1 //===-- ProcessorTrace.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 <algorithm>
10 #include <fstream>
11
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/Support/Error.h"
14 #include "llvm/Support/MathExtras.h"
15
16 #include "Plugins/Process/POSIX/ProcessPOSIXLog.h"
17 #include "ProcessorTrace.h"
18 #include "lldb/Host/linux/Support.h"
19
20 #include <sys/ioctl.h>
21 #include <sys/syscall.h>
22
23 using namespace lldb;
24 using namespace lldb_private;
25 using namespace process_linux;
26 using namespace llvm;
27
28 lldb::user_id_t ProcessorTraceMonitor::m_trace_num = 1;
29
GetTraceConfig(TraceOptions & config) const30 Status ProcessorTraceMonitor::GetTraceConfig(TraceOptions &config) const {
31 #ifndef PERF_ATTR_SIZE_VER5
32 llvm_unreachable("perf event not supported");
33 #else
34 Status error;
35
36 config.setType(lldb::TraceType::eTraceTypeProcessorTrace);
37 config.setMetaDataBufferSize(m_mmap_meta->data_size);
38
39 config.setTraceBufferSize(m_mmap_meta->aux_size);
40
41 error = GetCPUType(config);
42
43 return error;
44 #endif
45 }
46
StartTrace(lldb::pid_t pid,lldb::tid_t tid,const TraceOptions & config)47 Status ProcessorTraceMonitor::StartTrace(lldb::pid_t pid, lldb::tid_t tid,
48 const TraceOptions &config) {
49 #ifndef PERF_ATTR_SIZE_VER5
50 llvm_unreachable("perf event not supported");
51 #else
52 Status error;
53 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
54
55 LLDB_LOG(log, "called thread id {0}", tid);
56 uint64_t page_size = getpagesize();
57 uint64_t bufsize = config.getTraceBufferSize();
58 uint64_t metabufsize = config.getMetaDataBufferSize();
59
60 uint64_t numpages = static_cast<uint64_t>(
61 llvm::PowerOf2Floor((bufsize + page_size - 1) / page_size));
62 numpages = std::max<uint64_t>(1, numpages);
63 bufsize = page_size * numpages;
64
65 numpages = static_cast<uint64_t>(
66 llvm::PowerOf2Floor((metabufsize + page_size - 1) / page_size));
67 metabufsize = page_size * numpages;
68
69 perf_event_attr attr;
70 memset(&attr, 0, sizeof(attr));
71 attr.size = sizeof(attr);
72 attr.exclude_kernel = 1;
73 attr.sample_type = PERF_SAMPLE_TIME;
74 attr.sample_id_all = 1;
75 attr.exclude_hv = 1;
76 attr.exclude_idle = 1;
77 attr.mmap = 1;
78
79 int intel_pt_type = 0;
80
81 auto ret = llvm::MemoryBuffer::getFileAsStream(
82 "/sys/bus/event_source/devices/intel_pt/type");
83 if (!ret) {
84 LLDB_LOG(log, "failed to open Config file");
85 return ret.getError();
86 }
87
88 StringRef rest = ret.get()->getBuffer();
89 if (rest.empty() || rest.trim().getAsInteger(10, intel_pt_type)) {
90 LLDB_LOG(log, "failed to read Config file");
91 error.SetErrorString("invalid file");
92 return error;
93 }
94
95 rest.trim().getAsInteger(10, intel_pt_type);
96 LLDB_LOG(log, "intel pt type {0}", intel_pt_type);
97 attr.type = intel_pt_type;
98
99 LLDB_LOG(log, "meta buffer size {0}", metabufsize);
100 LLDB_LOG(log, "buffer size {0} ", bufsize);
101
102 if (error.Fail()) {
103 LLDB_LOG(log, "Status in custom config");
104
105 return error;
106 }
107
108 errno = 0;
109 auto fd =
110 syscall(SYS_perf_event_open, &attr, static_cast<::tid_t>(tid), -1, -1, 0);
