1 // Copyright 2013 Google LLC
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28
29 // stackwalker_mips.cc: MIPS-specific stackwalker.
30 //
31 // See stackwalker_mips.h for documentation.
32 //
33 // Author: Tata Elxsi
34
35 #ifdef HAVE_CONFIG_H
36 #include <config.h> // Must come first
37 #endif
38
39 #include "common/scoped_ptr.h"
40 #include "google_breakpad/processor/call_stack.h"
41 #include "google_breakpad/processor/code_modules.h"
42 #include "google_breakpad/processor/memory_region.h"
43 #include "google_breakpad/processor/source_line_resolver_interface.h"
44 #include "google_breakpad/processor/stack_frame_cpu.h"
45 #include "processor/cfi_frame_info.h"
46 #include "processor/logging.h"
47 #include "processor/postfix_evaluator-inl.h"
48 #include "processor/stackwalker_mips.h"
49 #include "processor/windows_frame_info.h"
50 #include "google_breakpad/common/minidump_cpu_mips.h"
51
52 namespace google_breakpad {
53
StackwalkerMIPS(const SystemInfo * system_info,const MDRawContextMIPS * context,MemoryRegion * memory,const CodeModules * modules,StackFrameSymbolizer * resolver_helper)54 StackwalkerMIPS::StackwalkerMIPS(const SystemInfo* system_info,
55 const MDRawContextMIPS* context,
56 MemoryRegion* memory,
57 const CodeModules* modules,
58 StackFrameSymbolizer* resolver_helper)
59 : Stackwalker(system_info, memory, modules, resolver_helper),
60 context_(context) {
61 if (memory_) {
62 if (context_->context_flags & MD_CONTEXT_MIPS64 ) {
63 if (0xffffffffffffffff - memory_->GetBase() < memory_->GetSize() - 1) {
64 BPLOG(ERROR) << "Memory out of range for stackwalking mips64: "
65 << HexString(memory_->GetBase())
66 << "+"
67 << HexString(memory_->GetSize());
68 memory_ = NULL;
69 }
70 } else {
71 if (0xffffffff - memory_->GetBase() < memory_->GetSize() - 1) {
72 BPLOG(ERROR) << "Memory out of range for stackwalking mips32: "
73 << HexString(memory_->GetBase())
74 << "+"
75 << HexString(memory_->GetSize());
76 memory_ = NULL;
77 }
78 }
79 }
80 }
81
GetContextFrame()82 StackFrame* StackwalkerMIPS::GetContextFrame() {
83 if (!context_) {
84 BPLOG(ERROR) << "Can't get context frame without context.";
85 return NULL;
86 }
87
88 StackFrameMIPS* frame = new StackFrameMIPS();
89
90 // The instruction pointer is stored directly in a register, so pull it
91 // straight out of the CPU context structure.
92 frame->context = *context_;
93 frame->context_validity = StackFrameMIPS::CONTEXT_VALID_ALL;
94 frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
95 frame->instruction = frame->context.epc;
96
97 return frame;
98 }
99
100 // Register names for mips.
101 static const char* const kRegisterNames[] = {
102 "$zero", "$at", "$v0", "$v1", "$a0", "$a1", "$a2", "$a3", "$to", "$t1",
103 "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$s0", "$s1", "$s2", "$s3",
104 "$s4", "$s5", "$s6", "$s7", "$t8", "$t9", "$k0", "$k1", "$gp", "$sp",
105 "$fp", "$ra", NULL
106 // TODO(gordanac): add float point save registers
107 };
108
GetCallerByCFIFrameInfo(const vector<StackFrame * > & frames,CFIFrameInfo * cfi_frame_info)109 StackFrameMIPS* StackwalkerMIPS::GetCallerByCFIFrameInfo(
110 const vector<StackFrame*>& frames,
111 CFIFrameInfo* cfi_frame_info) {
112 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
113
114 if (context_->context_flags & MD_CONTEXT_MIPS) {
115 uint32_t pc = 0;
116
117 // Populate a dictionary with the valid register values in last_frame.
118 CFIFrameInfo::RegisterValueMap<uint32_t> callee_registers;
119 // Use the STACK CFI data to recover the caller's register values.
