stackwalker_arm64.cc 11.3 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278
// Copyright (c) 2013 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// stackwalker_arm64.cc: arm64-specific stackwalker.
//
// See stackwalker_arm64.h for documentation.
//
// Author: Mark Mentovai, Ted Mielczarek, Jim Blandy, Colin Blundell

#include <vector>

#include "common/scoped_ptr.h"
#include "google_breakpad/processor/call_stack.h"
#include "google_breakpad/processor/memory_region.h"
#include "google_breakpad/processor/source_line_resolver_interface.h"
#include "google_breakpad/processor/stack_frame_cpu.h"
#include "processor/cfi_frame_info.h"
#include "processor/logging.h"
#include "processor/stackwalker_arm64.h"

namespace google_breakpad {


StackwalkerARM64::StackwalkerARM64(const SystemInfo* system_info,
                                   const MDRawContextARM64* context,
                                   MemoryRegion* memory,
                                   const CodeModules* modules,
                                   StackFrameSymbolizer* resolver_helper)
    : Stackwalker(system_info, memory, modules, resolver_helper),
      context_(context),
      context_frame_validity_(StackFrameARM64::CONTEXT_VALID_ALL) { }


StackFrame* StackwalkerARM64::GetContextFrame() {
  if (!context_) {
    BPLOG(ERROR) << "Can't get context frame without context";
    return NULL;
  }

  StackFrameARM64* frame = new StackFrameARM64();

  // The instruction pointer is stored directly in a register (x32), so pull it
  // straight out of the CPU context structure.
  frame->context = *context_;
  frame->context_validity = context_frame_validity_;
  frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
  frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC];

  return frame;
}

StackFrameARM64* StackwalkerARM64::GetCallerByCFIFrameInfo(
    const vector<StackFrame*> &frames,
    CFIFrameInfo* cfi_frame_info) {
  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());

  static const char* register_names[] = {
    "x0",  "x1",  "x2",  "x3",  "x4",  "x5",  "x6",  "x7",
    "x8",  "x9",  "x10", "x11", "x12", "x13", "x14", "x15",
    "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
    "x24", "x25", "x26", "x27", "x28", "x29", "x30", "sp",
    "pc",  NULL
  };

  // Populate a dictionary with the valid register values in last_frame.
  CFIFrameInfo::RegisterValueMap<uint64_t> callee_registers;
  for (int i = 0; register_names[i]; i++) {
    if (last_frame->context_validity & StackFrameARM64::RegisterValidFlag(i))
      callee_registers[register_names[i]] = last_frame->context.iregs[i];
  }

  // Use the STACK CFI data to recover the caller's register values.
  CFIFrameInfo::RegisterValueMap<uint64_t> caller_registers;
  if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
                                      &caller_registers)) {
    return NULL;
  }
  // Construct a new stack frame given the values the CFI recovered.
  scoped_ptr<StackFrameARM64> frame(new StackFrameARM64());
  for (int i = 0; register_names[i]; i++) {
    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
      caller_registers.find(register_names[i]);
    if (entry != caller_registers.end()) {
      // We recovered the value of this register; fill the context with the
      // value from caller_registers.
      frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
      frame->context.iregs[i] = entry->second;
    } else if (19 <= i && i <= 29 && (last_frame->context_validity &
                                      StackFrameARM64::RegisterValidFlag(i))) {
      // If the STACK CFI data doesn't mention some callee-saves register, and
      // it is valid in the callee, assume the callee has not yet changed it.
      // Registers r19 through r29 are callee-saves, according to the Procedure
      // Call Standard for the ARM AARCH64 Architecture, which the Linux ABI
      // follows.
      frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
      frame->context.iregs[i] = last_frame->context.iregs[i];
    }
  }
  // If the CFI doesn't recover the PC explicitly, then use .ra.
  if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_PC)) {
    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
      caller_registers.find(".ra");
    if (entry != caller_registers.end()) {
      frame->context_validity |= StackFrameARM64::CONTEXT_VALID_PC;
      frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = entry->second;
    }
  }
  // If the CFI doesn't recover the SP explicitly, then use .cfa.
  if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_SP)) {
    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
      caller_registers.find(".cfa");
    if (entry != caller_registers.end()) {
      frame->context_validity |= StackFrameARM64::CONTEXT_VALID_SP;
      frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = entry->second;
    }
  }

