1 //===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===//
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 // Implementation of the InstrumentationMap type for XRay sleds.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/XRay/InstrumentationMap.h"
14 #include "llvm/ADT/DenseMap.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/Object/Binary.h"
19 #include "llvm/Object/ELFObjectFile.h"
20 #include "llvm/Object/ObjectFile.h"
21 #include "llvm/Object/RelocationResolver.h"
22 #include "llvm/Support/DataExtractor.h"
23 #include "llvm/Support/Error.h"
24 #include "llvm/Support/FileSystem.h"
25 #include "llvm/Support/YAMLTraits.h"
26 #include "llvm/TargetParser/Triple.h"
27 #include <algorithm>
28 #include <cstddef>
29 #include <cstdint>
30 #include <system_error>
31 #include <vector>
32
33 using namespace llvm;
34 using namespace xray;
35
getFunctionId(uint64_t Addr) const36 std::optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const {
37 auto I = FunctionIds.find(Addr);
38 if (I != FunctionIds.end())
39 return I->second;
40 return std::nullopt;
41 }
42
43 std::optional<uint64_t>
getFunctionAddr(int32_t FuncId) const44 InstrumentationMap::getFunctionAddr(int32_t FuncId) const {
45 auto I = FunctionAddresses.find(FuncId);
46 if (I != FunctionAddresses.end())
47 return I->second;
48 return std::nullopt;
49 }
50
51 using RelocMap = DenseMap<uint64_t, uint64_t>;
52
53 static Error
loadObj(StringRef Filename,object::OwningBinary<object::ObjectFile> & ObjFile,InstrumentationMap::SledContainer & Sleds,InstrumentationMap::FunctionAddressMap & FunctionAddresses,InstrumentationMap::FunctionAddressReverseMap & FunctionIds)54 loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
55 InstrumentationMap::SledContainer &Sleds,
56 InstrumentationMap::FunctionAddressMap &FunctionAddresses,
57 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
58 InstrumentationMap Map;
59
60 // Find the section named "xray_instr_map".
61 if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) ||
62 !(ObjFile.getBinary()->getArch() == Triple::x86_64 ||
63 ObjFile.getBinary()->getArch() == Triple::loongarch64 ||
64 ObjFile.getBinary()->getArch() == Triple::ppc64le ||
65 ObjFile.getBinary()->getArch() == Triple::arm ||
66 ObjFile.getBinary()->getArch() == Triple::aarch64))
67 return make_error<StringError>(
68 "File format not supported (only does ELF and Mach-O little endian "
69 "64-bit).",
70 std::make_error_code(std::errc::not_supported));
71
72 StringRef Contents = "";
73 const auto &Sections = ObjFile.getBinary()->sections();
74 uint64_t Address = 0;
75 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) {
76 Expected<StringRef> NameOrErr = Section.getName();
77 if (NameOrErr) {
78 Address = Section.getAddress();
79 return *NameOrErr == "xray_instr_map";
80 }
81 consumeError(NameOrErr.takeError());
82 return false;
83 });
84
85 if (I == Sections.end())
86 return make_error<StringError>(
87 "Failed to find XRay instrumentation map.",
88 std::make_error_code(std::errc::executable_format_error));
89
90 if (Error E = I->getContents().moveInto(Contents))
91 return E;
92
93 RelocMap Relocs;
94 if (ObjFile.getBinary()->isELF()) {
95 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) {
96 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile))
97 return ELFObj->getELFFile().getRelativeRelocationType();
98 else if (const auto *ELFObj =
99 dyn_cast<object::ELF32BEObjectFile>(ObjFile))
100 return ELFObj->getELFFile().getRelativeRelocationType();
101 else if (const auto *ELFObj =
102 dyn_cast<object::ELF64LEObjectFile>(ObjFile))
103 return ELFObj->getELFFile().getRelativeRelocationType();
104 else if (const auto *ELFObj =
105 dyn_cast<object::ELF64BEObjectFile>(ObjFile))
106 return ELFObj->getELFFile().getRelativeRelocationType();
107 else
108 return static_cast<uint32_t>(0);
109 }(ObjFile.getBinary());
110
111 object::SupportsRelocation Supports;
112 object::RelocationResolver Resolver;
113 std::tie(Supports, Resolver) =
114 object::getRelocationResolver(*ObjFile.getBinary());
115
116 for (const object::SectionRef &Section : Sections) {
117 for (const object::RelocationRef &Reloc : Section.relocations()) {
118 if (ObjFile.getBinary()->getArch() == Triple::arm) {
119 if (Supports && Supports(Reloc.getType())) {
120 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
121 if (!ValueOrErr)
122 return ValueOrErr.takeError();
123 Relocs.insert(
124 {Reloc.getOffset(),
125 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)});
126 }
127 } else if (Supports && Supports(Reloc.getType())) {
128 auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend();
129 auto A = AddendOrErr ? *AddendOrErr : 0;
130 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
131 if (!ValueOrErr)
132 // TODO: Test this error.
133 return ValueOrErr.takeError();
134 Relocs.insert(
135 {Reloc.getOffset(),
136 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)});
137 } else if (Reloc.getType() == RelativeRelocation) {
138 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend())
139 Relocs.insert({Reloc.getOffset(), *AddendOrErr});
140 }
141 }
142 }
143 }
144
145 // Copy the instrumentation map data into the Sleds data structure.