120 CFIFrameInfo::RegisterValueMap<uint32_t> caller_registers;
121
122 for (int i = 0; kRegisterNames[i]; ++i) {
123 caller_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
124 callee_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
125 }
126
127 if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
128 &caller_registers)) {
129 return NULL;
130 }
131
132 CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator entry =
133 caller_registers.find(".cfa");
134
135 if (entry != caller_registers.end()) {
136 caller_registers["$sp"] = entry->second;
137 }
138
139 entry = caller_registers.find(".ra");
140 if (entry != caller_registers.end()) {
141 caller_registers["$ra"] = entry->second;
142 pc = entry->second - 2 * sizeof(pc);
143 }
144 caller_registers["$pc"] = pc;
145 // Construct a new stack frame given the values the CFI recovered.
146 scoped_ptr<StackFrameMIPS> frame(new StackFrameMIPS());
147
148 for (int i = 0; kRegisterNames[i]; ++i) {
149 CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator caller_entry =
150 caller_registers.find(kRegisterNames[i]);
151
152 if (caller_entry != caller_registers.end()) {
153 // The value of this register is recovered; fill the context with the
154 // value from caller_registers.
155 frame->context.iregs[i] = caller_entry->second;
156 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
157 } else if (((i >= INDEX_MIPS_REG_S0 && i <= INDEX_MIPS_REG_S7) ||
158 (i > INDEX_MIPS_REG_GP && i < INDEX_MIPS_REG_RA)) &&
159 (last_frame->context_validity &
160 StackFrameMIPS::RegisterValidFlag(i))) {
161 // If the STACK CFI data doesn't mention some callee-save register, and
162 // it is valid in the callee, assume the callee has not yet changed it.
163 // Calee-save registers according to the MIPS o32 ABI specification are:
164 // $s0 to $s7
165 // $sp, $s8
166 frame->context.iregs[i] = last_frame->context.iregs[i];
167 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
168 }
169 }
170
171 frame->context.epc = caller_registers["$pc"];
172 frame->instruction = caller_registers["$pc"];
173 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
174
175 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] = caller_registers["$ra"];
176 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
177
178 frame->trust = StackFrame::FRAME_TRUST_CFI;
179
180 return frame.release();
181 } else {
182 uint64_t pc = 0;
183
184 // Populate a dictionary with the valid register values in last_frame.
185 CFIFrameInfo::RegisterValueMap<uint64_t> callee_registers;
186 // Use the STACK CFI data to recover the caller's register values.
187 CFIFrameInfo::RegisterValueMap<uint64_t> caller_registers;
188
189 for (int i = 0; kRegisterNames[i]; ++i) {
190 caller_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
191 callee_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
192 }
193
194 if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
195 &caller_registers)) {
196 return NULL;
197 }
198
199 CFIFrameInfo::RegisterValueMap<uint64_t>::const_iterator entry =
200 caller_registers.find(".cfa");
201
202 if (entry != caller_registers.end()) {
203 caller_registers["$sp"] = entry->second;
204 }
205
206 entry = caller_registers.find(".ra");
207 if (entry != caller_registers.end()) {
208 caller_registers["$ra"] = entry->second;
209 pc = entry->second - 2 * sizeof(pc);
210 }
211 caller_registers["$pc"] = pc;
212 // Construct a new stack frame given the values the CFI recovered.
213 scoped_ptr<StackFrameMIPS> frame(new StackFrameMIPS());
214
215 for (int i = 0; kRegisterNames[i]; ++i) {
216 CFIFrameInfo::RegisterValueMap<uint64_t>::const_iterator caller_entry =
217 caller_registers.find(kRegisterNames[i]);
218
219 if (caller_entry != caller_registers.end()) {
220 // The value of this register is recovered; fill the context with the
221 // value from caller_registers.
222 frame->context.iregs[i] = caller_entry->second;
223 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
224 } else if (((i >= INDEX_MIPS_REG_S0 && i <= INDEX_MIPS_REG_S7) ||
225 (i >= INDEX_MIPS_REG_GP && i < INDEX_MIPS_REG_RA)) &&
226 (last_frame->context_validity &
227 StackFrameMIPS::RegisterValidFlag(i))) {
228 // If the STACK CFI data doesn't mention some callee-save register, and
229 // it is valid in the callee, assume the callee has not yet changed it.
