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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.
14 //     * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 // stackwalker.h: Generic stackwalker.
31 //
32 // The Stackwalker class is an abstract base class providing common generic
33 // methods that apply to stacks from all systems.  Specific implementations
34 // will extend this class by providing GetContextFrame and GetCallerFrame
35 // methods to fill in system-specific data in a StackFrame structure.
36 // Stackwalker assembles these StackFrame strucutres into a CallStack.
37 //
38 // Author: Mark Mentovai
39 
40 
41 #ifndef GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
42 #define GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
43 
44 #include <set>
45 #include <string>
46 #include <vector>
47 
48 #include "common/using_std_string.h"
49 #include "google_breakpad/common/breakpad_types.h"
50 #include "google_breakpad/processor/code_modules.h"
51 #include "google_breakpad/processor/memory_region.h"
52 #include "google_breakpad/processor/stack_frame_symbolizer.h"
53 
54 namespace google_breakpad {
55 
56 class CallStack;
57 class DumpContext;
58 class StackFrameSymbolizer;
59 
60 using std::set;
61 using std::vector;
62 
63 class Stackwalker {
64  public:
~Stackwalker()65   virtual ~Stackwalker() {}
66 
67   // Populates the given CallStack by calling GetContextFrame and
68   // GetCallerFrame.  The frames are further processed to fill all available
69   // data.  Returns true if the stackwalk completed, or false if it was
70   // interrupted by SymbolSupplier::GetSymbolFile().
71   // Upon return, |modules_without_symbols| will be populated with pointers to
72   // the code modules (CodeModule*) that DON'T have symbols.
73   // |modules_with_corrupt_symbols| will be populated with pointers to the
74   // modules which have corrupt symbols.  |modules_without_symbols| and
75   // |modules_with_corrupt_symbols| DO NOT take ownership of the code modules.
76   // The lifetime of these code modules is the same as the lifetime of the
77   // CodeModules passed to the StackWalker constructor (which currently
78   // happens to be the lifetime of the Breakpad's ProcessingState object).
79   // There is a check for duplicate modules so no duplicates are expected.
80   bool Walk(CallStack* stack,
81             vector<const CodeModule*>* modules_without_symbols,
82             vector<const CodeModule*>* modules_with_corrupt_symbols);
83 
84   // Returns a new concrete subclass suitable for the CPU that a stack was
85   // generated on, according to the CPU type indicated by the context
86   // argument.  If no suitable concrete subclass exists, returns NULL.
87   static Stackwalker* StackwalkerForCPU(
88      const SystemInfo* system_info,
89      DumpContext* context,
90      MemoryRegion* memory,
91      const CodeModules* modules,
92      StackFrameSymbolizer* resolver_helper);
93 
set_max_frames(uint32_t max_frames)94   static void set_max_frames(uint32_t max_frames) {
95     max_frames_ = max_frames;
96     max_frames_set_ = true;
97   }
max_frames()98   static uint32_t max_frames() { return max_frames_; }
99 
set_max_frames_scanned(uint32_t max_frames_scanned)100   static void set_max_frames_scanned(uint32_t max_frames_scanned) {
101     max_frames_scanned_ = max_frames_scanned;
102   }
103 
104  protected:
105   // system_info identifies the operating system, NULL or empty if unknown.
106   // memory identifies a MemoryRegion that provides the stack memory
107   // for the stack to walk.  modules, if non-NULL, is a CodeModules
108   // object that is used to look up which code module each stack frame is
109   // associated with.  frame_symbolizer is a StackFrameSymbolizer object that
110   // encapsulates the logic of how source line resolver interacts with symbol
111   // supplier to symbolize stack frame and look up caller frame information
112   // (see stack_frame_symbolizer.h).
113   // frame_symbolizer MUST NOT be NULL (asserted).
114   Stackwalker(const SystemInfo* system_info,
115               MemoryRegion* memory,
116               const CodeModules* modules,
117               StackFrameSymbolizer* frame_symbolizer);
118 
119   // This can be used to filter out potential return addresses when
120   // the stack walker resorts to stack scanning.
121   // Returns true if any of:
122   // * This address is within a loaded module, but we don't have symbols
123   //   for that module.
124   // * This address is within a loaded module for which we have symbols,
125   //   and falls inside a function in that module.
126   // Returns false otherwise.
127   bool InstructionAddressSeemsValid(uint64_t address);
128 
129   // The default number of words to search through on the stack
130   // for a return address.
