/*

 * Copyright (C) 2016 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 <stdint.h>

#include <string.h>

#include <functional>

#if defined(__BIONIC__)

#include <bionic/pac.h>

#endif

#include <unwindstack/Elf.h>

#include <unwindstack/MachineArm64.h>

#include <unwindstack/MapInfo.h>

#include <unwindstack/Memory.h>

#include <unwindstack/RegsArm64.h>

#include <unwindstack/UcontextArm64.h>

#include <unwindstack/UserArm64.h>

namespace unwindstack {

RegsArm64::RegsArm64()

    : RegsImpl<uint64_t>(ARM64_REG_LAST, Location(LOCATION_REGISTER, ARM64_REG_LR)) {

  ResetPseudoRegisters();

  pac_mask_ = 0;

}

ArchEnum RegsArm64::Arch() {

  return ARCH_ARM64;

}

uint64_t RegsArm64::pc() {

  return regs_[ARM64_REG_PC];

}

uint64_t RegsArm64::sp() {

  return regs_[ARM64_REG_SP];

}

static uint64_t strip_pac(uint64_t pc, uint64_t mask) {

  // If the target is aarch64 then the return address may have been

  // signed using the Armv8.3-A Pointer Authentication extension. The

  // original return address can be restored by stripping out the

  // authentication code using a mask or xpaclri. xpaclri is a NOP on

  // pre-Armv8.3-A architectures.

  if (mask) {

    pc &= ~mask;

  } else {

#if defined(__BIONIC__)

    pc = __bionic_clear_pac_bits(pc);

#endif

  }

  return pc;

}

void RegsArm64::set_pc(uint64_t pc) {

  if ((0 != pc) && IsRASigned()) {

    pc = strip_pac(pc, pac_mask_);

  }

  regs_[ARM64_REG_PC] = pc;

}

void RegsArm64::set_sp(uint64_t sp) {

  regs_[ARM64_REG_SP] = sp;

}

void RegsArm64::fallback_pc() {

  // As a last resort, try stripping the PC of the pointer

  // authentication code.

  regs_[ARM64_REG_PC] = strip_pac(regs_[ARM64_REG_PC], pac_mask_);

}

bool RegsArm64::SetPcFromReturnAddress(Memory*) {

  uint64_t lr = regs_[ARM64_REG_LR];

  if (regs_[ARM64_REG_PC] == lr) {

    return false;

  }

  regs_[ARM64_REG_PC] = lr;

  return true;

}

void RegsArm64::IterateRegisters(std::function<void(const char*, uint64_t)> fn) {

  fn("x0", regs_[ARM64_REG_R0]);

  fn("x1", regs_[ARM64_REG_R1]);

  fn("x2", regs_[ARM64_REG_R2]);

  fn("x3", regs_[ARM64_REG_R3]);

  fn("x4", regs_[ARM64_REG_R4]);

  fn("x5", regs_[ARM64_REG_R5]);

  fn("x6", regs_[ARM64_REG_R6]);

  fn("x7", regs_[ARM64_REG_R7]);

  fn("x8", regs_[ARM64_REG_R8]);

  fn("x9", regs_[ARM64_REG_R9]);

  fn("x10", regs_[ARM64_REG_R10]);

  fn("x11", regs_[ARM64_REG_R11]);

  fn("x12", regs_[ARM64_REG_R12]);

  fn("x13", regs_[ARM64_REG_R13]);

  fn("x14", regs_[ARM64_REG_R14]);

  fn("x15", regs_[ARM64_REG_R15]);

  fn("x16", regs_[ARM64_REG_R16]);

  fn("x17", regs_[ARM64_REG_R17]);

  fn("x18", regs_[ARM64_REG_R18]);

  fn("x19", regs_[ARM64_REG_R19]);

  fn("x20", regs_[ARM64_REG_R20]);

  fn("x21", regs_[ARM64_REG_R21]);

  fn("x22", regs_[ARM64_REG_R22]);

  fn("x23", regs_[ARM64_REG_R23]);

