1//===- InstrOrderFile.cpp ---- Late IR instrumentation for order file ----===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//===----------------------------------------------------------------------===//
11
12#include "llvm/Transforms/Instrumentation/InstrOrderFile.h"
13#include "llvm/ADT/Statistic.h"
14#include "llvm/IR/Constants.h"
15#include "llvm/IR/Function.h"
16#include "llvm/IR/GlobalValue.h"
17#include "llvm/IR/IRBuilder.h"
18#include "llvm/IR/Instruction.h"
19#include "llvm/IR/Instructions.h"
20#include "llvm/IR/Metadata.h"
21#include "llvm/IR/Module.h"
22#include "llvm/InitializePasses.h"
23#include "llvm/Pass.h"
24#include "llvm/PassRegistry.h"
25#include "llvm/ProfileData/InstrProf.h"
26#include "llvm/Support/CommandLine.h"
27#include "llvm/Support/Debug.h"
28#include "llvm/Support/FileSystem.h"
29#include "llvm/Support/Path.h"
30#include "llvm/Support/raw_ostream.h"
31#include "llvm/Transforms/Instrumentation.h"
32#include <fstream>
33#include <map>
34#include <mutex>
35#include <set>
36#include <sstream>
37
38using namespace llvm;
39#define DEBUG_TYPE "instrorderfile"
40
41static cl::opt<std::string> ClOrderFileWriteMapping(
42    "orderfile-write-mapping", cl::init(""),
43    cl::desc(
44        "Dump functions and their MD5 hash to deobfuscate profile data"),
45    cl::Hidden);
46
47namespace {
48
49// We need a global bitmap to tell if a function is executed. We also
50// need a global variable to save the order of functions. We can use a
51// fixed-size buffer that saves the MD5 hash of the function. We need
52// a global variable to save the index into the buffer.
53
54std::mutex MappingMutex;
55
56struct InstrOrderFile {
57private:
58  GlobalVariable *OrderFileBuffer;
59  GlobalVariable *BufferIdx;
60  GlobalVariable *BitMap;
61  ArrayType *BufferTy;
62  ArrayType *MapTy;
63
64public:
65  InstrOrderFile() {}
66
67  void createOrderFileData(Module &M) {
68    LLVMContext &Ctx = M.getContext();
69    int NumFunctions = 0;
70    for (Function &F : M) {
71      if (!F.isDeclaration())
72        NumFunctions++;
73    }
74
75    BufferTy =
76        ArrayType::get(Type::getInt64Ty(Ctx), INSTR_ORDER_FILE_BUFFER_SIZE);
77    Type *IdxTy = Type::getInt32Ty(Ctx);
78    MapTy = ArrayType::get(Type::getInt8Ty(Ctx), NumFunctions);
79
80    // Create the global variables.
81    std::string SymbolName = INSTR_PROF_ORDERFILE_BUFFER_NAME_STR;
82    OrderFileBuffer = new GlobalVariable(M, BufferTy, false, GlobalValue::LinkOnceODRLinkage,
83                           Constant::getNullValue(BufferTy), SymbolName);
84    Triple TT = Triple(M.getTargetTriple());
85    OrderFileBuffer->setSection(
86        getInstrProfSectionName(IPSK_orderfile, TT.getObjectFormat()));
87
88    std::string IndexName = INSTR_PROF_ORDERFILE_BUFFER_IDX_NAME_STR;
89    BufferIdx = new GlobalVariable(M, IdxTy, false, GlobalValue::LinkOnceODRLinkage,
90                           Constant::getNullValue(IdxTy), IndexName);
91
92    std::string BitMapName = "bitmap_0";
93    BitMap = new GlobalVariable(M, MapTy, false, GlobalValue::PrivateLinkage,
94                                Constant::getNullValue(MapTy), BitMapName);
95  }
96
97  // Generate the code sequence in the entry block of each function to
98  // update the buffer.
99  void generateCodeSequence(Module &M, Function &F, int FuncId) {
100    if (!ClOrderFileWriteMapping.empty()) {
101      std::lock_guard<std::mutex> LogLock(MappingMutex);
102      std::error_code EC;
103      llvm::raw_fd_ostream OS(ClOrderFileWriteMapping, EC,
104                              llvm::sys::fs::OF_Append);
105      if (EC) {
106        report_fatal_error(Twine("Failed to open ") + ClOrderFileWriteMapping +
107                           " to save mapping file for order file instrumentation\n");
108      } else {
109        std::stringstream stream;
110        stream << std::hex << MD5Hash(F.getName());
111        std::string singleLine = "MD5 " + stream.str() + " " +
112                                 std::string(F.getName()) + '\n';
113        OS << singleLine;
114      }
115    }
116
117    BasicBlock *OrigEntry = &F.getEntryBlock();
118
119    LLVMContext &Ctx = M.getContext();
120    IntegerType *Int32Ty = Type::getInt32Ty(Ctx);
121    IntegerType *Int8Ty = Type::getInt8Ty(Ctx);
122
123    // Create a new entry block for instrumentation. We will check the bitmap
124    // in this basic block.
