//===-- NativeRegisterContextLinux_mips64.cpp ---------------*- 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
//
//===----------------------------------------------------------------------===//

#if defined(__mips__)

#include "NativeRegisterContextLinux_mips64.h"


#include "Plugins/Process/Linux/NativeProcessLinux.h"
#include "Plugins/Process/Linux/Procfs.h"
#include "Plugins/Process/POSIX/ProcessPOSIXLog.h"
#include "Plugins/Process/Utility/RegisterContextLinux_mips.h"
#include "Plugins/Process/Utility/RegisterContextLinux_mips64.h"
#include "lldb/Core/EmulateInstruction.h"
#include "lldb/Host/Host.h"
#include "lldb/Host/HostInfo.h"
#include "lldb/Utility/DataBufferHeap.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-enumerations.h"
#include "lldb/lldb-private-enumerations.h"
#define NT_MIPS_MSA 0x600
#define CONFIG5_FRE (1 << 8)
#define SR_FR (1 << 26)
#define NUM_REGISTERS 32

#include <asm/ptrace.h>
#include <sys/ptrace.h>

#ifndef PTRACE_GET_WATCH_REGS
enum pt_watch_style { pt_watch_style_mips32, pt_watch_style_mips64 };
struct mips32_watch_regs {
  uint32_t watchlo[8];
  uint16_t watchhi[8];
  uint16_t watch_masks[8];
  uint32_t num_valid;
} __attribute__((aligned(8)));

struct mips64_watch_regs {
  uint64_t watchlo[8];
  uint16_t watchhi[8];
  uint16_t watch_masks[8];
  uint32_t num_valid;
} __attribute__((aligned(8)));

struct pt_watch_regs {
  enum pt_watch_style style;
  union {
    struct mips32_watch_regs mips32;
    struct mips64_watch_regs mips64;
  };
};

#define PTRACE_GET_WATCH_REGS 0xd0
#define PTRACE_SET_WATCH_REGS 0xd1
#endif

#define W (1 << 0)
#define R (1 << 1)
#define I (1 << 2)

#define IRW (I | R | W)

#ifndef PTRACE_GETREGSET
#define PTRACE_GETREGSET 0x4204
#endif
struct pt_watch_regs default_watch_regs;

using namespace lldb_private;
using namespace lldb_private::process_linux;

std::unique_ptr<NativeRegisterContextLinux>
NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
    const ArchSpec &target_arch, NativeThreadProtocol &native_thread) {
  return std::make_unique<NativeRegisterContextLinux_mips64>(target_arch,
                                                              native_thread);
}

#define REG_CONTEXT_SIZE                                                       \
  (GetRegisterInfoInterface().GetGPRSize() + sizeof(FPR_linux_mips) +          \
   sizeof(MSA_linux_mips))

// NativeRegisterContextLinux_mips64 members.

static RegisterInfoInterface *
CreateRegisterInfoInterface(const ArchSpec &target_arch) {
  if ((target_arch.GetMachine() == llvm::Triple::mips) ||
       (target_arch.GetMachine() == llvm::Triple::mipsel)) {
    // 32-bit hosts run with a RegisterContextLinux_mips context.
    return new RegisterContextLinux_mips(
        target_arch, NativeRegisterContextLinux_mips64::IsMSAAvailable());
  } else {
    return new RegisterContextLinux_mips64(
        target_arch, NativeRegisterContextLinux_mips64::IsMSAAvailable());
  }
}

NativeRegisterContextLinux_mips64::NativeRegisterContextLinux_mips64(
    const ArchSpec &target_arch, NativeThreadProtocol &native_thread)
    : NativeRegisterContextLinux(native_thread,
                                 CreateRegisterInfoInterface(target_arch)) {
  switch (target_arch.GetMachine()) {
  case llvm::Triple::mips:
  case llvm::Triple::mipsel:
    m_reg_info.num_registers = k_num_registers_mips;
    m_reg_info.num_gpr_registers = k_num_gpr_registers_mips;
    m_reg_info.num_fpr_registers = k_num_fpr_registers_mips;
    m_reg_info.last_gpr = k_last_gpr_mips;
    m_reg_info.first_fpr = k_first_fpr_mips;
    m_reg_info.last_fpr = k_last_fpr_mips;
    m_reg_info.first_msa = k_first_msa_mips;
    m_reg_info.last_msa = k_last_msa_mips;
    break;
  case llvm::Triple::mips64:
  case llvm::Triple::mips64el:
    m_reg_info.num_registers = k_num_registers_mips64;
    m_reg_info.num_gpr_registers = k_num_gpr_registers_mips64;
    m_reg_info.num_fpr_registers = k_num_fpr_registers_mips64;
    m_reg_info.last_gpr = k_last_gpr_mips64;
    m_reg_info.first_fpr = k_first_fpr_mips64;
    m_reg_info.last_fpr = k_last_fpr_mips64;
    m_reg_info.first_msa = k_first_msa_mips64;
    m_reg_info.last_msa = k_last_msa_mips64;
    break;
  default:
    assert(false && "Unhandled target architecture.");
    break;
  }

