1 //===- InstrOrderFile.cpp ---- Late IR instrumentation for order file ----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //===----------------------------------------------------------------------===//
10
11 #include "llvm/Transforms/Instrumentation/InstrOrderFile.h"
12 #include "llvm/IR/Constants.h"
13 #include "llvm/IR/Function.h"
14 #include "llvm/IR/GlobalValue.h"
15 #include "llvm/IR/IRBuilder.h"
16 #include "llvm/IR/Instructions.h"
17 #include "llvm/IR/Module.h"
18 #include "llvm/InitializePasses.h"
19 #include "llvm/Pass.h"
20 #include "llvm/PassRegistry.h"
21 #include "llvm/ProfileData/InstrProf.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/FileSystem.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Transforms/Instrumentation.h"
26 #include <fstream>
27 #include <mutex>
28 #include <sstream>
29
30 using namespace llvm;
31 #define DEBUG_TYPE "instrorderfile"
32
33 static cl::opt<std::string> ClOrderFileWriteMapping(
34 "orderfile-write-mapping", cl::init(""),
35 cl::desc(
36 "Dump functions and their MD5 hash to deobfuscate profile data"),
37 cl::Hidden);
38
39 namespace {
40
41 // We need a global bitmap to tell if a function is executed. We also
42 // need a global variable to save the order of functions. We can use a
43 // fixed-size buffer that saves the MD5 hash of the function. We need
44 // a global variable to save the index into the buffer.
45
46 std::mutex MappingMutex;
47
48 struct InstrOrderFile {
49 private:
50 GlobalVariable *OrderFileBuffer;
51 GlobalVariable *BufferIdx;
52 GlobalVariable *BitMap;
53 ArrayType *BufferTy;
54 ArrayType *MapTy;
55
56 public:
57 InstrOrderFile() = default;
58
createOrderFileData__anon590d2d540111::InstrOrderFile59 void createOrderFileData(Module &M) {
60 LLVMContext &Ctx = M.getContext();
61 int NumFunctions = 0;
62 for (Function &F : M) {
63 if (!F.isDeclaration())
64 NumFunctions++;
65 }
66
67 BufferTy =
68 ArrayType::get(Type::getInt64Ty(Ctx), INSTR_ORDER_FILE_BUFFER_SIZE);
69 Type *IdxTy = Type::getInt32Ty(Ctx);
70 MapTy = ArrayType::get(Type::getInt8Ty(Ctx), NumFunctions);
71
72 // Create the global variables.
73 std::string SymbolName = INSTR_PROF_ORDERFILE_BUFFER_NAME_STR;
74 OrderFileBuffer = new GlobalVariable(M, BufferTy, false, GlobalValue::LinkOnceODRLinkage,
75 Constant::getNullValue(BufferTy), SymbolName);
76 Triple TT = Triple(M.getTargetTriple());
77 OrderFileBuffer->setSection(
78 getInstrProfSectionName(IPSK_orderfile, TT.getObjectFormat()));
79
80 std::string IndexName = INSTR_PROF_ORDERFILE_BUFFER_IDX_NAME_STR;
81 BufferIdx = new GlobalVariable(M, IdxTy, false, GlobalValue::LinkOnceODRLinkage,
82 Constant::getNullValue(IdxTy), IndexName);
83
84 std::string BitMapName = "bitmap_0";
85 BitMap = new GlobalVariable(M, MapTy, false, GlobalValue::PrivateLinkage,
86 Constant::getNullValue(MapTy), BitMapName);
87 }
88
89 // Generate the code sequence in the entry block of each function to
90 // update the buffer.