146 auto C = Contents.bytes_begin();
147 bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit();
148 size_t ELFSledEntrySize = Is32Bit ? 16 : 32;
149
150 if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0)
151 return make_error<StringError>(
152 Twine("Instrumentation map entries not evenly divisible by size of "
153 "an XRay sled entry."),
154 std::make_error_code(std::errc::executable_format_error));
155
156 auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) {
157 if (!Address) {
158 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset;
159 RelocMap::const_iterator R = Relocs.find(A);
160 if (R != Relocs.end())
161 return R->second;
162 }
163 return Address;
164 };
165
166 const int WordSize = Is32Bit ? 4 : 8;
167 int32_t FuncId = 1;
168 uint64_t CurFn = 0;
169 for (; C != Contents.bytes_end(); C += ELFSledEntrySize) {
170 DataExtractor Extractor(
171 StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true,
172 8);
173 Sleds.push_back({});
174 auto &Entry = Sleds.back();
175 uint64_t OffsetPtr = 0;
176 uint64_t AddrOff = OffsetPtr;
177 if (Is32Bit)
178 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr));
179 else
180 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr));
181 uint64_t FuncOff = OffsetPtr;
182 if (Is32Bit)
183 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr));
184 else
185 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr));
186 auto Kind = Extractor.getU8(&OffsetPtr);
187 static constexpr SledEntry::FunctionKinds Kinds[] = {
188 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT,
189 SledEntry::FunctionKinds::TAIL,
190 SledEntry::FunctionKinds::LOG_ARGS_ENTER,
191 SledEntry::FunctionKinds::CUSTOM_EVENT};
192 if (Kind >= std::size(Kinds))
193 return errorCodeToError(
194 std::make_error_code(std::errc::executable_format_error));
195 Entry.Kind = Kinds[Kind];
196 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0;
197 Entry.Version = Extractor.getU8(&OffsetPtr);
198 if (Entry.Version >= 2) {
199 Entry.Address += C - Contents.bytes_begin() + Address;
200 Entry.Function += C - Contents.bytes_begin() + WordSize + Address;
201 }
202
203 // We do replicate the function id generation scheme implemented in the
204 // XRay runtime.
205 // FIXME: Figure out how to keep this consistent with the XRay runtime.
206 if (CurFn == 0) {
207 CurFn = Entry.Function;
208 FunctionAddresses[FuncId] = Entry.Function;
209 FunctionIds[Entry.Function] = FuncId;
210 }
211 if (Entry.Function != CurFn) {
212 ++FuncId;
213 CurFn = Entry.Function;
214 FunctionAddresses[FuncId] = Entry.Function;
215 FunctionIds[Entry.Function] = FuncId;
216 }
217 }
218 return Error::success();
219 }
220
221 static Error
loadYAML(sys::fs::file_t Fd,size_t FileSize,StringRef Filename,InstrumentationMap::SledContainer & Sleds,InstrumentationMap::FunctionAddressMap & FunctionAddresses,InstrumentationMap::FunctionAddressReverseMap & FunctionIds)222 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename,
223 InstrumentationMap::SledContainer &Sleds,
224 InstrumentationMap::FunctionAddressMap &FunctionAddresses,
225 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
226 std::error_code EC;
227 sys::fs::mapped_file_region MappedFile(
228 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC);
229 sys::fs::closeFile(Fd);
230 if (EC)
231 return make_error<StringError>(
232 Twine("Failed memory-mapping file '") + Filename + "'.", EC);
233
234 std::vector<YAMLXRaySledEntry> YAMLSleds;
235 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size()));
236 In >> YAMLSleds;
237 if (In.error())
238 return make_error<StringError>(
239 Twine("Failed loading YAML document from '") + Filename + "'.",
240 In.error());
241
242 Sleds.reserve(YAMLSleds.size());
243 for (const auto &Y : YAMLSleds) {
244 FunctionAddresses[Y.FuncId] = Y.Function;
245 FunctionIds[Y.Function] = Y.FuncId;
246 Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument,
247 Y.Version});
248 }
249 return Error::success();
250 }
251
252 // FIXME: Create error types that encapsulate a bit more information than what
253 // StringError instances contain.
254 Expected<InstrumentationMap>
loadInstrumentationMap(StringRef Filename)255 llvm::xray::loadInstrumentationMap(StringRef Filename) {
256 // At this point we assume the file is an object file -- and if that doesn't
257 // work, we treat it as YAML.
258 // FIXME: Extend to support non-ELF and non-x86_64 binaries.
259
260 InstrumentationMap Map;
261 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename);
262 if (!ObjectFileOrError) {
263 auto E = ObjectFileOrError.takeError();
264 // We try to load it as YAML if the ELF load didn't work.
265 Expected<sys::fs::file_t> FdOrErr =
266 sys::fs::openNativeFileForRead(Filename);
267 if (!FdOrErr) {
268 // Report the ELF load error if YAML failed.
269 consumeError(FdOrErr.takeError());
270 return std::move(E);
271 }
272
273 uint64_t FileSize;
274 if (sys::fs::file_size(Filename, FileSize))
275 return std::move(E);
276
277 // If the file is empty, we return the original error.
278 if (FileSize == 0)
279 return std::move(E);
280
281 // From this point on the errors will be only for the YAML parts, so we
282 // consume the errors at this point.
283 consumeError(std::move(E));
284 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds,
285 Map.FunctionAddresses, Map.FunctionIds))
286 return std::move(E);
287 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds,
288 Map.FunctionAddresses, Map.FunctionIds)) {
289 return std::move(E);
290 }
291 return Map;
292 }
293