path: root/source/Plugins/Process/Utility/RegisterContextLLDB.h

//===-- RegisterContextLLDB.h --------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef lldb_RegisterContextLLDB_h_
#define lldb_RegisterContextLLDB_h_

#include <vector>

#include "lldb/lldb-private.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Symbol/SymbolContext.h"
#include "UnwindLLDB.h"

namespace lldb_private {

class UnwindLLDB;

class RegisterContextLLDB : public lldb_private::RegisterContext
{
public:
    typedef std::shared_ptr<RegisterContextLLDB> SharedPtr;

    RegisterContextLLDB (lldb_private::Thread &thread,
                         const SharedPtr& next_frame,
                         lldb_private::SymbolContext& sym_ctx,
                         uint32_t frame_number, lldb_private::UnwindLLDB& unwind_lldb);

    ///
    // pure virtual functions from the base class that we must implement
    ///

    virtual
    ~RegisterContextLLDB () { }

    virtual void
    InvalidateAllRegisters ();

    virtual size_t
    GetRegisterCount ();

    virtual const lldb_private::RegisterInfo *
    GetRegisterInfoAtIndex (size_t reg);

    virtual size_t
    GetRegisterSetCount ();

    virtual const lldb_private::RegisterSet *
    GetRegisterSet (size_t reg_set);

    virtual bool
    ReadRegister (const lldb_private::RegisterInfo *reg_info, lldb_private::RegisterValue &value);

    virtual bool
    WriteRegister (const lldb_private::RegisterInfo *reg_info, const lldb_private::RegisterValue &value);

    virtual bool
    ReadAllRegisterValues (lldb::DataBufferSP &data_sp);

    virtual bool
    WriteAllRegisterValues (const lldb::DataBufferSP &data_sp);

    virtual uint32_t
    ConvertRegisterKindToRegisterNumber (lldb::RegisterKind kind, uint32_t num);

    bool
    IsValid () const;

    bool
    IsTrapHandlerFrame () const;

    bool
    GetCFA (lldb::addr_t& cfa);

    bool
    GetStartPC (lldb::addr_t& start_pc);

    bool
    ReadPC (lldb::addr_t& start_pc);

private:

    enum FrameType
    {
        eNormalFrame,
        eTrapHandlerFrame,
        eDebuggerFrame,  // a debugger inferior function call frame; we get caller's registers from debugger
        eSkipFrame,      // The unwind resulted in a bogus frame but may get back on track so we don't want to give up yet
        eNotAValidFrame  // this frame is invalid for some reason - most likely it is past the top (end) of the stack
    };

    // UnwindLLDB needs to pass around references to RegisterLocations
    friend class UnwindLLDB;

    // Indicates whether this frame is frame zero -- the currently
    // executing frame -- or not.
    bool
    IsFrameZero () const;

    void
    InitializeZerothFrame ();

    void
    InitializeNonZerothFrame();

    SharedPtr
    GetNextFrame () const;

    SharedPtr
    GetPrevFrame () const;

    // A SkipFrame occurs when the unwind out of frame 0 didn't go right -- we've got one bogus frame at frame #1.
    // There is a good chance we'll get back on track if we follow the frame pointer chain (or whatever is appropriate
    // on this ABI) so we allow one invalid frame to be in the stack.  Ideally we'll mark this frame specially at some
    // point and indicate to the user that the unwinder had a hiccup.  Often when this happens we will miss a frame of
    // the program's actual stack in the unwind and we want to flag that for the user somehow.
    bool
    IsSkipFrame () const;


    //------------------------------------------------------------------
    /// Determines if a SymbolContext is a trap handler or not
    ///
    /// Given a SymbolContext, determines if this is a trap handler function
    /// aka asynchronous signal handler.
    ///
    /// @return
    ///     Returns true if the SymbolContext is a trap handler.
    //------------------------------------------------------------------
    bool
    IsTrapHandlerSymbol (lldb_private::Process *process, const lldb_private::SymbolContext &m_sym_ctx) const;