131   static const int kRASearchWords;
132 
133   template<typename InstructionType>
ScanForReturnAddress(InstructionType location_start,InstructionType * location_found,InstructionType * ip_found,bool is_context_frame)134   bool ScanForReturnAddress(InstructionType location_start,
135                             InstructionType* location_found,
136                             InstructionType* ip_found,
137                             bool is_context_frame) {
138     // When searching for the caller of the context frame,
139     // allow the scanner to look farther down the stack.
140     const int search_words = is_context_frame ?
141       kRASearchWords * 4 :
142       kRASearchWords;
143 
144     return ScanForReturnAddress(location_start, location_found, ip_found,
145                                 search_words);
146   }
147 
148   // Scan the stack starting at location_start, looking for an address
149   // that looks like a valid instruction pointer. Addresses must
150   // 1) be contained in the current stack memory
151   // 2) pass the checks in InstructionAddressSeemsValid
152   //
153   // Returns true if a valid-looking instruction pointer was found.
154   // When returning true, sets location_found to the address at which
155   // the value was found, and ip_found to the value contained at that
156   // location in memory.
157   template<typename InstructionType>
ScanForReturnAddress(InstructionType location_start,InstructionType * location_found,InstructionType * ip_found,int searchwords)158   bool ScanForReturnAddress(InstructionType location_start,
159                             InstructionType* location_found,
160                             InstructionType* ip_found,
161                             int searchwords) {
162     for (InstructionType location = location_start;
163          location <= location_start + searchwords * sizeof(InstructionType);
164          location += sizeof(InstructionType)) {
165       InstructionType ip;
166       if (!memory_->GetMemoryAtAddress(location, &ip))
167         break;
168 
169       if (modules_ && modules_->GetModuleForAddress(ip) &&
170           InstructionAddressSeemsValid(ip)) {
171         *ip_found = ip;
172         *location_found = location;
173         return true;
174       }
175     }
176     // nothing found
177     return false;
178   }
179 
180   // Information about the system that produced the minidump.  Subclasses
181   // and the SymbolSupplier may find this information useful.
182   const SystemInfo* system_info_;
183 
184   // The stack memory to walk.  Subclasses will require this region to
185   // get information from the stack.
186   MemoryRegion* memory_;
187 
188   // A list of modules, for populating each StackFrame's module information.
189   // This field is optional and may be NULL.
190   const CodeModules* modules_;
191 
192  protected:
193   // The StackFrameSymbolizer implementation.
194   StackFrameSymbolizer* frame_symbolizer_;
195 
196  private:
197   // Obtains the context frame, the innermost called procedure in a stack
198   // trace.  Returns NULL on failure.  GetContextFrame allocates a new
199   // StackFrame (or StackFrame subclass), ownership of which is taken by
200   // the caller.
201   virtual StackFrame* GetContextFrame() = 0;
202 
203   // Obtains a caller frame.  Each call to GetCallerFrame should return the
204   // frame that called the last frame returned by GetContextFrame or
205   // GetCallerFrame.  To aid this purpose, stack contains the CallStack
206   // made of frames that have already been walked.  GetCallerFrame should
207   // return NULL on failure or when there are no more caller frames (when
208   // the end of the stack has been reached).  GetCallerFrame allocates a new
209   // StackFrame (or StackFrame subclass), ownership of which is taken by
210   // the caller.  |stack_scan_allowed| controls whether stack scanning is
211   // an allowable frame-recovery method, since it is desirable to be able to
212   // disable stack scanning in performance-critical use cases.
213   virtual StackFrame* GetCallerFrame(const CallStack* stack,
214                                      bool stack_scan_allowed) = 0;
215 
216   // The maximum number of frames Stackwalker will walk through.
217   // This defaults to 1024 to prevent infinite loops.
218   static uint32_t max_frames_;
219 
220   // Keep track of whether max_frames_ has been set by the user, since
221   // it affects whether or not an error message is printed in the case
222   // where an unwind got stopped by the limit.
223   static bool max_frames_set_;
224 
225   // The maximum number of stack-scanned and otherwise untrustworthy
226   // frames allowed.  Stack-scanning can be expensive, so the option to
227   // disable or limit it is helpful in cases where unwind performance is
228   // important.  This defaults to 1024, the same as max_frames_.
229   static uint32_t max_frames_scanned_;
230 };
231 
232 }  // namespace google_breakpad
233 
234 
235 #endif  // GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
236