  // Initialize m_iovec to point to the buffer and buffer size using the
  // conventions of Berkeley style UIO structures, as required by PTRACE
  // extensions.
  m_iovec.iov_base = &m_msa;
  m_iovec.iov_len = sizeof(MSA_linux_mips);

  // init h/w watchpoint addr map
  for (int index = 0; index <= MAX_NUM_WP; index++)
    hw_addr_map[index] = LLDB_INVALID_ADDRESS;

  ::memset(&m_gpr, 0, sizeof(GPR_linux_mips));
  ::memset(&m_fpr, 0, sizeof(FPR_linux_mips));
  ::memset(&m_msa, 0, sizeof(MSA_linux_mips));
}

uint32_t NativeRegisterContextLinux_mips64::GetRegisterSetCount() const {
  switch (GetRegisterInfoInterface().GetTargetArchitecture().GetMachine()) {
  case llvm::Triple::mips64:
  case llvm::Triple::mips64el: {
    const auto context = static_cast<const RegisterContextLinux_mips64 &>
                         (GetRegisterInfoInterface());
    return context.GetRegisterSetCount();
  }
  case llvm::Triple::mips:
  case llvm::Triple::mipsel: {
    const auto context = static_cast<const RegisterContextLinux_mips &>
                         (GetRegisterInfoInterface());
    return context.GetRegisterSetCount();
  }
  default:
    llvm_unreachable("Unhandled target architecture.");
  }
}

lldb::addr_t NativeRegisterContextLinux_mips64::GetPCfromBreakpointLocation(
    lldb::addr_t fail_value) {
  Status error;
  RegisterValue pc_value;
  lldb::addr_t pc = fail_value;
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_BREAKPOINTS));
  LLDB_LOG(log, "Reading PC from breakpoint location");

  // PC register is at index 34 of the register array
  const RegisterInfo *const pc_info_p = GetRegisterInfoAtIndex(gpr_pc_mips64);

  error = ReadRegister(pc_info_p, pc_value);
  if (error.Success()) {
    pc = pc_value.GetAsUInt64();

    // CAUSE register is at index 37 of the register array
    const RegisterInfo *const cause_info_p =
        GetRegisterInfoAtIndex(gpr_cause_mips64);
    RegisterValue cause_value;

    ReadRegister(cause_info_p, cause_value);

    uint64_t cause = cause_value.GetAsUInt64();
    LLDB_LOG(log, "PC {0:x} cause {1:x}", pc, cause);

    /*
     * The breakpoint might be in a delay slot. In this case PC points
     * to the delayed branch instruction rather then the instruction
     * in the delay slot. If the CAUSE.BD flag is set then adjust the
     * PC based on the size of the branch instruction.
    */
    if ((cause & (1 << 31)) != 0) {
      lldb::addr_t branch_delay = 0;
      branch_delay =
          4; // FIXME - Adjust according to size of branch instruction at PC
      pc = pc + branch_delay;
      pc_value.SetUInt64(pc);
      WriteRegister(pc_info_p, pc_value);
      LLDB_LOG(log, "New PC {0:x}", pc);
    }
  }

  return pc;
}

const RegisterSet *
NativeRegisterContextLinux_mips64::GetRegisterSet(uint32_t set_index) const {
  if (set_index >= GetRegisterSetCount())
    return nullptr;

  switch (GetRegisterInfoInterface().GetTargetArchitecture().GetMachine()) {
  case llvm::Triple::mips64:
  case llvm::Triple::mips64el: {
    const auto context = static_cast<const RegisterContextLinux_mips64 &>
                          (GetRegisterInfoInterface());
    return context.GetRegisterSet(set_index);
  }
  case llvm::Triple::mips:
  case llvm::Triple::mipsel: {
    const auto context = static_cast<const RegisterContextLinux_mips &>
                         (GetRegisterInfoInterface());
    return context.GetRegisterSet(set_index);
  }
  default:
    llvm_unreachable("Unhandled target architecture.");
  }
}

lldb_private::Status
NativeRegisterContextLinux_mips64::ReadRegister(const RegisterInfo *reg_info,
                                                RegisterValue &reg_value) {
  Status error;

  if (!reg_info) {
    error.SetErrorString("reg_info NULL");
    return error;
  }

  const uint32_t reg = reg_info->kinds[lldb::eRegisterKindLLDB];
  uint8_t byte_size = reg_info->byte_size;
  if (reg == LLDB_INVALID_REGNUM) {
    // This is likely an internal register for lldb use only and should not be
    // directly queried.
    error.SetErrorStringWithFormat("register \"%s\" is an internal-only lldb "
                                   "register, cannot read directly",
                                   reg_info->name);
    return error;
  }

