xref: /llvm-project/llvm/unittests/DebugInfo/DWARF/DWARFExpressionCopyBytesTest.cpp (revision b8220b986dcc8c5d0c44a125642009d8175fc11d) 
1 //===- llvm/unittest/DebugInfo/DWARFExpressionRawDataTest.cpp -------------===//
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 #include "llvm/ADT/ArrayRef.h"
10 #include "llvm/BinaryFormat/Dwarf.h"
11 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
12 #include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
13 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
14 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
15 #include "llvm/MC/MCAsmBackend.h"
16 #include "llvm/MC/MCAsmInfo.h"
17 #include "llvm/MC/MCCodeEmitter.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCInstrInfo.h"
20 #include "llvm/MC/MCObjectWriter.h"
21 #include "llvm/MC/MCRegisterInfo.h"
22 #include "llvm/MC/MCStreamer.h"
23 #include "llvm/MC/MCSubtargetInfo.h"
24 #include "llvm/MC/MCTargetOptions.h"
25 #include "llvm/MC/TargetRegistry.h"
26 #include "llvm/Object/Binary.h"
27 #include "llvm/Object/ELFObjectFile.h"
28 #include "llvm/Support/DataExtractor.h"
29 #include "llvm/Support/LEB128.h"
30 #include "llvm/Support/MemoryBuffer.h"
31 #include "llvm/Support/TargetSelect.h"
32 #include "llvm/TargetParser/Triple.h"
33 #include "llvm/Testing/Support/Error.h"
34 #include "gtest/gtest.h"
35 
36 using namespace llvm;
37 using namespace dwarf;
38 
39 namespace {
40 
41 /// Tests that a client of DebugInfo/DWARF is able to read raw data bytes of a
42 /// DWARFExpression parsed from CFI with the intent of writing them back as is
43 /// via MC layer / cfi_escape.
44 /// This is relevant for binary tools that need to rewrite/copy unwind and
45 /// debug info from input to output binary.
46 class DWARFExpressionCopyBytesTest : public ::testing::Test {
47 public:
48   const char *TripleName = "x86_64-pc-linux";
49   std::unique_ptr<MCRegisterInfo> MRI;
50   std::unique_ptr<MCAsmInfo> MAI;
51   std::unique_ptr<const MCSubtargetInfo> STI;
52   const Target *TheTarget;
53 
54   DWARFExpressionCopyBytesTest() {
55     InitializeAllTargets();
56     InitializeAllTargetMCs();
57     InitializeAllAsmPrinters();
58 
59     std::string ErrorStr;
60     TheTarget = TargetRegistry::lookupTarget(TripleName, ErrorStr);
61     if (!TheTarget)
62       return;
63 
64     MRI.reset(TheTarget->createMCRegInfo(TripleName));
65     MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName, MCTargetOptions()));
66     STI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
67   }
68 
69   struct StreamerContext {
70     std::unique_ptr<MCObjectFileInfo> MOFI;
71     std::unique_ptr<MCContext> Ctx;
72     std::unique_ptr<const MCInstrInfo> MII;
73     std::unique_ptr<MCStreamer> Streamer;
74   };
75 
76   /// Create all data structures necessary to operate an assembler
77   StreamerContext createStreamer(raw_pwrite_stream &OS);
78   /// Emit a dummy obj file with a single CFI instruction,
79   /// DW_CFA_def_cfa_expression, encoding as its operand the DWARF expression
80   /// represented by ExprBytes
81   SmallString<0> emitObjFile(StringRef ExprBytes);
82   /// Peruse the object file looking for the encoded DWARF expression, and check
83   /// that its operand was encoded correctly
84   void parseCFIsAndCheckExpression(const llvm::object::ObjectFile &E,
85                                    ArrayRef<uint8_t> Expected);
86   /// Open the in-memory relocatable object file and verify that it contains
87   /// the expected DWARF expression bytes
88   void readAndCheckObjFile(StringRef ObjFileData, ArrayRef<uint8_t> Expected);
89   /// Run this test on the DWARF expression represented by the bytes in
90   /// ExprData. Check that the getData() API retrieves these original bytes and
91   /// that we can use them to encode a CFI with those bytes as operands (via
92   /// cfi_escape).
