[yaml2obj][obj2yaml] - Do not create a symbol table by default.
[llvm-complete.git] / lib / ExecutionEngine / PerfJITEvents / PerfJITEventListener.cpp
blob184388dc4d7a7b3fa78494cdcc22812d224322b4
1 //===-- PerfJITEventListener.cpp - Tell Linux's perf about JITted code ----===//
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 // This file defines a JITEventListener object that tells perf about JITted
10 // functions, including source line information.
12 // Documentation for perf jit integration is available at:
13 // https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/tools/perf/Documentation/jitdump-specification.txt
14 // https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/tools/perf/Documentation/jit-interface.txt
16 //===----------------------------------------------------------------------===//
18 #include "llvm/ADT/Twine.h"
19 #include "llvm/Config/config.h"
20 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
21 #include "llvm/ExecutionEngine/JITEventListener.h"
22 #include "llvm/Object/ObjectFile.h"
23 #include "llvm/Object/SymbolSize.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/Errno.h"
26 #include "llvm/Support/FileSystem.h"
27 #include "llvm/Support/MemoryBuffer.h"
28 #include "llvm/Support/Mutex.h"
29 #include "llvm/Support/Path.h"
30 #include "llvm/Support/Process.h"
31 #include "llvm/Support/Threading.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include <mutex>
35 #include <sys/mman.h> // mmap()
36 #include <sys/types.h> // getpid()
37 #include <time.h> // clock_gettime(), time(), localtime_r() */
38 #include <unistd.h> // for getpid(), read(), close()
40 using namespace llvm;
41 using namespace llvm::object;
42 typedef DILineInfoSpecifier::FileLineInfoKind FileLineInfoKind;
44 namespace {
46 // language identifier (XXX: should we generate something better from debug
47 // info?)
48 #define JIT_LANG "llvm-IR"
49 #define LLVM_PERF_JIT_MAGIC \
50 ((uint32_t)'J' << 24 | (uint32_t)'i' << 16 | (uint32_t)'T' << 8 | \
51 (uint32_t)'D')
52 #define LLVM_PERF_JIT_VERSION 1
54 // bit 0: set if the jitdump file is using an architecture-specific timestamp
55 // clock source
56 #define JITDUMP_FLAGS_ARCH_TIMESTAMP (1ULL << 0)
58 struct LLVMPerfJitHeader;
60 class PerfJITEventListener : public JITEventListener {
61 public:
62 PerfJITEventListener();
63 ~PerfJITEventListener() {
64 if (MarkerAddr)
65 CloseMarker();
68 void notifyObjectLoaded(ObjectKey K, const ObjectFile &Obj,
69 const RuntimeDyld::LoadedObjectInfo &L) override;
70 void notifyFreeingObject(ObjectKey K) override;
72 private:
73 bool InitDebuggingDir();
74 bool OpenMarker();
75 void CloseMarker();
76 static bool FillMachine(LLVMPerfJitHeader &hdr);
78 void NotifyCode(Expected<llvm::StringRef> &Symbol, uint64_t CodeAddr,
79 uint64_t CodeSize);
80 void NotifyDebug(uint64_t CodeAddr, DILineInfoTable Lines);
82 // cache lookups
83 pid_t Pid;
85 // base directory for output data
86 std::string JitPath;
88 // output data stream, closed via Dumpstream
89 int DumpFd = -1;
91 // output data stream
92 std::unique_ptr<raw_fd_ostream> Dumpstream;
94 // prevent concurrent dumps from messing up the output file
95 sys::Mutex Mutex;
97 // perf mmap marker
98 void *MarkerAddr = NULL;
100 // perf support ready
101 bool SuccessfullyInitialized = false;
103 // identifier for functions, primarily to identify when moving them around
104 uint64_t CodeGeneration = 1;
107 // The following are POD struct definitions from the perf jit specification
109 enum LLVMPerfJitRecordType {
110 JIT_CODE_LOAD = 0,
111 JIT_CODE_MOVE = 1, // not emitted, code isn't moved
112 JIT_CODE_DEBUG_INFO = 2,
