lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux.cpp

//===-- NativeRegisterContextLinux.cpp ------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "NativeRegisterContextLinux.h"

#include "Plugins/Process/Linux/NativeProcessLinux.h"
#include "Plugins/Process/POSIX/ProcessPOSIXLog.h"
#include "lldb/Host/HostInfo.h"
#include "lldb/Host/common/NativeProcessProtocol.h"
#include "lldb/Host/common/NativeThreadProtocol.h"
#include "lldb/Utility/RegisterValue.h"

// System includes - They have to be included after framework includes because
// they define some macros which collide with variable names in other modules.
#include <sys/ptrace.h>
#include <sys/uio.h>

#ifndef PTRACE_GETREGS
#define PTRACE_GETREGS 12
#endif

#ifndef PTRACE_SETREGS
#define PTRACE_SETREGS 13
#endif

#ifndef PTRACE_GETFPREGS
#define PTRACE_GETFPREGS 14
#endif

#ifndef PTRACE_SETFPREGS
#define PTRACE_SETFPREGS 15
#endif

#ifndef PTRACE_GETREGSET
#define PTRACE_GETREGSET 0x4204
#endif

#ifndef PTRACE_SETREGSET
#define PTRACE_SETREGSET 0x4205
#endif

using namespace lldb_private;
using namespace lldb_private::process_linux;

lldb::ByteOrder NativeRegisterContextLinux::GetByteOrder() const {
  return m_thread.GetProcess().GetByteOrder();
}

Status NativeRegisterContextLinux::ReadRegisterRaw(uint32_t reg_index,
                                                   RegisterValue &reg_value) {
  const RegisterInfo *const reg_info = GetRegisterInfoAtIndex(reg_index);
  if (!reg_info)
    return Status::FromErrorStringWithFormat("register %" PRIu32 " not found",
                                             reg_index);

  return DoReadRegisterValue(GetPtraceOffset(reg_index), reg_info->name,
                             reg_info->byte_size, reg_value);
}

Status
NativeRegisterContextLinux::WriteRegisterRaw(uint32_t reg_index,
                                             const RegisterValue &reg_value) {
  uint32_t reg_to_write = reg_index;
  RegisterValue value_to_write = reg_value;

  // Check if this is a subregister of a full register.
  const RegisterInfo *reg_info = GetRegisterInfoAtIndex(reg_index);
  assert(reg_info && "Expected valid register info for reg_index.");
  if (reg_info->invalidate_regs &&
      (reg_info->invalidate_regs[0] != LLDB_INVALID_REGNUM)) {
    Status error;

    RegisterValue full_value;
    uint32_t full_reg = reg_info->invalidate_regs[0];
    const RegisterInfo *full_reg_info = GetRegisterInfoAtIndex(full_reg);

    // Read the full register.
    error = ReadRegister(full_reg_info, full_value);
    if (error.Fail()) {
      // full_reg_info was nullptr, or we couldn't read the register.
      return error;
    }

    lldb::ByteOrder byte_order = GetByteOrder();
    RegisterValue::BytesContainer dst(full_reg_info->byte_size);

    // Get the bytes for the full register.
    const uint32_t dest_size = full_value.GetAsMemoryData(
        *full_reg_info, dst.data(), dst.size(), byte_order, error);
    if (error.Success() && dest_size) {
      RegisterValue::BytesContainer src(reg_info->byte_size);

      // Get the bytes for the source data.
      const uint32_t src_size = reg_value.GetAsMemoryData(
          *reg_info, src.data(), src.size(), byte_order, error);
      if (error.Success() && src_size && (src_size < dest_size)) {
        // Copy the src bytes to the destination.
        memcpy(dst.data() + (reg_info->byte_offset & 0x1), src.data(),
               src_size);
        // Set this full register as the value to write.
        value_to_write.SetBytes(dst.data(), full_value.GetByteSize(),
                                byte_order);
        value_to_write.SetType(*full_reg_info);
        reg_to_write = full_reg;
      }
    }
  }

  const RegisterInfo *const register_to_write_info_p =
      GetRegisterInfoAtIndex(reg_to_write);
  assert(register_to_write_info_p &&
         "register to write does not have valid RegisterInfo");
  if (!register_to_write_info_p)
    return Status::FromErrorStringWithFormat(
        "NativeRegisterContextLinux::%s failed to get RegisterInfo "
        "for write register index %" PRIu32,
        __FUNCTION__, reg_to_write);

  return DoWriteRegisterValue(GetPtraceOffset(reg_index), reg_info->name,
                              reg_value);
}

