ABI.h

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//===-- ABI.h ---------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLDB_TARGET_ABI_H
#define LLDB_TARGET_ABI_H
 
#include "lldb/Core/PluginInterface.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/DynamicRegisterInfo.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-forward.h"
#include "lldb/lldb-private.h"
 
#include "llvm/ADT/ArrayRef.h"
#include "llvm/MC/MCRegisterInfo.h"
 
namespace llvm {
class Type;
}
 
namespace lldb_private {
 
class ABI : public PluginInterface {
public:
  struct CallArgument {
    enum eType {
      HostPointer = 0, /* pointer to host data */
      TargetValue,     /* value is on the target or literal */
    };
    eType type;  /* value of eType */
    size_t size; /* size in bytes of this argument */
 
    lldb::addr_t value;                 /* literal value */
    std::unique_ptr<uint8_t[]> data_up; /* host data pointer */
  };
 
  ~ABI() override;
 
  virtual size_t GetRedZoneSize() const = 0;
 
  virtual bool PrepareTrivialCall(lldb_private::Thread &thread, lldb::addr_t sp,
                                  lldb::addr_t functionAddress,
                                  lldb::addr_t returnAddress,
                                  llvm::ArrayRef<lldb::addr_t> args) const = 0;
 
  // Prepare trivial call used from ThreadPlanFunctionCallUsingABI
  // AD:
  //  . Because i don't want to change other ABI's this is not declared pure
  //  virtual.
  //    The dummy implementation will simply fail.  Only HexagonABI will
  //    currently
  //    use this method.
  //  . Two PrepareTrivialCall's is not good design so perhaps this should be
  //  combined.
  //
  virtual bool PrepareTrivialCall(lldb_private::Thread &thread, lldb::addr_t sp,
                                  lldb::addr_t functionAddress,
                                  lldb::addr_t returnAddress,
                                  llvm::Type &prototype,
                                  llvm::ArrayRef<CallArgument> args) const;
 
  virtual bool GetArgumentValues(Thread &thread, ValueList &values) const = 0;
 
  lldb::ValueObjectSP GetReturnValueObject(Thread &thread, CompilerType &type,
                                           bool persistent = true) const;
 
  // specialized to work with llvm IR types
  lldb::ValueObjectSP GetReturnValueObject(Thread &thread, llvm::Type &type,
                                           bool persistent = true) const;
 
  // Set the Return value object in the current frame as though a function with
  virtual Status SetReturnValueObject(lldb::StackFrameSP &frame_sp,
                                      lldb::ValueObjectSP &new_value) = 0;
 
protected:
  // This is the method the ABI will call to actually calculate the return
  // value. Don't put it in a persistent value object, that will be done by the
  // ABI::GetReturnValueObject.
  virtual lldb::ValueObjectSP
  GetReturnValueObjectImpl(Thread &thread, CompilerType &ast_type) const = 0;
 
  // specialized to work with llvm IR types
  virtual lldb::ValueObjectSP
  GetReturnValueObjectImpl(Thread &thread, llvm::Type &ir_type) const;
 
  /// Request to get a Process shared pointer.
  ///
  /// This ABI object may not have been created with a Process object,
  /// or the Process object may no longer be alive.  Be sure to handle
  /// the case where the shared pointer returned does not have an
  /// object inside it.
  lldb::ProcessSP GetProcessSP() const { return m_process_wp.lock(); }
 
public:
  virtual lldb::UnwindPlanSP CreateFunctionEntryUnwindPlan() = 0;
 
  virtual lldb::UnwindPlanSP CreateDefaultUnwindPlan() = 0;
 
  virtual bool RegisterIsVolatile(const RegisterInfo *reg_info) = 0;
 
  virtual bool GetFallbackRegisterLocation(
      const RegisterInfo *reg_info,
      UnwindPlan::Row::AbstractRegisterLocation &unwind_regloc);
 
  // Should take a look at a call frame address (CFA) which is just the stack
  // pointer value upon entry to a function. ABIs usually impose alignment
  // restrictions (4, 8 or 16 byte aligned), and zero is usually not allowed.
  // This function should return true if "cfa" is valid call frame address for
  // the ABI, and false otherwise. This is used by the generic stack frame
  // unwinding code to help determine when a stack ends.
  virtual bool CallFrameAddressIsValid(lldb::addr_t cfa) = 0;
 
  // Validates a possible PC value and returns true if an opcode can be at
  // "pc".
  virtual bool CodeAddressIsValid(lldb::addr_t pc) = 0;
 
  /// Some targets might use bits in a code address to indicate a mode switch.
  /// ARM uses bit zero to signify a code address is thumb, so any ARM ABI
  /// plug-ins would strip those bits.
  /// @{
  virtual lldb::addr_t FixCodeAddress(lldb::addr_t pc);
  virtual lldb::addr_t FixDataAddress(lldb::addr_t pc);
  /// @}
 
