1 //===-- RegisterContextLLDB.h --------------------------------------------*- C++
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
8 //===----------------------------------------------------------------------===//
10 #ifndef lldb_RegisterContextLLDB_h_
11 #define lldb_RegisterContextLLDB_h_
15 #include "UnwindLLDB.h"
16 #include "lldb/Symbol/SymbolContext.h"
17 #include "lldb/Symbol/UnwindPlan.h"
18 #include "lldb/Target/RegisterContext.h"
19 #include "lldb/Target/RegisterNumber.h"
20 #include "lldb/lldb-private.h"
22 namespace lldb_private {
26 class RegisterContextLLDB : public lldb_private::RegisterContext {
28 typedef std::shared_ptr<RegisterContextLLDB> SharedPtr;
30 RegisterContextLLDB(lldb_private::Thread &thread, const SharedPtr &next_frame,
31 lldb_private::SymbolContext &sym_ctx,
32 uint32_t frame_number,
33 lldb_private::UnwindLLDB &unwind_lldb);
35 ~RegisterContextLLDB() override = default;
37 void InvalidateAllRegisters() override;
39 size_t GetRegisterCount() override;
41 const lldb_private::RegisterInfo *GetRegisterInfoAtIndex(size_t reg) override;
43 size_t GetRegisterSetCount() override;
45 const lldb_private::RegisterSet *GetRegisterSet(size_t reg_set) override;
47 bool ReadRegister(const lldb_private::RegisterInfo *reg_info,
48 lldb_private::RegisterValue &value) override;
50 bool WriteRegister(const lldb_private::RegisterInfo *reg_info,
51 const lldb_private::RegisterValue &value) override;
53 bool ReadAllRegisterValues(lldb::DataBufferSP &data_sp) override;
55 bool WriteAllRegisterValues(const lldb::DataBufferSP &data_sp) override;
57 uint32_t ConvertRegisterKindToRegisterNumber(lldb::RegisterKind kind,
58 uint32_t num) override;
62 bool IsTrapHandlerFrame() const;
64 bool GetCFA(lldb::addr_t &cfa);
66 bool GetStartPC(lldb::addr_t &start_pc);
68 bool ReadPC(lldb::addr_t &start_pc);
74 eDebuggerFrame, // a debugger inferior function call frame; we get caller's
75 // registers from debugger
76 eSkipFrame, // The unwind resulted in a bogus frame but may get back on
77 // track so we don't want to give up yet
78 eNotAValidFrame // this frame is invalid for some reason - most likely it is
79 // past the top (end) of the stack
82 // UnwindLLDB needs to pass around references to RegisterLocations
83 friend class UnwindLLDB;
85 // Returns true if we have an unwind loop -- the same stack frame unwinding
87 bool CheckIfLoopingStack();
89 // Indicates whether this frame is frame zero -- the currently
90 // executing frame -- or not.
91 bool IsFrameZero() const;
93 void InitializeZerothFrame();
95 void InitializeNonZerothFrame();
97 SharedPtr GetNextFrame() const;
99 SharedPtr GetPrevFrame() const;
101 // A SkipFrame occurs when the unwind out of frame 0 didn't go right -- we've
102 // got one bogus frame at frame #1.
103 // There is a good chance we'll get back on track if we follow the frame
104 // pointer chain (or whatever is appropriate
105 // on this ABI) so we allow one invalid frame to be in the stack. Ideally
106 // we'll mark this frame specially at some
107 // point and indicate to the user that the unwinder had a hiccup. Often when
108 // this happens we will miss a frame of
109 // the program's actual stack in the unwind and we want to flag that for the
111 bool IsSkipFrame() const;
113 /// Determines if a SymbolContext is a trap handler or not
115 /// Given a SymbolContext, determines if this is a trap handler function
116 /// aka asynchronous signal handler.
119 /// Returns true if the SymbolContext is a trap handler.
120 bool IsTrapHandlerSymbol(lldb_private::Process *process,
121 const lldb_private::SymbolContext &m_sym_ctx) const;
123 // Provide a location for where THIS function saved the CALLER's register
125 // Or a frame "below" this one saved it, i.e. a function called by this one,
126 // preserved a register that this
127 // function didn't modify/use.
129 // The RegisterLocation type may be set to eRegisterNotAvailable -- this will
130 // happen for a volatile register
131 // being queried mid-stack. Instead of floating frame 0's contents of that
132 // register up the stack (which may
133 // or may not be the value of that reg when the function was executing), we
134 // won't return any value.
136 // If a non-volatile register (a "preserved" register) is requested mid-stack
137 // and no frames "below" the requested
138 // stack have saved the register anywhere, it is safe to assume that frame 0's
139 // register values are still the same
140 // as the requesting frame's.
