1 /*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define _GNU_SOURCE 1
18 #include <elf.h>
19 #include <inttypes.h>
20 #include <stdint.h>
21 #include <string.h>
22 #include <sys/types.h>
23 #include <unistd.h>
24
25 #include <algorithm>
26
27 #include <android-base/stringprintf.h>
28 #include <android-base/strings.h>
29
30 #include <demangle.h>
31
32 #include <unwindstack/Elf.h>
33 #include <unwindstack/JitDebug.h>
34 #include <unwindstack/MapInfo.h>
35 #include <unwindstack/Maps.h>
36 #include <unwindstack/Memory.h>
37 #include <unwindstack/Unwinder.h>
38
39 #if !defined(NO_LIBDEXFILE_SUPPORT)
40 #include <unwindstack/DexFiles.h>
41 #endif
42
43 namespace unwindstack {
44
45 // Inject extra 'virtual' frame that represents the dex pc data.
46 // The dex pc is a magic register defined in the Mterp interpreter,
47 // and thus it will be restored/observed in the frame after it.
48 // Adding the dex frame first here will create something like:
49 // #7 pc 0015fa20 core.vdex java.util.Arrays.binarySearch+8
50 // #8 pc 006b1ba1 libartd.so ExecuteMterpImpl+14625
51 // #9 pc 0039a1ef libartd.so art::interpreter::Execute+719
FillInDexFrame()52 void Unwinder::FillInDexFrame() {
53 size_t frame_num = frames_.size();
54 frames_.resize(frame_num + 1);
55 FrameData* frame = &frames_.at(frame_num);
56 frame->num = frame_num;
57
58 uint64_t dex_pc = regs_->dex_pc();
59 frame->pc = dex_pc;
60 frame->sp = regs_->sp();
61
62 MapInfo* info = maps_->Find(dex_pc);
63 if (info != nullptr) {
64 frame->map_start = info->start;
65 frame->map_end = info->end;
66 frame->map_elf_start_offset = info->elf_start_offset;
67 frame->map_exact_offset = info->offset;
68 frame->map_load_bias = info->load_bias;
69 frame->map_flags = info->flags;
70 if (resolve_names_) {
71 frame->map_name = info->name;
72 }
73 frame->rel_pc = dex_pc - info->start;
74 } else {
75 frame->rel_pc = dex_pc;
76 return;
77 }
78
79 if (!resolve_names_) {
80 return;
81 }
82
83 #if !defined(NO_LIBDEXFILE_SUPPORT)
84 if (dex_files_ == nullptr) {
85 return;
86 }
87
88 dex_files_->GetMethodInformation(maps_, info, dex_pc, &frame->function_name,
89 &frame->function_offset);
90 #endif
91 }
92
FillInFrame(MapInfo * map_info,Elf * elf,uint64_t rel_pc,uint64_t pc_adjustment)93 FrameData* Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc,
94 uint64_t pc_adjustment) {
95 size_t frame_num = frames_.size();
96 frames_.resize(frame_num + 1);
97 FrameData* frame = &frames_.at(frame_num);
98 frame->num = frame_num;
99 frame->sp = regs_->sp();
100 frame->rel_pc = rel_pc - pc_adjustment;
101 frame->pc = regs_->pc() - pc_adjustment;
102
103 if (map_info == nullptr) {
104 // Nothing else to update.
105 return nullptr;
106 }
107
108 if (resolve_names_) {
109 frame->map_name = map_info->name;
110 if (embedded_soname_ && map_info->elf_start_offset != 0 && !frame->map_name.empty()) {
111 std::string soname = elf->GetSoname();
112 if (!soname.empty()) {
113 frame->map_name += '!' + soname;
114 }
115 }
116 }
117 frame->map_elf_start_offset = map_info->elf_start_offset;
118 frame->map_exact_offset = map_info->offset;
119 frame->map_start = map_info->start;
120 frame->map_end = map_info->end;
121 frame->map_flags = map_info->flags;
122 frame->map_load_bias = elf->GetLoadBias();
123 return frame;
124 }
125
ShouldStop(const std::vector<std::string> * map_suffixes_to_ignore,std::string & map_name)126 static bool ShouldStop(const std::vector<std::string>* map_suffixes_to_ignore,
127 std::string& map_name) {
128 if (map_suffixes_to_ignore == nullptr) {
129 return false;
130 }
131 auto pos = map_name.find_last_of('.');
132 if (pos == std::string::npos) {
133 return false;
134 }
135
136 return std::find(map_suffixes_to_ignore->begin(), map_suffixes_to_ignore->end(),
137 map_name.substr(pos + 1)) != map_suffixes_to_ignore->end();
138 }
139
Unwind(const std::vector<std::string> * initial_map_names_to_skip,const std::vector<std::string> * map_suffixes_to_ignore)140 void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
141 const std::vector<std::string>* map_suffixes_to_ignore) {
142 frames_.clear();
143 last_error_.code = ERROR_NONE;
144 last_error_.address = 0;
145 elf_from_memory_not_file_ = false;
146
147 ArchEnum arch = regs_->Arch();
148
149 bool return_address_attempt = false;
150 bool adjust_pc = false;
151 for (; frames_.size() < max_frames_;) {
152 uint64_t cur_pc = regs_->pc();
153 uint64_t cur_sp = regs_->sp();
154
155 MapInfo* map_info = maps_->Find(regs_->pc());
156 uint64_t pc_adjustment = 0;
157 uint64_t step_pc;
158 uint64_t rel_pc;
159 Elf* elf;
160 if (map_info == nullptr) {
161 step_pc = regs_->pc();
162 rel_pc = step_pc;
163 last_error_.code = ERROR_INVALID_MAP;
164 } else {
165 if (ShouldStop(map_suffixes_to_ignore, map_info->name)) {
166 break;
167 }
168 elf = map_info->GetElf(process_memory_, arch);
169 // If this elf is memory backed, and there is a valid file, then set
170 // an indicator that we couldn't open the file.
