1 //===-- AppleObjCTrampolineHandler.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_AppleObjCTrampolineHandler_h_
10 #define lldb_AppleObjCTrampolineHandler_h_
11 
12 #include <map>
13 #include <mutex>
14 #include <vector>
15 
16 #include "lldb/Expression/UtilityFunction.h"
17 #include "lldb/lldb-public.h"
18 
19 namespace lldb_private {
20 
21 class AppleObjCTrampolineHandler {
22 public:
23   AppleObjCTrampolineHandler(const lldb::ProcessSP &process_sp,
24                              const lldb::ModuleSP &objc_module_sp);
25 
26   ~AppleObjCTrampolineHandler();
27 
28   lldb::ThreadPlanSP GetStepThroughDispatchPlan(Thread &thread,
29                                                 bool stop_others);
30 
31   FunctionCaller *GetLookupImplementationFunctionCaller();
32 
33   bool AddrIsMsgForward(lldb::addr_t addr) const {
34     return (addr == m_msg_forward_addr || addr == m_msg_forward_stret_addr);
35   }
36 
37   struct DispatchFunction {
38   public:
39     enum FixUpState { eFixUpNone, eFixUpFixed, eFixUpToFix };
40 
41     const char *name;
42     bool stret_return;
43     bool is_super;
44     bool is_super2;
45     FixUpState fixedup;
46   };
47 
48   lldb::addr_t SetupDispatchFunction(Thread &thread,
49                                      ValueList &dispatch_values);
50 
51 private:
52   static const char *g_lookup_implementation_function_name;
53   static const char *g_lookup_implementation_with_stret_function_code;
54   static const char *g_lookup_implementation_no_stret_function_code;
55 
56   class AppleObjCVTables {
57   public:
58     // These come from objc-gdb.h.
59     enum VTableFlags {
60       eOBJC_TRAMPOLINE_MESSAGE = (1 << 0), // trampoline acts like objc_msgSend
61       eOBJC_TRAMPOLINE_STRET = (1 << 1),   // trampoline is struct-returning
62       eOBJC_TRAMPOLINE_VTABLE = (1 << 2)   // trampoline is vtable dispatcher
63     };
64 
65   private:
66     struct VTableDescriptor {
67       VTableDescriptor(uint32_t in_flags, lldb::addr_t in_code_start)
68           : flags(in_flags), code_start(in_code_start) {}
69 
70       uint32_t flags;
71       lldb::addr_t code_start;
72     };
73 
74     class VTableRegion {
75     public:
76       VTableRegion()
77           : m_valid(false), m_owner(nullptr),
78             m_header_addr(LLDB_INVALID_ADDRESS), m_code_start_addr(0),
79             m_code_end_addr(0), m_next_region(0) {}
80 
81       VTableRegion(AppleObjCVTables *owner, lldb::addr_t header_addr);
82 
83       void SetUpRegion();
84 
85       lldb::addr_t GetNextRegionAddr() { return m_next_region; }
86 
87       lldb::addr_t GetCodeStart() { return m_code_start_addr; }
88 
89       lldb::addr_t GetCodeEnd() { return m_code_end_addr; }
90 
91       uint32_t GetFlagsForVTableAtAddress(lldb::addr_t address) { return 0; }
92 
93       bool IsValid() { return m_valid; }
94 
95       bool AddressInRegion(lldb::addr_t addr, uint32_t &flags);
96 
97       void Dump(Stream &s);
98 
99     public:
100       bool m_valid;
101       AppleObjCVTables *m_owner;
102       lldb::addr_t m_header_addr;
103       lldb::addr_t m_code_start_addr;
104       lldb::addr_t m_code_end_addr;
105       std::vector<VTableDescriptor> m_descriptors;
106       lldb::addr_t m_next_region;
107     };
108 
109   public:
110     AppleObjCVTables(const lldb::ProcessSP &process_sp,
111                      const lldb::ModuleSP &objc_module_sp);
112 
113     ~AppleObjCVTables();
114 
115     bool InitializeVTableSymbols();
116 
117     static bool RefreshTrampolines(void *baton,
118                                    StoppointCallbackContext *context,
119                                    lldb::user_id_t break_id,
120                                    lldb::user_id_t break_loc_id);
121     bool ReadRegions();
122 
123     bool ReadRegions(lldb::addr_t region_addr);
124 
125     bool IsAddressInVTables(lldb::addr_t addr, uint32_t &flags);
126 
127     lldb::ProcessSP GetProcessSP() { return m_process_wp.lock(); }
128 
129   private:
130     lldb::ProcessWP m_process_wp;
131     typedef std::vector<VTableRegion> region_collection;
132     lldb::addr_t m_trampoline_header;
133     lldb::break_id_t m_trampolines_changed_bp_id;
134     region_collection m_regions;
135     lldb::ModuleSP m_objc_module_sp;
136   };
137 
138   static const DispatchFunction g_dispatch_functions[];
139 
140   typedef std::map<lldb::addr_t, int> MsgsendMap; // This table maps an dispatch
141                                                   // fn address to the index in
142                                                   // g_dispatch_functions
143   MsgsendMap m_msgSend_map;
144   lldb::ProcessWP m_process_wp;
145   lldb::ModuleSP m_objc_module_sp;
146   const char *m_lookup_implementation_function_code;
147   std::unique_ptr<UtilityFunction> m_impl_code;
148   std::mutex m_impl_function_mutex;
149   lldb::addr_t m_impl_fn_addr;
150   lldb::addr_t m_impl_stret_fn_addr;
151   lldb::addr_t m_msg_forward_addr;
152   lldb::addr_t m_msg_forward_stret_addr;
153   std::unique_ptr<AppleObjCVTables> m_vtables_up;
154 };
155 
156 } // namespace lldb_private
157 
158 #endif // lldb_AppleObjCTrampolineHandler_h_
159