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 (at) mozilla.com> <jimb (at) 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 41 namespace google_breakpad { 42 43 template <typename RegisterType, class RawContextType> 44 bool 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_ 120