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// 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.
// stackwalker.h: Generic stackwalker.
//
// The Stackwalker class is an abstract base class providing common generic
// methods that apply to stacks from all systems. Specific implementations
// will extend this class by providing GetContextFrame and GetCallerFrame
// methods to fill in system-specific data in a StackFrame structure.
// Stackwalker assembles these StackFrame strucutres into a CallStack.
//
// Author: Mark Mentovai
#ifndef GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
#define GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
#include <set>
#include <string>
#include <vector>
#include "common/using_std_string.h"
#include "google_breakpad/common/breakpad_types.h"
#include "google_breakpad/processor/code_modules.h"
#include "google_breakpad/processor/memory_region.h"
#include "google_breakpad/processor/stack_frame_symbolizer.h"
namespace google_breakpad {
class CallStack;
class DumpContext;
class StackFrameSymbolizer;
using std::set;
using std::vector;
class Stackwalker {
public:
virtual ~Stackwalker() {}
// Populates the given CallStack by calling GetContextFrame and
// GetCallerFrame. The frames are further processed to fill all available
// data. Returns true if the stackwalk completed, or false if it was
// interrupted by SymbolSupplier::GetSymbolFile().
// Upon return, |modules_without_symbols| will be populated with pointers to
// the code modules (CodeModule*) that DON'T have symbols.
// |modules_with_corrupt_symbols| will be populated with pointers to the
// modules which have corrupt symbols. |modules_without_symbols| and
// |modules_with_corrupt_symbols| DO NOT take ownership of the code modules.
// The lifetime of these code modules is the same as the lifetime of the
// CodeModules passed to the StackWalker constructor (which currently
// happens to be the lifetime of the Breakpad's ProcessingState object).
// There is a check for duplicate modules so no duplicates are expected.
bool Walk(CallStack* stack,
vector<const CodeModule*>* modules_without_symbols,
vector<const CodeModule*>* modules_with_corrupt_symbols);
// Returns a new concrete subclass suitable for the CPU that a stack was
// generated on, according to the CPU type indicated by the context
// argument. If no suitable concrete subclass exists, returns NULL.
static Stackwalker* StackwalkerForCPU(
const SystemInfo* system_info,
DumpContext* context,
MemoryRegion* memory,
const CodeModules* modules,
const CodeModules* unloaded_modules,
StackFrameSymbolizer* resolver_helper);
static void set_max_frames(uint32_t max_frames) {
max_frames_ = max_frames;
max_frames_set_ = true;
}
static uint32_t max_frames() { return max_frames_; }
static void set_max_frames_scanned(uint32_t max_frames_scanned) {
max_frames_scanned_ = max_frames_scanned;
}
protected:
// system_info identifies the operating system, NULL or empty if unknown.
// memory identifies a MemoryRegion that provides the stack memory
// for the stack to walk. modules, if non-NULL, is a CodeModules
// object that is used to look up which code module each stack frame is
// associated with. frame_symbolizer is a StackFrameSymbolizer object that
// encapsulates the logic of how source line resolver interacts with symbol
// supplier to symbolize stack frame and look up caller frame information
// (see stack_frame_symbolizer.h).
// frame_symbolizer MUST NOT be NULL (asserted).
Stackwalker(const SystemInfo* system_info,
MemoryRegion* memory,
const CodeModules* modules,
StackFrameSymbolizer* frame_symbolizer);
// This can be used to filter out potential return addresses when
// the stack walker resorts to stack scanning.
// Returns true if any of:
// * This address is within a loaded module, but we don't have symbols
// for that module.
// * This address is within a loaded module for which we have symbols,
// and falls inside a function in that module.
// Returns false otherwise.
bool InstructionAddressSeemsValid(uint64_t address) const;
// Checks whether we should stop the stack trace.