  if (IsMSA(reg) && !IsMSAAvailable()) {
    error.SetErrorString("MSA not available on this processor");
    return error;
  }

  if (IsMSA(reg) || IsFPR(reg)) {
    uint8_t *src = nullptr;
    lldbassert(reg_info->byte_offset < sizeof(UserArea));

    error = ReadCP1();

    if (!error.Success()) {
      error.SetErrorString("failed to read co-processor 1 register");
      return error;
    }

    if (IsFPR(reg)) {
      if (IsFR0() && (byte_size != 4)) {
        byte_size = 4;
        uint8_t ptrace_index;
        ptrace_index = reg_info->kinds[lldb::eRegisterKindProcessPlugin];
        src = ReturnFPOffset(ptrace_index, reg_info->byte_offset);
      } else
        src = (uint8_t *)&m_fpr + reg_info->byte_offset - sizeof(m_gpr);
    } else
      src = (uint8_t *)&m_msa + reg_info->byte_offset -
            (sizeof(m_gpr) + sizeof(m_fpr));
    switch (byte_size) {
    case 4:
      reg_value.SetUInt32(*(uint32_t *)src);
      break;
    case 8:
      reg_value.SetUInt64(*(uint64_t *)src);
      break;
    case 16:
      reg_value.SetBytes((const void *)src, 16, GetByteOrder());
      break;
    default:
      assert(false && "Unhandled data size.");
      error.SetErrorStringWithFormat("unhandled byte size: %" PRIu32,
                                     reg_info->byte_size);
      break;
    }
  } else {
    error = ReadRegisterRaw(reg, reg_value);
  }

  return error;
}

lldb_private::Status NativeRegisterContextLinux_mips64::WriteRegister(
    const RegisterInfo *reg_info, const RegisterValue &reg_value) {
  Status error;

  assert(reg_info && "reg_info is null");

  const uint32_t reg_index = reg_info->kinds[lldb::eRegisterKindLLDB];

  if (reg_index == LLDB_INVALID_REGNUM)
    return Status("no lldb regnum for %s", reg_info && reg_info->name
                                               ? reg_info->name
                                               : "<unknown register>");

  if (IsMSA(reg_index) && !IsMSAAvailable()) {
    error.SetErrorString("MSA not available on this processor");
    return error;
  }

  if (IsFPR(reg_index) || IsMSA(reg_index)) {
    uint8_t *dst = nullptr;
    uint64_t *src = nullptr;
    uint8_t byte_size = reg_info->byte_size;
    lldbassert(reg_info->byte_offset < sizeof(UserArea));

    // Initialise the FP and MSA buffers by reading all co-processor 1
    // registers
    ReadCP1();

    if (IsFPR(reg_index)) {
      if (IsFR0() && (byte_size != 4)) {
        byte_size = 4;
        uint8_t ptrace_index;
        ptrace_index = reg_info->kinds[lldb::eRegisterKindProcessPlugin];
        dst = ReturnFPOffset(ptrace_index, reg_info->byte_offset);
      } else
        dst = (uint8_t *)&m_fpr + reg_info->byte_offset - sizeof(m_gpr);
    } else
      dst = (uint8_t *)&m_msa + reg_info->byte_offset -
            (sizeof(m_gpr) + sizeof(m_fpr));
    switch (byte_size) {
    case 4:
      *(uint32_t *)dst = reg_value.GetAsUInt32();
      break;
    case 8:
      *(uint64_t *)dst = reg_value.GetAsUInt64();
      break;
    case 16:
      src = (uint64_t *)reg_value.GetBytes();
      *(uint64_t *)dst = *src;
      *(uint64_t *)(dst + 8) = *(src + 1);
      break;
    default:
      assert(false && "Unhandled data size.");
      error.SetErrorStringWithFormat("unhandled byte size: %" PRIu32,
                                     reg_info->byte_size);
      break;
    }
    error = WriteCP1();
    if (!error.Success()) {
      error.SetErrorString("failed to write co-processor 1 register");
      return error;
    }
  } else {
    error = WriteRegisterRaw(reg_index, reg_value);
  }

  return error;
}

Status NativeRegisterContextLinux_mips64::ReadAllRegisterValues(
    lldb::DataBufferSP &data_sp) {
  Status error;

  data_sp.reset(new DataBufferHeap(REG_CONTEXT_SIZE, 0));
  error = ReadGPR();
  if (!error.Success()) {
    error.SetErrorString("ReadGPR() failed");
    return error;
  }

  error = ReadCP1();
  if (!error.Success()) {
    error.SetErrorString("ReadCP1() failed");
    return error;
  }

  uint8_t *dst = data_sp->GetBytes();
  ::memcpy(dst, &m_gpr, GetRegisterInfoInterface().GetGPRSize());
  dst += GetRegisterInfoInterface().GetGPRSize();

