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29
30 // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
31
32 // cfi_frame_info.cc: Implementation of CFIFrameInfo class.
33 // See cfi_frame_info.h for details.
34
35 #include "processor/cfi_frame_info.h"
36
37 #include <string.h>
38
39 #include <sstream>
40
41 #include "common/scoped_ptr.h"
42 #include "processor/postfix_evaluator-inl.h"
43
44 namespace google_breakpad {
45
46 #ifdef _WIN32
47 #define strtok_r strtok_s
48 #endif
49
50 template<typename V>
FindCallerRegs(const RegisterValueMap<V> & registers,const MemoryRegion & memory,RegisterValueMap<V> * caller_registers) const51 bool CFIFrameInfo::FindCallerRegs(const RegisterValueMap<V> ®isters,
52 const MemoryRegion &memory,
53 RegisterValueMap<V> *caller_registers) const {
54 // If there are not rules for both .ra and .cfa in effect at this address,
55 // don't use this CFI data for stack walking.
56 if (cfa_rule_.empty() || ra_rule_.empty())
57 return false;
58
59 RegisterValueMap<V> working;
60 PostfixEvaluator<V> evaluator(&working, &memory);
61
62 caller_registers->clear();
63
64 // First, compute the CFA.
65 V cfa;
66 working = registers;
67 if (!evaluator.EvaluateForValue(cfa_rule_, &cfa))
68 return false;
69
70 // Then, compute the return address.
71 V ra;
72 working = registers;
73 working[".cfa"] = cfa;
74 if (!evaluator.EvaluateForValue(ra_rule_, &ra))
75 return false;
76
77 // Now, compute values for all the registers register_rules_ mentions.
78 for (RuleMap::const_iterator it = register_rules_.begin();
79 it != register_rules_.end(); it++) {
80 V value;
81 working = registers;
82 working[".cfa"] = cfa;
83 if (!evaluator.EvaluateForValue(it->second, &value))
84 return false;
85 (*caller_registers)[it->first] = value;
86 }
87
88 (*caller_registers)[".ra"] = ra;
89 (*caller_registers)[".cfa"] = cfa;
90
91 return true;
92 }
93
94 // Explicit instantiations for 32-bit and 64-bit architectures.
95 template bool CFIFrameInfo::FindCallerRegs<uint32_t>(
96 const RegisterValueMap<uint32_t> ®isters,
97 const MemoryRegion &memory,
98 RegisterValueMap<uint32_t> *caller_registers) const;
99 template bool CFIFrameInfo::FindCallerRegs<uint64_t>(
100 const RegisterValueMap<uint64_t> ®isters,
101 const MemoryRegion &memory,
102 RegisterValueMap<uint64_t> *caller_registers) const;
103
Serialize() const104 string CFIFrameInfo::Serialize() const {
105 std::ostringstream stream;
106
107 if (!cfa_rule_.empty()) {
108 stream << ".cfa: " << cfa_rule_;
109 }
110 if (!ra_rule_.empty()) {
111 if (static_cast<std::streamoff>(stream.tellp()) != 0)
112 stream << " ";
113 stream << ".ra: " << ra_rule_;
114 }
115 for (RuleMap::const_iterator iter = register_rules_.begin();
116 iter != register_rules_.end();
117 ++iter) {
118 if (static_cast<std::streamoff>(stream.tellp()) != 0)
119 stream << " ";
120 stream << iter->first << ": " << iter->second;
121 }
122
123 return stream.str();
124 }
125
Parse(const string & rule_set)126 bool CFIRuleParser::Parse(const string &rule_set) {
127 size_t rule_set_len = rule_set.size();
128 scoped_array<char> working_copy(new char[rule_set_len + 1]);
129 memcpy(working_copy.get(), rule_set.data(), rule_set_len);
130 working_copy[rule_set_len] = '\0';
131
132 name_.clear();
133 expression_.clear();
134
135 char *cursor;
136 static const char token_breaks[] = " \t\r\n";
137 char *token = strtok_r(working_copy.get(), token_breaks, &cursor);
138
139 for (;;) {
140 // End of rule set?
141 if (!token) return Report();
142
143 // Register/pseudoregister name?
144 size_t token_len = strlen(token);
145 if (token_len >= 1 && token[token_len - 1] == ':') {
146 // Names can't be empty.
147 if (token_len < 2) return false;
148 // If there is any pending content, report it.
149 if (!name_.empty() || !expression_.empty()) {
150 if (!Report()) return false;
151 }
152 name_.assign(token, token_len - 1);
153 expression_.clear();
154 } else {
155 // Another expression component.
156 assert(token_len > 0); // strtok_r guarantees this, I think.
157 if (!expression_.empty())
158 expression_ += ' ';
159 expression_ += token;
160 }
161 token = strtok_r(NULL, token_breaks, &cursor);
162 }
163 }
164
Report()165 bool CFIRuleParser::Report() {
166 if (name_.empty() || expression_.empty()) return false;
167 if (name_ == ".cfa") handler_->CFARule(expression_);
168 else if (name_ == ".ra") handler_->RARule(expression_);
169 else handler_->RegisterRule(name_, expression_);
170 return true;
171 }
172
CFARule(const string & expression)173 void CFIFrameInfoParseHandler::CFARule(const string &expression) {
174 frame_info_->SetCFARule(expression);
175 }
176
RARule(const string & expression)177 void CFIFrameInfoParseHandler::RARule(const string &expression) {
178 frame_info_->SetRARule(expression);
179 }
180
RegisterRule(const string & name,const string & expression)181 void CFIFrameInfoParseHandler::RegisterRule(const string &name,
182 const string &expression) {
183 frame_info_->SetRegisterRule(name, expression);
184 }
185
186 } // namespace google_breakpad
187