llvm-project/lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp

//===-- NativeThreadLinux.cpp --------------------------------- -*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "NativeThreadLinux.h"

#include <signal.h>
#include <sstream>

#include "NativeProcessLinux.h"
#include "NativeRegisterContextLinux.h"
#include "SingleStepCheck.h"

#include "lldb/Core/Log.h"
#include "lldb/Core/State.h"
#include "lldb/Host/HostNativeThread.h"
#include "lldb/Host/linux/Ptrace.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/lldb-enumerations.h"

#include "llvm/ADT/SmallString.h"

#include "Plugins/Process/POSIX/CrashReason.h"

#include <sys/syscall.h>
// Try to define a macro to encapsulate the tgkill syscall
#define tgkill(pid, tid, sig)                                                  \
  syscall(__NR_tgkill, static_cast<::pid_t>(pid), static_cast<::pid_t>(tid),   \
          sig)

using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::process_linux;

namespace {
void LogThreadStopInfo(Log &log, const ThreadStopInfo &stop_info,
                       const char *const header) {
  switch (stop_info.reason) {
  case eStopReasonNone:
    log.Printf("%s: %s no stop reason", __FUNCTION__, header);
    return;
  case eStopReasonTrace:
    log.Printf("%s: %s trace, stopping signal 0x%" PRIx32, __FUNCTION__, header,
               stop_info.details.signal.signo);
    return;
  case eStopReasonBreakpoint:
    log.Printf("%s: %s breakpoint, stopping signal 0x%" PRIx32, __FUNCTION__,
               header, stop_info.details.signal.signo);
    return;
  case eStopReasonWatchpoint:
    log.Printf("%s: %s watchpoint, stopping signal 0x%" PRIx32, __FUNCTION__,
               header, stop_info.details.signal.signo);
    return;
  case eStopReasonSignal:
    log.Printf("%s: %s signal 0x%02" PRIx32, __FUNCTION__, header,
               stop_info.details.signal.signo);
    return;
  case eStopReasonException:
    log.Printf("%s: %s exception type 0x%02" PRIx64, __FUNCTION__, header,
               stop_info.details.exception.type);
    return;
  case eStopReasonExec:
    log.Printf("%s: %s exec, stopping signal 0x%" PRIx32, __FUNCTION__, header,
               stop_info.details.signal.signo);
    return;
  case eStopReasonPlanComplete:
    log.Printf("%s: %s plan complete", __FUNCTION__, header);
    return;
  case eStopReasonThreadExiting:
    log.Printf("%s: %s thread exiting", __FUNCTION__, header);
    return;
  case eStopReasonInstrumentation:
    log.Printf("%s: %s instrumentation", __FUNCTION__, header);
    return;
  default:
    log.Printf("%s: %s invalid stop reason %" PRIu32, __FUNCTION__, header,
               static_cast<uint32_t>(stop_info.reason));
  }
}
}

NativeThreadLinux::NativeThreadLinux(NativeProcessLinux *process,
                                     lldb::tid_t tid)
    : NativeThreadProtocol(process, tid), m_state(StateType::eStateInvalid),
      m_stop_info(), m_reg_context_sp(), m_stop_description() {}

std::string NativeThreadLinux::GetName() {
  NativeProcessProtocolSP process_sp = m_process_wp.lock();
  if (!process_sp)
    return "<unknown: no process>";

  // const NativeProcessLinux *const process =
  // reinterpret_cast<NativeProcessLinux*> (process_sp->get ());
  llvm::SmallString<32> thread_name;
  HostNativeThread::GetName(GetID(), thread_name);
  return thread_name.c_str();
}

lldb::StateType NativeThreadLinux::GetState() { return m_state; }

bool NativeThreadLinux::GetStopReason(ThreadStopInfo &stop_info,
                                      std::string &description) {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));

  description.clear();

  switch (m_state) {
  case eStateStopped:
  case eStateCrashed:
  case eStateExited:
  case eStateSuspended:
  case eStateUnloaded:
    if (log)
      LogThreadStopInfo(*log, m_stop_info, "m_stop_info in thread:");
    stop_info = m_stop_info;
    description = m_stop_description;
    if (log)
      LogThreadStopInfo(*log, stop_info, "returned stop_info:");

    return true;

  case eStateInvalid:
  case eStateConnected:
  case eStateAttaching:
  case eStateLaunching:
  case eStateRunning:
  case eStateStepping:
  case eStateDetached:
    if (log) {
      log->Printf("NativeThreadLinux::%s tid %" PRIu64
                  " in state %s cannot answer stop reason",
                  __FUNCTION__, GetID(), StateAsCString(m_state));
    }
    return false;
  }
  llvm_unreachable("unhandled StateType!");
}