171 if (!elf_from_memory_not_file_ && map_info->memory_backed_elf && !map_info->name.empty() &&
172 map_info->name[0] != '[' && !android::base::StartsWith(map_info->name, "/memfd:")) {
173 elf_from_memory_not_file_ = true;
174 }
175 step_pc = regs_->pc();
176 rel_pc = elf->GetRelPc(step_pc, map_info);
177 // Everyone except elf data in gdb jit debug maps uses the relative pc.
178 if (!(map_info->flags & MAPS_FLAGS_JIT_SYMFILE_MAP)) {
179 step_pc = rel_pc;
180 }
181 if (adjust_pc) {
182 pc_adjustment = regs_->GetPcAdjustment(rel_pc, elf);
183 } else {
184 pc_adjustment = 0;
185 }
186 step_pc -= pc_adjustment;
187
188 // If the pc is in an invalid elf file, try and get an Elf object
189 // using the jit debug information.
190 if (!elf->valid() && jit_debug_ != nullptr) {
191 uint64_t adjusted_jit_pc = regs_->pc() - pc_adjustment;
192 Elf* jit_elf = jit_debug_->GetElf(maps_, adjusted_jit_pc);
193 if (jit_elf != nullptr) {
194 // The jit debug information requires a non relative adjusted pc.
195 step_pc = adjusted_jit_pc;
196 elf = jit_elf;
197 }
198 }
199 }
200
201 FrameData* frame = nullptr;
202 if (map_info == nullptr || initial_map_names_to_skip == nullptr ||
203 std::find(initial_map_names_to_skip->begin(), initial_map_names_to_skip->end(),
204 basename(map_info->name.c_str())) == initial_map_names_to_skip->end()) {
205 if (regs_->dex_pc() != 0) {
206 // Add a frame to represent the dex file.
207 FillInDexFrame();
208 // Clear the dex pc so that we don't repeat this frame later.
209 regs_->set_dex_pc(0);
210
211 // Make sure there is enough room for the real frame.
212 if (frames_.size() == max_frames_) {
213 last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
214 break;
215 }
216 }
217
218 frame = FillInFrame(map_info, elf, rel_pc, pc_adjustment);
219
220 // Once a frame is added, stop skipping frames.
221 initial_map_names_to_skip = nullptr;
222 }
223 adjust_pc = true;
224
225 bool stepped = false;
226 bool in_device_map = false;
227 bool finished = false;
228 if (map_info != nullptr) {
229 if (map_info->flags & MAPS_FLAGS_DEVICE_MAP) {
230 // Do not stop here, fall through in case we are
231 // in the speculative unwind path and need to remove
232 // some of the speculative frames.
233 in_device_map = true;
234 } else {
235 MapInfo* sp_info = maps_->Find(regs_->sp());
236 if (sp_info != nullptr && sp_info->flags & MAPS_FLAGS_DEVICE_MAP) {
237 // Do not stop here, fall through in case we are
238 // in the speculative unwind path and need to remove
239 // some of the speculative frames.
240 in_device_map = true;
241 } else {
242 if (elf->StepIfSignalHandler(rel_pc, regs_, process_memory_.get())) {
243 stepped = true;
244 if (frame != nullptr) {
245 // Need to adjust the relative pc because the signal handler
246 // pc should not be adjusted.
247 frame->rel_pc = rel_pc;
248 frame->pc += pc_adjustment;
249 step_pc = rel_pc;
250 }
251 } else if (elf->Step(step_pc, regs_, process_memory_.get(), &finished)) {
252 stepped = true;
253 }
254 elf->GetLastError(&last_error_);
255 }
256 }
257 }
258
259 if (frame != nullptr) {
260 if (!resolve_names_ ||
261 !elf->GetFunctionName(step_pc, &frame->function_name, &frame->function_offset)) {
262 frame->function_name = "";
263 frame->function_offset = 0;
264 }
265 }
266
267 if (finished) {
268 break;
269 }
270
271 if (!stepped) {
272 if (return_address_attempt) {
273 // Only remove the speculative frame if there are more than two frames
274 // or the pc in the first frame is in a valid map.