// (either we reached the end-of-stack or we detected a
// broken callstack invariant)
bool TerminateWalk(uint64_t caller_ip,
uint64_t caller_sp,
uint64_t callee_sp,
bool first_unwind) const;
// The default number of words to search through on the stack
// for a return address.
static const int kRASearchWords;
template<typename InstructionType>
bool ScanForReturnAddress(InstructionType location_start,
InstructionType* location_found,
InstructionType* ip_found,
bool is_context_frame) {
// When searching for the caller of the context frame,
// allow the scanner to look farther down the stack.
const int search_words = is_context_frame ?
kRASearchWords * 4 :
kRASearchWords;
return ScanForReturnAddress(location_start, location_found, ip_found,
search_words);
}
// Scan the stack starting at location_start, looking for an address
// that looks like a valid instruction pointer. Addresses must
// 1) be contained in the current stack memory
// 2) pass the checks in InstructionAddressSeemsValid
//
// Returns true if a valid-looking instruction pointer was found.
// When returning true, sets location_found to the address at which
// the value was found, and ip_found to the value contained at that
// location in memory.
template<typename InstructionType>
bool ScanForReturnAddress(InstructionType location_start,
InstructionType* location_found,
InstructionType* ip_found,
int searchwords) {
for (InstructionType location = location_start;
location <= location_start + searchwords * sizeof(InstructionType);
location += sizeof(InstructionType)) {
InstructionType ip;
if (!memory_->GetMemoryAtAddress(location, &ip))
break;
if (modules_ && modules_->GetModuleForAddress(ip) &&
InstructionAddressSeemsValid(ip)) {
*ip_found = ip;
*location_found = location;
return true;
}
}
// nothing found
return false;
}
// Information about the system that produced the minidump. Subclasses
// and the SymbolSupplier may find this information useful.
const SystemInfo* system_info_;
// The stack memory to walk. Subclasses will require this region to
// get information from the stack.
MemoryRegion* memory_;
// A list of modules, for populating each StackFrame's module information.
// This field is optional and may be NULL.
const CodeModules* modules_;
// A list of unloaded modules, for populating frames which aren't matched
// to any loaded modules.
// This field is optional and may be NULL.
const CodeModules* unloaded_modules_;
protected:
// The StackFrameSymbolizer implementation.
StackFrameSymbolizer* frame_symbolizer_;
private:
// Obtains the context frame, the innermost called procedure in a stack
// trace. Returns NULL on failure. GetContextFrame allocates a new
// StackFrame (or StackFrame subclass), ownership of which is taken by
// the caller.
virtual StackFrame* GetContextFrame() = 0;
// Obtains a caller frame. Each call to GetCallerFrame should return the
// frame that called the last frame returned by GetContextFrame or
// GetCallerFrame. To aid this purpose, stack contains the CallStack
// made of frames that have already been walked. GetCallerFrame should
// return NULL on failure or when there are no more caller frames (when
// the end of the stack has been reached). GetCallerFrame allocates a new
// StackFrame (or StackFrame subclass), ownership of which is taken by
// the caller. |stack_scan_allowed| controls whether stack scanning is
// an allowable frame-recovery method, since it is desirable to be able to
// disable stack scanning in performance-critical use cases.
//
// CONSIDER: a way to differentiate between:
// - full stack traces
// - explicitly truncated traces (max_frames_)
// - stopping after max scanned frames
// - failed stack walk (breaking one of the stack walk invariants)
//
virtual StackFrame* GetCallerFrame(const CallStack* stack,
bool stack_scan_allowed) = 0;
// The maximum number of frames Stackwalker will walk through.
// This defaults to 1024 to prevent infinite loops.
static uint32_t max_frames_;
// Keep track of whether max_frames_ has been set by the user, since
// it affects whether or not an error message is printed in the case
// where an unwind got stopped by the limit.
static bool max_frames_set_;
// The maximum number of stack-scanned and otherwise untrustworthy
// frames allowed. Stack-scanning can be expensive, so the option to
// disable or limit it is helpful in cases where unwind performance is
// important. This defaults to 1024, the same as max_frames_.
static uint32_t max_frames_scanned_;
};
} // namespace google_breakpad
#endif // GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__