111 if (fd == -1) {
112 LLDB_LOG(log, "syscall error {0}", errno);
113 error.SetErrorString("perf event syscall Failed");
114 return error;
115 }
116
117 m_fd = std::unique_ptr<int, file_close>(new int(fd), file_close());
118
119 errno = 0;
120 auto base =
121 mmap(nullptr, (metabufsize + page_size), PROT_WRITE, MAP_SHARED, fd, 0);
122
123 if (base == MAP_FAILED) {
124 LLDB_LOG(log, "mmap base error {0}", errno);
125 error.SetErrorString("Meta buffer allocation failed");
126 return error;
127 }
128
129 m_mmap_meta = std::unique_ptr<perf_event_mmap_page, munmap_delete>(
130 reinterpret_cast<perf_event_mmap_page *>(base),
131 munmap_delete(metabufsize + page_size));
132
133 m_mmap_meta->aux_offset = m_mmap_meta->data_offset + m_mmap_meta->data_size;
134 m_mmap_meta->aux_size = bufsize;
135
136 errno = 0;
137 auto mmap_aux = mmap(nullptr, bufsize, PROT_READ, MAP_SHARED, fd,
138 static_cast<long int>(m_mmap_meta->aux_offset));
139
140 if (mmap_aux == MAP_FAILED) {
141 LLDB_LOG(log, "second mmap done {0}", errno);
142 error.SetErrorString("Trace buffer allocation failed");
143 return error;
144 }
145 m_mmap_aux = std::unique_ptr<uint8_t, munmap_delete>(
146 reinterpret_cast<uint8_t *>(mmap_aux), munmap_delete(bufsize));
147 return error;
148 #endif
149 }
150
GetDataBuffer()151 llvm::MutableArrayRef<uint8_t> ProcessorTraceMonitor::GetDataBuffer() {
152 #ifndef PERF_ATTR_SIZE_VER5
153 llvm_unreachable("perf event not supported");
154 #else
155 return MutableArrayRef<uint8_t>(
156 (reinterpret_cast<uint8_t *>(m_mmap_meta.get()) +
157 m_mmap_meta->data_offset),
158 m_mmap_meta->data_size);
159 #endif
160 }
161
GetAuxBuffer()162 llvm::MutableArrayRef<uint8_t> ProcessorTraceMonitor::GetAuxBuffer() {
163 #ifndef PERF_ATTR_SIZE_VER5
164 llvm_unreachable("perf event not supported");
165 #else
166 return MutableArrayRef<uint8_t>(m_mmap_aux.get(), m_mmap_meta->aux_size);
167 #endif
168 }
169
GetCPUType(TraceOptions & config)170 Status ProcessorTraceMonitor::GetCPUType(TraceOptions &config) {
171
172 Status error;
173 uint64_t cpu_family = -1;
174 uint64_t model = -1;
175 uint64_t stepping = -1;
176 std::string vendor_id;
177
178 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
179
180 auto BufferOrError = getProcFile("cpuinfo");
181 if (!BufferOrError)
182 return BufferOrError.getError();
183
184 LLDB_LOG(log, "GetCPUType Function");
185
186 StringRef Rest = BufferOrError.get()->getBuffer();
187 while (!Rest.empty()) {
188 StringRef Line;
189 std::tie(Line, Rest) = Rest.split('\n');
190
191 SmallVector<StringRef, 2> columns;
192 Line.split(columns, StringRef(":"), -1, false);
193
194 if (columns.size() < 2)
195 continue; // continue searching
196
197 columns[1] = columns[1].trim(" ");
198 if (columns[0].contains("cpu family") &&
199 columns[1].getAsInteger(10, cpu_family))
200 continue;
201
202 else if (columns[0].contains("model") && columns[1].getAsInteger(10, model))
203 continue;
204
205 else if (columns[0].contains("stepping") &&
206 columns[1].getAsInteger(10, stepping))
207 continue;
208
