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 <unwindstack/Elf.h>
31 #include <unwindstack/JitDebug.h>
32 #include <unwindstack/MapInfo.h>
33 #include <unwindstack/Maps.h>
34 #include <unwindstack/Memory.h>
35 #include <unwindstack/Unwinder.h>
36
37 #include <unwindstack/DexFiles.h>
38
39 // Use the demangler from libc++.
40 extern "C" char* __cxa_demangle(const char*, char*, size_t*, int* status);
41
42 namespace unwindstack {
43
44 // Inject extra 'virtual' frame that represents the dex pc data.
45 // The dex pc is a magic register defined in the Mterp interpreter,
46 // and thus it will be restored/observed in the frame after it.
47 // Adding the dex frame first here will create something like:
48 // #7 pc 0015fa20 core.vdex java.util.Arrays.binarySearch+8
49 // #8 pc 006b1ba1 libartd.so ExecuteMterpImpl+14625
50 // #9 pc 0039a1ef libartd.so art::interpreter::Execute+719
FillInDexFrame()51 void Unwinder::FillInDexFrame() {
52 size_t frame_num = frames_.size();
53 frames_.resize(frame_num + 1);
54 FrameData* frame = &frames_.at(frame_num);
55 frame->num = frame_num;
56
57 uint64_t dex_pc = regs_->dex_pc();
58 frame->pc = dex_pc;
59 frame->sp = regs_->sp();
60
61 MapInfo* info = maps_->Find(dex_pc);
62 if (info != nullptr) {
63 frame->map_start = info->start;
64 frame->map_end = info->end;
65 // Since this is a dex file frame, the elf_start_offset is not set
66 // by any of the normal code paths. Use the offset of the map since
67 // that matches the actual offset.
68 frame->map_elf_start_offset = info->offset;
69 frame->map_exact_offset = info->offset;
70 frame->map_load_bias = info->load_bias;
71 frame->map_flags = info->flags;
72 if (resolve_names_) {
73 frame->map_name = info->name;
74 }
75 frame->rel_pc = dex_pc - info->start;
76 } else {
77 frame->rel_pc = dex_pc;
78 return;
79 }
80
81 if (!resolve_names_) {
82 return;
83 }
84
85 #if defined(DEXFILE_SUPPORT)
86 if (dex_files_ == nullptr) {
87 return;
88 }
89
90 dex_files_->GetMethodInformation(maps_, info, dex_pc, &frame->function_name,
91 &frame->function_offset);
92 #endif
93 }
94
FillInFrame(MapInfo * map_info,Elf * elf,uint64_t rel_pc,uint64_t pc_adjustment)95 FrameData* Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc,
96 uint64_t pc_adjustment) {
97 size_t frame_num = frames_.size();
98 frames_.resize(frame_num + 1);
99 FrameData* frame = &frames_.at(frame_num);
100 frame->num = frame_num;
101 frame->sp = regs_->sp();
102 frame->rel_pc = rel_pc - pc_adjustment;
103 frame->pc = regs_->pc() - pc_adjustment;
104
105 if (map_info == nullptr) {
106 // Nothing else to update.
107 return nullptr;
108 }
109
110 if (resolve_names_) {
111 frame->map_name = map_info->name;
112 if (embedded_soname_ && map_info->elf_start_offset != 0 && !frame->map_name.empty()) {
113 std::string soname = elf->GetSoname();
114 if (!soname.empty()) {
115 frame->map_name += '!' + soname;
116 }
117 }
118 }
119 frame->map_elf_start_offset = map_info->elf_start_offset;
120 frame->map_exact_offset = map_info->offset;
121 frame->map_start = map_info->start;
122 frame->map_end = map_info->end;
123 frame->map_flags = map_info->flags;
124 frame->map_load_bias = elf->GetLoadBias();
125 return frame;
126 }
127
ShouldStop(const std::vector<std::string> * map_suffixes_to_ignore,std::string & map_name)128 static bool ShouldStop(const std::vector<std::string>* map_suffixes_to_ignore,
129 std::string& map_name) {
130 if (map_suffixes_to_ignore == nullptr) {
131 return false;
132 }
133 auto pos = map_name.find_last_of('.');
134 if (pos == std::string::npos) {
135 return false;
136 }
137
138 return std::find(map_suffixes_to_ignore->begin(), map_suffixes_to_ignore->end(),
139 map_name.substr(pos + 1)) != map_suffixes_to_ignore->end();
140 }
141
Unwind(const std::vector<std::string> * initial_map_names_to_skip,const std::vector<std::string> * map_suffixes_to_ignore)142 void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
143 const std::vector<std::string>* map_suffixes_to_ignore) {
144 frames_.clear();
145 last_error_.code = ERROR_NONE;
146 last_error_.address = 0;
147 elf_from_memory_not_file_ = false;
148
149 ArchEnum arch = regs_->Arch();
150
151 bool return_address_attempt = false;
152 bool adjust_pc = false;
153 for (; frames_.size() < max_frames_;) {
154 uint64_t cur_pc = regs_->pc();
155 uint64_t cur_sp = regs_->sp();
156
157 MapInfo* map_info = maps_->Find(regs_->pc());
158 uint64_t pc_adjustment = 0;
159 uint64_t step_pc;
160 uint64_t rel_pc;
161 Elf* elf;
162 if (map_info == nullptr) {
163 step_pc = regs_->pc();
164 rel_pc = step_pc;
165 last_error_.code = ERROR_INVALID_MAP;
166 } else {
167 if (ShouldStop(map_suffixes_to_ignore, map_info->name)) {
168 break;
169 }
170 elf = map_info->GetElf(process_memory_, arch);
171 // If this elf is memory backed, and there is a valid file, then set
172 // an indicator that we couldn't open the file.
