1 //===-- RegisterContext.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_REGISTERCONTEXT_H
10 #define LLDB_TARGET_REGISTERCONTEXT_H
11 
12 #include "lldb/Target/ExecutionContextScope.h"
13 #include "lldb/lldb-private.h"
14 
15 namespace lldb_private {
16 
17 class RegisterContext : public std::enable_shared_from_this<RegisterContext>,
18                         public ExecutionContextScope {
19 public:
20   // Constructors and Destructors
21   RegisterContext(Thread &thread, uint32_t concrete_frame_idx);
22 
23   ~RegisterContext() override;
24 
25   void InvalidateIfNeeded(bool force);
26 
27   // Subclasses must override these functions
28   virtual void InvalidateAllRegisters() = 0;
29 
30   virtual size_t GetRegisterCount() = 0;
31 
32   virtual const RegisterInfo *GetRegisterInfoAtIndex(size_t reg) = 0;
33 
34   virtual size_t GetRegisterSetCount() = 0;
35 
36   virtual const RegisterSet *GetRegisterSet(size_t reg_set) = 0;
37 
38   virtual lldb::ByteOrder GetByteOrder();
39 
40   virtual bool ReadRegister(const RegisterInfo *reg_info,
41                             RegisterValue &reg_value) = 0;
42 
43   virtual bool WriteRegister(const RegisterInfo *reg_info,
44                              const RegisterValue &reg_value) = 0;
45 
46   virtual bool ReadAllRegisterValues(lldb::DataBufferSP &data_sp) {
47     return false;
48   }
49 
50   virtual bool WriteAllRegisterValues(const lldb::DataBufferSP &data_sp) {
51     return false;
52   }
53 
54   // These two functions are used to implement "push" and "pop" of register
55   // states.  They are used primarily for expression evaluation, where we need
56   // to push a new state (storing the old one in data_sp) and then restoring
57   // the original state by passing the data_sp we got from ReadAllRegisters to
58   // WriteAllRegisterValues. ReadAllRegisters will do what is necessary to
59   // return a coherent set of register values for this thread, which may mean
60   // e.g. interrupting a thread that is sitting in a kernel trap.  That is a
61   // somewhat disruptive operation, so these API's should only be used when
62   // this behavior is needed.
63 
64   virtual bool
65   ReadAllRegisterValues(lldb_private::RegisterCheckpoint &reg_checkpoint);
66 
67   virtual bool WriteAllRegisterValues(
68       const lldb_private::RegisterCheckpoint &reg_checkpoint);
69 
70   bool CopyFromRegisterContext(lldb::RegisterContextSP context);
71 
72   /// Convert from a given register numbering scheme to the lldb register
73   /// numbering scheme
74   ///
75   /// There may be multiple ways to enumerate the registers for a given
76   /// architecture.  ABI references will specify one to be used with
77   /// DWARF, the register numberings from process plugin, there may
78   /// be a variation used for eh_frame unwind instructions (e.g. on Darwin),
79   /// and so on.  Register 5 by itself is meaningless - RegisterKind
80   /// enumeration tells you what context that number should be translated as.
81   ///
82   /// Inside lldb, register numbers are in the eRegisterKindLLDB scheme;
83   /// arguments which take a register number should take one in that
84   /// scheme.
85   ///
86   /// eRegisterKindGeneric is a special numbering scheme which gives us
87   /// constant values for the pc, frame register, stack register, etc., for
88   /// use within lldb.  They may not be defined for all architectures but
89   /// it allows generic code to translate these common registers into the
90   /// lldb numbering scheme.
91   ///
92   /// This method translates a given register kind + register number into
93   /// the eRegisterKindLLDB register numbering.
94   ///
95   /// \param [in] kind
96   ///     The register numbering scheme (RegisterKind) that the following
97   ///     register number is in.
98   ///
99   /// \param [in] num
100   ///     A register number in the 'kind' register numbering scheme.
101   ///
102   /// \return
103   ///     The equivalent register number in the eRegisterKindLLDB
104   ///     numbering scheme, if possible, else LLDB_INVALID_REGNUM.
105   virtual uint32_t ConvertRegisterKindToRegisterNumber(lldb::RegisterKind kind,
106                                                        uint32_t num);
107 
108   // Subclasses can override these functions if desired
109   virtual uint32_t NumSupportedHardwareBreakpoints();
110 
111   virtual uint32_t SetHardwareBreakpoint(lldb::addr_t addr, size_t size);
112 
113   virtual bool ClearHardwareBreakpoint(uint32_t hw_idx);
114 
115   virtual uint32_t NumSupportedHardwareWatchpoints();
116 
117   virtual uint32_t SetHardwareWatchpoint(lldb::addr_t addr, size_t size,
118                                          bool read, bool write);
119 
120   virtual bool ClearHardwareWatchpoint(uint32_t hw_index);
121 
122   virtual bool HardwareSingleStep(bool enable);
123 
124   virtual Status
125   ReadRegisterValueFromMemory(const lldb_private::RegisterInfo *reg_info,
126                               lldb::addr_t src_addr, uint32_t src_len,
127                               RegisterValue &reg_value);
128 
129   virtual Status
130   WriteRegisterValueToMemory(const lldb_private::RegisterInfo *reg_info,
131                              lldb::addr_t dst_addr, uint32_t dst_len,
132                              const RegisterValue &reg_value);
133 
134   // Subclasses should not override these
135   virtual lldb::tid_t GetThreadID() const;
136 
137   virtual Thread &GetThread() { return m_thread; }
138 
139   const RegisterInfo *GetRegisterInfoByName(llvm::StringRef reg_name,
140                                             uint32_t start_idx = 0);
141 
142   const RegisterInfo *GetRegisterInfo(lldb::RegisterKind reg_kind,
143                                       uint32_t reg_num);
144 
145   uint64_t GetPC(uint64_t fail_value = LLDB_INVALID_ADDRESS);
146 
147   /// Get an address suitable for symbolication.