230 // Calee-save registers according to the MIPS o32 ABI specification are:
231 // $s0 to $s7
232 // $sp, $s8
233 frame->context.iregs[i] = last_frame->context.iregs[i];
234 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
235 }
236 }
237
238 frame->context.epc = caller_registers["$pc"];
239 frame->instruction = caller_registers["$pc"];
240 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
241
242 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] = caller_registers["$ra"];
243 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
244
245 frame->trust = StackFrame::FRAME_TRUST_CFI;
246
247 return frame.release();
248 }
249 }
250
GetCallerFrame(const CallStack * stack,bool stack_scan_allowed)251 StackFrame* StackwalkerMIPS::GetCallerFrame(const CallStack* stack,
252 bool stack_scan_allowed) {
253 if (!memory_ || !stack) {
254 BPLOG(ERROR) << "Can't get caller frame without memory or stack";
255 return NULL;
256 }
257
258 const vector<StackFrame*>& frames = *stack->frames();
259 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
260 scoped_ptr<StackFrameMIPS> new_frame;
261
262 // See if there is DWARF call frame information covering this address.
263 scoped_ptr<CFIFrameInfo> cfi_frame_info(
264 frame_symbolizer_->FindCFIFrameInfo(last_frame));
265 if (cfi_frame_info.get())
266 new_frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));
267
268 // If caller frame is not found in CFI try analyzing the stack.
269 if (stack_scan_allowed && !new_frame.get()) {
270 new_frame.reset(GetCallerByStackScan(frames));
271 }
272
273 // If nothing worked, tell the caller.
274 if (!new_frame.get()) {
275 return NULL;
276 }
277
278 // Should we terminate the stack walk? (end-of-stack or broken invariant)
279 if (TerminateWalk(new_frame->context.epc,
280 new_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP],
281 last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP],
282 /*first_unwind=*/last_frame->trust ==
283 StackFrame::FRAME_TRUST_CONTEXT)) {
284 return NULL;
285 }
286
287 return new_frame.release();
288 }
289
GetCallerByStackScan(const vector<StackFrame * > & frames)290 StackFrameMIPS* StackwalkerMIPS::GetCallerByStackScan(
291 const vector<StackFrame*>& frames) {
292 const uint32_t kMaxFrameStackSize = 1024;
293 const uint32_t kMinArgsOnStack = 4;
294
295 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
296
297 if (context_->context_flags & MD_CONTEXT_MIPS) {
298 uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP];
299 uint32_t caller_pc, caller_sp, caller_fp;
300
301 // Return address cannot be obtained directly.
302 // Force stackwalking.
303
304 // We cannot use frame pointer to get the return address.
305 // We'll scan the stack for a
306 // return address. This can happen if last_frame is executing code
307 // for a module for which we don't have symbols.
308 int count = kMaxFrameStackSize / sizeof(caller_pc);
309
310 if (frames.size() > 1) {
311 // In case of mips32 ABI stack frame of a nonleaf function
312 // must have minimum stack frame assigned for 4 arguments (4 words).
313 // Move stack pointer for 4 words to avoid reporting non-existing frames
314 // for all frames except the topmost one.
315 // There is no way of knowing if topmost frame belongs to a leaf or
316 // a nonleaf function.
317 last_sp += kMinArgsOnStack * sizeof(caller_pc);
318 // Adjust 'count' so that return address is scanned only in limits
319 // of one stack frame.
320 count -= kMinArgsOnStack;
321 }
322
323 do {
324 // Scanning for return address from stack pointer of the last frame.
325 if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, count)) {
326 // If we can't find an instruction pointer even with stack scanning,
327 // give up.
328 BPLOG(ERROR) << " ScanForReturnAddress failed ";
329 return NULL;
330 }
331 // Get $fp stored in the stack frame.