generateCodeSequence__anon590d2d540111::InstrOrderFile91 void generateCodeSequence(Module &M, Function &F, int FuncId) {
92 if (!ClOrderFileWriteMapping.empty()) {
93 std::lock_guard<std::mutex> LogLock(MappingMutex);
94 std::error_code EC;
95 llvm::raw_fd_ostream OS(ClOrderFileWriteMapping, EC,
96 llvm::sys::fs::OF_Append);
97 if (EC) {
98 report_fatal_error(Twine("Failed to open ") + ClOrderFileWriteMapping +
99 " to save mapping file for order file instrumentation\n");
100 } else {
101 std::stringstream stream;
102 stream << std::hex << MD5Hash(F.getName());
103 std::string singleLine = "MD5 " + stream.str() + " " +
104 std::string(F.getName()) + '\n';
105 OS << singleLine;
106 }
107 }
108
109 BasicBlock *OrigEntry = &F.getEntryBlock();
110
111 LLVMContext &Ctx = M.getContext();
112 IntegerType *Int32Ty = Type::getInt32Ty(Ctx);
113 IntegerType *Int8Ty = Type::getInt8Ty(Ctx);
114
115 // Create a new entry block for instrumentation. We will check the bitmap
116 // in this basic block.
117 BasicBlock *NewEntry =
118 BasicBlock::Create(M.getContext(), "order_file_entry", &F, OrigEntry);
119 IRBuilder<> entryB(NewEntry);
120 // Create a basic block for updating the circular buffer.
121 BasicBlock *UpdateOrderFileBB =
122 BasicBlock::Create(M.getContext(), "order_file_set", &F, OrigEntry);
123 IRBuilder<> updateB(UpdateOrderFileBB);
124
125 // Check the bitmap, if it is already 1, do nothing.
126 // Otherwise, set the bit, grab the index, update the buffer.
127 Value *IdxFlags[] = {ConstantInt::get(Int32Ty, 0),
128 ConstantInt::get(Int32Ty, FuncId)};
129 Value *MapAddr = entryB.CreateGEP(MapTy, BitMap, IdxFlags, "");
130 LoadInst *loadBitMap = entryB.CreateLoad(Int8Ty, MapAddr, "");
131 entryB.CreateStore(ConstantInt::get(Int8Ty, 1), MapAddr);
132 Value *IsNotExecuted =
133 entryB.CreateICmpEQ(loadBitMap, ConstantInt::get(Int8Ty, 0));
134 entryB.CreateCondBr(IsNotExecuted, UpdateOrderFileBB, OrigEntry);
135
136 // Fill up UpdateOrderFileBB: grab the index, update the buffer!
137 Value *IdxVal = updateB.CreateAtomicRMW(
138 AtomicRMWInst::Add, BufferIdx, ConstantInt::get(Int32Ty, 1),
139 MaybeAlign(), AtomicOrdering::SequentiallyConsistent);
140 // We need to wrap around the index to fit it inside the buffer.
141 Value *WrappedIdx = updateB.CreateAnd(
142 IdxVal, ConstantInt::get(Int32Ty, INSTR_ORDER_FILE_BUFFER_MASK));
143 Value *BufferGEPIdx[] = {ConstantInt::get(Int32Ty, 0), WrappedIdx};
144 Value *BufferAddr =
145 updateB.CreateGEP(BufferTy, OrderFileBuffer, BufferGEPIdx, "");
146 updateB.CreateStore(ConstantInt::get(Type::getInt64Ty(Ctx), MD5Hash(F.getName())),
147 BufferAddr);
148 updateB.CreateBr(OrigEntry);
149 }
150
run__anon590d2d540111::InstrOrderFile151 bool run(Module &M) {
152 createOrderFileData(M);
153
154 int FuncId = 0;
155 for (Function &F : M) {
156 if (F.isDeclaration())
157 continue;
158 generateCodeSequence(M, F, FuncId);
159 ++FuncId;
160 }
161
162 return true;
163 }
164
165 }; // End of InstrOrderFile struct
166 } // End anonymous namespace
167
168 PreservedAnalyses
run(Module & M,ModuleAnalysisManager & AM)169 InstrOrderFilePass::run(Module &M, ModuleAnalysisManager &AM) {
170 if (InstrOrderFile().run(M))
171 return PreservedAnalyses::none();
172 return PreservedAnalyses::all();
173 }
174