93   void testExpr(ArrayRef<uint8_t> ExprData);
94 };
95 
96 } // namespace
97 
98 DWARFExpressionCopyBytesTest::StreamerContext
99 DWARFExpressionCopyBytesTest::createStreamer(raw_pwrite_stream &OS) {
100   StreamerContext Res;
101   Res.Ctx =
102       std::make_unique<MCContext>(Triple(TripleName), MAI.get(), MRI.get(),
103                                   /*MSTI=*/nullptr);
104   Res.MOFI.reset(TheTarget->createMCObjectFileInfo(*Res.Ctx,
105                                                    /*PIC=*/false));
106   Res.Ctx->setObjectFileInfo(Res.MOFI.get());
107 
108   Res.MII.reset(TheTarget->createMCInstrInfo());
109   MCCodeEmitter *MCE = TheTarget->createMCCodeEmitter(*Res.MII, *Res.Ctx);
110   MCAsmBackend *MAB =
111       TheTarget->createMCAsmBackend(*STI, *MRI, MCTargetOptions());
112   std::unique_ptr<MCObjectWriter> OW = MAB->createObjectWriter(OS);
113   Res.Streamer.reset(TheTarget->createMCObjectStreamer(
114       Triple(TripleName), *Res.Ctx, std::unique_ptr<MCAsmBackend>(MAB),
115       std::move(OW), std::unique_ptr<MCCodeEmitter>(MCE), *STI));
116   return Res;
117 }
118 
119 SmallString<0> DWARFExpressionCopyBytesTest::emitObjFile(StringRef ExprBytes) {
120   auto EncodeDefCfaExpr = [&](StringRef Bytes) {
121     std::string Str;
122     raw_string_ostream OS(Str);
123     OS << static_cast<uint8_t>(dwarf::DW_CFA_def_cfa_expression);
124     encodeULEB128(Bytes.size(), OS);
125     OS << Bytes;
126     return Str;
127   };
128 
129   SmallString<0> Storage;
130   raw_svector_ostream VecOS(Storage);
131   StreamerContext C = createStreamer(VecOS);
132   C.Streamer->initSections(false, *STI);
133   MCSection *Section = C.MOFI->getTextSection();
134   Section->setHasInstructions(true);
135   C.Streamer->switchSection(Section);
136   C.Streamer->emitCFIStartProc(true);
137   auto Str = EncodeDefCfaExpr(ExprBytes);
138   C.Streamer->emitCFIEscape(Str);
139   C.Streamer->emitNops(4, 1, SMLoc(), *STI);
140   C.Streamer->emitCFIEndProc();
141   C.Streamer->finish();
142   return Storage;
143 }
144 
145 void DWARFExpressionCopyBytesTest::parseCFIsAndCheckExpression(
146     const llvm::object::ObjectFile &E, ArrayRef<uint8_t> Expected) {
147   auto FetchFirstCfaExpression = [](const DWARFDebugFrame &EHFrame)
148       -> std::optional<CFIProgram::Instruction> {
149     for (const dwarf::FrameEntry &Entry : EHFrame.entries()) {
150       const auto *CurFDE = dyn_cast<dwarf::FDE>(&Entry);
151       if (!CurFDE)
152         continue;
153       for (const CFIProgram::Instruction &Instr : CurFDE->cfis()) {
154         if (Instr.Opcode != dwarf::DW_CFA_def_cfa_expression)
155           continue;
156         return Instr;
157       }
158     }
159     return std::nullopt;
160   };
161 
162   std::unique_ptr<DWARFContext> Ctx = DWARFContext::create(E);
163   const DWARFDebugFrame *EHFrame = cantFail(Ctx->getEHFrame());
164   ASSERT_NE(nullptr, EHFrame);
165   auto CfiInstr = FetchFirstCfaExpression(*EHFrame);
166   ASSERT_TRUE(CfiInstr);
167   DWARFExpression Expr = *(CfiInstr->Expression);
168   StringRef ExprData = Expr.getData();
169   EXPECT_EQ(ExprData.size(), Expected.size());
170   for (unsigned I = 0, E = ExprData.size(); I != E; ++I) {
171     EXPECT_EQ(static_cast<uint8_t>(ExprData[I]), Expected[I]);
172   }
173 }
174 
175 void DWARFExpressionCopyBytesTest::readAndCheckObjFile(
176     StringRef ObjFileData, ArrayRef<uint8_t> Expected) {
177   std::unique_ptr<MemoryBuffer> MB =
178       MemoryBuffer::getMemBuffer(ObjFileData, "", false);
179   std::unique_ptr<object::Binary> Bin =
180       cantFail(llvm::object::createBinary(MB->getMemBufferRef()));
181   if (auto *E = dyn_cast<llvm::object::ELFObjectFileBase>(&*Bin)) {
182     parseCFIsAndCheckExpression(*E, Expected);
183   }
184 }
185 
186 void DWARFExpressionCopyBytesTest::testExpr(ArrayRef<uint8_t> ExprData) {
187   // If we didn't build x86, do not run the test.
188   if (!MRI)
189     GTEST_SKIP();
190 
191   DataExtractor DE(ExprData, true, 8);
192   DWARFExpression Expr(DE, 8);
193 
194   // Copy this expression into the CFI of a binary and check that we are able to
195   // get it back correctly from this binary.
196   const SmallString<0> EmittedBinContents = emitObjFile(Expr.getData());
197   readAndCheckObjFile(EmittedBinContents.str(), ExprData);
198 }
199 
200 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_reg0) { testExpr({DW_OP_reg0}); }
201 
202 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_reg10) { testExpr({DW_OP_reg10}); }
203 
204 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_regx) {
205   testExpr({DW_OP_regx, 0x80, 0x02});
206 }
207 
208 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0) {
209   testExpr({DW_OP_breg0, 0x04});
210 }
211 
212 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0_large_offset) {
213   testExpr({DW_OP_breg0, 0x80, 0x02});
214 }
215 
216 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg13) {
217   testExpr({DW_OP_breg13, 0x10});
218 }
219 
220 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg13_zero_offset) {
221   testExpr({DW_OP_breg13, 0x00});
222 }
223 
224 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0_negative) {
225   testExpr({DW_OP_breg0, 0x70});
226 }
227 
228 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_bregx) {
229   testExpr({DW_OP_bregx, 0x0d, 0x28});
230 }
231 
232 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_stack_value) {
233   testExpr({DW_OP_breg13, 0x04, DW_OP_stack_value});
234 }
235 
236 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_entry_value) {
237   testExpr({DW_OP_entry_value, 0x01, DW_OP_reg0, DW_OP_stack_value});
238 }
239 
240 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_entry_value_mem) {
241   testExpr({DW_OP_entry_value, 0x02, DW_OP_breg13, 0x10, DW_OP_stack_value});
242 }
243