xref: /llvm-project/llvm/unittests/DebugInfo/DWARF/DWARFExpressionCopyBytesTest.cpp (revision f5907ea1c0debddac72f5e4d15fc7fed30e36a72) 
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/ADT/Triple.h"
11 #include "llvm/BinaryFormat/Dwarf.h"
12 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
13 #include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
14 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
15 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
16 #include "llvm/MC/MCAsmBackend.h"
17 #include "llvm/MC/MCAsmInfo.h"
18 #include "llvm/MC/MCCodeEmitter.h"
19 #include "llvm/MC/MCContext.h"
20 #include "llvm/MC/MCInstrInfo.h"
21 #include "llvm/MC/MCObjectWriter.h"
22 #include "llvm/MC/MCStreamer.h"
23 #include "llvm/MC/MCTargetOptions.h"
24 #include "llvm/MC/TargetRegistry.h"
25 #include "llvm/Object/Binary.h"
26 #include "llvm/Support/DataExtractor.h"
27 #include "llvm/Support/LEB128.h"
28 #include "llvm/Support/TargetSelect.h"
29 #include "llvm/Testing/Support/Error.h"
30 #include "gtest/gtest.h"
31 
32 using namespace llvm;
33 using namespace dwarf;
34 
35 namespace {
36 
37 /// Tests that a client of DebugInfo/DWARF is able to read raw data bytes of a
38 /// DWARFExpression parsed from CFI with the intent of writing them back as is
39 /// via MC layer / cfi_escape.
40 /// This is relevant for binary tools that need to rewrite/copy unwind and
41 /// debug info from input to output binary.
42 class DWARFExpressionCopyBytesTest : public ::testing::Test {
43 public:
44   const char *TripleName = "x86_64-pc-linux";
45   std::unique_ptr<MCRegisterInfo> MRI;
46   std::unique_ptr<MCAsmInfo> MAI;
47   std::unique_ptr<const MCSubtargetInfo> STI;
48   const Target *TheTarget;
49 
50   DWARFExpressionCopyBytesTest() {
51     InitializeAllTargets();
52     InitializeAllTargetMCs();
53     InitializeAllAsmPrinters();
54 
55     std::string ErrorStr;
56     TheTarget = TargetRegistry::lookupTarget(TripleName, ErrorStr);
57     if (!TheTarget)
58       return;
59 
60     MRI.reset(TheTarget->createMCRegInfo(TripleName));
61     MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName, MCTargetOptions()));
62     STI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
63   }
64 
65   struct StreamerContext {
66     std::unique_ptr<MCObjectFileInfo> MOFI;
67     std::unique_ptr<MCContext> Ctx;
68     std::unique_ptr<const MCInstrInfo> MII;
69     std::unique_ptr<MCStreamer> Streamer;
70   };
71 
72   /// Create all data structures necessary to operate an assembler
73   StreamerContext createStreamer(raw_pwrite_stream &OS);
74   /// Emit a dummy obj file with a single CFI instruction,
75   /// DW_CFA_def_cfa_expression, encoding as its operand the DWARF expression
76   /// represented by ExprBytes
77   SmallString<0> emitObjFile(StringRef ExprBytes);
78   /// Peruse the object file looking for the encoded DWARF expression, and check
79   /// that its operand was encoded correctly
80   void parseCFIsAndCheckExpression(const llvm::object::ObjectFile &E,
81                                    ArrayRef<uint8_t> Expected);
82   /// Open the in-memory relocatable object file and verify that it contains
83   /// the expected DWARF expression bytes
84   void readAndCheckObjFile(StringRef ObjFileData, ArrayRef<uint8_t> Expected);
85   /// Run this test on the DWARF expression represented by the bytes in
86   /// ExprData. Check that the getData() API retrieves these original bytes and
87   /// that we can use them to encode a CFI with those bytes as operands (via
88   /// cfi_escape).