148   /// When symbolicating -- computing line, block, function --
149   /// for a function in the middle of the stack, using the return
150   /// address can lead to unexpected results for the user.
151   /// A function that ends in a tail-call may have another function
152   /// as the "return" address, but it will never actually return.
153   /// Or a noreturn call in the middle of a function is the end of
154   /// a block of instructions, and a DWARF location list entry for
155   /// the return address may be a very different code path with
156   /// incorrect results when printing variables for this frame.
157   ///
158   /// At a source line view, the user expects the current-line indictation
159   /// to point to the function call they're under, not the next source line.
160   ///
161   /// The return address (GetPC()) should always be shown to the user,
162   /// but when computing context, keeping within the bounds of the
163   /// call instruction is what the user expects to see.
164   ///
165   /// \param [out] address
166   ///     An Address object that will be filled in, if a PC can be retrieved.
167   ///
168   /// \return
169   ///     Returns true if the Address param was filled in.
170   bool GetPCForSymbolication(Address &address);
171 
172   bool SetPC(uint64_t pc);
173 
174   bool SetPC(Address addr);
175 
176   uint64_t GetSP(uint64_t fail_value = LLDB_INVALID_ADDRESS);
177 
178   bool SetSP(uint64_t sp);
179 
180   uint64_t GetFP(uint64_t fail_value = LLDB_INVALID_ADDRESS);
181 
182   bool SetFP(uint64_t fp);
183 
184   const char *GetRegisterName(uint32_t reg);
185 
186   uint64_t GetReturnAddress(uint64_t fail_value = LLDB_INVALID_ADDRESS);
187 
188   uint64_t GetFlags(uint64_t fail_value = 0);
189 
190   uint64_t ReadRegisterAsUnsigned(uint32_t reg, uint64_t fail_value);
191 
192   uint64_t ReadRegisterAsUnsigned(const RegisterInfo *reg_info,
193                                   uint64_t fail_value);
194 
195   bool WriteRegisterFromUnsigned(uint32_t reg, uint64_t uval);
196 
197   bool WriteRegisterFromUnsigned(const RegisterInfo *reg_info, uint64_t uval);
198 
199   bool ConvertBetweenRegisterKinds(lldb::RegisterKind source_rk,
200                                    uint32_t source_regnum,
201                                    lldb::RegisterKind target_rk,
202                                    uint32_t &target_regnum);
203 
204   // lldb::ExecutionContextScope pure virtual functions
205   lldb::TargetSP CalculateTarget() override;
206 
207   lldb::ProcessSP CalculateProcess() override;
208 
209   lldb::ThreadSP CalculateThread() override;
210 
211   lldb::StackFrameSP CalculateStackFrame() override;
212 
213   void CalculateExecutionContext(ExecutionContext &exe_ctx) override;
214 
215   uint32_t GetStopID() const { return m_stop_id; }
216 
217   void SetStopID(uint32_t stop_id) { m_stop_id = stop_id; }
218 
219 protected:
220   /// Indicates that this frame is currently executing code,
221   /// that the PC value is not a return-pc but an actual executing
222   /// instruction.  Some places in lldb will treat a return-pc
223   /// value differently than the currently-executing-pc value,
224   /// and this method can indicate if that should be done.
225   /// The base class implementation only uses the frame index,
226   /// but subclasses may have additional information that they
227   /// can use to detect frames in this state, for instance a
228   /// frame above a trap handler (sigtramp etc)..
229   virtual bool BehavesLikeZerothFrame() const {
230     return m_concrete_frame_idx == 0;
231   }
232 
233   // Classes that inherit from RegisterContext can see and modify these
234   Thread &m_thread; // The thread that this register context belongs to.
235   uint32_t m_concrete_frame_idx; // The concrete frame index for this register
236                                  // context
237   uint32_t m_stop_id; // The stop ID that any data in this context is valid for
238 private:
239   // For RegisterContext only
240   RegisterContext(const RegisterContext &) = delete;
241   const RegisterContext &operator=(const RegisterContext &) = delete;
242 };
243 
244 } // namespace lldb_private
245 
246 #endif // LLDB_TARGET_REGISTERCONTEXT_H
247