173 if (!elf_from_memory_not_file_ && map_info->memory_backed_elf && !map_info->name.empty() &&
174 map_info->name[0] != '[' && !android::base::StartsWith(map_info->name, "/memfd:")) {
175 elf_from_memory_not_file_ = true;
176 }
177 step_pc = regs_->pc();
178 rel_pc = elf->GetRelPc(step_pc, map_info);
179 // Everyone except elf data in gdb jit debug maps uses the relative pc.
180 if (!(map_info->flags & MAPS_FLAGS_JIT_SYMFILE_MAP)) {
181 step_pc = rel_pc;
182 }
183 if (adjust_pc) {
184 pc_adjustment = regs_->GetPcAdjustment(rel_pc, elf);
185 } else {
186 pc_adjustment = 0;
187 }
188 step_pc -= pc_adjustment;
189
190 // If the pc is in an invalid elf file, try and get an Elf object
191 // using the jit debug information.
192 if (!elf->valid() && jit_debug_ != nullptr) {
193 uint64_t adjusted_jit_pc = regs_->pc() - pc_adjustment;
194 Elf* jit_elf = jit_debug_->GetElf(maps_, adjusted_jit_pc);
195 if (jit_elf != nullptr) {
196 // The jit debug information requires a non relative adjusted pc.
197 step_pc = adjusted_jit_pc;
198 elf = jit_elf;
199 }
200 }
201 }
202
203 FrameData* frame = nullptr;
204 if (map_info == nullptr || initial_map_names_to_skip == nullptr ||
205 std::find(initial_map_names_to_skip->begin(), initial_map_names_to_skip->end(),
206 basename(map_info->name.c_str())) == initial_map_names_to_skip->end()) {
207 if (regs_->dex_pc() != 0) {
208 // Add a frame to represent the dex file.
209 FillInDexFrame();
210 // Clear the dex pc so that we don't repeat this frame later.
211 regs_->set_dex_pc(0);
212
213 // Make sure there is enough room for the real frame.
214 if (frames_.size() == max_frames_) {
215 last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
216 break;
217 }
218 }
219
220 frame = FillInFrame(map_info, elf, rel_pc, pc_adjustment);
221
222 // Once a frame is added, stop skipping frames.
223 initial_map_names_to_skip = nullptr;
224 }
225 adjust_pc = true;
226
227 bool stepped = false;
228 bool in_device_map = false;
229 bool finished = false;
230 if (map_info != nullptr) {
231 if (map_info->flags & MAPS_FLAGS_DEVICE_MAP) {
232 // Do not stop here, fall through in case we are
233 // in the speculative unwind path and need to remove
234 // some of the speculative frames.
235 in_device_map = true;
236 } else {
237 MapInfo* sp_info = maps_->Find(regs_->sp());
238 if (sp_info != nullptr && sp_info->flags & MAPS_FLAGS_DEVICE_MAP) {
239 // Do not stop here, fall through in case we are
240 // in the speculative unwind path and need to remove
241 // some of the speculative frames.
242 in_device_map = true;
243 } else {
244 if (elf->StepIfSignalHandler(rel_pc, regs_, process_memory_.get())) {
245 stepped = true;
246 if (frame != nullptr) {
247 // Need to adjust the relative pc because the signal handler
248 // pc should not be adjusted.
249 frame->rel_pc = rel_pc;
250 frame->pc += pc_adjustment;
251 step_pc = rel_pc;
252 }
253 } else if (elf->Step(step_pc, regs_, process_memory_.get(), &finished)) {
254 stepped = true;
255 }
256 elf->GetLastError(&last_error_);
257 }
258 }
259 }
260
261 if (frame != nullptr) {
262 if (!resolve_names_ ||
263 !elf->GetFunctionName(step_pc, &frame->function_name, &frame->function_offset)) {
264 frame->function_name = "";
265 frame->function_offset = 0;
266 }
267 }
268
269 if (finished) {
270 break;
271 }
272
273 if (!stepped) {
274 if (return_address_attempt) {
275 // Only remove the speculative frame if there are more than two frames
276 // or the pc in the first frame is in a valid map.