89   void testExpr(ArrayRef<uint8_t> ExprData);
90 };
91 
92 } // namespace
93 
94 DWARFExpressionCopyBytesTest::StreamerContext
95 DWARFExpressionCopyBytesTest::createStreamer(raw_pwrite_stream &OS) {
96   StreamerContext Res;
97   Res.Ctx =
98       std::make_unique<MCContext>(Triple(TripleName), MAI.get(), MRI.get(),
99                                   /*MSTI=*/nullptr);
100   Res.MOFI.reset(TheTarget->createMCObjectFileInfo(*Res.Ctx.get(),
101                                                    /*PIC=*/false));
102   Res.Ctx->setObjectFileInfo(Res.MOFI.get());
103 
104   Res.MII.reset(TheTarget->createMCInstrInfo());
105   MCCodeEmitter *MCE = TheTarget->createMCCodeEmitter(*Res.MII, *MRI, *Res.Ctx);
106   MCAsmBackend *MAB =
107       TheTarget->createMCAsmBackend(*STI, *MRI, MCTargetOptions());
108   std::unique_ptr<MCObjectWriter> OW = MAB->createObjectWriter(OS);
109   Res.Streamer.reset(TheTarget->createMCObjectStreamer(
110       Triple(TripleName), *Res.Ctx, std::unique_ptr<MCAsmBackend>(MAB),
111       std::move(OW), std::unique_ptr<MCCodeEmitter>(MCE), *STI,
112       /* RelaxAll */ false,
113       /* IncrementalLinkerCompatible */ false,
114       /* DWARFMustBeAtTheEnd */ false));
115   return Res;
116 }
117 
118 SmallString<0> DWARFExpressionCopyBytesTest::emitObjFile(StringRef ExprBytes) {
119   auto EncodeDefCfaExpr = [&](StringRef Bytes) {
120     std::string Str;
121     raw_string_ostream OS(Str);
122     OS << static_cast<uint8_t>(dwarf::DW_CFA_def_cfa_expression);
123     encodeULEB128(Bytes.size(), OS);
124     OS << Bytes;
125     return Str;
126   };
127 
128   SmallString<0> Storage;
129   raw_svector_ostream VecOS(Storage);
130   StreamerContext C = createStreamer(VecOS);
131   C.Streamer->initSections(false, *STI);
132   MCSection *Section = C.MOFI->getTextSection();
133   Section->setHasInstructions(true);
134   C.Streamer->SwitchSection(Section);
135   C.Streamer->emitCFIStartProc(true);
136   auto Str = EncodeDefCfaExpr(ExprBytes);
137   C.Streamer->emitCFIEscape(Str);
138   C.Streamer->emitNops(4, 1, SMLoc(), *STI);
139   C.Streamer->emitCFIEndProc();
140   C.Streamer->Finish();
141   return Storage;
142 }
143 
144 void DWARFExpressionCopyBytesTest::parseCFIsAndCheckExpression(
145     const llvm::object::ObjectFile &E, ArrayRef<uint8_t> Expected) {
146   auto FetchFirstCfaExpression =
147       [](const DWARFDebugFrame &EHFrame) -> Optional<CFIProgram::Instruction> {
148     for (const dwarf::FrameEntry &Entry : EHFrame.entries()) {
149       const auto *CurFDE = dyn_cast<dwarf::FDE>(&Entry);
150       if (!CurFDE)
151         continue;
152       for (const CFIProgram::Instruction &Instr : CurFDE->cfis()) {
153         if (Instr.Opcode != dwarf::DW_CFA_def_cfa_expression)
154           continue;
155         return Instr;
156       }
157     }
158     return NoneType();
159   };
160 
161   std::unique_ptr<DWARFContext> Ctx = DWARFContext::create(E);
162   const DWARFDebugFrame *EHFrame = cantFail(Ctx->getEHFrame());
163   ASSERT_NE(nullptr, EHFrame);
164   auto CfiInstr = FetchFirstCfaExpression(*EHFrame);
165   ASSERT_TRUE(CfiInstr);
166   DWARFExpression Expr = *(CfiInstr->Expression);
167   StringRef ExprData = Expr.getData();
168   EXPECT_EQ(ExprData.size(), Expected.size());
169   for (unsigned I = 0, E = ExprData.size(); I != E; ++I) {
170     EXPECT_EQ(static_cast<uint8_t>(ExprData[I]), Expected[I]);
171   }
172 }
173 
174 void DWARFExpressionCopyBytesTest::readAndCheckObjFile(
175     StringRef ObjFileData, ArrayRef<uint8_t> Expected) {
176   std::unique_ptr<MemoryBuffer> MB =
177       MemoryBuffer::getMemBuffer(ObjFileData, "", false);
178   std::unique_ptr<object::Binary> Bin =
179       cantFail(llvm::object::createBinary(MB->getMemBufferRef()));
180   if (auto *E = dyn_cast<llvm::object::ELFObjectFileBase>(&*Bin)) {
181     parseCFIsAndCheckExpression(*E, Expected);
182   }
183 }
184 
185 void DWARFExpressionCopyBytesTest::testExpr(ArrayRef<uint8_t> ExprData) {
186   // If we didn't build x86, do not run the test.
187   if (!MRI)
188     GTEST_SKIP();
189 
190   DataExtractor DE(ExprData, true, 8);
191   DWARFExpression Expr(DE, 8);
192 
193   // Copy this expression into the CFI of a binary and check that we are able to
194   // get it back correctly from this binary.
195   const SmallString<0> EmittedBinContents = emitObjFile(Expr.getData());
196   readAndCheckObjFile(EmittedBinContents.str(), ExprData);
197 }
198 
199 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_reg0) { testExpr({DW_OP_reg0}); }
200 
201 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_reg10) { testExpr({DW_OP_reg10}); }
202 
203 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_regx) {
204   testExpr({DW_OP_regx, 0x80, 0x02});
205 }
206 
207 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0) {
208   testExpr({DW_OP_breg0, 0x04});
209 }
210 
211 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0_large_offset) {
212   testExpr({DW_OP_breg0, 0x80, 0x02});
213 }
214 
215 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg13) {
216   testExpr({DW_OP_breg13, 0x10});
217 }
218 
219 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg13_zero_offset) {
220   testExpr({DW_OP_breg13, 0x00});
221 }
222 
223 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_breg0_negative) {
224   testExpr({DW_OP_breg0, 0x70});
225 }
226 
227 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_bregx) {
228   testExpr({DW_OP_bregx, 0x0d, 0x28});
229 }
230 
231 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_stack_value) {
232   testExpr({DW_OP_breg13, 0x04, DW_OP_stack_value});
233 }
234 
235 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_entry_value) {
236   testExpr({DW_OP_entry_value, 0x01, DW_OP_reg0, DW_OP_stack_value});
237 }
238 
239 TEST_F(DWARFExpressionCopyBytesTest, Test_OP_entry_value_mem) {
240   testExpr({DW_OP_entry_value, 0x02, DW_OP_breg13, 0x10, DW_OP_stack_value});
241 }
242