209 else if (columns[0].contains("vendor_id")) {
210 vendor_id = columns[1].str();
211 if (!vendor_id.empty())
212 continue;
213 }
214 LLDB_LOG(log, "{0}:{1}:{2}:{3}", cpu_family, model, stepping, vendor_id);
215
216 if ((cpu_family != static_cast<uint64_t>(-1)) &&
217 (model != static_cast<uint64_t>(-1)) &&
218 (stepping != static_cast<uint64_t>(-1)) && (!vendor_id.empty())) {
219 auto params_dict = std::make_shared<StructuredData::Dictionary>();
220 params_dict->AddIntegerItem("cpu_family", cpu_family);
221 params_dict->AddIntegerItem("cpu_model", model);
222 params_dict->AddIntegerItem("cpu_stepping", stepping);
223 params_dict->AddStringItem("cpu_vendor", vendor_id);
224
225 llvm::StringRef intel_custom_params_key("intel-pt");
226
227 auto intel_custom_params = std::make_shared<StructuredData::Dictionary>();
228 intel_custom_params->AddItem(
229 intel_custom_params_key,
230 StructuredData::ObjectSP(std::move(params_dict)));
231
232 config.setTraceParams(intel_custom_params);
233 return error; // we are done
234 }
235 }
236
237 error.SetErrorString("cpu info not found");
238 return error;
239 }
240
241 llvm::Expected<ProcessorTraceMonitorUP>
Create(lldb::pid_t pid,lldb::tid_t tid,const TraceOptions & config,bool useProcessSettings)242 ProcessorTraceMonitor::Create(lldb::pid_t pid, lldb::tid_t tid,
243 const TraceOptions &config,
244 bool useProcessSettings) {
245
246 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
247
248 Status error;
249 if (tid == LLDB_INVALID_THREAD_ID) {
250 error.SetErrorString("thread not specified");
251 return error.ToError();
252 }
253
254 ProcessorTraceMonitorUP pt_monitor_up(new ProcessorTraceMonitor);
255
256 error = pt_monitor_up->StartTrace(pid, tid, config);
257 if (error.Fail())
258 return error.ToError();
259
260 pt_monitor_up->SetThreadID(tid);
261
262 if (useProcessSettings) {
263 pt_monitor_up->SetTraceID(0);
264 } else {
265 pt_monitor_up->SetTraceID(m_trace_num++);
266 LLDB_LOG(log, "Trace ID {0}", m_trace_num);
267 }
268 return std::move(pt_monitor_up);
269 }
270
271 Status
ReadPerfTraceAux(llvm::MutableArrayRef<uint8_t> & buffer,size_t offset)272 ProcessorTraceMonitor::ReadPerfTraceAux(llvm::MutableArrayRef<uint8_t> &buffer,
273 size_t offset) {
274 #ifndef PERF_ATTR_SIZE_VER5
275 llvm_unreachable("perf event not supported");
276 #else
277 // Disable the perf event to force a flush out of the CPU's internal buffer.
278 // Besides, we can guarantee that the CPU won't override any data as we are
279 // reading the buffer.
280 //
281 // The Intel documentation says:
282 //
283 // Packets are first buffered internally and then written out asynchronously.
284 // To collect packet output for postprocessing, a collector needs first to
285 // ensure that all packet data has been flushed from internal buffers.
286 // Software can ensure this by stopping packet generation by clearing
287 // IA32_RTIT_CTL.TraceEn (see “Disabling Packet Generation” in
288 // Section 35.2.7.2).
289 //
290 // This is achieved by the PERF_EVENT_IOC_DISABLE ioctl request, as mentioned
291 // in the man page of perf_event_open.
