1 // Copyright (c) 2013 Google Inc.
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
8 // * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
13 // distribution.
14 // * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30 // stackwalker_mips.cc: MIPS-specific stackwalker.
31 //
32 // See stackwalker_mips.h for documentation.
33 //
34 // Author: Tata Elxsi
35
36 #include "common/scoped_ptr.h"
37 #include "google_breakpad/processor/call_stack.h"
38 #include "google_breakpad/processor/code_modules.h"
39 #include "google_breakpad/processor/memory_region.h"
40 #include "google_breakpad/processor/source_line_resolver_interface.h"
41 #include "google_breakpad/processor/stack_frame_cpu.h"
42 #include "processor/cfi_frame_info.h"
43 #include "processor/logging.h"
44 #include "processor/postfix_evaluator-inl.h"
45 #include "processor/stackwalker_mips.h"
46 #include "processor/windows_frame_info.h"
47 #include "google_breakpad/common/minidump_cpu_mips.h"
48
49 namespace google_breakpad {
50
StackwalkerMIPS(const SystemInfo * system_info,const MDRawContextMIPS * context,MemoryRegion * memory,const CodeModules * modules,StackFrameSymbolizer * resolver_helper)51 StackwalkerMIPS::StackwalkerMIPS(const SystemInfo* system_info,
52 const MDRawContextMIPS* context,
53 MemoryRegion* memory,
54 const CodeModules* modules,
55 StackFrameSymbolizer* resolver_helper)
56 : Stackwalker(system_info, memory, modules, resolver_helper),
57 context_(context) {
58 if (memory_ && memory_->GetBase() + memory_->GetSize() - 1 > 0xffffffff) {
59 BPLOG(ERROR) << "Memory out of range for stackwalking: "
60 << HexString(memory_->GetBase())
61 << "+"
62 << HexString(memory_->GetSize());
63 memory_ = NULL;
64 }
65 }
66
GetContextFrame()67 StackFrame* StackwalkerMIPS::GetContextFrame() {
68 if (!context_) {
69 BPLOG(ERROR) << "Can't get context frame without context.";
70 return NULL;
71 }
72
73 StackFrameMIPS* frame = new StackFrameMIPS();
74
75 // The instruction pointer is stored directly in a register, so pull it
76 // straight out of the CPU context structure.
77 frame->context = *context_;
78 frame->context_validity = StackFrameMIPS::CONTEXT_VALID_ALL;
79 frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
80 frame->instruction = frame->context.epc;
81
82 return frame;
83 }
84
85 // Register names for mips.
86 static const char* const kRegisterNames[] = {
87 "$zero", "$at", "$v0", "$v1", "$a0", "$a1", "$a2", "$a3", "$to", "$t1",
88 "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$s0", "$s1", "$s2", "$s3",
89 "$s4", "$s5", "$s6", "$s7", "$t8", "$t9", "$k0", "$k1", "$gp", "$sp",
90 "$fp", "$ra", NULL
91 // TODO(gordanac): add float point save registers
92 };
93
GetCallerByCFIFrameInfo(const vector<StackFrame * > & frames,CFIFrameInfo * cfi_frame_info)94 StackFrameMIPS* StackwalkerMIPS::GetCallerByCFIFrameInfo(
95 const vector<StackFrame*>& frames,
96 CFIFrameInfo* cfi_frame_info) {
97 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
98
99 uint32_t sp = 0, pc = 0;
100
101 // Populate a dictionary with the valid register values in last_frame.
102 CFIFrameInfo::RegisterValueMap<uint32_t> callee_registers;
103 // Use the STACK CFI data to recover the caller's register values.
104 CFIFrameInfo::RegisterValueMap<uint32_t> caller_registers;
105
106 for (int i = 0; kRegisterNames[i]; ++i) {
107 caller_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
108 callee_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
109 }
110
111 if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
112 &caller_registers)) {
113 return NULL;
114 }
115
116 CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator entry =
117 caller_registers.find(".cfa");
118
119 if (entry != caller_registers.end()) {
120 sp = entry->second;
121 caller_registers["$sp"] = entry->second;
122 }
123
124 entry = caller_registers.find(".ra");
125 if (entry != caller_registers.end()) {
126 caller_registers["$ra"] = entry->second;
127 pc = entry->second - 2 * sizeof(pc);
128 }
129 caller_registers["$pc"] = pc;
130 // Construct a new stack frame given the values the CFI recovered.
131 scoped_ptr<StackFrameMIPS> frame(new StackFrameMIPS());
132
133 for (int i = 0; kRegisterNames[i]; ++i) {
134 CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator caller_entry =
135 caller_registers.find(kRegisterNames[i]);
136
137 if (caller_entry != caller_registers.end()) {
138 // The value of this register is recovered; fill the context with the
139 // value from caller_registers.
140 frame->context.iregs[i] = caller_entry->second;
141 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
142 } else if (((i >= INDEX_MIPS_REG_S0 && i <= INDEX_MIPS_REG_S7) ||
143 (i > INDEX_MIPS_REG_GP && i < INDEX_MIPS_REG_RA)) &&
144 (last_frame->context_validity &
145 StackFrameMIPS::RegisterValidFlag(i))) {
146 // If the STACK CFI data doesn't mention some callee-save register, and
147 // it is valid in the callee, assume the callee has not yet changed it.
