1 //===-- Trace.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 "lldb/Target/Trace.h"
10 
11 #include "llvm/Support/Format.h"
12 
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/PluginManager.h"
15 #include "lldb/Symbol/Function.h"
16 #include "lldb/Target/ExecutionContext.h"
17 #include "lldb/Target/Process.h"
18 #include "lldb/Target/SectionLoadList.h"
19 #include "lldb/Target/Thread.h"
20 #include "lldb/Target/ThreadPostMortemTrace.h"
21 #include "lldb/Utility/Stream.h"
22 
23 using namespace lldb;
24 using namespace lldb_private;
25 using namespace llvm;
26 
27 // Helper structs used to extract the type of a trace session json without
28 // having to parse the entire object.
29 
30 struct JSONSimplePluginSettings {
31   std::string type;
32 };
33 
34 struct JSONSimpleTraceSession {
35   JSONSimplePluginSettings trace;
36 };
37 
38 namespace llvm {
39 namespace json {
40 
41 bool fromJSON(const Value &value, JSONSimplePluginSettings &plugin_settings,
42               Path path) {
43   json::ObjectMapper o(value, path);
44   return o && o.map("type", plugin_settings.type);
45 }
46 
47 bool fromJSON(const Value &value, JSONSimpleTraceSession &session, Path path) {
48   json::ObjectMapper o(value, path);
49   return o && o.map("trace", session.trace);
50 }
51 
52 } // namespace json
53 } // namespace llvm
54 
55 static Error createInvalidPlugInError(StringRef plugin_name) {
56   return createStringError(
57       std::errc::invalid_argument,
58       "no trace plug-in matches the specified type: \"%s\"",
59       plugin_name.data());
60 }
61 
62 Expected<lldb::TraceSP>
63 Trace::FindPluginForPostMortemProcess(Debugger &debugger,
64                                       const json::Value &trace_session_file,
65                                       StringRef session_file_dir) {
66   JSONSimpleTraceSession json_session;
67   json::Path::Root root("traceSession");
68   if (!json::fromJSON(trace_session_file, json_session, root))
69     return root.getError();
70 
71   ConstString plugin_name(json_session.trace.type);
72   if (auto create_callback = PluginManager::GetTraceCreateCallback(plugin_name))
73     return create_callback(trace_session_file, session_file_dir, debugger);
74 
75   return createInvalidPlugInError(json_session.trace.type);
76 }
77 
78 Expected<lldb::TraceSP>
79 Trace::FindPluginForLiveProcess(llvm::StringRef plugin_name, Process &process) {
80   if (!process.IsLiveDebugSession())
81     return createStringError(inconvertibleErrorCode(),
82                              "Can't trace non-live processes");
83 
84   ConstString name(plugin_name);
85   if (auto create_callback =
86           PluginManager::GetTraceCreateCallbackForLiveProcess(name))
87     return create_callback(process);
88 
89   return createInvalidPlugInError(plugin_name);
90 }
91 
92 Expected<StringRef> Trace::FindPluginSchema(StringRef name) {
93   ConstString plugin_name(name);
94   StringRef schema = PluginManager::GetTraceSchema(plugin_name);
95   if (!schema.empty())
96     return schema;
97 
98   return createInvalidPlugInError(name);
99 }
100 
101 static int GetNumberOfDigits(size_t num) {
102   return num == 0 ? 1 : static_cast<int>(log10(num)) + 1;
103 }
104 
105 /// \return
106 ///     \b true if the provided line entries match line, column and source file.
107 ///     This function assumes that the line entries are valid.
108 static bool FileLineAndColumnMatches(const LineEntry &a, const LineEntry &b) {
109   if (a.line != b.line)
110     return false;
111   if (a.column != b.column)
112     return false;
113   return a.file == b.file;
114 }
115 
116 // This custom LineEntry validator is neded because some line_entries have
117 // 0 as line, which is meaningless. Notice that LineEntry::IsValid only
118 // checks that line is not LLDB_INVALID_LINE_NUMBER, i.e. UINT32_MAX.
119 static bool IsLineEntryValid(const LineEntry &line_entry) {
120   return line_entry.IsValid() && line_entry.line > 0;
121 }
122 
123 /// Helper structure for \a TraverseInstructionsWithSymbolInfo.
124 struct InstructionSymbolInfo {
125   SymbolContext sc;
126   Address address;
127   lldb::addr_t load_address;
128   lldb::DisassemblerSP disassembler;
129   lldb::InstructionSP instruction;
130   lldb_private::ExecutionContext exe_ctx;
131 };
132 
133 /// InstructionSymbolInfo object with symbol information for the given
134 /// instruction, calculated efficiently.
