1 // Copyright (c) 2010 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_arm.cc: arm-specific stackwalker. 31 // 32 // See stackwalker_arm.h for documentation. 33 // 34 // Author: Mark Mentovai, Ted Mielczarek, Jim Blandy 35 36 #include <vector> 37 38 #include "common/scoped_ptr.h" 39 #include "google_breakpad/processor/call_stack.h" 40 #include "google_breakpad/processor/memory_region.h" 41 #include "google_breakpad/processor/source_line_resolver_interface.h" 42 #include "google_breakpad/processor/stack_frame_cpu.h" 43 #include "processor/cfi_frame_info.h" 44 #include "processor/logging.h" 45 #include "processor/stackwalker_arm.h" 46 47 namespace google_breakpad { 48 49 50 StackwalkerARM::StackwalkerARM(const SystemInfo* system_info, 51 const MDRawContextARM* context, 52 int fp_register, 53 MemoryRegion* memory, 54 const CodeModules* modules, 55 StackFrameSymbolizer* resolver_helper) 56 : Stackwalker(system_info, memory, modules, resolver_helper), 57 context_(context), fp_register_(fp_register), 58 context_frame_validity_(StackFrameARM::CONTEXT_VALID_ALL) { } 59 60 61 StackFrame* StackwalkerARM::GetContextFrame() { 62 if (!context_) { 63 BPLOG(ERROR) << "Can't get context frame without context"; 64 return NULL; 65 } 66 67 StackFrameARM* frame = new StackFrameARM(); 68 69 // The instruction pointer is stored directly in a register (r15), so pull it 70 // straight out of the CPU context structure. 71 frame->context = *context_; 72 frame->context_validity = context_frame_validity_; 73 frame->trust = StackFrame::FRAME_TRUST_CONTEXT; 74 frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC]; 75 76 return frame; 77 } 78 79 StackFrameARM* StackwalkerARM::GetCallerByCFIFrameInfo( 80 const vector<StackFrame*> &frames, 81 CFIFrameInfo* cfi_frame_info) { 82 StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back()); 83 84 static const char* register_names[] = { 85 "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", 86 "r8", "r9", "r10", "r11", "r12", "sp", "lr", "pc", 87 "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", 88 "fps", "cpsr", 89 NULL 90 }; 91 92 // Populate a dictionary with the valid register values in last_frame. 93 CFIFrameInfo::RegisterValueMap<uint32_t> callee_registers; 94 for (int i = 0; register_names[i]; i++) 95 if (last_frame->context_validity & StackFrameARM::RegisterValidFlag(i)) 96 callee_registers[register_names[i]] = last_frame->context.iregs[i]; 97 98 // Use the STACK CFI data to recover the caller's register values. 99 CFIFrameInfo::RegisterValueMap<uint32_t> caller_registers; 100 if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_, 101 &caller_registers)) 102 return NULL; 103 104 // Construct a new stack frame given the values the CFI recovered. 105 scoped_ptr<StackFrameARM> frame(new StackFrameARM()); 106 for (int i = 0; register_names[i]; i++) { 107 CFIFrameInfo::RegisterValueMap<uint32_t>::iterator entry = 108 caller_registers.find(register_names[i]); 109 if (entry != caller_registers.end()) { 110 // We recovered the value of this register; fill the context with the 111 // value from caller_registers. 112 frame->context_validity |= StackFrameARM::RegisterValidFlag(i); 113 frame->context.iregs[i] = entry->second; 114 } else if (4 <= i && i <= 11 && (last_frame->context_validity & 115 StackFrameARM::RegisterValidFlag(i))) { 116 // If the STACK CFI data doesn't mention some callee-saves register, and 117 // it is valid in the callee, assume the callee has not yet changed it. 118 // Registers r4 through r11 are callee-saves, according to the Procedure 119 // Call Standard for the ARM Architecture, which the Linux ABI follows. 120 frame->context_validity |= StackFrameARM::RegisterValidFlag(i); 121 frame->context.iregs[i] = last_frame->context.iregs[i]; 122 } 123 } 124 // If the CFI doesn't recover the PC explicitly, then use .ra. 125 if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_PC)) { 126 CFIFrameInfo::RegisterValueMap<uint32_t>::iterator entry = 127 caller_registers.find(".ra"); 128 if (entry != caller_registers.end()) { 129 if (fp_register_ == -1) { 130 frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC; 131 frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = entry->second; 132 } else { 133 // The CFI updated the link register and not the program counter. 134 // Handle getting the program counter from the link register. 135 frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC; 136 frame->context_validity |= StackFrameARM::CONTEXT_VALID_LR; 137 frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = entry->second; 138 frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = 139 last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR]; 140 } 141 } 142 } 143 // If the CFI doesn't recover the SP explicitly, then use .cfa. 144 if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_SP)) { 145 CFIFrameInfo::RegisterValueMap<uint32_t>::iterator entry = 146 caller_registers.find(".cfa"); 147 if (entry != caller_registers.end()) { 148 frame->context_validity |= StackFrameARM::CONTEXT_VALID_SP; 149 frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = entry->second; 150 } 151 } 152 153 // If we didn't recover the PC and the SP, then the frame isn't very useful. 