1 //===-- UnwindLLDB.h --------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLDB_TARGET_UNWINDLLDB_H
10 #define LLDB_TARGET_UNWINDLLDB_H
11 
12 #include <vector>
13 
14 #include "lldb/Symbol/FuncUnwinders.h"
15 #include "lldb/Symbol/SymbolContext.h"
16 #include "lldb/Symbol/UnwindPlan.h"
17 #include "lldb/Target/RegisterContext.h"
18 #include "lldb/Target/Unwind.h"
19 #include "lldb/Utility/ConstString.h"
20 #include "lldb/lldb-public.h"
21 
22 namespace lldb_private {
23 
24 class RegisterContextUnwind;
25 
26 class UnwindLLDB : public lldb_private::Unwind {
27 public:
28   UnwindLLDB(lldb_private::Thread &thread);
29 
30   ~UnwindLLDB() override = default;
31 
32   enum RegisterSearchResult {
33     eRegisterFound = 0,
34     eRegisterNotFound,
35     eRegisterIsVolatile
36   };
37 
38 protected:
39   friend class lldb_private::RegisterContextUnwind;
40 
41   struct RegisterLocation {
42     enum RegisterLocationTypes {
43       eRegisterNotSaved = 0, // register was not preserved by callee.  If
44                              // volatile reg, is unavailable
45       eRegisterSavedAtMemoryLocation, // register is saved at a specific word of
46                                       // target mem (target_memory_location)
47       eRegisterInRegister, // register is available in a (possible other)
48                            // register (register_number)
49       eRegisterSavedAtHostMemoryLocation, // register is saved at a word in
50                                           // lldb's address space
51       eRegisterValueInferred,        // register val was computed (and is in
52                                      // inferred_value)
53       eRegisterInLiveRegisterContext // register value is in a live (stack frame
54                                      // #0) register
55     };
56     int type;
57     union {
58       lldb::addr_t target_memory_location;
59       uint32_t
60           register_number; // in eRegisterKindLLDB register numbering system
61       void *host_memory_location;
62       uint64_t inferred_value; // eRegisterValueInferred - e.g. stack pointer ==
63                                // cfa + offset
64     } location;
65   };
66 
67   void DoClear() override {
68     m_frames.clear();
69     m_candidate_frame.reset();
70     m_unwind_complete = false;
71   }
72 
73   uint32_t DoGetFrameCount() override;
74 
75   bool DoGetFrameInfoAtIndex(uint32_t frame_idx, lldb::addr_t &cfa,
76                              lldb::addr_t &start_pc,
77                              bool &behaves_like_zeroth_frame) override;
78 
79   lldb::RegisterContextSP
80   DoCreateRegisterContextForFrame(lldb_private::StackFrame *frame) override;
81 
82   typedef std::shared_ptr<RegisterContextUnwind> RegisterContextLLDBSP;
83 
84   // Needed to retrieve the "next" frame (e.g. frame 2 needs to retrieve frame
85   // 1's RegisterContextUnwind)
86   // The RegisterContext for frame_num must already exist or this returns an
87   // empty shared pointer.
88   RegisterContextLLDBSP GetRegisterContextForFrameNum(uint32_t frame_num);
89 
90   // Iterate over the RegisterContextUnwind's in our m_frames vector, look for
91   // the first one that has a saved location for this reg.
92   bool SearchForSavedLocationForRegister(
93       uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc,
94       uint32_t starting_frame_num, bool pc_register);
95 
96   /// Provide the list of user-specified trap handler functions
97   ///
98   /// The Platform is one source of trap handler function names; that
99   /// may be augmented via a setting.  The setting needs to be converted
100   /// into an array of ConstStrings before it can be used - we only want
101   /// to do that once per thread so it's here in the UnwindLLDB object.
102   ///
103   /// \return
104   ///     Vector of ConstStrings of trap handler function names.  May be
105   ///     empty.
106   const std::vector<ConstString> &GetUserSpecifiedTrapHandlerFunctionNames() {
107     return m_user_supplied_trap_handler_functions;
108   }
109 
110 private:
111   struct Cursor {
112     lldb::addr_t start_pc =
113         LLDB_INVALID_ADDRESS; // The start address of the function/symbol for
114                               // this frame - current pc if unknown
115     lldb::addr_t cfa = LLDB_INVALID_ADDRESS; // The canonical frame address for
116                                              // this stack frame
117     lldb_private::SymbolContext sctx; // A symbol context we'll contribute to &
118                                       // provide to the StackFrame creation
119     RegisterContextLLDBSP
120         reg_ctx_lldb_sp; // These are all RegisterContextUnwind's
121 
122     Cursor() = default;
123 
124   private:
125     Cursor(const Cursor &) = delete;
126     const Cursor &operator=(const Cursor &) = delete;
127   };
128 
129   typedef std::shared_ptr<Cursor> CursorSP;
130   std::vector<CursorSP> m_frames;
131   CursorSP m_candidate_frame;
132   bool m_unwind_complete; // If this is true, we've enumerated all the frames in
133                           // the stack, and m_frames.size() is the
134   // number of frames, etc.  Otherwise we've only gone as far as directly asked,
135   // and m_frames.size()
136   // is how far we've currently gone.
137 
138   std::vector<ConstString> m_user_supplied_trap_handler_functions;
139 
140   // Check if Full UnwindPlan of First frame is valid or not.
141   // If not then try Fallback UnwindPlan of the frame. If Fallback
142   // UnwindPlan succeeds then update the Full UnwindPlan with the
143   // Fallback UnwindPlan.
144   void UpdateUnwindPlanForFirstFrameIfInvalid(ABI *abi);
145 
146   CursorSP GetOneMoreFrame(ABI *abi);
147 
148   bool AddOneMoreFrame(ABI *abi);
149 
150   bool AddFirstFrame();
151 
152   // For UnwindLLDB only
153   UnwindLLDB(const UnwindLLDB &) = delete;
154   const UnwindLLDB &operator=(const UnwindLLDB &) = delete;
155 };
156 
157 } // namespace lldb_private
158 
159 #endif // LLDB_TARGET_UNWINDLLDB_H
160