michael@0: // -*- mode: C++ -*-
michael@0: 
michael@0: // Copyright (c) 2010, Google Inc.
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michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
michael@0: 
michael@0: // cfi_frame_info-inl.h: Definitions for cfi_frame_info.h inlined functions.
michael@0: 
michael@0: #ifndef PROCESSOR_CFI_FRAME_INFO_INL_H_
michael@0: #define PROCESSOR_CFI_FRAME_INFO_INL_H_
michael@0: 
michael@0: #include <string.h>
michael@0: 
michael@0: namespace google_breakpad {
michael@0: 
michael@0: template <typename RegisterValueType, class RawContextType>
michael@0: bool SimpleCFIWalker<RegisterValueType, RawContextType>::FindCallerRegisters(
michael@0:     const MemoryRegion &memory,
michael@0:     const CFIFrameInfo &cfi_frame_info,
michael@0:     const RawContextType &callee_context,
michael@0:     int callee_validity,
michael@0:     RawContextType *caller_context,
michael@0:     int *caller_validity) const {
michael@0:   typedef CFIFrameInfo::RegisterValueMap<RegisterValueType> ValueMap;
michael@0:   ValueMap callee_registers;
michael@0:   ValueMap caller_registers;
michael@0: 
michael@0:   // Populate callee_registers with register values from callee_context.
michael@0:   for (size_t i = 0; i < map_size_; i++) {
michael@0:     const RegisterSet &r = register_map_[i];
michael@0:     if (callee_validity & r.validity_flag)
michael@0:       callee_registers.set(r.name, callee_context.*r.context_member);
michael@0:   }
michael@0: 
michael@0:   // Apply the rules, and see what register values they yield.
michael@0:   if (!cfi_frame_info
michael@0:        .FindCallerRegs<RegisterValueType>(callee_registers, memory,
michael@0:                                           &caller_registers))
michael@0:     return false;
michael@0: 
michael@0:   // Populate *caller_context with the values the rules placed in
michael@0:   // caller_registers.
michael@0:   memset(caller_context, 0xda, sizeof(*caller_context));
michael@0:   *caller_validity = 0;
michael@0:   for (size_t i = 0; i < map_size_; i++) {
michael@0:     const RegisterSet &r = register_map_[i];
michael@0: 
michael@0:     // Did the rules provide a value for this register by its name?
michael@0:     bool found = false;
michael@0:     RegisterValueType v = caller_registers.get(&found, r.name);
michael@0:     if (found) {
michael@0:       caller_context->*r.context_member = v;
michael@0:       *caller_validity |= r.validity_flag;
michael@0:       continue;
michael@0:     }
michael@0: 
michael@0:     // Did the rules provide a value for this register under its
michael@0:     // alternate name?
michael@0:     if (r.alternate_name) {
michael@0:       found = false;
michael@0:       v = caller_registers.get(&found, r.alternate_name);
michael@0:       if (found) {
michael@0:         caller_context->*r.context_member = v;
michael@0:         *caller_validity |= r.validity_flag;
michael@0:         continue;
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     // Is this a callee-saves register? The walker assumes that these
michael@0:     // still hold the caller's value if the CFI doesn't mention them.
michael@0:     //
michael@0:     // Note that other frame walkers may fail to recover callee-saves
michael@0:     // registers; for example, the x86 "traditional" strategy only
michael@0:     // recovers %eip, %esp, and %ebp, even though %ebx, %esi, and %edi
michael@0:     // are callee-saves, too. It is not correct to blindly set the
michael@0:     // valid bit for all callee-saves registers, without first
michael@0:     // checking its validity bit in the callee.
michael@0:     if (r.callee_saves && (callee_validity & r.validity_flag) != 0) {
michael@0:       caller_context->*r.context_member = callee_context.*r.context_member;
michael@0:       *caller_validity |= r.validity_flag;
michael@0:       continue;
michael@0:     }
michael@0: 
michael@0:     // Otherwise, the register's value is unknown.
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: } // namespace google_breakpad
michael@0: 
michael@0: #endif // PROCESSOR_CFI_FRAME_INFO_INL_H_