  ::memcpy(dst, &m_fpr, GetFPRSize());
  dst += GetFPRSize();

  ::memcpy(dst, &m_msa, sizeof(MSA_linux_mips));

  return error;
}

Status NativeRegisterContextLinux_mips64::WriteAllRegisterValues(
    const lldb::DataBufferSP &data_sp) {
  Status error;

  if (!data_sp) {
    error.SetErrorStringWithFormat(
        "NativeRegisterContextLinux_mips64::%s invalid data_sp provided",
        __FUNCTION__);
    return error;
  }

  if (data_sp->GetByteSize() != REG_CONTEXT_SIZE) {
    error.SetErrorStringWithFormat(
        "NativeRegisterContextLinux_mips64::%s data_sp contained mismatched "
        "data size, expected %" PRIu64 ", actual %" PRIu64,
        __FUNCTION__, REG_CONTEXT_SIZE, data_sp->GetByteSize());
    return error;
  }

  uint8_t *src = data_sp->GetBytes();
  if (src == nullptr) {
    error.SetErrorStringWithFormat("NativeRegisterContextLinux_mips64::%s "
                                   "DataBuffer::GetBytes() returned a null "
                                   "pointer",
                                   __FUNCTION__);
    return error;
  }

  ::memcpy(&m_gpr, src, GetRegisterInfoInterface().GetGPRSize());
  src += GetRegisterInfoInterface().GetGPRSize();

  ::memcpy(&m_fpr, src, GetFPRSize());
  src += GetFPRSize();

  ::memcpy(&m_msa, src, sizeof(MSA_linux_mips));

  error = WriteGPR();
  if (!error.Success()) {
    error.SetErrorStringWithFormat(
        "NativeRegisterContextLinux_mips64::%s WriteGPR() failed",
        __FUNCTION__);
    return error;
  }

  error = WriteCP1();
  if (!error.Success()) {
    error.SetErrorStringWithFormat(
        "NativeRegisterContextLinux_mips64::%s WriteCP1() failed",
        __FUNCTION__);
    return error;
  }

  return error;
}

Status NativeRegisterContextLinux_mips64::ReadCP1() {
  Status error;

  uint8_t *src = nullptr;
  uint8_t *dst = nullptr;

  lldb::ByteOrder byte_order = GetByteOrder();

  bool IsBigEndian = (byte_order == lldb::eByteOrderBig);

  if (IsMSAAvailable()) {
    error = NativeRegisterContextLinux::ReadRegisterSet(
        &m_iovec, sizeof(MSA_linux_mips), NT_MIPS_MSA);
    src = (uint8_t *)&m_msa + (IsBigEndian * 8);
    dst = (uint8_t *)&m_fpr;
    for (int i = 0; i < NUM_REGISTERS; i++) {
      // Copy fp values from msa buffer fetched via ptrace
      *(uint64_t *)dst = *(uint64_t *)src;
      src = src + 16;
      dst = dst + 8;
    }
    m_fpr.fir = m_msa.fir;
    m_fpr.fcsr = m_msa.fcsr;
    m_fpr.config5 = m_msa.config5;
  } else {
    error = NativeRegisterContextLinux::ReadFPR();
  }
  return error;
}

uint8_t *
NativeRegisterContextLinux_mips64::ReturnFPOffset(uint8_t reg_index,
                                                  uint32_t byte_offset) {

  uint8_t *fp_buffer_ptr = nullptr;
  lldb::ByteOrder byte_order = GetByteOrder();
  bool IsBigEndian = (byte_order == lldb::eByteOrderBig);
  if (reg_index % 2) {
    uint8_t offset_diff = (IsBigEndian) ? 8 : 4;
    fp_buffer_ptr =
        (uint8_t *)&m_fpr + byte_offset - offset_diff - sizeof(m_gpr);
  } else {
    fp_buffer_ptr =
        (uint8_t *)&m_fpr + byte_offset + 4 * (IsBigEndian) - sizeof(m_gpr);
  }
  return fp_buffer_ptr;
}

Status NativeRegisterContextLinux_mips64::WriteCP1() {
  Status error;

  uint8_t *src = nullptr;
  uint8_t *dst = nullptr;

  lldb::ByteOrder byte_order = GetByteOrder();

  bool IsBigEndian = (byte_order == lldb::eByteOrderBig);

  if (IsMSAAvailable()) {
    dst = (uint8_t *)&m_msa + (IsBigEndian * 8);
    src = (uint8_t *)&m_fpr;
    for (int i = 0; i < NUM_REGISTERS; i++) {
      // Copy fp values to msa buffer for ptrace
      *(uint64_t *)dst = *(uint64_t *)src;
      dst = dst + 16;
      src = src + 8;
    }
    m_msa.fir = m_fpr.fir;
    m_msa.fcsr = m_fpr.fcsr;
    m_msa.config5 = m_fpr.config5;
    error = NativeRegisterContextLinux::WriteRegisterSet(
        &m_iovec, sizeof(MSA_linux_mips), NT_MIPS_MSA);
  } else {
    error = NativeRegisterContextLinux::WriteFPR();
  }

  return error;
}

bool NativeRegisterContextLinux_mips64::IsFR0() {
  const RegisterInfo *const reg_info_p = GetRegisterInfoAtIndex(gpr_sr_mips64);

