/*
 * Copyright (C) 2023 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "berberis/guest_state/guest_state_opaque.h"

#include "berberis/base/checks.h"
#include "berberis/base/mmap.h"
#include "berberis/guest_state/guest_addr.h"
#include "berberis/guest_state/guest_state.h"
#include "native_bridge_support/guest_state_accessor/accessor.h"

#include <atomic>   // std::memory_order_relaxed
#include <cstddef>  // size_t
#include <cstdint>  // uint_least8_t
#include <cstring>  // memset
#include <new>

namespace berberis {

namespace {

#if defined(NATIVE_BRIDGE_GUEST_ARCH_ARM) && defined(__i386__)

const uint32_t kGuestArch = NATIVE_BRIDGE_ARCH_ARM;
const uint32_t kHostArch = NATIVE_BRIDGE_ARCH_X86;

#elif defined(NATIVE_BRIDGE_GUEST_ARCH_ARM64) && defined(__x86_64__)

const uint32_t kGuestArch = NATIVE_BRIDGE_ARCH_ARM64;
const uint32_t kHostArch = NATIVE_BRIDGE_ARCH_X86_64;

#elif defined(NATIVE_BRIDGE_GUEST_ARCH_RISCV64) && defined(__x86_64__)

const uint32_t kGuestArch = NATIVE_BRIDGE_ARCH_RISCV64;
const uint32_t kHostArch = NATIVE_BRIDGE_ARCH_X86_64;

#else

#error "Unknown guest/host arch combination"

#endif

const size_t kThreadStatePageAlignedSize = AlignUpPageSize(sizeof(ThreadState));
const size_t kThreadStateStoragePageAlignedSize = AlignUpPageSize(
    AlignUp(sizeof(NativeBridgeGuestStateHeader), alignof(ThreadState)) + sizeof(ThreadState));

void InitThreadState(ThreadState* state) {
  // This is needed to set all flag values to 0.
  memset(&(state->cpu), 0, sizeof(CPUState));

  // ATTENTION: Set fields specific for current thread when actually attaching to host thread!
  state->thread = nullptr;
  SetTlsAddr(*state, 0);

  state->pending_signals_status.store(kPendingSignalsDisabled, std::memory_order_relaxed);
  state->residence = kOutsideGeneratedCode;
  state->instrument_data = nullptr;
}

void InitializeNativeBridgeGuestStateHeader(NativeBridgeGuestStateHeader* guest_state_header,
                                            const ThreadState* state) {
  guest_state_header->signature = NATIVE_BRIDGE_GUEST_STATE_SIGNATURE;
  guest_state_header->native_bridge_host_arch = kHostArch;
  guest_state_header->native_bridge_guest_arch = kGuestArch;
  guest_state_header->guest_state_data = state;
  guest_state_header->guest_state_data_size = kThreadStatePageAlignedSize;
}

}  // namespace

ThreadState* CreateThreadState() {
  void* storage = Mmap(kThreadStateStoragePageAlignedSize);
  if (storage == MAP_FAILED) {
    return nullptr;
  }
  ThreadState* state =
      new (AlignUp(reinterpret_cast<uint8_t*>(storage) + sizeof(NativeBridgeGuestStateHeader),
                   alignof(ThreadState))) ThreadState;
  CHECK(state);
  state->thread_state_storage = storage;

  InitThreadState(state);

  InitializeNativeBridgeGuestStateHeader(static_cast<NativeBridgeGuestStateHeader*>(storage),
                                         state);

  return state;
};

void DestroyThreadState(ThreadState* state) {
  CHECK(state);
  MunmapOrDie(state->thread_state_storage, kThreadStateStoragePageAlignedSize);
}

class GuestThread;
void* GetThreadStateStorage(ThreadState& state) {
  return state.thread_state_storage;
}

void SetGuestThread(ThreadState& state, GuestThread* thread) {
  state.thread = thread;
}

GuestThread* GetGuestThread(const ThreadState& state) {
  return state.thread;
}

GuestThreadResidence GetResidence(const ThreadState& state) {
  return state.residence;
}

void SetResidence(ThreadState& state, GuestThreadResidence residence) {
  state.residence = residence;
}

std::atomic<uint_least8_t>& GetPendingSignalsStatusAtomic(ThreadState& state) {
  return state.pending_signals_status;
}

void SetPendingSignalsStatusAtomic(ThreadState& state, PendingSignalsStatus status) {
  state.pending_signals_status = status;
}

bool ArePendingSignalsPresent(const ThreadState& state) {
  return state.pending_signals_status.load(std::memory_order_relaxed) == kPendingSignalsPresent;
}

const CPUState& GetCPUState(const ThreadState& state) {
  return state.cpu;
}

CPUState& GetCPUState(ThreadState& state) {
  return state.cpu;
}

void SetCPUState(ThreadState& state, const CPUState& cpu) {
  state.cpu = cpu;
}

void SetInsnAddr(CPUState& cpu, GuestAddr addr) {
  cpu.insn_addr = addr;
}

GuestAddr GetInsnAddr(const CPUState& cpu) {
  return cpu.insn_addr;
}

}  // namespace berberis