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
41 namespace google_breakpad {
42
43 template <typename RegisterType, class RawContextType>
FindCallerRegisters(const MemoryRegion & memory,const CFIFrameInfo & cfi_frame_info,const RawContextType & callee_context,int callee_validity,RawContextType * caller_context,int * caller_validity)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