  RegisterValue reg_value;
  ReadRegister(reg_info_p, reg_value);

  uint64_t value = reg_value.GetAsUInt64();

  return (!(value & SR_FR));
}

bool NativeRegisterContextLinux_mips64::IsFRE() {
  const RegisterInfo *const reg_info_p =
      GetRegisterInfoAtIndex(gpr_config5_mips64);

  RegisterValue reg_value;
  ReadRegister(reg_info_p, reg_value);

  uint64_t config5 = reg_value.GetAsUInt64();

  return (config5 & CONFIG5_FRE);
}

bool NativeRegisterContextLinux_mips64::IsFPR(uint32_t reg_index) const {
  return (m_reg_info.first_fpr <= reg_index &&
          reg_index <= m_reg_info.last_fpr);
}

static uint32_t GetWatchHi(struct pt_watch_regs *regs, uint32_t index) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    return regs->mips32.watchhi[index];
  else if (regs->style == pt_watch_style_mips64)
    return regs->mips64.watchhi[index];
  LLDB_LOG(log, "Invalid watch register style");
  return 0;
}

static void SetWatchHi(struct pt_watch_regs *regs, uint32_t index,
                       uint16_t value) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    regs->mips32.watchhi[index] = value;
  else if (regs->style == pt_watch_style_mips64)
    regs->mips64.watchhi[index] = value;
  LLDB_LOG(log, "Invalid watch register style");
  return;
}

static lldb::addr_t GetWatchLo(struct pt_watch_regs *regs, uint32_t index) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    return regs->mips32.watchlo[index];
  else if (regs->style == pt_watch_style_mips64)
    return regs->mips64.watchlo[index];
  LLDB_LOG(log, "Invalid watch register style");
  return LLDB_INVALID_ADDRESS;
}

static void SetWatchLo(struct pt_watch_regs *regs, uint32_t index,
                       uint64_t value) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    regs->mips32.watchlo[index] = (uint32_t)value;
  else if (regs->style == pt_watch_style_mips64)
    regs->mips64.watchlo[index] = value;
  else
    LLDB_LOG(log, "Invalid watch register style");
}

static uint32_t GetIRWMask(struct pt_watch_regs *regs, uint32_t index) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    return regs->mips32.watch_masks[index] & IRW;
  else if (regs->style == pt_watch_style_mips64)
    return regs->mips64.watch_masks[index] & IRW;
  LLDB_LOG(log, "Invalid watch register style");
  return 0;
}

static uint32_t GetRegMask(struct pt_watch_regs *regs, uint32_t index) {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  if (regs->style == pt_watch_style_mips32)
    return regs->mips32.watch_masks[index] & ~IRW;
  else if (regs->style == pt_watch_style_mips64)
    return regs->mips64.watch_masks[index] & ~IRW;
  LLDB_LOG(log, "Invalid watch register style");
  return 0;
}

static lldb::addr_t GetRangeMask(lldb::addr_t mask) {
  lldb::addr_t mask_bit = 1;
  while (mask_bit < mask) {
    mask = mask | mask_bit;
    mask_bit <<= 1;
  }
  return mask;
}

static int GetVacantWatchIndex(struct pt_watch_regs *regs, lldb::addr_t addr,
                               uint32_t size, uint32_t irw,
                               uint32_t num_valid) {
  lldb::addr_t last_byte = addr + size - 1;
  lldb::addr_t mask = GetRangeMask(addr ^ last_byte) | IRW;
  lldb::addr_t base_addr = addr & ~mask;

  // Check if this address is already watched by previous watch points.
  lldb::addr_t lo;
  uint16_t hi;
  uint32_t vacant_watches = 0;
  for (uint32_t index = 0; index < num_valid; index++) {
    lo = GetWatchLo(regs, index);
    if (lo != 0 && irw == ((uint32_t)lo & irw)) {
      hi = GetWatchHi(regs, index) | IRW;
      lo &= ~(lldb::addr_t)hi;
      if (addr >= lo && last_byte <= (lo + hi))
        return index;
    } else
      vacant_watches++;
  }