275 // This allows for a case where the code jumps into the middle of
276 // nowhere, but there is no other unwind information after that.
277 if (frames_.size() > 2 || (frames_.size() > 0 && maps_->Find(frames_[0].pc) != nullptr)) {
278 // Remove the speculative frame.
279 frames_.pop_back();
280 }
281 break;
282 } else if (in_device_map) {
283 // Do not attempt any other unwinding, pc or sp is in a device
284 // map.
285 break;
286 } else {
287 // Steping didn't work, try this secondary method.
288 if (!regs_->SetPcFromReturnAddress(process_memory_.get())) {
289 break;
290 }
291 return_address_attempt = true;
292 }
293 } else {
294 return_address_attempt = false;
295 if (max_frames_ == frames_.size()) {
296 last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
297 }
298 }
299
300 // If the pc and sp didn't change, then consider everything stopped.
301 if (cur_pc == regs_->pc() && cur_sp == regs_->sp()) {
302 last_error_.code = ERROR_REPEATED_FRAME;
303 break;
304 }
305 }
306 }
307
FormatFrame(const FrameData & frame)308 std::string Unwinder::FormatFrame(const FrameData& frame) {
309 std::string data;
310 if (regs_->Is32Bit()) {
311 data += android::base::StringPrintf(" #%02zu pc %08" PRIx64, frame.num, frame.rel_pc);
312 } else {
313 data += android::base::StringPrintf(" #%02zu pc %016" PRIx64, frame.num, frame.rel_pc);
314 }
315
316 if (frame.map_start == frame.map_end) {
317 // No valid map associated with this frame.
318 data += " <unknown>";
319 } else if (!frame.map_name.empty()) {
320 data += " " + frame.map_name;
321 } else {
322 data += android::base::StringPrintf(" <anonymous:%" PRIx64 ">", frame.map_start);
323 }
324
325 if (frame.map_elf_start_offset != 0) {
326 data += android::base::StringPrintf(" (offset 0x%" PRIx64 ")", frame.map_elf_start_offset);
327 }
328
329 if (!frame.function_name.empty()) {
330 data += " (" + demangle(frame.function_name.c_str());
331 if (frame.function_offset != 0) {
332 data += android::base::StringPrintf("+%" PRId64, frame.function_offset);
333 }
334 data += ')';
335 }
336
337 MapInfo* map_info = maps_->Find(frame.map_start);
338 if (map_info != nullptr && display_build_id_) {
339 std::string build_id = map_info->GetPrintableBuildID();
340 if (!build_id.empty()) {
341 data += " (BuildId: " + build_id + ')';
342 }
343 }
344 return data;
345 }
346
FormatFrame(size_t frame_num)347 std::string Unwinder::FormatFrame(size_t frame_num) {
348 if (frame_num >= frames_.size()) {
349 return "";
350 }
351 return FormatFrame(frames_[frame_num]);
352 }
353
SetJitDebug(JitDebug * jit_debug,ArchEnum arch)354 void Unwinder::SetJitDebug(JitDebug* jit_debug, ArchEnum arch) {
355 jit_debug->SetArch(arch);
356 jit_debug_ = jit_debug;
357 }
358
359 #if !defined(NO_LIBDEXFILE_SUPPORT)
SetDexFiles(DexFiles * dex_files,ArchEnum arch)360 void Unwinder::SetDexFiles(DexFiles* dex_files, ArchEnum arch) {
361 dex_files->SetArch(arch);
362 dex_files_ = dex_files;
363 }
364 #endif
365
Init(ArchEnum arch)366 bool UnwinderFromPid::Init(ArchEnum arch) {
367 if (pid_ == getpid()) {
368 maps_ptr_.reset(new LocalMaps());
369 } else {
370 maps_ptr_.reset(new RemoteMaps(pid_));
371 }
372 if (!maps_ptr_->Parse()) {
373 return false;
374 }
375 maps_ = maps_ptr_.get();
376
377 process_memory_ = Memory::CreateProcessMemoryCached(pid_);
378
379 jit_debug_ptr_.reset(new JitDebug(process_memory_));
380 jit_debug_ = jit_debug_ptr_.get();
381 SetJitDebug(jit_debug_, arch);
382 #if !defined(NO_LIBDEXFILE_SUPPORT)
383 dex_files_ptr_.reset(new DexFiles(process_memory_));
384 dex_files_ = dex_files_ptr_.get();
385 SetDexFiles(dex_files_, arch);
386 #endif
387
388 return true;
389 }
390
391 } // namespace unwindstack
392