154 static const int essentials = (StackFrameARM::CONTEXT_VALID_SP 155 | StackFrameARM::CONTEXT_VALID_PC); 156 if ((frame->context_validity & essentials) != essentials) 157 return NULL; 158 159 frame->trust = StackFrame::FRAME_TRUST_CFI; 160 return frame.release(); 161 } 162 163 StackFrameARM* StackwalkerARM::GetCallerByStackScan( 164 const vector<StackFrame*> &frames) { 165 StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back()); 166 uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP]; 167 uint32_t caller_sp, caller_pc; 168 169 if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, 170 frames.size() == 1 /* is_context_frame */)) { 171 // No plausible return address was found. 172 return NULL; 173 } 174 175 // ScanForReturnAddress found a reasonable return address. Advance 176 // %sp to the location above the one where the return address was 177 // found. 178 caller_sp += 4; 179 180 // Create a new stack frame (ownership will be transferred to the caller) 181 // and fill it in. 182 StackFrameARM* frame = new StackFrameARM(); 183 184 frame->trust = StackFrame::FRAME_TRUST_SCAN; 185 frame->context = last_frame->context; 186 frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = caller_pc; 187 frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp; 188 frame->context_validity = StackFrameARM::CONTEXT_VALID_PC | 189 StackFrameARM::CONTEXT_VALID_SP; 190 191 return frame; 192 } 193 194 StackFrameARM* StackwalkerARM::GetCallerByFramePointer( 195 const vector<StackFrame*> &frames) { 196 StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back()); 197 198 if (!(last_frame->context_validity & 199 StackFrameARM::RegisterValidFlag(fp_register_))) { 200 return NULL; 201 } 202 203 uint32_t last_fp = last_frame->context.iregs[fp_register_]; 204 205 uint32_t caller_fp = 0; 206 if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) { 207 BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x" 208 << std::hex << last_fp; 209 return NULL; 210 } 211 212 uint32_t caller_lr = 0; 213 if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 4, &caller_lr)) { 214 BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 4: 0x" 215 << std::hex << (last_fp + 4); 216 return NULL; 217 } 218 219 uint32_t caller_sp = last_fp ? last_fp + 8 : 220 last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP]; 221 222 // Create a new stack frame (ownership will be transferred to the caller) 223 // and fill it in. 224 StackFrameARM* frame = new StackFrameARM(); 225 226 frame->trust = StackFrame::FRAME_TRUST_FP; 227 frame->context = last_frame->context; 228 frame->context.iregs[fp_register_] = caller_fp; 229 frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp; 230 frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = 231 last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR]; 232 frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = caller_lr; 233 frame->context_validity = StackFrameARM::CONTEXT_VALID_PC | 234 StackFrameARM::CONTEXT_VALID_LR | 235 StackFrameARM::RegisterValidFlag(fp_register_) | 236 StackFrameARM::CONTEXT_VALID_SP; 237 return frame; 238 } 239 240 StackFrame* StackwalkerARM::GetCallerFrame(const CallStack* stack, 241 bool stack_scan_allowed) { 242 if (!memory_ || !stack) { 243 BPLOG(ERROR) << "Can't get caller frame without memory or stack"; 244 return NULL; 245 } 246 247 const vector<StackFrame*> &frames = *stack->frames(); 248 StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back()); 249 scoped_ptr<StackFrameARM> frame; 250 251 // See if there is DWARF call frame information covering this address. 252 scoped_ptr<CFIFrameInfo> cfi_frame_info( 253 frame_symbolizer_->FindCFIFrameInfo(last_frame)); 254 if (cfi_frame_info.get()) 255 frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get())); 256 257 // If CFI failed, or there wasn't CFI available, fall back 258 // to frame pointer, if this is configured. 259 if (fp_register_ >= 0 && !frame.get()) 260 frame.reset(GetCallerByFramePointer(frames)); 261 262 // If everuthing failed, fall back to stack scanning. 263 if (stack_scan_allowed && !frame.get()) 264 frame.reset(GetCallerByStackScan(frames)); 265 266 // If nothing worked, tell the caller. 267 if (!frame.get()) 268 return NULL; 269 270 271 // An instruction address of zero marks the end of the stack. 272 if (frame->context.iregs[MD_CONTEXT_ARM_REG_PC] == 0) 273 return NULL; 274 275 // If the new stack pointer is at a lower address than the old, then 276 // that's clearly incorrect. Treat this as end-of-stack to enforce 277 // progress and avoid infinite loops. 278 if (frame->context.iregs[MD_CONTEXT_ARM_REG_SP] 279 < last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP]) 280 return NULL; 281 282 // The new frame's context's PC is the return address, which is one 283 // instruction past the instruction that caused us to arrive at the 284 // callee. Set new_frame->instruction to one less than the PC. This won't 285 // reference the beginning of the call instruction, but it's at least 286 // within it, which is sufficient to get the source line information to 287 // match up with the line that contains the function call. Callers that 288 // require the exact return address value may access 289 // frame->context.iregs[MD_CONTEXT_ARM_REG_PC]. 290 frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC] - 2; 291 292 return frame.release(); 293 } 294 295 296 } // namespace google_breakpad 297