113 JIT_CODE_CLOSE = 3, // not emitted, unnecessary
114 JIT_CODE_UNWINDING_INFO = 4, // not emitted
116 JIT_CODE_MAX
119 struct LLVMPerfJitHeader {
120 uint32_t Magic; // characters "JiTD"
121 uint32_t Version; // header version
122 uint32_t TotalSize; // total size of header
123 uint32_t ElfMach; // elf mach target
124 uint32_t Pad1; // reserved
125 uint32_t Pid;
126 uint64_t Timestamp; // timestamp
127 uint64_t Flags; // flags
130 // record prefix (mandatory in each record)
131 struct LLVMPerfJitRecordPrefix {
132 uint32_t Id; // record type identifier
133 uint32_t TotalSize;
134 uint64_t Timestamp;
137 struct LLVMPerfJitRecordCodeLoad {
138 LLVMPerfJitRecordPrefix Prefix;
140 uint32_t Pid;
141 uint32_t Tid;
142 uint64_t Vma;
143 uint64_t CodeAddr;
144 uint64_t CodeSize;
145 uint64_t CodeIndex;
148 struct LLVMPerfJitDebugEntry {
149 uint64_t Addr;
150 int Lineno; // source line number starting at 1
151 int Discrim; // column discriminator, 0 is default
152 // followed by null terminated filename, \xff\0 if same as previous entry
155 struct LLVMPerfJitRecordDebugInfo {
156 LLVMPerfJitRecordPrefix Prefix;
158 uint64_t CodeAddr;
159 uint64_t NrEntry;
160 // followed by NrEntry LLVMPerfJitDebugEntry records
163 static inline uint64_t timespec_to_ns(const struct timespec *ts) {
164 const uint64_t NanoSecPerSec = 1000000000;
165 return ((uint64_t)ts->tv_sec * NanoSecPerSec) + ts->tv_nsec;
168 static inline uint64_t perf_get_timestamp(void) {
169 struct timespec ts;
170 int ret;
172 ret = clock_gettime(CLOCK_MONOTONIC, &ts);
173 if (ret)
174 return 0;
176 return timespec_to_ns(&ts);
179 PerfJITEventListener::PerfJITEventListener() : Pid(::getpid()) {
180 // check if clock-source is supported
181 if (!perf_get_timestamp()) {
182 errs() << "kernel does not support CLOCK_MONOTONIC\n";
183 return;
186 if (!InitDebuggingDir()) {
187 errs() << "could not initialize debugging directory\n";
188 return;
191 std::string Filename;
192 raw_string_ostream FilenameBuf(Filename);
193 FilenameBuf << JitPath << "/jit-" << Pid << ".dump";
195 // Need to open ourselves, because we need to hand the FD to OpenMarker() and
196 // raw_fd_ostream doesn't expose the FD.
197 using sys::fs::openFileForWrite;
198 if (auto EC =
199 openFileForReadWrite(FilenameBuf.str(), DumpFd,
200 sys::fs::CD_CreateNew, sys::fs::OF_None)) {
201 errs() << "could not open JIT dump file " << FilenameBuf.str() << ": "
202 << EC.message() << "\n";
203 return;
206 Dumpstream = std::make_unique<raw_fd_ostream>(DumpFd, true);
208 LLVMPerfJitHeader Header = {0};
209 if (!FillMachine(Header))
210 return;
212 // signal this process emits JIT information
213 if (!OpenMarker())
214 return;
216 // emit dumpstream header
217 Header.Magic = LLVM_PERF_JIT_MAGIC;
218 Header.Version = LLVM_PERF_JIT_VERSION;
219 Header.TotalSize = sizeof(Header);
220 Header.Pid = Pid;
221 Header.Timestamp = perf_get_timestamp();
222 Dumpstream->write(reinterpret_cast<const char *>(&Header), sizeof(Header));
224 // Everything initialized, can do profiling now.
225 if (!Dumpstream->has_error())
226 SuccessfullyInitialized = true;
229 void PerfJITEventListener::notifyObjectLoaded(
230 ObjectKey K, const ObjectFile &Obj,
231 const RuntimeDyld::LoadedObjectInfo &L) {
233 if (!SuccessfullyInitialized)
234 return;
236 OwningBinary<ObjectFile> DebugObjOwner = L.getObjectForDebug(Obj);
237 const ObjectFile &DebugObj = *DebugObjOwner.getBinary();
239 // Get the address of the object image for use as a unique identifier
240 std::unique_ptr<DIContext> Context = DWARFContext::create(DebugObj);
242 // Use symbol info to iterate over functions in the object.