  fn("x24", regs_[ARM64_REG_R24]);

  fn("x25", regs_[ARM64_REG_R25]);

  fn("x26", regs_[ARM64_REG_R26]);

  fn("x27", regs_[ARM64_REG_R27]);

  fn("x28", regs_[ARM64_REG_R28]);

  fn("x29", regs_[ARM64_REG_R29]);

  fn("lr", regs_[ARM64_REG_LR]);

  fn("sp", regs_[ARM64_REG_SP]);

  fn("pc", regs_[ARM64_REG_PC]);

  fn("pst", regs_[ARM64_REG_PSTATE]);

}

Regs* RegsArm64::Read(const void* remote_data) {

  const arm64_user_regs* user = reinterpret_cast<const arm64_user_regs*>(remote_data);

  RegsArm64* regs = new RegsArm64();

  memcpy(regs->RawData(), &user->regs[0], (ARM64_REG_R30 + 1) * sizeof(uint64_t));

  uint64_t* reg_data = reinterpret_cast<uint64_t*>(regs->RawData());

  reg_data[ARM64_REG_SP] = user->sp;

  reg_data[ARM64_REG_PC] = user->pc;

  reg_data[ARM64_REG_PSTATE] = user->pstate;

  return regs;

}

Regs* RegsArm64::CreateFromUcontext(void* ucontext) {

  arm64_ucontext_t* arm64_ucontext = reinterpret_cast<arm64_ucontext_t*>(ucontext);

  RegsArm64* regs = new RegsArm64();

  memcpy(regs->RawData(), &arm64_ucontext->uc_mcontext.regs[0], ARM64_REG_LAST * sizeof(uint64_t));

  return regs;

}

bool RegsArm64::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {

  // Read from elf memory since it is usually more expensive to read from

  // process memory.

  uint64_t data;

  if (!elf->memory()->ReadFully(elf_offset, &data, sizeof(data))) {

    return false;

  }

  // Look for the kernel sigreturn function.

  // __kernel_rt_sigreturn:

  // 0xd2801168     mov x8, #0x8b

  // 0xd4000001     svc #0x0

  if (data != 0xd4000001d2801168ULL) {

    return false;

  }

  // SP + sizeof(siginfo_t) + uc_mcontext offset + X0 offset.

  if (!process_memory->ReadFully(regs_[ARM64_REG_SP] + 0x80 + 0xb0 + 0x08, regs_.data(),

                                 sizeof(uint64_t) * ARM64_REG_LAST)) {

    return false;

  }

  return true;

}

void RegsArm64::ResetPseudoRegisters(void) {

  // DWARF for AArch64 says RA_SIGN_STATE should be initialized to 0.

  this->SetPseudoRegister(Arm64Reg::ARM64_PREG_RA_SIGN_STATE, 0);

}

bool RegsArm64::SetPseudoRegister(uint16_t id, uint64_t value) {

  if ((id >= Arm64Reg::ARM64_PREG_FIRST) && (id < Arm64Reg::ARM64_PREG_LAST)) {

    pseudo_regs_[id - Arm64Reg::ARM64_PREG_FIRST] = value;

    return true;

  }

  return false;

}

bool RegsArm64::GetPseudoRegister(uint16_t id, uint64_t* value) {

  if ((id >= Arm64Reg::ARM64_PREG_FIRST) && (id < Arm64Reg::ARM64_PREG_LAST)) {

    *value = pseudo_regs_[id - Arm64Reg::ARM64_PREG_FIRST];

    return true;

  }

  return false;

}

bool RegsArm64::IsRASigned() {

  uint64_t value;

  auto result = this->GetPseudoRegister(Arm64Reg::ARM64_PREG_RA_SIGN_STATE, &value);

  return (result && (value != 0));

}

void RegsArm64::SetPACMask(uint64_t mask) {

  pac_mask_ = mask;

}

Regs* RegsArm64::Clone() {

  return new RegsArm64(*this);

}

}  // namespace unwindstack