332 if (!memory_->GetMemoryAtAddress(caller_sp - sizeof(caller_pc),
333 &caller_fp)) {
334 BPLOG(INFO) << " GetMemoryAtAddress for fp failed " ;
335 return NULL;
336 }
337
338 count = count - (caller_sp - last_sp) / sizeof(caller_pc);
339 // Now scan the next address in the stack.
340 last_sp = caller_sp + sizeof(caller_pc);
341 } while ((caller_fp - caller_sp >= kMaxFrameStackSize) && count > 0);
342
343 if (!count) {
344 BPLOG(INFO) << " No frame found " ;
345 return NULL;
346 }
347
348 // ScanForReturnAddress found a reasonable return address. Advance
349 // $sp to the location above the one where the return address was
350 // found.
351 caller_sp += sizeof(caller_pc);
352 // caller_pc is actually containing $ra value;
353 // $pc is two instructions before $ra,
354 // so the caller_pc needs to be decremented accordingly.
355 caller_pc -= 2 * sizeof(caller_pc);
356
357 // Create a new stack frame (ownership will be transferred to the caller)
358 // and fill it in.
359 StackFrameMIPS* frame = new StackFrameMIPS();
360 frame->trust = StackFrame::FRAME_TRUST_SCAN;
361 frame->context = last_frame->context;
362 frame->context.epc = caller_pc;
363 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
364 frame->instruction = caller_pc;
365
366 frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] = caller_sp;
367 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_SP;
368 frame->context.iregs[MD_CONTEXT_MIPS_REG_FP] = caller_fp;
369 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_FP;
370
371 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] =
372 caller_pc + 2 * sizeof(caller_pc);
373 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
374
375 return frame;
376 } else {
377 uint64_t last_sp = last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP];
378 uint64_t caller_pc, caller_sp, caller_fp;
379
380 // Return address cannot be obtained directly.
381 // Force stackwalking.
382
383 // We cannot use frame pointer to get the return address.
384 // We'll scan the stack for a
385 // return address. This can happen if last_frame is executing code
386 // for a module for which we don't have symbols.
387 int count = kMaxFrameStackSize / sizeof(caller_pc);
388
389 do {
390 // Scanning for return address from stack pointer of the last frame.
391 if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, count)) {
392 // If we can't find an instruction pointer even with stack scanning,
393 // give up.
394 BPLOG(ERROR) << " ScanForReturnAddress failed ";
395 return NULL;
396 }
397 // Get $fp stored in the stack frame.
398 if (!memory_->GetMemoryAtAddress(caller_sp - sizeof(caller_pc),
399 &caller_fp)) {
400 BPLOG(INFO) << " GetMemoryAtAddress for fp failed " ;
401 return NULL;
402 }
403
404 count = count - (caller_sp - last_sp) / sizeof(caller_pc);
405 // Now scan the next address in the stack.
406 last_sp = caller_sp + sizeof(caller_pc);
407 } while ((caller_fp - caller_sp >= kMaxFrameStackSize) && count > 0);
408
409 if (!count) {
410 BPLOG(INFO) << " No frame found " ;
411 return NULL;
412 }
413
414 // ScanForReturnAddress found a reasonable return address. Advance
415 // $sp to the location above the one where the return address was
416 // found.
417 caller_sp += sizeof(caller_pc);
418 // caller_pc is actually containing $ra value;
419 // $pc is two instructions before $ra,
420 // so the caller_pc needs to be decremented accordingly.
421 caller_pc -= 2 * sizeof(caller_pc);
422
423 // Create a new stack frame (ownership will be transferred to the caller)
424 // and fill it in.
425 StackFrameMIPS* frame = new StackFrameMIPS();
426 frame->trust = StackFrame::FRAME_TRUST_SCAN;
427 frame->context = last_frame->context;
428 frame->context.epc = caller_pc;
429 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
430 frame->instruction = caller_pc;
431
432 frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] = caller_sp;
433 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_SP;
434 frame->context.iregs[MD_CONTEXT_MIPS_REG_FP] = caller_fp;
435 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_FP;
436
437 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] =
438 caller_pc + 2 * sizeof(caller_pc);
439 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
440
441 return frame;
442 }
443 }
444
445 } // namespace google_breakpad
446
447