243 for (const std::pair<SymbolRef, uint64_t> &P : computeSymbolSizes(DebugObj)) {
244 SymbolRef Sym = P.first;
245 std::string SourceFileName;
247 Expected<SymbolRef::Type> SymTypeOrErr = Sym.getType();
248 if (!SymTypeOrErr) {
249 // There's not much we can with errors here
250 consumeError(SymTypeOrErr.takeError());
251 continue;
253 SymbolRef::Type SymType = *SymTypeOrErr;
254 if (SymType != SymbolRef::ST_Function)
255 continue;
257 Expected<StringRef> Name = Sym.getName();
258 if (!Name) {
259 consumeError(Name.takeError());
260 continue;
263 Expected<uint64_t> AddrOrErr = Sym.getAddress();
264 if (!AddrOrErr) {
265 consumeError(AddrOrErr.takeError());
266 continue;
268 uint64_t Size = P.second;
269 object::SectionedAddress Address;
270 Address.Address = *AddrOrErr;
272 uint64_t SectionIndex = object::SectionedAddress::UndefSection;
273 if (auto SectOrErr = Sym.getSection())
274 if (*SectOrErr != Obj.section_end())
275 SectionIndex = SectOrErr.get()->getIndex();
277 // According to spec debugging info has to come before loading the
278 // corresonding code load.
279 DILineInfoTable Lines = Context->getLineInfoForAddressRange(
280 {*AddrOrErr, SectionIndex}, Size, FileLineInfoKind::AbsoluteFilePath);
282 NotifyDebug(*AddrOrErr, Lines);
283 NotifyCode(Name, *AddrOrErr, Size);
286 Dumpstream->flush();
289 void PerfJITEventListener::notifyFreeingObject(ObjectKey K) {
290 // perf currently doesn't have an interface for unloading. But munmap()ing the
291 // code section does, so that's ok.
294 bool PerfJITEventListener::InitDebuggingDir() {
295 time_t Time;
296 struct tm LocalTime;
297 char TimeBuffer[sizeof("YYYYMMDD")];
298 SmallString<64> Path;
300 // search for location to dump data to
301 if (const char *BaseDir = getenv("JITDUMPDIR"))
302 Path.append(BaseDir);
303 else if (!sys::path::home_directory(Path))
304 Path = ".";
306 // create debug directory
307 Path += "/.debug/jit/";
308 if (auto EC = sys::fs::create_directories(Path)) {
309 errs() << "could not create jit cache directory " << Path << ": "
310 << EC.message() << "\n";
311 return false;
314 // create unique directory for dump data related to this process
315 time(&Time);
316 localtime_r(&Time, &LocalTime);
317 strftime(TimeBuffer, sizeof(TimeBuffer), "%Y%m%d", &LocalTime);
318 Path += JIT_LANG "-jit-";
319 Path += TimeBuffer;
321 SmallString<128> UniqueDebugDir;
323 using sys::fs::createUniqueDirectory;
324 if (auto EC = createUniqueDirectory(Path, UniqueDebugDir)) {
325 errs() << "could not create unique jit cache directory " << UniqueDebugDir
326 << ": " << EC.message() << "\n";
327 return false;
330 JitPath = UniqueDebugDir.str();
332 return true;
335 bool PerfJITEventListener::OpenMarker() {
336 // We mmap the jitdump to create an MMAP RECORD in perf.data file. The mmap
337 // is captured either live (perf record running when we mmap) or in deferred
338 // mode, via /proc/PID/maps. The MMAP record is used as a marker of a jitdump
339 // file for more meta data info about the jitted code. Perf report/annotate
340 // detect this special filename and process the jitdump file.
342 // Mapping must be PROT_EXEC to ensure it is captured by perf record
343 // even when not using -d option.
344 MarkerAddr = ::mmap(NULL, sys::Process::getPageSizeEstimate(),
345 PROT_READ | PROT_EXEC, MAP_PRIVATE, DumpFd, 0);
347 if (MarkerAddr == MAP_FAILED) {
348 errs() << "could not mmap JIT marker\n";
349 return false;
351 return true;
354 void PerfJITEventListener::CloseMarker() {
355 if (!MarkerAddr)
356 return;
358 munmap(MarkerAddr, sys::Process::getPageSizeEstimate());
359 MarkerAddr = nullptr;
362 bool PerfJITEventListener::FillMachine(LLVMPerfJitHeader &hdr) {
363 char id[16];
364 struct {
365 uint16_t e_type;
366 uint16_t e_machine;
367 } info;
369 size_t RequiredMemory = sizeof(id) + sizeof(info);
371 ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
372 MemoryBuffer::getFileSlice("/proc/self/exe",
373 RequiredMemory,
376 // This'll not guarantee that enough data was actually read from the
377 // underlying file. Instead the trailing part of the buffer would be
378 // zeroed. Given the ELF signature check below that seems ok though,
379 // it's unlikely that the file ends just after that, and the
380 // consequence would just be that perf wouldn't recognize the
381 // signature.