  // If we didn't recover the PC and the SP, then the frame isn't very useful.
  static const uint64_t essentials = (StackFrameARM64::CONTEXT_VALID_SP
                                     | StackFrameARM64::CONTEXT_VALID_PC);
  if ((frame->context_validity & essentials) != essentials)
    return NULL;

  frame->trust = StackFrame::FRAME_TRUST_CFI;
  return frame.release();
}

StackFrameARM64* StackwalkerARM64::GetCallerByStackScan(
    const vector<StackFrame*> &frames) {
  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
  uint64_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];
  uint64_t caller_sp, caller_pc;

  if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc,
                            frames.size() == 1 /* is_context_frame */)) {
    // No plausible return address was found.
    return NULL;
  }

  // ScanForReturnAddress found a reasonable return address. Advance
  // %sp to the location above the one where the return address was
  // found.
  caller_sp += 8;

  // Create a new stack frame (ownership will be transferred to the caller)
  // and fill it in.
  StackFrameARM64* frame = new StackFrameARM64();

  frame->trust = StackFrame::FRAME_TRUST_SCAN;
  frame->context = last_frame->context;
  frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = caller_pc;
  frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
  frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
                            StackFrameARM64::CONTEXT_VALID_SP;

  return frame;
}

StackFrameARM64* StackwalkerARM64::GetCallerByFramePointer(
    const vector<StackFrame*> &frames) {
  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());

  uint64_t last_fp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP];

  uint64_t caller_fp = 0;
  if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) {
    BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x"
                 << std::hex << last_fp;
    return NULL;
  }

  uint64_t caller_lr = 0;
  if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 8, &caller_lr)) {
    BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 8: 0x"
                 << std::hex << (last_fp + 8);
    return NULL;
  }

  uint64_t caller_sp = last_fp ? last_fp + 16 :
      last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];

  // Create a new stack frame (ownership will be transferred to the caller)
  // and fill it in.
  StackFrameARM64* frame = new StackFrameARM64();

  frame->trust = StackFrame::FRAME_TRUST_FP;
  frame->context = last_frame->context;
  frame->context.iregs[MD_CONTEXT_ARM64_REG_FP] = caller_fp;
  frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
  frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] =
      last_frame->context.iregs[MD_CONTEXT_ARM64_REG_LR];
  frame->context.iregs[MD_CONTEXT_ARM64_REG_LR] = caller_lr;
  frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
                            StackFrameARM64::CONTEXT_VALID_LR |
                            StackFrameARM64::CONTEXT_VALID_FP |
                            StackFrameARM64::CONTEXT_VALID_SP;
  return frame;
}

StackFrame* StackwalkerARM64::GetCallerFrame(const CallStack* stack,
                                             bool stack_scan_allowed) {
  if (!memory_ || !stack) {
    BPLOG(ERROR) << "Can't get caller frame without memory or stack";
    return NULL;
  }

  const vector<StackFrame*> &frames = *stack->frames();
  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
  scoped_ptr<StackFrameARM64> frame;

  // See if there is DWARF call frame information covering this address.
  scoped_ptr<CFIFrameInfo> cfi_frame_info(
      frame_symbolizer_->FindCFIFrameInfo(last_frame));
  if (cfi_frame_info.get())
    frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));

  // If CFI failed, or there wasn't CFI available, fall back to frame pointer.
  if (!frame.get())
    frame.reset(GetCallerByFramePointer(frames));

  // If everything failed, fall back to stack scanning.
  if (stack_scan_allowed && !frame.get())
    frame.reset(GetCallerByStackScan(frames));

  // If nothing worked, tell the caller.
  if (!frame.get())
    return NULL;

  // An instruction address of zero marks the end of the stack.
  if (frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] == 0)
    return NULL;

  // If the new stack pointer is at a lower address than the old, then
  // that's clearly incorrect. Treat this as end-of-stack to enforce
  // progress and avoid infinite loops.
  if (frame->context.iregs[MD_CONTEXT_ARM64_REG_SP]
      < last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP])
    return NULL;

  // The new frame's context's PC is the return address, which is one
  // instruction past the instruction that caused us to arrive at the callee.
  // ARM64 instructions have a uniform 4-byte encoding, so subtracting 4 off
  // the return address gets back to the beginning of the call instruction.
  // Callers that require the exact return address value may access
  // frame->context.iregs[MD_CONTEXT_ARM64_REG_PC].
  frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] - 4;

  return frame.release();
}


}  // namespace google_breakpad