135 ///
136 /// \param[in] symbol_scope
137 ///     If not \b 0, then the \a InstructionSymbolInfo will have its
138 ///     SymbolContext calculated up to that level.
139 ///
140 /// \param[in] include_disassembler
141 ///     If \b true, then the \a InstructionSymbolInfo will have the
142 ///     \a disassembler and \a instruction objects calculated.
143 static void TraverseInstructionsWithSymbolInfo(
144     Trace &trace, Thread &thread, size_t position,
145     Trace::TraceDirection direction, SymbolContextItem symbol_scope,
146     bool include_disassembler,
147     std::function<bool(size_t index, Expected<InstructionSymbolInfo> insn)>
148         callback) {
149   InstructionSymbolInfo prev_insn;
150 
151   Target &target = thread.GetProcess()->GetTarget();
152   ExecutionContext exe_ctx;
153   target.CalculateExecutionContext(exe_ctx);
154   const ArchSpec &arch = target.GetArchitecture();
155 
156   // Find the symbol context for the given address reusing the previous
157   // instruction's symbol context when possible.
158   auto calculate_symbol_context = [&](const Address &address) {
159     AddressRange range;
160     if (prev_insn.sc.GetAddressRange(symbol_scope, 0,
161                                      /*inline_block_range*/ false, range) &&
162         range.Contains(address))
163       return prev_insn.sc;
164 
165     SymbolContext sc;
166     address.CalculateSymbolContext(&sc, symbol_scope);
167     return sc;
168   };
169 
170   // Find the disassembler for the given address reusing the previous
171   // instruction's disassembler when possible.
172   auto calculate_disass = [&](const Address &address, const SymbolContext &sc) {
173     if (prev_insn.disassembler) {
174       if (InstructionSP instruction =
175               prev_insn.disassembler->GetInstructionList()
176                   .GetInstructionAtAddress(address))
177         return std::make_tuple(prev_insn.disassembler, instruction);
178     }
179 
180     if (sc.function) {
181       if (DisassemblerSP disassembler =
182               sc.function->GetInstructions(exe_ctx, nullptr)) {
183         if (InstructionSP instruction =
184                 disassembler->GetInstructionList().GetInstructionAtAddress(
185                     address))
186           return std::make_tuple(disassembler, instruction);
187       }
188     }
189     // We fallback to a single instruction disassembler
190     AddressRange range(address, arch.GetMaximumOpcodeByteSize());
191     DisassemblerSP disassembler =
192         Disassembler::DisassembleRange(arch, /*plugin_name*/ nullptr,
193                                        /*flavor*/ nullptr, target, range);
194     return std::make_tuple(disassembler,
195                            disassembler ? disassembler->GetInstructionList()
196                                               .GetInstructionAtAddress(address)
197                                         : InstructionSP());
198   };
199 
200   trace.TraverseInstructions(
201       thread, position, direction,
202       [&](size_t index, Expected<lldb::addr_t> load_address) -> bool {
203         if (!load_address)
204           return callback(index, load_address.takeError());
205 
206         InstructionSymbolInfo insn;
207         insn.load_address = *load_address;
208         insn.exe_ctx = exe_ctx;
209         insn.address.SetLoadAddress(*load_address, &target);
210         if (symbol_scope != 0)
211           insn.sc = calculate_symbol_context(insn.address);
212         if (include_disassembler)
213           std::tie(insn.disassembler, insn.instruction) =
214               calculate_disass(insn.address, insn.sc);
215         prev_insn = insn;
216         return callback(index, insn);
217       });
218 }
219 
220 /// Compare the symbol contexts of the provided \a InstructionSymbolInfo
221 /// objects.
222 ///
223 /// \return
224 ///     \a true if both instructions belong to the same scope level analized
225 ///     in the following order:
226 ///       - module
227 ///       - symbol
228 ///       - function
229 ///       - line
230 static bool
231 IsSameInstructionSymbolContext(const InstructionSymbolInfo &prev_insn,
232                                const InstructionSymbolInfo &insn) {
233   // module checks
234   if (insn.sc.module_sp != prev_insn.sc.module_sp)
235     return false;
236 
237   // symbol checks
238   if (insn.sc.symbol != prev_insn.sc.symbol)
239     return false;
240 
241   // function checks
242   if (!insn.sc.function && !prev_insn.sc.function)
243     return true;
244   else if (insn.sc.function != prev_insn.sc.function)
245     return false;
246 
247   // line entry checks
248   const bool curr_line_valid = IsLineEntryValid(insn.sc.line_entry);
249   const bool prev_line_valid = IsLineEntryValid(prev_insn.sc.line_entry);
250   if (curr_line_valid && prev_line_valid)
251     return FileLineAndColumnMatches(insn.sc.line_entry,
252                                     prev_insn.sc.line_entry);
253   return curr_line_valid == prev_line_valid;
254 }
255 
256 /// Dump the symbol context of the given instruction address if it's different
257 /// from the symbol context of the previous instruction in the trace.