Status NativeRegisterContextLinux::ReadGPR() {
  return NativeProcessLinux::PtraceWrapper(
      PTRACE_GETREGS, m_thread.GetID(), nullptr, GetGPRBuffer(), GetGPRSize());
}

Status NativeRegisterContextLinux::WriteGPR() {
  return NativeProcessLinux::PtraceWrapper(
      PTRACE_SETREGS, m_thread.GetID(), nullptr, GetGPRBuffer(), GetGPRSize());
}

Status NativeRegisterContextLinux::ReadFPR() {
  return NativeProcessLinux::PtraceWrapper(PTRACE_GETFPREGS, m_thread.GetID(),
                                           nullptr, GetFPRBuffer(),
                                           GetFPRSize());
}

Status NativeRegisterContextLinux::WriteFPR() {
  return NativeProcessLinux::PtraceWrapper(PTRACE_SETFPREGS, m_thread.GetID(),
                                           nullptr, GetFPRBuffer(),
                                           GetFPRSize());
}

Status NativeRegisterContextLinux::ReadRegisterSet(void *buf, size_t buf_size,
                                                   unsigned int regset) {
  return NativeProcessLinux::PtraceWrapper(PTRACE_GETREGSET, m_thread.GetID(),
                                           static_cast<void *>(&regset), buf,
                                           buf_size);
}

Status NativeRegisterContextLinux::WriteRegisterSet(void *buf, size_t buf_size,
                                                    unsigned int regset) {
  return NativeProcessLinux::PtraceWrapper(PTRACE_SETREGSET, m_thread.GetID(),
                                           static_cast<void *>(&regset), buf,
                                           buf_size);
}

Status NativeRegisterContextLinux::DoReadRegisterValue(uint32_t offset,
                                                       const char *reg_name,
                                                       uint32_t size,
                                                       RegisterValue &value) {
  Log *log = GetLog(POSIXLog::Registers);

  long data;
  Status error = NativeProcessLinux::PtraceWrapper(
      PTRACE_PEEKUSER, m_thread.GetID(), reinterpret_cast<void *>(offset),
      nullptr, 0, &data);

  if (error.Success())
    // First cast to an unsigned of the same size to avoid sign extension.
    value.SetUInt(static_cast<unsigned long>(data), size);

  LLDB_LOG(log, "{0}: {1:x}", reg_name, data);
  return error;
}

Status NativeRegisterContextLinux::DoWriteRegisterValue(
    uint32_t offset, const char *reg_name, const RegisterValue &value) {
  Log *log = GetLog(POSIXLog::Registers);

  void *buf = reinterpret_cast<void *>(value.GetAsUInt64());
  LLDB_LOG(log, "{0}: {1}", reg_name, buf);

  return NativeProcessLinux::PtraceWrapper(
      PTRACE_POKEUSER, m_thread.GetID(), reinterpret_cast<void *>(offset), buf);
}

llvm::Expected<ArchSpec>
NativeRegisterContextLinux::DetermineArchitectureViaGPR(lldb::tid_t tid,
                                                        size_t gpr64_size) {
  std::unique_ptr<uint8_t[]> data = std::make_unique<uint8_t[]>(gpr64_size);
  struct iovec iov;
  iov.iov_base = data.get();
  iov.iov_len = gpr64_size;
  unsigned int regset = llvm::ELF::NT_PRSTATUS;
  Status ST = NativeProcessLinux::PtraceWrapper(PTRACE_GETREGSET, tid, &regset,
                                                &iov, sizeof(iov));
  if (ST.Fail())
    return ST.ToError();
  return HostInfo::GetArchitecture(
      iov.iov_len < gpr64_size ? HostInfo::eArchKind32 : HostInfo::eArchKind64);
}