1 //===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===//
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 // Implementation of the InstrumentationMap type for XRay sleds.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/XRay/InstrumentationMap.h"
15 #include "llvm/ADT/None.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/ADT/Twine.h"
20 #include "llvm/Object/Binary.h"
21 #include "llvm/Object/ObjectFile.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 <algorithm>
27 #include <cstddef>
28 #include <cstdint>
29 #include <system_error>
30 #include <vector>
31
32 using namespace llvm;
33 using namespace xray;
34
getFunctionId(uint64_t Addr) const35 Optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const {
36 auto I = FunctionIds.find(Addr);
37 if (I != FunctionIds.end())
38 return I->second;
39 return None;
40 }
41
getFunctionAddr(int32_t FuncId) const42 Optional<uint64_t> InstrumentationMap::getFunctionAddr(int32_t FuncId) const {
43 auto I = FunctionAddresses.find(FuncId);
44 if (I != FunctionAddresses.end())
45 return I->second;
46 return None;
47 }
48
49 static Error
loadELF64(StringRef Filename,object::OwningBinary<object::ObjectFile> & ObjFile,InstrumentationMap::SledContainer & Sleds,InstrumentationMap::FunctionAddressMap & FunctionAddresses,InstrumentationMap::FunctionAddressReverseMap & FunctionIds)50 loadELF64(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
51 InstrumentationMap::SledContainer &Sleds,
52 InstrumentationMap::FunctionAddressMap &FunctionAddresses,
53 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
54 InstrumentationMap Map;
55
56 // Find the section named "xray_instr_map".
57 if (!ObjFile.getBinary()->isELF() ||
58 !(ObjFile.getBinary()->getArch() == Triple::x86_64 ||
59 ObjFile.getBinary()->getArch() == Triple::ppc64le))
60 return make_error<StringError>(
61 "File format not supported (only does ELF little endian 64-bit).",
62 std::make_error_code(std::errc::not_supported));
63
64 StringRef Contents = "";
65 const auto &Sections = ObjFile.getBinary()->sections();
66 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) {
67 StringRef Name = "";
68 if (Section.getName(Name))
69 return false;
70 return Name == "xray_instr_map";
71 });
72
73 if (I == Sections.end())
74 return make_error<StringError>(
75 "Failed to find XRay instrumentation map.",
76 std::make_error_code(std::errc::executable_format_error));
77
78 if (I->getContents(Contents))
79 return errorCodeToError(
80 std::make_error_code(std::errc::executable_format_error));
81
82 // Copy the instrumentation map data into the Sleds data structure.
83 auto C = Contents.bytes_begin();
84 static constexpr size_t ELF64SledEntrySize = 32;
85
86 if ((C - Contents.bytes_end()) % ELF64SledEntrySize != 0)
87 return make_error<StringError>(
88 Twine("Instrumentation map entries not evenly divisible by size of "
89 "an XRay sled entry in ELF64."),
90 std::make_error_code(std::errc::executable_format_error));
91
92 int32_t FuncId = 1;
93 uint64_t CurFn = 0;
94 for (; C != Contents.bytes_end(); C += ELF64SledEntrySize) {
95 DataExtractor Extractor(
96 StringRef(reinterpret_cast<const char *>(C), ELF64SledEntrySize), true,
97 8);
98 Sleds.push_back({});
99 auto &Entry = Sleds.back();
100 uint32_t OffsetPtr = 0;
101 Entry.Address = Extractor.getU64(&OffsetPtr);
102 Entry.Function = Extractor.getU64(&OffsetPtr);
103 auto Kind = Extractor.getU8(&OffsetPtr);
104 static constexpr SledEntry::FunctionKinds Kinds[] = {
105 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT,
106 SledEntry::FunctionKinds::TAIL,
107 SledEntry::FunctionKinds::LOG_ARGS_ENTER,
108 SledEntry::FunctionKinds::CUSTOM_EVENT};
109 if (Kind >= sizeof(Kinds))
110 return errorCodeToError(
111 std::make_error_code(std::errc::executable_format_error));
112 Entry.Kind = Kinds[Kind];
113 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0;
114
115 // We do replicate the function id generation scheme implemented in the
116 // XRay runtime.
117 // FIXME: Figure out how to keep this consistent with the XRay runtime.
118 if (CurFn == 0) {
119 CurFn = Entry.Function;
120 FunctionAddresses[FuncId] = Entry.Function;
121 FunctionIds[Entry.Function] = FuncId;
122 }
123 if (Entry.Function != CurFn) {
124 ++FuncId;
125 CurFn = Entry.Function;
126 FunctionAddresses[FuncId] = Entry.Function;
127 FunctionIds[Entry.Function] = FuncId;
128 }
129 }
130 return Error::success();
131 }
132
133 static Error
loadYAML(int Fd,size_t FileSize,StringRef Filename,InstrumentationMap::SledContainer & Sleds,InstrumentationMap::FunctionAddressMap & FunctionAddresses,InstrumentationMap::FunctionAddressReverseMap & FunctionIds)134 loadYAML(int Fd, size_t FileSize, StringRef Filename,
135 InstrumentationMap::SledContainer &Sleds,
136 InstrumentationMap::FunctionAddressMap &FunctionAddresses,
137 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
138 std::error_code EC;
139 sys::fs::mapped_file_region MappedFile(
140 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC);
141 if (EC)
142 return make_error<StringError>(
143 Twine("Failed memory-mapping file '") + Filename + "'.", EC);
144
145 std::vector<YAMLXRaySledEntry> YAMLSleds;
146 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size()));
147 In >> YAMLSleds;
148 if (In.error())
149 return make_error<StringError>(
150 Twine("Failed loading YAML document from '") + Filename + "'.",
151 In.error());
152
153 Sleds.reserve(YAMLSleds.size());
154 for (const auto &Y : YAMLSleds) {
155 FunctionAddresses[Y.FuncId] = Y.Function;
156 FunctionIds[Y.Function] = Y.FuncId;
157 Sleds.push_back(
158 SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument});
159 }
160 return Error::success();
161 }
162
163 // FIXME: Create error types that encapsulate a bit more information than what
164 // StringError instances contain.
165 Expected<InstrumentationMap>
loadInstrumentationMap(StringRef Filename)166 llvm::xray::loadInstrumentationMap(StringRef Filename) {
167 // At this point we assume the file is an object file -- and if that doesn't
168 // work, we treat it as YAML.
169 // FIXME: Extend to support non-ELF and non-x86_64 binaries.
170
171 InstrumentationMap Map;
172 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename);
173 if (!ObjectFileOrError) {
174 auto E = ObjectFileOrError.takeError();
175 // We try to load it as YAML if the ELF load didn't work.
176 int Fd;
177 if (sys::fs::openFileForRead(Filename, Fd))
178 return std::move(E);
179
180 uint64_t FileSize;
181 if (sys::fs::file_size(Filename, FileSize))
182 return std::move(E);
183
184 // If the file is empty, we return the original error.
185 if (FileSize == 0)
186 return std::move(E);
187
188 // From this point on the errors will be only for the YAML parts, so we
189 // consume the errors at this point.
190 consumeError(std::move(E));
191 if (auto E = loadYAML(Fd, FileSize, Filename, Map.Sleds,
192 Map.FunctionAddresses, Map.FunctionIds))
193 return std::move(E);
194 } else if (auto E = loadELF64(Filename, *ObjectFileOrError, Map.Sleds,
195 Map.FunctionAddresses, Map.FunctionIds)) {
196 return std::move(E);
197 }
198 return Map;
199 }
200