258 ///
259 /// \param[in] prev_sc
260 ///     The symbol context of the previous instruction in the trace.
261 ///
262 /// \param[in] address
263 ///     The address whose symbol information will be dumped.
264 ///
265 /// \return
266 ///     The symbol context of the current address, which might differ from the
267 ///     previous one.
268 static void
269 DumpInstructionSymbolContext(Stream &s,
270                              Optional<InstructionSymbolInfo> prev_insn,
271                              InstructionSymbolInfo &insn) {
272   if (prev_insn && IsSameInstructionSymbolContext(*prev_insn, insn))
273     return;
274 
275   s.Printf("  ");
276 
277   if (!insn.sc.module_sp)
278     s.Printf("(none)");
279   else if (!insn.sc.function && !insn.sc.symbol)
280     s.Printf("%s`(none)",
281              insn.sc.module_sp->GetFileSpec().GetFilename().AsCString());
282   else
283     insn.sc.DumpStopContext(&s, insn.exe_ctx.GetTargetPtr(), insn.address,
284                             /*show_fullpath*/ false,
285                             /*show_module*/ true, /*show_inlined_frames*/ false,
286                             /*show_function_arguments*/ true,
287                             /*show_function_name*/ true);
288   s.Printf("\n");
289 }
290 
291 static void DumpInstructionDisassembly(Stream &s, InstructionSymbolInfo &insn) {
292   if (!insn.instruction)
293     return;
294   insn.instruction->Dump(&s, /*show_address*/ false, /*show_bytes*/ false,
295                          /*max_opcode_byte_size*/ 0, &insn.exe_ctx, &insn.sc,
296                          /*prev_sym_ctx*/ nullptr,
297                          /*disassembly_addr_format*/ nullptr,
298                          /*max_address_text_size*/ 0);
299 }
300 
301 void Trace::DumpTraceInstructions(Thread &thread, Stream &s, size_t count,
302                                   size_t end_position, bool raw) {
303   Optional<size_t> instructions_count = GetInstructionCount(thread);
304   if (!instructions_count) {
305     s.Printf("thread #%u: tid = %" PRIu64 ", not traced\n", thread.GetIndexID(),
306              thread.GetID());
307     return;
308   }
309 
310   s.Printf("thread #%u: tid = %" PRIu64 ", total instructions = %zu\n",
311            thread.GetIndexID(), thread.GetID(), *instructions_count);
312 
313   if (count == 0 || end_position >= *instructions_count)
314     return;
315 
316   int digits_count = GetNumberOfDigits(end_position);
317   size_t start_position =
318       end_position + 1 < count ? 0 : end_position + 1 - count;
319   auto printInstructionIndex = [&](size_t index) {
320     s.Printf("    [%*zu] ", digits_count, index);
321   };
322 
323   bool was_prev_instruction_an_error = false;
324   Optional<InstructionSymbolInfo> prev_insn;
325 
326   TraverseInstructionsWithSymbolInfo(
327       *this, thread, start_position, TraceDirection::Forwards,
328       eSymbolContextEverything, /*disassembler*/ true,
329       [&](size_t index, Expected<InstructionSymbolInfo> insn) -> bool {
330         if (!insn) {
331           printInstructionIndex(index);
332           s << toString(insn.takeError());
333 
334           prev_insn = None;
335           was_prev_instruction_an_error = true;
336         } else {
337           if (was_prev_instruction_an_error)
338             s.Printf("    ...missing instructions\n");
339 
340           if (!raw)
341             DumpInstructionSymbolContext(s, prev_insn, *insn);
342 
343           printInstructionIndex(index);
344           s.Printf("0x%016" PRIx64 "    ", insn->load_address);
345 
346           if (!raw)
347             DumpInstructionDisassembly(s, *insn);
348 
349           prev_insn = *insn;
350           was_prev_instruction_an_error = false;
351         }
352 
353         s.Printf("\n");
354         return index < end_position;
355       });
356 }
357 
358 Error Trace::Start(const llvm::json::Value &request) {
359   if (!m_live_process)
360     return createStringError(inconvertibleErrorCode(),
361                              "Tracing requires a live process.");
362   return m_live_process->TraceStart(request);
363 }
364 
365 Error Trace::StopProcess() {
366   if (!m_live_process)
367     return createStringError(inconvertibleErrorCode(),
368                              "Tracing requires a live process.");
