1 //===- SanitizerBinaryMetadata.cpp 2 //----------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of SanitizerBinaryMetadata. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Transforms/Instrumentation/SanitizerBinaryMetadata.h" 15 #include "llvm/CodeGen/MachineFrameInfo.h" 16 #include "llvm/CodeGen/MachineFunction.h" 17 #include "llvm/CodeGen/MachineFunctionPass.h" 18 #include "llvm/CodeGen/Passes.h" 19 #include "llvm/IR/IRBuilder.h" 20 #include "llvm/IR/MDBuilder.h" 21 #include "llvm/InitializePasses.h" 22 #include "llvm/Pass.h" 23 #include <algorithm> 24 25 using namespace llvm; 26 27 namespace { 28 class MachineSanitizerBinaryMetadata : public MachineFunctionPass { 29 public: 30 static char ID; 31 32 MachineSanitizerBinaryMetadata(); 33 bool runOnMachineFunction(MachineFunction &F) override; 34 }; 35 } // namespace 36 37 INITIALIZE_PASS(MachineSanitizerBinaryMetadata, "machine-sanmd", 38 "Machine Sanitizer Binary Metadata", false, false) 39 40 char MachineSanitizerBinaryMetadata::ID = 0; 41 char &llvm::MachineSanitizerBinaryMetadataID = 42 MachineSanitizerBinaryMetadata::ID; 43 44 MachineSanitizerBinaryMetadata::MachineSanitizerBinaryMetadata() 45 : MachineFunctionPass(ID) { 46 initializeMachineSanitizerBinaryMetadataPass( 47 *PassRegistry::getPassRegistry()); 48 } 49 50 bool MachineSanitizerBinaryMetadata::runOnMachineFunction(MachineFunction &MF) { 51 MDNode *MD = MF.getFunction().getMetadata(LLVMContext::MD_pcsections); 52 if (!MD) 53 return false; 54 const auto &Section = *cast<MDString>(MD->getOperand(0)); 55 if (!Section.getString().starts_with(kSanitizerBinaryMetadataCoveredSection)) 56 return false; 57 auto &AuxMDs = *cast<MDTuple>(MD->getOperand(1)); 58 // Assume it currently only has features. 59 assert(AuxMDs.getNumOperands() == 1); 60 Constant *Features = 61 cast<ConstantAsMetadata>(AuxMDs.getOperand(0))->getValue(); 62 if (!Features->getUniqueInteger()[kSanitizerBinaryMetadataUARBit]) 63 return false; 64 // Calculate size of stack args for the function. 65 int64_t Size = 0; 66 uint64_t Align = 0; 67 const MachineFrameInfo &MFI = MF.getFrameInfo(); 68 for (int i = -1; i >= (int)-MFI.getNumFixedObjects(); --i) { 69 Size = std::max(Size, MFI.getObjectOffset(i) + MFI.getObjectSize(i)); 70 Align = std::max(Align, MFI.getObjectAlign(i).value()); 71 } 72 Size = (Size + Align - 1) & ~(Align - 1); 73 if (!Size) 74 return false; 75 // Non-zero size, update metadata. 76 auto &F = MF.getFunction(); 77 IRBuilder<> IRB(F.getContext()); 78 MDBuilder MDB(F.getContext()); 79 // Keep the features and append size of stack args to the metadata. 80 APInt NewFeatures = Features->getUniqueInteger(); 81 NewFeatures.setBit(kSanitizerBinaryMetadataUARHasSizeBit); 82 F.setMetadata( 83 LLVMContext::MD_pcsections, 84 MDB.createPCSections({{Section.getString(), 85 {IRB.getInt(NewFeatures), IRB.getInt32(Size)}}})); 86 return false; 87 } 88