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/thirdparty/breakpad/processor/cfi_frame_info-inl.h

http://github.com/tomahawk-player/tomahawk
C++ Header | 119 lines | 53 code | 17 blank | 49 comment | 12 complexity | 6d16a38c2eb2e54f372cb65da56bca6a MD5 | raw file
  1// -*- mode: C++ -*-
  2
  3// Copyright (c) 2010, Google Inc.
  4// All rights reserved.
  5//
  6// Redistribution and use in source and binary forms, with or without
  7// modification, are permitted provided that the following conditions are
  8// met:
  9//
 10//     * Redistributions of source code must retain the above copyright
 11// notice, this list of conditions and the following disclaimer.
 12//     * Redistributions in binary form must reproduce the above
 13// copyright notice, this list of conditions and the following disclaimer
 14// in the documentation and/or other materials provided with the
 15// distribution.
 16//     * Neither the name of Google Inc. nor the names of its
 17// contributors may be used to endorse or promote products derived from
 18// this software without specific prior written permission.
 19//
 20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 22// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 24// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 25// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 30// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 31
 32// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
 33
 34// cfi_frame_info-inl.h: Definitions for cfi_frame_info.h inlined functions.
 35
 36#ifndef PROCESSOR_CFI_FRAME_INFO_INL_H_
 37#define PROCESSOR_CFI_FRAME_INFO_INL_H_
 38
 39#include <string.h>
 40
 41namespace google_breakpad {
 42
 43template <typename RegisterType, class RawContextType>
 44bool SimpleCFIWalker<RegisterType, RawContextType>::FindCallerRegisters(
 45    const MemoryRegion &memory,
 46    const CFIFrameInfo &cfi_frame_info,
 47    const RawContextType &callee_context,
 48    int callee_validity,
 49    RawContextType *caller_context,
 50    int *caller_validity) const {
 51  typedef CFIFrameInfo::RegisterValueMap<RegisterType> ValueMap;
 52  ValueMap callee_registers;
 53  ValueMap caller_registers;
 54  // Just for brevity.
 55  typename ValueMap::const_iterator caller_none = caller_registers.end();
 56
 57  // Populate callee_registers with register values from callee_context.
 58  for (size_t i = 0; i < map_size_; i++) {
 59    const RegisterSet &r = register_map_[i];
 60    if (callee_validity & r.validity_flag)
 61      callee_registers[r.name] = callee_context.*r.context_member;
 62  }
 63
 64  // Apply the rules, and see what register values they yield.
 65  if (!cfi_frame_info.FindCallerRegs<RegisterType>(callee_registers, memory,
 66                                                   &caller_registers))
 67    return false;
 68
 69  // Populate *caller_context with the values the rules placed in
 70  // caller_registers.
 71  memset(caller_context, 0xda, sizeof(*caller_context));
 72  *caller_validity = 0;
 73  for (size_t i = 0; i < map_size_; i++) {
 74    const RegisterSet &r = register_map_[i];
 75    typename ValueMap::const_iterator caller_entry;
 76
 77    // Did the rules provide a value for this register by its name?
 78    caller_entry = caller_registers.find(r.name);
 79    if (caller_entry != caller_none) {
 80      caller_context->*r.context_member = caller_entry->second;
 81      *caller_validity |= r.validity_flag;
 82      continue;
 83    }
 84
 85    // Did the rules provide a value for this register under its
 86    // alternate name?
 87    if (r.alternate_name) {
 88      caller_entry = caller_registers.find(r.alternate_name);
 89      if (caller_entry != caller_none) {
 90        caller_context->*r.context_member = caller_entry->second;
 91        *caller_validity |= r.validity_flag;
 92        continue;
 93      }
 94    }
 95
 96    // Is this a callee-saves register? The walker assumes that these
 97    // still hold the caller's value if the CFI doesn't mention them.
 98    //
 99    // Note that other frame walkers may fail to recover callee-saves
100    // registers; for example, the x86 "traditional" strategy only
101    // recovers %eip, %esp, and %ebp, even though %ebx, %esi, and %edi
102    // are callee-saves, too. It is not correct to blindly set the
103    // valid bit for all callee-saves registers, without first
104    // checking its validity bit in the callee.
105    if (r.callee_saves && (callee_validity & r.validity_flag) != 0) {
106      caller_context->*r.context_member = callee_context.*r.context_member;
107      *caller_validity |= r.validity_flag;
108      continue;
109    }
110
111    // Otherwise, the register's value is unknown.
112  }
113
114  return true;
115}
116
117} // namespace google_breakpad
118
119#endif // PROCESSOR_CFI_FRAME_INFO_INL_H_