  /// Use this method when you do not know, or do not care what kind of address
  /// you are fixing. On platforms where there would be a difference between the
  /// two types, it will pick the safest option.
  ///
  /// Its purpose is to signal that no specific choice was made and provide an
  /// alternative to randomly picking FixCode/FixData address. Which could break
  /// platforms where there is a difference (only Arm Thumb at this time).
  virtual lldb::addr_t FixAnyAddress(lldb::addr_t pc) {
    // On Arm Thumb fixing a code address zeroes the bottom bit, so FixData is
    // the safe choice. On any other platform (so far) code and data addresses
    // are fixed in the same way.
    return FixDataAddress(pc);
  }
 
  llvm::MCRegisterInfo &GetMCRegisterInfo() { return *m_mc_register_info_up; }
 
  virtual void
  AugmentRegisterInfo(std::vector<DynamicRegisterInfo::Register> &regs) = 0;
 
  virtual bool GetPointerReturnRegister(const char *&name) { return false; }
 
  virtual uint64_t GetStackFrameSize() { return 512 * 1024; }
 
  static lldb::ABISP FindPlugin(lldb::ProcessSP process_sp, const ArchSpec &arch);
 
  struct MemoryPermissions {
    // Both of these are sets of lldb::Permissions values.
    // Overlay are the permissions being applied to the original permissions.
    uint32_t overlay;
    // Effective is the result of applying the overlay to the original
    // permissions. Calculating this is done by the plugin because some
    // permission overlays are done as positive (add permissions) and some as
    // negative (remove permissions).
    uint32_t effective;
  };
 
  /// Get the effective memory permissions that result when the permissions
  /// referred to by a protection key are applied to the original permissions.
  ///
  /// This is intended for architectures that have some sort of permission
  /// overlay system. Where the protection key is used to look up a set of
  /// permissions that modifies the original permissions.
  ///
  /// \returns the overlay permissions (that the protection key refers to) and
  ///   the effective permissions. If the target does not have an overlay
  ///   system, or it does and the protection key is invalid, returns nullopt.
  virtual std::optional<MemoryPermissions>
  GetMemoryPermissions(lldb_private::RegisterContext &reg_ctx,
                       unsigned protection_key, uint32_t original_permissions) {
    return std::nullopt;
  }
 
protected:
  ABI(lldb::ProcessSP process_sp, std::unique_ptr<llvm::MCRegisterInfo> info_up)
      : m_process_wp(process_sp), m_mc_register_info_up(std::move(info_up)) {
    assert(m_mc_register_info_up && "ABI must have MCRegisterInfo");
  }
 
  /// Utility function to construct a MCRegisterInfo using the ArchSpec triple.
  /// Plugins wishing to customize the construction can construct the
  /// MCRegisterInfo themselves.
  static std::unique_ptr<llvm::MCRegisterInfo>
  MakeMCRegisterInfo(const ArchSpec &arch);
 
  lldb::ProcessWP m_process_wp;
  std::unique_ptr<llvm::MCRegisterInfo> m_mc_register_info_up;
 
private:
  ABI(const ABI &) = delete;
  const ABI &operator=(const ABI &) = delete;
};
 
class RegInfoBasedABI : public ABI {
public:
  void AugmentRegisterInfo(
      std::vector<DynamicRegisterInfo::Register> &regs) override;
 
protected:
  using ABI::ABI;
 
  bool GetRegisterInfoByName(llvm::StringRef name, RegisterInfo &info);
 
  virtual const RegisterInfo *GetRegisterInfoArray(uint32_t &count) = 0;
};
 
class MCBasedABI : public ABI {
public:
  void AugmentRegisterInfo(
      std::vector<DynamicRegisterInfo::Register> &regs) override;
 
  /// If the register name is of the form "<from_prefix>[<number>]" then change
  /// the name to "<to_prefix>[<number>]". Otherwise, leave the name unchanged.
  static void MapRegisterName(std::string &reg, llvm::StringRef from_prefix,
                              llvm::StringRef to_prefix);
 
protected:
  using ABI::ABI;
 
  /// Return eh_frame and dwarf numbers for the given register.
  virtual std::pair<uint32_t, uint32_t> GetEHAndDWARFNums(llvm::StringRef reg);
 
  /// Return the generic number of the given register.
  virtual uint32_t GetGenericNum(llvm::StringRef reg) = 0;
 
  /// For the given (capitalized) lldb register name, return the name of this
  /// register in the MCRegisterInfo struct.
  virtual std::string GetMCName(std::string reg) { return reg; }
};
 
} // namespace lldb_private
 
#endif // LLDB_TARGET_ABI_H