382 if (auto EC = MB.getError()) {
383 errs() << "could not open /proc/self/exe: " << EC.message() << "\n";
384 return false;
387 memcpy(&id, (*MB)->getBufferStart(), sizeof(id));
388 memcpy(&info, (*MB)->getBufferStart() + sizeof(id), sizeof(info));
390 // check ELF signature
391 if (id[0] != 0x7f || id[1] != 'E' || id[2] != 'L' || id[3] != 'F') {
392 errs() << "invalid elf signature\n";
393 return false;
396 hdr.ElfMach = info.e_machine;
398 return true;
401 void PerfJITEventListener::NotifyCode(Expected<llvm::StringRef> &Symbol,
402 uint64_t CodeAddr, uint64_t CodeSize) {
403 assert(SuccessfullyInitialized);
405 // 0 length functions can't have samples.
406 if (CodeSize == 0)
407 return;
409 LLVMPerfJitRecordCodeLoad rec;
410 rec.Prefix.Id = JIT_CODE_LOAD;
411 rec.Prefix.TotalSize = sizeof(rec) + // debug record itself
412 Symbol->size() + 1 + // symbol name
413 CodeSize; // and code
414 rec.Prefix.Timestamp = perf_get_timestamp();
416 rec.CodeSize = CodeSize;
417 rec.Vma = 0;
418 rec.CodeAddr = CodeAddr;
419 rec.Pid = Pid;
420 rec.Tid = get_threadid();
422 // avoid interspersing output
423 std::lock_guard<sys::Mutex> Guard(Mutex);
425 rec.CodeIndex = CodeGeneration++; // under lock!
427 Dumpstream->write(reinterpret_cast<const char *>(&rec), sizeof(rec));
428 Dumpstream->write(Symbol->data(), Symbol->size() + 1);
429 Dumpstream->write(reinterpret_cast<const char *>(CodeAddr), CodeSize);
432 void PerfJITEventListener::NotifyDebug(uint64_t CodeAddr,
433 DILineInfoTable Lines) {
434 assert(SuccessfullyInitialized);
436 // Didn't get useful debug info.
437 if (Lines.empty())
438 return;
440 LLVMPerfJitRecordDebugInfo rec;
441 rec.Prefix.Id = JIT_CODE_DEBUG_INFO;
442 rec.Prefix.TotalSize = sizeof(rec); // will be increased further
443 rec.Prefix.Timestamp = perf_get_timestamp();
444 rec.CodeAddr = CodeAddr;
445 rec.NrEntry = Lines.size();
447 // compute total size size of record (variable due to filenames)
448 DILineInfoTable::iterator Begin = Lines.begin();
449 DILineInfoTable::iterator End = Lines.end();
450 for (DILineInfoTable::iterator It = Begin; It != End; ++It) {
451 DILineInfo &line = It->second;
452 rec.Prefix.TotalSize += sizeof(LLVMPerfJitDebugEntry);
453 rec.Prefix.TotalSize += line.FileName.size() + 1;
456 // The debug_entry describes the source line information. It is defined as
457 // follows in order:
458 // * uint64_t code_addr: address of function for which the debug information
459 // is generated
460 // * uint32_t line : source file line number (starting at 1)
461 // * uint32_t discrim : column discriminator, 0 is default
462 // * char name[n] : source file name in ASCII, including null termination
464 // avoid interspersing output
465 std::lock_guard<sys::Mutex> Guard(Mutex);
467 Dumpstream->write(reinterpret_cast<const char *>(&rec), sizeof(rec));
469 for (DILineInfoTable::iterator It = Begin; It != End; ++It) {
470 LLVMPerfJitDebugEntry LineInfo;
471 DILineInfo &Line = It->second;
473 LineInfo.Addr = It->first;
474 // The function re-created by perf is preceded by a elf
475 // header. Need to adjust for that, otherwise the results are
476 // wrong.
477 LineInfo.Addr += 0x40;
478 LineInfo.Lineno = Line.Line;
479 LineInfo.Discrim = Line.Discriminator;
481 Dumpstream->write(reinterpret_cast<const char *>(&LineInfo),
482 sizeof(LineInfo));
483 Dumpstream->write(Line.FileName.c_str(), Line.FileName.size() + 1);
487 // There should be only a single event listener per process, otherwise perf gets
488 // confused.
489 llvm::ManagedStatic<PerfJITEventListener> PerfListener;
491 } // end anonymous namespace
493 namespace llvm {
494 JITEventListener *JITEventListener::createPerfJITEventListener() {
495 return &*PerfListener;
498 } // namespace llvm
500 LLVMJITEventListenerRef LLVMCreatePerfJITEventListener(void)
502 return wrap(JITEventListener::createPerfJITEventListener());