125    BasicBlock *NewEntry =
126        BasicBlock::Create(M.getContext(), "order_file_entry", &F, OrigEntry);
127    IRBuilder<> entryB(NewEntry);
128    // Create a basic block for updating the circular buffer.
129    BasicBlock *UpdateOrderFileBB =
130        BasicBlock::Create(M.getContext(), "order_file_set", &F, OrigEntry);
131    IRBuilder<> updateB(UpdateOrderFileBB);
132
133    // Check the bitmap, if it is already 1, do nothing.
134    // Otherwise, set the bit, grab the index, update the buffer.
135    Value *IdxFlags[] = {ConstantInt::get(Int32Ty, 0),
136                         ConstantInt::get(Int32Ty, FuncId)};
137    Value *MapAddr = entryB.CreateGEP(MapTy, BitMap, IdxFlags, "");
138    LoadInst *loadBitMap = entryB.CreateLoad(Int8Ty, MapAddr, "");
139    entryB.CreateStore(ConstantInt::get(Int8Ty, 1), MapAddr);
140    Value *IsNotExecuted =
141        entryB.CreateICmpEQ(loadBitMap, ConstantInt::get(Int8Ty, 0));
142    entryB.CreateCondBr(IsNotExecuted, UpdateOrderFileBB, OrigEntry);
143
144    // Fill up UpdateOrderFileBB: grab the index, update the buffer!
145    Value *IdxVal = updateB.CreateAtomicRMW(
146        AtomicRMWInst::Add, BufferIdx, ConstantInt::get(Int32Ty, 1),
147        AtomicOrdering::SequentiallyConsistent);
148    // We need to wrap around the index to fit it inside the buffer.
149    Value *WrappedIdx = updateB.CreateAnd(
150        IdxVal, ConstantInt::get(Int32Ty, INSTR_ORDER_FILE_BUFFER_MASK));
151    Value *BufferGEPIdx[] = {ConstantInt::get(Int32Ty, 0), WrappedIdx};
152    Value *BufferAddr =
153        updateB.CreateGEP(BufferTy, OrderFileBuffer, BufferGEPIdx, "");
154    updateB.CreateStore(ConstantInt::get(Type::getInt64Ty(Ctx), MD5Hash(F.getName())),
155                        BufferAddr);
156    updateB.CreateBr(OrigEntry);
157  }
158
159  bool run(Module &M) {
160    createOrderFileData(M);
161
162    int FuncId = 0;
163    for (Function &F : M) {
164      if (F.isDeclaration())
165        continue;
166      generateCodeSequence(M, F, FuncId);
167      ++FuncId;
168    }
169
170    return true;
171  }
172
173}; // End of InstrOrderFile struct
174
175class InstrOrderFileLegacyPass : public ModulePass {
176public:
177  static char ID;
178
179  InstrOrderFileLegacyPass() : ModulePass(ID) {
180    initializeInstrOrderFileLegacyPassPass(
181        *PassRegistry::getPassRegistry());
182  }
183
184  bool runOnModule(Module &M) override;
185};
186
187} // End anonymous namespace
188
189bool InstrOrderFileLegacyPass::runOnModule(Module &M) {
190  if (skipModule(M))
191    return false;
192
193  return InstrOrderFile().run(M);
194}
195
196PreservedAnalyses
197InstrOrderFilePass::run(Module &M, ModuleAnalysisManager &AM) {
198  if (InstrOrderFile().run(M))
199    return PreservedAnalyses::none();
200  return PreservedAnalyses::all();
201}
202
203INITIALIZE_PASS_BEGIN(InstrOrderFileLegacyPass, "instrorderfile",
204                      "Instrumentation for Order File", false, false)
205INITIALIZE_PASS_END(InstrOrderFileLegacyPass, "instrorderfile",
206                    "Instrumentation for Order File", false, false)
207
208char InstrOrderFileLegacyPass::ID = 0;
209
210ModulePass *llvm::createInstrOrderFilePass() {
211  return new InstrOrderFileLegacyPass();
212}
213