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Diffstat (limited to 'src/processor/cfi_frame_info.h')
| -rw-r--r-- | src/processor/cfi_frame_info.h | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/src/processor/cfi_frame_info.h b/src/processor/cfi_frame_info.h new file mode 100644 index 00000000..f537296a --- /dev/null +++ b/src/processor/cfi_frame_info.h @@ -0,0 +1,271 @@ +// -*- mode: C++ -*- + +// Copyright (c) 2010, Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com> + +// cfi_frame_info.h: Define the CFIFrameInfo class, which holds the +// set of 'STACK CFI'-derived register recovery rules that apply at a +// given instruction. + +#ifndef PROCESSOR_CFI_FRAME_INFO_H_ +#define PROCESSOR_CFI_FRAME_INFO_H_ + +#include <map> +#include <string> + +#include "google_breakpad/common/breakpad_types.h" + +namespace google_breakpad { + +using std::map; +using std::string; + +class MemoryRegion; + +// A set of rules for recovering the calling frame's registers' +// values, when the PC is at a given address in the current frame's +// function. See the description of 'STACK CFI' records at: +// +// http://code.google.com/p/google-breakpad/wiki/SymbolFiles +// +// To prepare an instance of CFIFrameInfo for use at a given +// instruction, first populate it with the rules from the 'STACK CFI +// INIT' record that covers that instruction, and then apply the +// changes given by the 'STACK CFI' records up to our instruction's +// address. Then, use the FindCallerRegs member function to apply the +// rules to the callee frame's register values, yielding the caller +// frame's register values. +class CFIFrameInfo { + public: + // A map from register names onto values. + template<typename ValueType> class RegisterValueMap: + public map<string, ValueType> { }; + + // Set the expression for computing a call frame address, return + // address, or register's value. At least the CFA rule and the RA + // rule must be set before calling FindCallerRegs. + void SetCFARule(const string &expression) { cfa_rule_ = expression; } + void SetRARule(const string &expression) { ra_rule_ = expression; } + void SetRegisterRule(const string ®ister_name, const string &expression) { + register_rules_[register_name] = expression; + } + + // Compute the values of the calling frame's registers, according to + // this rule set. Use ValueType in expression evaluation; this + // should be u_int32_t on machines with 32-bit addresses, or + // u_int64_t on machines with 64-bit addresses. + // + // Return true on success, false otherwise. + // + // MEMORY provides access to the contents of the stack. REGISTERS is + // a dictionary mapping the names of registers whose values are + // known in the current frame to their values. CALLER_REGISTERS is + // populated with the values of the recoverable registers in the + // frame that called the current frame. + // + // In addition, CALLER_REGISTERS[".ra"] will be the return address, + // and CALLER_REGISTERS[".cfa"] will be the call frame address. + // These may be helpful in computing the caller's PC and stack + // pointer, if their values are not explicitly specified. + template<typename ValueType> + bool FindCallerRegs(const RegisterValueMap<ValueType> ®isters, + const MemoryRegion &memory, + RegisterValueMap<ValueType> *caller_registers) const; + + private: + + // A map from register names onto evaluation rules. + typedef map<string, string> RuleMap; + + // In this type, a "postfix expression" is an expression of the sort + // interpreted by google_breakpad::PostfixEvaluator. + + // A postfix expression for computing the current frame's CFA (call + // frame address). The CFA is a reference address for the frame that + // remains unchanged throughout the frame's lifetime. You should + // evaluate this expression with a dictionary initially populated + // with the values of the current frame's known registers. + string cfa_rule_; + + // The following expressions should be evaluated with a dictionary + // initially populated with the values of the current frame's known + // registers, and with ".cfa" set to the result of evaluating the + // cfa_rule expression, above. + + // A postfix expression for computing the current frame's return + // address. + string ra_rule_; + + // For a register named REG, rules[REG] is a postfix expression + // which leaves the value of REG in the calling frame on the top of + // the stack. You should evaluate this expression + RuleMap register_rules_; +}; + +// A parser for STACK CFI-style rule sets. +// This may seem bureaucratic: there's no legitimate run-time reason +// to use a parser/handler pattern for this, as it's not a likely +// reuse boundary. But doing so makes finer-grained unit testing +// possible. +class CFIRuleParser { + public: + + class Handler { + public: + Handler() { } + virtual ~Handler() { } + + // The input specifies EXPRESSION as the CFA/RA computation rule. + virtual void CFARule(const string &expression) = 0; + virtual void RARule(const string &expression) = 0; + + // The input specifies EXPRESSION as the recovery rule for register NAME. + virtual void RegisterRule(const string &name, const string &expression) = 0; + }; + + // Construct a parser which feeds its results to HANDLER. + CFIRuleParser(Handler *handler) : handler_(handler) { } + + // Parse RULE_SET as a set of CFA computation and RA/register + // recovery rules, as appearing in STACK CFI records. Report the + // results of parsing by making the appropriate calls to handler_. + // Return true if parsing was successful, false otherwise. + bool Parse(const string &rule_set); + + private: + // Report any accumulated rule to handler_ + bool Report(); + + // The handler to which the parser reports its findings. + Handler *handler_; + + // Working data. + string name_, expression_; +}; + +// A handler for rule set parsing that populates a CFIFrameInfo with +// the results. +class CFIFrameInfoParseHandler: public CFIRuleParser::Handler { + public: + // Populate FRAME_INFO with the results of parsing. + CFIFrameInfoParseHandler(CFIFrameInfo *frame_info) + : frame_info_(frame_info) { } + + void CFARule(const string &expression); + void RARule(const string &expression); + void RegisterRule(const string &name, const string &expression); + + private: + CFIFrameInfo *frame_info_; +}; + +// A utility class template for simple 'STACK CFI'-driven stack walkers. +// Given a CFIFrameInfo instance, a table describing the architecture's +// register set, and a context holding the last frame's registers, an +// instance of this class can populate a new context with the caller's +// registers. +// +// This class template doesn't use any internal knowledge of CFIFrameInfo +// or the other stack walking structures; it just uses the public interface +// of CFIFrameInfo to do the usual things. But the logic it handles should +// be common to many different architectures' stack walkers, so wrapping it +// up in a class should allow the walkers to share code. +// +// RegisterType should be the type of this architecture's registers, either +// u_int32_t or u_int64_t. RawContextType should be the raw context +// structure type for this architecture. +template <typename RegisterType, class RawContextType> +class SimpleCFIWalker { + public: + // A structure describing one architecture register. + struct RegisterSet { + // The register name, as it appears in STACK CFI rules. + const char *name; + + // An alternate name that the register's value might be found + // under in a register value dictionary, or NULL. When generating + // names, prefer NAME to this value. It's common to list ".cfa" as + // an alternative name for the stack pointer, and ".ra" as an + // alternative name for the instruction pointer. + const char *alternate_name; + + // True if the callee is expected to preserve the value of this + // register. If this flag is true for some register R, and the STACK + // CFI records provide no rule to recover R, then SimpleCFIWalker + // assumes that the callee has not changed R's value, and the caller's + // value for R is that currently in the callee's context. + bool callee_saves; + + // The ContextValidity flag representing the register's presence. + int validity_flag; + + // A pointer to the RawContextType member that holds the + // register's value. + RegisterType RawContextType::*context_member; + }; + + // Create a simple CFI-based frame walker, given a description of the + // architecture's register set. REGISTER_MAP is an array of + // RegisterSet structures; MAP_SIZE is the number of elements in the + // array. + SimpleCFIWalker(const RegisterSet *register_map, size_t map_size) + : register_map_(register_map), map_size_(map_size) { } + + // Compute the calling frame's raw context given the callee's raw + // context. + // + // Given: + // + // - MEMORY, holding the stack's contents, + // - CFI_FRAME_INFO, describing the called function, + // - CALLEE_CONTEXT, holding the called frame's registers, and + // - CALLEE_VALIDITY, indicating which registers in CALLEE_CONTEXT are valid, + // + // fill in CALLER_CONTEXT with the caller's register values, and set + // CALLER_VALIDITY to indicate which registers are valid in + // CALLER_CONTEXT. Return true on success, or false on failure. + bool FindCallerRegisters(const MemoryRegion &memory, + const CFIFrameInfo &cfi_frame_info, + const RawContextType &callee_context, + int callee_validity, + RawContextType *caller_context, + int *caller_validity) const; + + private: + const RegisterSet *register_map_; + size_t map_size_; +}; + +} // namespace google_breakpad + +#include "cfi_frame_info-inl.h" + +#endif // PROCESSOR_CFI_FRAME_INFO_H_ |