/*

 * 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 <errno.h>

#include <stdint.h>

#include <string.h>

#include <sys/ptrace.h>

#include <sys/uio.h>

#include <algorithm>

#include <vector>

#include <unwindstack/Elf.h>

#include <unwindstack/Log.h>

#include <unwindstack/MapInfo.h>

#include <unwindstack/Regs.h>

#include <unwindstack/RegsArm.h>

#include <unwindstack/RegsArm64.h>

#include <unwindstack/RegsRiscv64.h>

#include <unwindstack/RegsX86.h>

#include <unwindstack/RegsX86_64.h>

#include <unwindstack/UserArm.h>

#include <unwindstack/UserArm64.h>

#include <unwindstack/UserRiscv64.h>

#include <unwindstack/UserX86.h>

#include <unwindstack/UserX86_64.h>

namespace unwindstack {

// The largest user structure.

// constexpr size_t MAX_USER_REGS_SIZE = sizeof(mips64_user_regs) + 10;

static constexpr size_t kMaxUserRegsSize = std::max(

    sizeof(arm_user_regs),

    std::max(sizeof(arm64_user_regs), std::max(sizeof(x86_user_regs), sizeof(x86_64_user_regs))));

// This function assumes that reg_data is already aligned to a 64 bit value.

// If not this could crash with an unaligned access.

Regs* Regs::RemoteGet(pid_t pid, ErrorCode* error_code) {

  // Make the buffer large enough to contain the largest registers type.

  std::vector<uint64_t> buffer(kMaxUserRegsSize / sizeof(uint64_t));

  struct iovec io {

    .iov_base = buffer.data(), .iov_len = buffer.size() * sizeof(uint64_t)

  };

  if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, reinterpret_cast<void*>(&io)) == -1) {

    Log::Error("PTRACE_GETREGSET failed for pid %d: %s", pid, strerror(errno));

    if (error_code != nullptr) {

      *error_code = ERROR_PTRACE_CALL;

    }

    return nullptr;

  }

  // Infer the process architecture from the size of its register structure.

  switch (io.iov_len) {

  case sizeof(x86_user_regs):

    return RegsX86::Read(buffer.data());

  case sizeof(x86_64_user_regs):

    return RegsX86_64::Read(buffer.data());

  case sizeof(arm_user_regs):

    return RegsArm::Read(buffer.data());

  case sizeof(arm64_user_regs):

    return RegsArm64::Read(buffer.data());

  case sizeof(riscv64_user_regs):

    return RegsRiscv64::Read(buffer.data(), pid);

  }

  Log::Error("No matching size of user regs structure for pid %d: size %zu", pid, io.iov_len);

  if (error_code != nullptr) {

    *error_code = ERROR_UNSUPPORTED;

  }

  return nullptr;

}

ArchEnum Regs::RemoteGetArch(pid_t pid, ErrorCode* error_code) {

  // Make the buffer large enough to contain the largest registers type.

  std::vector<uint64_t> buffer(kMaxUserRegsSize / sizeof(uint64_t));

  struct iovec io;

  io.iov_base = buffer.data();

  io.iov_len = buffer.size() * sizeof(uint64_t);

  if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, reinterpret_cast<void*>(&io)) == -1) {

    Log::Error("PTRACE_GETREGSET failed for pid %d: %s", pid, strerror(errno));

    if (error_code != nullptr) {

      *error_code = ERROR_PTRACE_CALL;

    }

    return ARCH_UNKNOWN;

  }

  // Infer the process architecture from the size of its register structure.

  switch (io.iov_len) {

    case sizeof(x86_user_regs):

      return ARCH_X86;

    case sizeof(x86_64_user_regs):

      return ARCH_X86_64;

    case sizeof(arm_user_regs):

      return ARCH_ARM;

    case sizeof(arm64_user_regs):

      return ARCH_ARM64;

    case sizeof(riscv64_user_regs):

      return ARCH_RISCV64;

  }

  Log::Error("No matching size of user regs structure for pid %d: size %zu", pid, io.iov_len);

  if (error_code != nullptr) {

    *error_code = ERROR_UNSUPPORTED;

  }

  return ARCH_UNKNOWN;

}

Regs* Regs::CreateFromUcontext(ArchEnum arch, void* ucontext) {

  switch (arch) {

    case ARCH_X86:

      return RegsX86::CreateFromUcontext(ucontext);

    case ARCH_X86_64:

      return RegsX86_64::CreateFromUcontext(ucontext);

    case ARCH_ARM:

      return RegsArm::CreateFromUcontext(ucontext);

    case ARCH_ARM64:

      return RegsArm64::CreateFromUcontext(ucontext);

    case ARCH_RISCV64:

      return RegsRiscv64::CreateFromUcontext(ucontext);

    case ARCH_UNKNOWN:

    default:

      return nullptr;

  }

}

ArchEnum Regs::CurrentArch() {

#if defined(__arm__)

  return ARCH_ARM;

#elif defined(__aarch64__)

  return ARCH_ARM64;

#elif defined(__i386__)

  return ARCH_X86;

#elif defined(__x86_64__)

  return ARCH_X86_64;

#elif defined(__riscv)

  return ARCH_RISCV64;

#else

  abort();

#endif

}

Regs* Regs::CreateFromLocal() {

  Regs* regs;

#if defined(__arm__)

  regs = new RegsArm();

#elif defined(__aarch64__)

  regs = new RegsArm64();

#elif defined(__i386__)

  regs = new RegsX86();

#elif defined(__x86_64__)

  regs = new RegsX86_64();

#elif defined(__riscv)

  regs = new RegsRiscv64();

#else

  abort();

#endif

  return regs;

}

uint64_t GetPcAdjustment(uint64_t rel_pc, Elf* elf, ArchEnum arch) {

  switch (arch) {

    case ARCH_ARM: {

      if (!elf->valid()) {

        return 2;

      }

      uint64_t load_bias = elf->GetLoadBias();

      if (rel_pc < load_bias) {

        if (rel_pc < 2) {

          return 0;

        }

        return 2;

      }

      uint64_t adjusted_rel_pc = rel_pc - load_bias;

      if (adjusted_rel_pc < 5) {

        if (adjusted_rel_pc < 2) {

          return 0;

        }

        return 2;

      }

      if (adjusted_rel_pc & 1) {

        // This is a thumb instruction, it could be 2 or 4 bytes.

        uint32_t value;

        if (!elf->memory()->ReadFully(adjusted_rel_pc - 5, &value, sizeof(value)) ||

            (value & 0xe000f000) != 0xe000f000) {

          return 2;

        }

      }

      return 4;

    }

    case ARCH_ARM64:

    case ARCH_RISCV64: {

      if (rel_pc < 4) {

        return 0;

      }

      return 4;

    }

  case ARCH_X86:

  case ARCH_X86_64: {

    if (rel_pc == 0) {

      return 0;

    }

    return 1;

  }

  case ARCH_UNKNOWN:

    return 0;

  }

}

}  // namespace unwindstack