277 // This allows for a case where the code jumps into the middle of
278 // nowhere, but there is no other unwind information after that.
279 if (frames_.size() > 2 || (frames_.size() > 0 && maps_->Find(frames_[0].pc) != nullptr)) {
280 // Remove the speculative frame.
281 frames_.pop_back();
282 }
283 break;
284 } else if (in_device_map) {
285 // Do not attempt any other unwinding, pc or sp is in a device
286 // map.
287 break;
288 } else {
289 // Steping didn't work, try this secondary method.
290 if (!regs_->SetPcFromReturnAddress(process_memory_.get())) {
291 break;
292 }
293 return_address_attempt = true;
294 }
295 } else {
296 return_address_attempt = false;
297 if (max_frames_ == frames_.size()) {
298 last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
299 }
300 }
301
302 // If the pc and sp didn't change, then consider everything stopped.
303 if (cur_pc == regs_->pc() && cur_sp == regs_->sp()) {
304 last_error_.code = ERROR_REPEATED_FRAME;
305 break;
306 }
307 }
308 }
309
FormatFrame(const FrameData & frame) const310 std::string Unwinder::FormatFrame(const FrameData& frame) const {
311 std::string data;
312 if (regs_->Is32Bit()) {
313 data += android::base::StringPrintf(" #%02zu pc %08" PRIx64, frame.num, frame.rel_pc);
314 } else {
315 data += android::base::StringPrintf(" #%02zu pc %016" PRIx64, frame.num, frame.rel_pc);
316 }
317
318 if (frame.map_start == frame.map_end) {
319 // No valid map associated with this frame.
320 data += " <unknown>";
321 } else if (!frame.map_name.empty()) {
322 data += " " + frame.map_name;
323 } else {
324 data += android::base::StringPrintf(" <anonymous:%" PRIx64 ">", frame.map_start);
325 }
326
327 if (frame.map_elf_start_offset != 0) {
328 data += android::base::StringPrintf(" (offset 0x%" PRIx64 ")", frame.map_elf_start_offset);
329 }
330
331 if (!frame.function_name.empty()) {
332 char* demangled_name = __cxa_demangle(frame.function_name.c_str(), nullptr, nullptr, nullptr);
333 if (demangled_name == nullptr) {
334 data += " (" + frame.function_name;
335 } else {
336 data += " (";
337 data += demangled_name;
338 free(demangled_name);
339 }
340 if (frame.function_offset != 0) {
341 data += android::base::StringPrintf("+%" PRId64, frame.function_offset);
342 }
343 data += ')';
344 }
345
346 MapInfo* map_info = maps_->Find(frame.map_start);
347 if (map_info != nullptr && display_build_id_) {
348 std::string build_id = map_info->GetPrintableBuildID();
349 if (!build_id.empty()) {
350 data += " (BuildId: " + build_id + ')';
351 }
352 }
353 return data;
354 }
355
FormatFrame(size_t frame_num) const356 std::string Unwinder::FormatFrame(size_t frame_num) const {
357 if (frame_num >= frames_.size()) {
358 return "";
359 }
360 return FormatFrame(frames_[frame_num]);
361 }
362
SetJitDebug(JitDebug * jit_debug,ArchEnum arch)363 void Unwinder::SetJitDebug(JitDebug* jit_debug, ArchEnum arch) {
364 jit_debug->SetArch(arch);
365 jit_debug_ = jit_debug;
366 }
367
SetDexFiles(DexFiles * dex_files,ArchEnum arch)368 void Unwinder::SetDexFiles(DexFiles* dex_files, ArchEnum arch) {
369 dex_files->SetArch(arch);
370 dex_files_ = dex_files;
371 }
372
Init(ArchEnum arch)373 bool UnwinderFromPid::Init(ArchEnum arch) {
374 if (pid_ == getpid()) {
375 maps_ptr_.reset(new LocalMaps());
376 } else {
377 maps_ptr_.reset(new RemoteMaps(pid_));
378 }
379 if (!maps_ptr_->Parse()) {
380 return false;
381 }
382 maps_ = maps_ptr_.get();
383
384 process_memory_ = Memory::CreateProcessMemoryCached(pid_);
385
386 jit_debug_ptr_.reset(new JitDebug(process_memory_));
387 jit_debug_ = jit_debug_ptr_.get();
388 SetJitDebug(jit_debug_, arch);
389 #if defined(DEXFILE_SUPPORT)
390 dex_files_ptr_.reset(new DexFiles(process_memory_));
391 dex_files_ = dex_files_ptr_.get();
392 SetDexFiles(dex_files_, arch);
393 #endif
394
395 return true;
396 }
397
398 } // namespace unwindstack
399