llvm/lib/CodeGen/SanitizerBinaryMetadata.cpp

   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 }