148 // Calee-save registers according to the MIPS o32 ABI specification are:
149 // $s0 to $s7
150 // $sp, $s8
151 frame->context.iregs[i] = last_frame->context.iregs[i];
152 frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
153 }
154 }
155
156 frame->context.epc = caller_registers["$pc"];
157 frame->instruction = caller_registers["$pc"];
158 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
159
160 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] = caller_registers["$ra"];
161 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
162
163 frame->trust = StackFrame::FRAME_TRUST_CFI;
164
165 return frame.release();
166 }
167
GetCallerFrame(const CallStack * stack,bool stack_scan_allowed)168 StackFrame* StackwalkerMIPS::GetCallerFrame(const CallStack* stack,
169 bool stack_scan_allowed) {
170 if (!memory_ || !stack) {
171 BPLOG(ERROR) << "Can't get caller frame without memory or stack";
172 return NULL;
173 }
174
175 const vector<StackFrame*>& frames = *stack->frames();
176 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
177 scoped_ptr<StackFrameMIPS> new_frame;
178
179 // See if there is DWARF call frame information covering this address.
180 scoped_ptr<CFIFrameInfo> cfi_frame_info(
181 frame_symbolizer_->FindCFIFrameInfo(last_frame));
182 if (cfi_frame_info.get())
183 new_frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));
184
185 // If caller frame is not found in CFI try analyzing the stack.
186 if (stack_scan_allowed && !new_frame.get()) {
187 new_frame.reset(GetCallerByStackScan(frames));
188 }
189
190 // If nothing worked, tell the caller.
191 if (!new_frame.get()) {
192 return NULL;
193 }
194
195 // Treat an instruction address of 0 as end-of-stack.
196 if (new_frame->context.epc == 0) {
197 return NULL;
198 }
199
200 // If the new stack pointer is at a lower address than the old, then
201 // that's clearly incorrect. Treat this as end-of-stack to enforce
202 // progress and avoid infinite loops.
203 if (new_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] <=
204 last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP]) {
205 return NULL;
206 }
207
208 return new_frame.release();
209 }
210
GetCallerByStackScan(const vector<StackFrame * > & frames)211 StackFrameMIPS* StackwalkerMIPS::GetCallerByStackScan(
212 const vector<StackFrame*>& frames) {
213 const uint32_t kMaxFrameStackSize = 1024;
214 const uint32_t kMinArgsOnStack = 4;
215
216 StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
217
218 uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP];
219 uint32_t caller_pc, caller_sp, caller_fp;
220
221 // Return address cannot be obtained directly.
222 // Force stackwalking.
223
224 // We cannot use frame pointer to get the return address.
225 // We'll scan the stack for a
226 // return address. This can happen if last_frame is executing code
227 // for a module for which we don't have symbols.
228 int count = kMaxFrameStackSize / sizeof(caller_pc);
229
230 if (frames.size() > 1) {
231 // In case of mips32 ABI stack frame of a nonleaf function
232 // must have minimum stack frame assigned for 4 arguments (4 words).
233 // Move stack pointer for 4 words to avoid reporting non-existing frames
234 // for all frames except the topmost one.
235 // There is no way of knowing if topmost frame belongs to a leaf or
236 // a nonleaf function.
237 last_sp += kMinArgsOnStack * sizeof(caller_pc);
238 // Adjust 'count' so that return address is scanned only in limits
239 // of one stack frame.
240 count -= kMinArgsOnStack;
241 }
242
243 do {
244 // Scanning for return address from stack pointer of the last frame.
245 if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, count)) {
246 // If we can't find an instruction pointer even with stack scanning,
247 // give up.
248 BPLOG(ERROR) << " ScanForReturnAddress failed ";
249 return NULL;
250 }
251 // Get $fp stored in the stack frame.
252 if (!memory_->GetMemoryAtAddress(caller_sp - sizeof(caller_pc),
253 &caller_fp)) {
254 BPLOG(INFO) << " GetMemoryAtAddress for fp failed " ;
255 return NULL;
256 }
257
258 count = count - (caller_sp - last_sp) / sizeof(caller_pc);
259 // Now scan the next address in the stack.
260 last_sp = caller_sp + sizeof(caller_pc);
261 } while ((caller_fp - caller_sp >= kMaxFrameStackSize) && count > 0);
262
263 if (!count) {
264 BPLOG(INFO) << " No frame found " ;
265 return NULL;
266 }
267
268 // ScanForReturnAddress found a reasonable return address. Advance
269 // $sp to the location above the one where the return address was
270 // found.
271 caller_sp += sizeof(caller_pc);
272 // caller_pc is actually containing $ra value;
273 // $pc is two instructions before $ra,
274 // so the caller_pc needs to be decremented accordingly.
275 caller_pc -= 2 * sizeof(caller_pc);
276
277
278 // Create a new stack frame (ownership will be transferred to the caller)
279 // and fill it in.
280 StackFrameMIPS* frame = new StackFrameMIPS();
281 frame->trust = StackFrame::FRAME_TRUST_SCAN;
282 frame->context = last_frame->context;
283 frame->context.epc = caller_pc;
284 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
285 frame->instruction = caller_pc;
286
287 frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] = caller_sp;
288 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_SP;
289 frame->context.iregs[MD_CONTEXT_MIPS_REG_FP] = caller_fp;
290 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_FP;
291
292 frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] =
293 caller_pc + 2 * sizeof(caller_pc);
294 frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
295
296 return frame;
297 }
298
299 } // namespace google_breakpad
300
301