (PragmaClangTextSection.Valid && D.isFunctionDefinition() &&
       !NewFD->hasAttr<SectionAttr>())
     NewFD->addAttr(PragmaClangTextSectionAttr::CreateImplicit(
         Context, PragmaClangTextSection.SectionName,
         PragmaClangTextSection.PragmaLocation, AttributeCommonInfo::AS_Pragma));
 
+  if (D.isFunctionDefinition()) {
+    if (PragmaClangBSSSection.Valid)
+      NewFD->addAttr(PragmaClangBSSSectionAttr::CreateImplicit(
+          Context, PragmaClangBSSSection.SectionName,
+          PragmaClangBSSSection.PragmaLocation));
+    if (PragmaClangDataSection.Valid)
+      NewFD->addAttr(PragmaClangDataSectionAttr::CreateImplicit(
+          Context, PragmaClangDataSection.SectionName,
+          PragmaClangDataSection.PragmaLocation));
+    if (PragmaClangRodataSection.Valid)
+      NewFD->addAttr(PragmaClangRodataSectionAttr::CreateImplicit(
+          Context, PragmaClangRodataSection.SectionName,
+          PragmaClangRodataSection.PragmaLocation));
+    if (PragmaClangRelroSection.Valid)
+      NewFD->addAttr(PragmaClangRelroSectionAttr::CreateImplicit(
+          Context, PragmaClangRelroSection.SectionName,
+          PragmaClangRelroSection.PragmaLocation));
+  }
+
   // Apply an implicit SectionAttr if #pragma code_seg is active.
   if (CodeSegStack.CurrentValue && D.isFunctionDefinition() &&
       !NewFD->hasAttr<SectionAttr>()) {
     NewFD->addAttr(SectionAttr::CreateImplicit(
         Context, CodeSegStack.CurrentValue->getString(),
         CodeSegStack.CurrentPragmaLocation, AttributeCommonInfo::AS_Pragma,
         SectionAttr::Declspec_allocate));
     if (UnifySection(CodeSegStack.CurrentValue->getString(),

clang/test/CodeGen/cfi-pragma-section.c

+// Check that CFI-generated data structures are tagged with
+// "#pragma clang section" attributes
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-icall \
+// RUN:     -fno-sanitize-trap=cfi-icall -emit-llvm -o - %s | FileCheck %s
+
+// CHECK-DAG: attributes [[ATTR:#[0-9]+]]{{.*}}bss-section{{.*}}data-section{{.*}}rodata-section
+// CHECK-DAG: @.src = private unnamed_addr constant{{.*}}cfi-pragma-section.c{{.*}}[[ATTR]]
+// CHECK-DAG: @{{[0-9]+}} = private unnamed_addr constant{{.*}}int (int){{.*}}[[ATTR]]
+// CHECK-DAG: @{{[0-9]+}} = private unnamed_addr global{{.*}}@.src{{.*}}[[ATTR]]
+
+typedef int (*int_arg_fn)(int);
+
+static int int_arg1(int arg) {
+    return 0;
+}
+
+static int int_arg2(int arg) {
+    return 1;
+}
+
+int_arg_fn int_funcs[2] = {int_arg1, int_arg2};
+
+#pragma clang section bss = ".bss.mycfi"
+#pragma clang section data = ".data.mycfi"
+#pragma clang section rodata = ".rodata.mycfi"
+
+int main(int argc, const char *argv[]) {
+
+    int idx = argv[1][0] - '0';
+    return int_funcs[argc](idx);
+}