    // Provide a location for where THIS function saved the CALLER's register value
    // Or a frame "below" this one saved it, i.e. a function called by this one, preserved a register that this
    // function didn't modify/use.
    //
    // The RegisterLocation type may be set to eRegisterNotAvailable -- this will happen for a volatile register
    // being queried mid-stack.  Instead of floating frame 0's contents of that register up the stack (which may
    // or may not be the value of that reg when the function was executing), we won't return any value.
    //
    // If a non-volatile register (a "preserved" register) is requested mid-stack and no frames "below" the requested
    // stack have saved the register anywhere, it is safe to assume that frame 0's register values are still the same
    // as the requesting frame's.
    lldb_private::UnwindLLDB::RegisterSearchResult
    SavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc);

    bool
    ReadRegisterValueFromRegisterLocation (lldb_private::UnwindLLDB::RegisterLocation regloc,
                                           const lldb_private::RegisterInfo *reg_info,
                                           lldb_private::RegisterValue &value);

    bool
    WriteRegisterValueToRegisterLocation (lldb_private::UnwindLLDB::RegisterLocation regloc,
                                          const lldb_private::RegisterInfo *reg_info,
                                          const lldb_private::RegisterValue &value);

    //------------------------------------------------------------------
    /// If the unwind has to the caller frame has failed, try something else
    ///
    /// If lldb is using an assembly language based UnwindPlan for a frame and
    /// the unwind to the caller frame fails, try falling back to a generic
    /// UnwindPlan (architecture default unwindplan) to see if that might work
    /// better.  This is mostly helping to work around problems where the 
    /// assembly language inspection fails on hand-written assembly code.
    ///
    /// @return
    ///     Returns true if a fallback unwindplan was found & was installed.
    //------------------------------------------------------------------
    bool
    TryFallbackUnwindPlan ();

    // Get the contents of a general purpose (address-size) register for this frame
    // (usually retrieved from the next frame)
    bool
    ReadGPRValue (lldb::RegisterKind register_kind, uint32_t regnum, lldb::addr_t &value);

    lldb::UnwindPlanSP
    GetFastUnwindPlanForFrame ();

    lldb::UnwindPlanSP
    GetFullUnwindPlanForFrame ();

    void
    UnwindLogMsg (const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));

    void
    UnwindLogMsgVerbose (const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));

    bool
    IsUnwindPlanValidForCurrentPC(lldb::UnwindPlanSP unwind_plan_sp, int &valid_pc_offset);


    lldb_private::Thread& m_thread;

    ///
    // The following tell us how to retrieve the CALLER's register values (ie the "previous" frame, aka the frame above)
    // i.e. where THIS frame saved them
    ///

    lldb::UnwindPlanSP m_fast_unwind_plan_sp;     // may be NULL
    lldb::UnwindPlanSP m_full_unwind_plan_sp;
    lldb::UnwindPlanSP m_fallback_unwind_plan_sp; // may be NULL

    bool m_all_registers_available;               // Can we retrieve all regs or just nonvolatile regs?
    int m_frame_type;                             // enum FrameType

    lldb::addr_t m_cfa;
    lldb_private::Address m_start_pc;
    lldb_private::Address m_current_pc;

    int m_current_offset;                         // how far into the function we've executed; -1 if unknown
                                                  // 0 if no instructions have been executed yet.

    int m_current_offset_backed_up_one;           // how far into the function we've executed; -1 if unknown
                                                  // 0 if no instructions have been executed yet.
                                                  // On architectures where the return address on the stack points
                                                  // to the instruction after the CALL, this value will have 1
                                                  // subtracted from it.  Else a function that ends in a CALL will
                                                  // have an offset pointing into the next function's address range.
                                                  // m_current_pc has the actual address of the "current" pc.

    lldb_private::SymbolContext& m_sym_ctx;
    bool m_sym_ctx_valid;                         // if ResolveSymbolContextForAddress fails, don't try to use m_sym_ctx

    uint32_t m_frame_number;                      // What stack frame this RegisterContext is

    std::map<uint32_t, lldb_private::UnwindLLDB::RegisterLocation> m_registers; // where to find reg values for this frame

    lldb_private::UnwindLLDB& m_parent_unwind;    // The UnwindLLDB that is creating this RegisterContextLLDB

    //------------------------------------------------------------------
    // For RegisterContextLLDB only
    //------------------------------------------------------------------

    DISALLOW_COPY_AND_ASSIGN (RegisterContextLLDB);
};

} // namespace lldb_private

#endif  // lldb_RegisterContextLLDB_h_