  // Now try to find a vacant index
  if (vacant_watches > 0) {
    vacant_watches = 0;
    for (uint32_t index = 0; index < num_valid; index++) {
      lo = GetWatchLo(regs, index);
      if (lo == 0 && irw == (GetIRWMask(regs, index) & irw)) {
        if (mask <= (GetRegMask(regs, index) | IRW)) {
          // It fits, we can use it.
          SetWatchLo(regs, index, base_addr | irw);
          SetWatchHi(regs, index, mask & ~IRW);
          return index;
        } else {
          // It doesn't fit, but has the proper IRW capabilities
          vacant_watches++;
        }
      }
    }

    if (vacant_watches > 1) {
      // Split this watchpoint accross several registers
      struct pt_watch_regs regs_copy;
      regs_copy = *regs;
      lldb::addr_t break_addr;
      uint32_t segment_size;
      for (uint32_t index = 0; index < num_valid; index++) {
        lo = GetWatchLo(&regs_copy, index);
        hi = GetRegMask(&regs_copy, index) | IRW;
        if (lo == 0 && irw == (hi & irw)) {
          lo = addr & ~(lldb::addr_t)hi;
          break_addr = lo + hi + 1;
          if (break_addr >= addr + size)
            segment_size = size;
          else
            segment_size = break_addr - addr;
          mask = GetRangeMask(addr ^ (addr + segment_size - 1));
          SetWatchLo(&regs_copy, index, (addr & ~mask) | irw);
          SetWatchHi(&regs_copy, index, mask & ~IRW);
          if (break_addr >= addr + size) {
            *regs = regs_copy;
            return index;
          }
          size = addr + size - break_addr;
          addr = break_addr;
        }
      }
    }
  }
  return LLDB_INVALID_INDEX32;
}

bool NativeRegisterContextLinux_mips64::IsMSA(uint32_t reg_index) const {
  return (m_reg_info.first_msa <= reg_index &&
          reg_index <= m_reg_info.last_msa);
}

bool NativeRegisterContextLinux_mips64::IsMSAAvailable() {
  MSA_linux_mips msa_buf;
  unsigned int regset = NT_MIPS_MSA;

  Status error = NativeProcessLinux::PtraceWrapper(
      PTRACE_GETREGSET, Host::GetCurrentProcessID(),
      static_cast<void *>(&regset), &msa_buf, sizeof(MSA_linux_mips));

  if (error.Success() && msa_buf.mir) {
    return true;
  }

  return false;
}

Status NativeRegisterContextLinux_mips64::IsWatchpointHit(uint32_t wp_index,
                                                          bool &is_hit) {
  if (wp_index >= NumSupportedHardwareWatchpoints())
    return Status("Watchpoint index out of range");

  // reading the current state of watch regs
  struct pt_watch_regs watch_readback;
  Status error = DoReadWatchPointRegisterValue(
      m_thread.GetID(), static_cast<void *>(&watch_readback));

  if (GetWatchHi(&watch_readback, wp_index) & (IRW)) {
    // clear hit flag in watchhi
    SetWatchHi(&watch_readback, wp_index,
               (GetWatchHi(&watch_readback, wp_index) & ~(IRW)));
    DoWriteWatchPointRegisterValue(m_thread.GetID(),
                                   static_cast<void *>(&watch_readback));

    is_hit = true;
    return error;
  }
  is_hit = false;
  return error;
}

Status NativeRegisterContextLinux_mips64::GetWatchpointHitIndex(
    uint32_t &wp_index, lldb::addr_t trap_addr) {
  uint32_t num_hw_wps = NumSupportedHardwareWatchpoints();
  for (wp_index = 0; wp_index < num_hw_wps; ++wp_index) {
    bool is_hit;
    Status error = IsWatchpointHit(wp_index, is_hit);
    if (error.Fail()) {
      wp_index = LLDB_INVALID_INDEX32;
    } else if (is_hit) {
      return error;
    }
  }
  wp_index = LLDB_INVALID_INDEX32;
  return Status();
}

Status NativeRegisterContextLinux_mips64::IsWatchpointVacant(uint32_t wp_index,
                                                             bool &is_vacant) {
  is_vacant = false;
  return Status("MIPS TODO: "
                "NativeRegisterContextLinux_mips64::IsWatchpointVacant not "
                "implemented");
}

bool NativeRegisterContextLinux_mips64::ClearHardwareWatchpoint(
    uint32_t wp_index) {
  if (wp_index >= NumSupportedHardwareWatchpoints())
    return false;

  struct pt_watch_regs regs;
  // First reading the current state of watch regs
  DoReadWatchPointRegisterValue(m_thread.GetID(), static_cast<void *>(&regs));

  if (regs.style == pt_watch_style_mips32) {
    regs.mips32.watchlo[wp_index] = default_watch_regs.mips32.watchlo[wp_index];
    regs.mips32.watchhi[wp_index] = default_watch_regs.mips32.watchhi[wp_index];
    regs.mips32.watch_masks[wp_index] =
        default_watch_regs.mips32.watch_masks[wp_index];
  } else // pt_watch_style_mips64
  {
    regs.mips64.watchlo[wp_index] = default_watch_regs.mips64.watchlo[wp_index];
    regs.mips64.watchhi[wp_index] = default_watch_regs.mips64.watchhi[wp_index];
    regs.mips64.watch_masks[wp_index] =
        default_watch_regs.mips64.watch_masks[wp_index];
  }