292 ioctl(*m_fd, PERF_EVENT_IOC_DISABLE);
293
294 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
295 Status error;
296 uint64_t head = m_mmap_meta->aux_head;
297
298 LLDB_LOG(log, "Aux size -{0} , Head - {1}", m_mmap_meta->aux_size, head);
299
300 /**
301 * When configured as ring buffer, the aux buffer keeps wrapping around
302 * the buffer and its not possible to detect how many times the buffer
303 * wrapped. Initially the buffer is filled with zeros,as shown below
304 * so in order to get complete buffer we first copy firstpartsize, followed
305 * by any left over part from beginning to aux_head
306 *
307 * aux_offset [d,d,d,d,d,d,d,d,0,0,0,0,0,0,0,0,0,0,0] aux_size
308 * aux_head->||<- firstpartsize ->|
309 *
310 * */
311
312 ReadCyclicBuffer(buffer, GetAuxBuffer(), static_cast<size_t>(head), offset);
313 LLDB_LOG(log, "ReadCyclic BUffer Done");
314
315 // Reenable tracing now we have read the buffer
316 ioctl(*m_fd, PERF_EVENT_IOC_ENABLE);
317 return error;
318 #endif
319 }
320
321 Status
ReadPerfTraceData(llvm::MutableArrayRef<uint8_t> & buffer,size_t offset)322 ProcessorTraceMonitor::ReadPerfTraceData(llvm::MutableArrayRef<uint8_t> &buffer,
323 size_t offset) {
324 #ifndef PERF_ATTR_SIZE_VER5
325 llvm_unreachable("perf event not supported");
326 #else
327 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
328 uint64_t bytes_remaining = buffer.size();
329 Status error;
330
331 uint64_t head = m_mmap_meta->data_head;
332
333 /*
334 * The data buffer and aux buffer have different implementations
335 * with respect to their definition of head pointer. In the case
336 * of Aux data buffer the head always wraps around the aux buffer
337 * and we don't need to care about it, whereas the data_head keeps
338 * increasing and needs to be wrapped by modulus operator
339 */
340
341 LLDB_LOG(log, "bytes_remaining - {0}", bytes_remaining);
342
343 auto data_buffer = GetDataBuffer();
344
345 if (head > data_buffer.size()) {
346 head = head % data_buffer.size();
347 LLDB_LOG(log, "Data size -{0} Head - {1}", m_mmap_meta->data_size, head);
348
349 ReadCyclicBuffer(buffer, data_buffer, static_cast<size_t>(head), offset);
350 bytes_remaining -= buffer.size();
351 } else {
352 LLDB_LOG(log, "Head - {0}", head);
353 if (offset >= head) {
354 LLDB_LOG(log, "Invalid Offset ");
355 error.SetErrorString("invalid offset");
356 buffer = buffer.slice(buffer.size());
357 return error;
358 }
359
360 auto data = data_buffer.slice(offset, (head - offset));
361 auto remaining = std::copy(data.begin(), data.end(), buffer.begin());
362 bytes_remaining -= (remaining - buffer.begin());
363 }
364 buffer = buffer.drop_back(bytes_remaining);
365 return error;
366 #endif
367 }
368
ReadCyclicBuffer(llvm::MutableArrayRef<uint8_t> & dst,llvm::MutableArrayRef<uint8_t> src,size_t src_cyc_index,size_t offset)369 void ProcessorTraceMonitor::ReadCyclicBuffer(
370 llvm::MutableArrayRef<uint8_t> &dst, llvm::MutableArrayRef<uint8_t> src,
371 size_t src_cyc_index, size_t offset) {
372
373 Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
374
375 if (dst.empty() || src.empty()) {
376 dst = dst.drop_back(dst.size());
377 return;
378 }
379
380 if (dst.data() == nullptr || src.data() == nullptr) {
381 dst = dst.drop_back(dst.size());
382 return;
383 }
384
385 if (src_cyc_index > src.size()) {
386 dst = dst.drop_back(dst.size());
387 return;
388 }
389
390 if (offset >= src.size()) {
391 LLDB_LOG(log, "Too Big offset ");
392 dst = dst.drop_back(dst.size());
393 return;
394 }
395
396 llvm::SmallVector<MutableArrayRef<uint8_t>, 2> parts = {
397 src.slice(src_cyc_index), src.take_front(src_cyc_index)};
398
399 if (offset > parts[0].size()) {
400 parts[1] = parts[1].slice(offset - parts[0].size());
401 parts[0] = parts[0].drop_back(parts[0].size());
402 } else if (offset == parts[0].size()) {
403 parts[0] = parts[0].drop_back(parts[0].size());
404 } else {
405 parts[0] = parts[0].slice(offset);
406 }
407 auto next = dst.begin();
408 auto bytes_left = dst.size();
409 for (auto part : parts) {
410 size_t chunk_size = std::min(part.size(), bytes_left);
411 next = std::copy_n(part.begin(), chunk_size, next);
412 bytes_left -= chunk_size;
413 }
414 dst = dst.drop_back(bytes_left);
415 }
416