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      1 // Copyright (c) 2010, Google Inc.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are
      6 // met:
      7 //
      8 //     * Redistributions of source code must retain the above copyright
      9 // notice, this list of conditions and the following disclaimer.
     10 //     * Redistributions in binary form must reproduce the above
     11 // copyright notice, this list of conditions and the following disclaimer
     12 // in the documentation and/or other materials provided with the
     13 // distribution.
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     17 //
     18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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     21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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     25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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     27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 
     30 // Original author: Jim Blandy <jimb (at) mozilla.com> <jimb (at) 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>
     51 bool CFIFrameInfo::FindCallerRegs(const RegisterValueMap<V> &registers,
     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> &registers,
     97     const MemoryRegion &memory,
     98     RegisterValueMap<uint32_t> *caller_registers) const;
     99 template bool CFIFrameInfo::FindCallerRegs<uint64_t>(
    100     const RegisterValueMap<uint64_t> &registers,
    101     const MemoryRegion &memory,
    102     RegisterValueMap<uint64_t> *caller_registers) const;
    103 
    104 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 
    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 
    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 
    173 void CFIFrameInfoParseHandler::CFARule(const string &expression) {
    174   frame_info_->SetCFARule(expression);
    175 }
    176 
    177 void CFIFrameInfoParseHandler::RARule(const string &expression) {
    178   frame_info_->SetRARule(expression);
    179 }
    180 
    181 void CFIFrameInfoParseHandler::RegisterRule(const string &name,
    182                                             const string &expression) {
    183   frame_info_->SetRegisterRule(name, expression);
    184 }
    185 
    186 } // namespace google_breakpad
    187