  Status error = DoWriteWatchPointRegisterValue(m_thread.GetID(),
                                                static_cast<void *>(&regs));
  if (!error.Fail()) {
    hw_addr_map[wp_index] = LLDB_INVALID_ADDRESS;
    return true;
  }
  return false;
}

Status NativeRegisterContextLinux_mips64::ClearAllHardwareWatchpoints() {
  return DoWriteWatchPointRegisterValue(
      m_thread.GetID(), static_cast<void *>(&default_watch_regs));
}

Status NativeRegisterContextLinux_mips64::SetHardwareWatchpointWithIndex(
    lldb::addr_t addr, size_t size, uint32_t watch_flags, uint32_t wp_index) {
  Status error;
  error.SetErrorString("MIPS TODO: "
                       "NativeRegisterContextLinux_mips64::"
                       "SetHardwareWatchpointWithIndex not implemented");
  return error;
}

uint32_t NativeRegisterContextLinux_mips64::SetHardwareWatchpoint(
    lldb::addr_t addr, size_t size, uint32_t watch_flags) {
  struct pt_watch_regs regs;

  // First reading the current state of watch regs
  DoReadWatchPointRegisterValue(m_thread.GetID(), static_cast<void *>(&regs));

  // Try if a new watch point fits in this state
  int index = GetVacantWatchIndex(&regs, addr, size, watch_flags,
                                  NumSupportedHardwareWatchpoints());

  // New watchpoint doesn't fit
  if (index == LLDB_INVALID_INDEX32)
    return LLDB_INVALID_INDEX32;

  // It fits, so we go ahead with updating the state of watch regs
  DoWriteWatchPointRegisterValue(m_thread.GetID(), static_cast<void *>(&regs));

  // Storing exact address
  hw_addr_map[index] = addr;
  return index;
}

lldb::addr_t
NativeRegisterContextLinux_mips64::GetWatchpointAddress(uint32_t wp_index) {
  if (wp_index >= NumSupportedHardwareWatchpoints())
    return LLDB_INVALID_ADDRESS;

  return hw_addr_map[wp_index];
}

struct EmulatorBaton {
  lldb::addr_t m_watch_hit_addr;
  NativeProcessLinux *m_process;
  NativeRegisterContext *m_reg_context;

  EmulatorBaton(NativeProcessLinux *process, NativeRegisterContext *reg_context)
      : m_watch_hit_addr(LLDB_INVALID_ADDRESS), m_process(process),
        m_reg_context(reg_context) {}
};

static size_t ReadMemoryCallback(EmulateInstruction *instruction, void *baton,
                                 const EmulateInstruction::Context &context,
                                 lldb::addr_t addr, void *dst, size_t length) {
  size_t bytes_read;
  EmulatorBaton *emulator_baton = static_cast<EmulatorBaton *>(baton);
  emulator_baton->m_process->ReadMemory(addr, dst, length, bytes_read);
  return bytes_read;
}

static size_t WriteMemoryCallback(EmulateInstruction *instruction, void *baton,
                                  const EmulateInstruction::Context &context,
                                  lldb::addr_t addr, const void *dst,
                                  size_t length) {
  return length;
}

static bool ReadRegisterCallback(EmulateInstruction *instruction, void *baton,
                                 const RegisterInfo *reg_info,
                                 RegisterValue &reg_value) {
  EmulatorBaton *emulator_baton = static_cast<EmulatorBaton *>(baton);

  const RegisterInfo *full_reg_info =
      emulator_baton->m_reg_context->GetRegisterInfo(
          lldb::eRegisterKindDWARF, reg_info->kinds[lldb::eRegisterKindDWARF]);

  Status error =
      emulator_baton->m_reg_context->ReadRegister(full_reg_info, reg_value);
  if (error.Success())
    return true;

  return false;
}

static bool WriteRegisterCallback(EmulateInstruction *instruction, void *baton,
                                  const EmulateInstruction::Context &context,
                                  const RegisterInfo *reg_info,
                                  const RegisterValue &reg_value) {
  if (reg_info->kinds[lldb::eRegisterKindDWARF] == dwarf_bad_mips64) {
    EmulatorBaton *emulator_baton = static_cast<EmulatorBaton *>(baton);
    emulator_baton->m_watch_hit_addr = reg_value.GetAsUInt64();
  }

  return true;
}

/*
 * MIPS Linux kernel returns a masked address (last 3bits are masked)
 * when a HW watchpoint is hit. However user may not have set a watchpoint
 * on this address. Emulate instruction at PC and find the base address of
 * the load/store instruction. This will give the exact address used to
 * read/write the variable. Send this exact address to client so that
 * it can decide to stop or continue the thread.
*/
lldb::addr_t
NativeRegisterContextLinux_mips64::GetWatchpointHitAddress(uint32_t wp_index) {
  if (wp_index >= NumSupportedHardwareWatchpoints())
    return LLDB_INVALID_ADDRESS;

  lldb_private::ArchSpec arch;
  arch = GetRegisterInfoInterface().GetTargetArchitecture();
  std::unique_ptr<EmulateInstruction> emulator_up(
      EmulateInstruction::FindPlugin(arch, lldb_private::eInstructionTypeAny,
                                     nullptr));

  if (emulator_up == nullptr)
    return LLDB_INVALID_ADDRESS;