141 lldb_private::UnwindLLDB::RegisterSearchResult
142 SavedLocationForRegister(uint32_t lldb_regnum,
143 lldb_private::UnwindLLDB::RegisterLocation ®loc);
145 bool ReadRegisterValueFromRegisterLocation(
146 lldb_private::UnwindLLDB::RegisterLocation regloc,
147 const lldb_private::RegisterInfo *reg_info,
148 lldb_private::RegisterValue &value);
150 bool WriteRegisterValueToRegisterLocation(
151 lldb_private::UnwindLLDB::RegisterLocation regloc,
152 const lldb_private::RegisterInfo *reg_info,
153 const lldb_private::RegisterValue &value);
155 /// If the unwind has to the caller frame has failed, try something else
157 /// If lldb is using an assembly language based UnwindPlan for a frame and
158 /// the unwind to the caller frame fails, try falling back to a generic
159 /// UnwindPlan (architecture default unwindplan) to see if that might work
160 /// better. This is mostly helping to work around problems where the
161 /// assembly language inspection fails on hand-written assembly code.
164 /// Returns true if a fallback unwindplan was found & was installed.
165 bool TryFallbackUnwindPlan();
167 /// Switch to the fallback unwind plan unconditionally without any safety
168 /// checks that it is providing better results than the normal unwind plan.
170 /// The only time it is valid to call this method is if the full unwindplan is
171 /// found to be fundamentally incorrect/impossible.
173 /// Returns true if it was able to install the fallback unwind plan.
174 bool ForceSwitchToFallbackUnwindPlan();
176 // Get the contents of a general purpose (address-size) register for this
178 // (usually retrieved from the next frame)
179 bool ReadGPRValue(lldb::RegisterKind register_kind, uint32_t regnum,
180 lldb::addr_t &value);
182 bool ReadGPRValue(const RegisterNumber ®_num, lldb::addr_t &value);
184 // Get the Frame Address register for a given frame.
185 bool ReadFrameAddress(lldb::RegisterKind register_kind,
186 UnwindPlan::Row::FAValue &fa, lldb::addr_t &address);
188 lldb::UnwindPlanSP GetFastUnwindPlanForFrame();
190 lldb::UnwindPlanSP GetFullUnwindPlanForFrame();
192 void UnwindLogMsg(const char *fmt, ...) __attribute__((format(printf, 2, 3)));
194 void UnwindLogMsgVerbose(const char *fmt, ...)
195 __attribute__((format(printf, 2, 3)));
197 bool IsUnwindPlanValidForCurrentPC(lldb::UnwindPlanSP unwind_plan_sp,
198 int &valid_pc_offset);
200 lldb_private::Thread &m_thread;
203 // The following tell us how to retrieve the CALLER's register values (ie the
204 // "previous" frame, aka the frame above)
205 // i.e. where THIS frame saved them
208 lldb::UnwindPlanSP m_fast_unwind_plan_sp; // may be NULL
209 lldb::UnwindPlanSP m_full_unwind_plan_sp;
210 lldb::UnwindPlanSP m_fallback_unwind_plan_sp; // may be NULL
212 bool m_all_registers_available; // Can we retrieve all regs or just
214 int m_frame_type; // enum FrameType
218 lldb_private::Address m_start_pc;
219 lldb_private::Address m_current_pc;
221 int m_current_offset; // how far into the function we've executed; -1 if
223 // 0 if no instructions have been executed yet.
225 int m_current_offset_backed_up_one; // how far into the function we've
226 // executed; -1 if unknown
227 // 0 if no instructions have been executed yet.
228 // On architectures where the return address on the stack points
229 // to the instruction after the CALL, this value will have 1
230 // subtracted from it. Else a function that ends in a CALL will
231 // have an offset pointing into the next function's address range.
232 // m_current_pc has the actual address of the "current" pc.
234 lldb_private::SymbolContext &m_sym_ctx;
235 bool m_sym_ctx_valid; // if ResolveSymbolContextForAddress fails, don't try to
238 uint32_t m_frame_number; // What stack frame this RegisterContext is
240 std::map<uint32_t, lldb_private::UnwindLLDB::RegisterLocation>
241 m_registers; // where to find reg values for this frame
243 lldb_private::UnwindLLDB &m_parent_unwind; // The UnwindLLDB that is creating
244 // this RegisterContextLLDB
246 // For RegisterContextLLDB only
248 DISALLOW_COPY_AND_ASSIGN(RegisterContextLLDB);
251 } // namespace lldb_private
253 #endif // lldb_RegisterContextLLDB_h_