369   return m_live_process->TraceStop(
370       TraceStopRequest(GetPluginName().AsCString()));
371 }
372 
373 Error Trace::StopThreads(const std::vector<lldb::tid_t> &tids) {
374   if (!m_live_process)
375     return createStringError(inconvertibleErrorCode(),
376                              "Tracing requires a live process.");
377   return m_live_process->TraceStop(
378       TraceStopRequest(GetPluginName().AsCString(), tids));
379 }
380 
381 Expected<std::string> Trace::GetLiveProcessState() {
382   if (!m_live_process)
383     return createStringError(inconvertibleErrorCode(),
384                              "Tracing requires a live process.");
385   return m_live_process->TraceGetState(GetPluginName().AsCString());
386 }
387 
388 Optional<size_t> Trace::GetLiveThreadBinaryDataSize(lldb::tid_t tid,
389                                                     llvm::StringRef kind) {
390   auto it = m_live_thread_data.find(tid);
391   if (it == m_live_thread_data.end())
392     return None;
393   std::unordered_map<std::string, size_t> &single_thread_data = it->second;
394   auto single_thread_data_it = single_thread_data.find(kind.str());
395   if (single_thread_data_it == single_thread_data.end())
396     return None;
397   return single_thread_data_it->second;
398 }
399 
400 Optional<size_t> Trace::GetLiveProcessBinaryDataSize(llvm::StringRef kind) {
401   auto data_it = m_live_process_data.find(kind.str());
402   if (data_it == m_live_process_data.end())
403     return None;
404   return data_it->second;
405 }
406 
407 Expected<std::vector<uint8_t>>
408 Trace::GetLiveThreadBinaryData(lldb::tid_t tid, llvm::StringRef kind) {
409   if (!m_live_process)
410     return createStringError(inconvertibleErrorCode(),
411                              "Tracing requires a live process.");
412   llvm::Optional<size_t> size = GetLiveThreadBinaryDataSize(tid, kind);
413   if (!size)
414     return createStringError(
415         inconvertibleErrorCode(),
416         "Tracing data \"%s\" is not available for thread %" PRIu64 ".",
417         kind.data(), tid);
418 
419   TraceGetBinaryDataRequest request{GetPluginName().AsCString(), kind.str(),
420                                     static_cast<int64_t>(tid), 0,
421                                     static_cast<int64_t>(*size)};
422   return m_live_process->TraceGetBinaryData(request);
423 }
424 
425 Expected<std::vector<uint8_t>>
426 Trace::GetLiveProcessBinaryData(llvm::StringRef kind) {
427   if (!m_live_process)
428     return createStringError(inconvertibleErrorCode(),
429                              "Tracing requires a live process.");
430   llvm::Optional<size_t> size = GetLiveProcessBinaryDataSize(kind);
431   if (!size)
432     return createStringError(
433         inconvertibleErrorCode(),
434         "Tracing data \"%s\" is not available for the process.", kind.data());
435 
436   TraceGetBinaryDataRequest request{GetPluginName().AsCString(), kind.str(),
437                                     None, 0, static_cast<int64_t>(*size)};
438   return m_live_process->TraceGetBinaryData(request);
439 }
440 
441 void Trace::RefreshLiveProcessState() {
442   if (!m_live_process)
443     return;
444 
445   uint32_t new_stop_id = m_live_process->GetStopID();
446   if (new_stop_id == m_stop_id)
447     return;
448 
449   m_stop_id = new_stop_id;
450   m_live_thread_data.clear();
451 
452   Expected<std::string> json_string = GetLiveProcessState();
453   if (!json_string) {
454     DoRefreshLiveProcessState(json_string.takeError());
455     return;
456   }
457   Expected<TraceGetStateResponse> live_process_state =
458       json::parse<TraceGetStateResponse>(*json_string, "TraceGetStateResponse");
459   if (!live_process_state) {
460     DoRefreshLiveProcessState(live_process_state.takeError());
461     return;
462   }
463 
464   for (const TraceThreadState &thread_state :
465        live_process_state->tracedThreads) {
466     for (const TraceBinaryData &item : thread_state.binaryData)
467       m_live_thread_data[thread_state.tid][item.kind] = item.size;
468   }
469 
470   for (const TraceBinaryData &item : live_process_state->processBinaryData)
471     m_live_process_data[item.kind] = item.size;
472 
473   DoRefreshLiveProcessState(std::move(live_process_state));
474 }
475