  EmulatorBaton baton(
      static_cast<NativeProcessLinux *>(&m_thread.GetProcess()), this);
  emulator_up->SetBaton(&baton);
  emulator_up->SetReadMemCallback(&ReadMemoryCallback);
  emulator_up->SetReadRegCallback(&ReadRegisterCallback);
  emulator_up->SetWriteMemCallback(&WriteMemoryCallback);
  emulator_up->SetWriteRegCallback(&WriteRegisterCallback);

  if (!emulator_up->ReadInstruction())
    return LLDB_INVALID_ADDRESS;

  if (emulator_up->EvaluateInstruction(lldb::eEmulateInstructionOptionNone))
    return baton.m_watch_hit_addr;

  return LLDB_INVALID_ADDRESS;
}

uint32_t NativeRegisterContextLinux_mips64::NumSupportedHardwareWatchpoints() {
  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_WATCHPOINTS));
  struct pt_watch_regs regs;
  static int num_valid = 0;
  if (!num_valid) {
    DoReadWatchPointRegisterValue(m_thread.GetID(), static_cast<void *>(&regs));
    default_watch_regs =
        regs; // Keeping default watch regs values for future use
    switch (regs.style) {
    case pt_watch_style_mips32:
      num_valid = regs.mips32.num_valid; // Using num_valid as cache
      return num_valid;
    case pt_watch_style_mips64:
      num_valid = regs.mips64.num_valid;
      return num_valid;
    }
    LLDB_LOG(log, "Invalid watch register style");
    return 0;
  }
  return num_valid;
}

Status
NativeRegisterContextLinux_mips64::ReadRegisterRaw(uint32_t reg_index,
                                                   RegisterValue &value) {
  const RegisterInfo *const reg_info = GetRegisterInfoAtIndex(reg_index);

  if (!reg_info)
    return Status("register %" PRIu32 " not found", reg_index);

  uint32_t offset = reg_info->kinds[lldb::eRegisterKindProcessPlugin];

  if ((offset == ptrace_sr_mips) || (offset == ptrace_config5_mips))
    return Read_SR_Config(reg_info->byte_offset, reg_info->name,
                          reg_info->byte_size, value);

  return DoReadRegisterValue(offset, reg_info->name, reg_info->byte_size,
                             value);
}

Status NativeRegisterContextLinux_mips64::WriteRegisterRaw(
    uint32_t reg_index, const RegisterValue &value) {
  const RegisterInfo *const reg_info = GetRegisterInfoAtIndex(reg_index);

  if (!reg_info)
    return Status("register %" PRIu32 " not found", reg_index);

  if (reg_info->invalidate_regs)
    lldbassert(false && "reg_info->invalidate_regs is unhandled");

  uint32_t offset = reg_info->kinds[lldb::eRegisterKindProcessPlugin];
  return DoWriteRegisterValue(offset, reg_info->name, value);
}

Status NativeRegisterContextLinux_mips64::Read_SR_Config(uint32_t offset,
                                                         const char *reg_name,
                                                         uint32_t size,
                                                         RegisterValue &value) {
  GPR_linux_mips regs;
  ::memset(&regs, 0, sizeof(GPR_linux_mips));

  Status error = NativeProcessLinux::PtraceWrapper(
      PTRACE_GETREGS, m_thread.GetID(), NULL, &regs, sizeof regs);
  if (error.Success()) {
    const lldb_private::ArchSpec &arch =
        m_thread.GetProcess().GetArchitecture();
    void *target_address = ((uint8_t *)&regs) + offset +
                           4 * (arch.GetMachine() == llvm::Triple::mips);
    value.SetUInt(*(uint32_t *)target_address, size);
  }
  return error;
}

Status NativeRegisterContextLinux_mips64::DoReadWatchPointRegisterValue(
    lldb::tid_t tid, void *watch_readback) {
  return NativeProcessLinux::PtraceWrapper(PTRACE_GET_WATCH_REGS,
                                           m_thread.GetID(), watch_readback);
}

Status NativeRegisterContextLinux_mips64::DoWriteWatchPointRegisterValue(
    lldb::tid_t tid, void *watch_reg_value) {
  return NativeProcessLinux::PtraceWrapper(PTRACE_SET_WATCH_REGS,
                                           m_thread.GetID(), watch_reg_value);
}

#endif // defined (__mips__)