NativeRegisterContextSP NativeThreadLinux::GetRegisterContext() {
  // Return the register context if we already created it.
  if (m_reg_context_sp)
    return m_reg_context_sp;

  NativeProcessProtocolSP m_process_sp = m_process_wp.lock();
  if (!m_process_sp)
    return NativeRegisterContextSP();

  ArchSpec target_arch;
  if (!m_process_sp->GetArchitecture(target_arch))
    return NativeRegisterContextSP();

  const uint32_t concrete_frame_idx = 0;
  m_reg_context_sp.reset(
      NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
          target_arch, *this, concrete_frame_idx));

  return m_reg_context_sp;
}

Error NativeThreadLinux::SetWatchpoint(lldb::addr_t addr, size_t size,
                                       uint32_t watch_flags, bool hardware) {
  if (!hardware)
    return Error("not implemented");
  if (m_state == eStateLaunching)
    return Error();
  Error error = RemoveWatchpoint(addr);
  if (error.Fail())
    return error;
  NativeRegisterContextSP reg_ctx = GetRegisterContext();
  uint32_t wp_index = reg_ctx->SetHardwareWatchpoint(addr, size, watch_flags);
  if (wp_index == LLDB_INVALID_INDEX32)
    return Error("Setting hardware watchpoint failed.");
  m_watchpoint_index_map.insert({addr, wp_index});
  return Error();
}

Error NativeThreadLinux::RemoveWatchpoint(lldb::addr_t addr) {
  auto wp = m_watchpoint_index_map.find(addr);
  if (wp == m_watchpoint_index_map.end())
    return Error();
  uint32_t wp_index = wp->second;
  m_watchpoint_index_map.erase(wp);
  if (GetRegisterContext()->ClearHardwareWatchpoint(wp_index))
    return Error();
  return Error("Clearing hardware watchpoint failed.");
}

Error NativeThreadLinux::Resume(uint32_t signo) {
  const StateType new_state = StateType::eStateRunning;
  MaybeLogStateChange(new_state);
  m_state = new_state;

  m_stop_info.reason = StopReason::eStopReasonNone;
  m_stop_description.clear();

  // If watchpoints have been set, but none on this thread,
  // then this is a new thread. So set all existing watchpoints.
  if (m_watchpoint_index_map.empty()) {
    NativeProcessLinux &process = GetProcess();

    const auto &watchpoint_map = process.GetWatchpointMap();
    GetRegisterContext()->ClearAllHardwareWatchpoints();
    for (const auto &pair : watchpoint_map) {
      const auto &wp = pair.second;
      SetWatchpoint(wp.m_addr, wp.m_size, wp.m_watch_flags, wp.m_hardware);
    }
  }

  intptr_t data = 0;

  if (signo != LLDB_INVALID_SIGNAL_NUMBER)
    data = signo;

  return NativeProcessLinux::PtraceWrapper(PTRACE_CONT, GetID(), nullptr,
                                           reinterpret_cast<void *>(data));
}

void NativeThreadLinux::MaybePrepareSingleStepWorkaround() {
  if (!SingleStepWorkaroundNeeded())
    return;

  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));

  if (sched_getaffinity(static_cast<::pid_t>(m_tid), sizeof m_original_cpu_set,
                        &m_original_cpu_set) != 0) {
    // This should really not fail. But, just in case...
    if (log) {
      Error error(errno, eErrorTypePOSIX);
      log->Printf(
          "NativeThreadLinux::%s Unable to get cpu affinity for thread %" PRIx64
          ": %s",
          __FUNCTION__, m_tid, error.AsCString());
    }
    return;
  }

  cpu_set_t set;
  CPU_ZERO(&set);
  CPU_SET(0, &set);
  if (sched_setaffinity(static_cast<::pid_t>(m_tid), sizeof set, &set) != 0 &&
      log) {
    // This may fail in very locked down systems, if the thread is not allowed
    // to run on
    // cpu 0. If that happens, only thing we can do is it log it and continue...
    Error error(errno, eErrorTypePOSIX);
    log->Printf(
        "NativeThreadLinux::%s Unable to set cpu affinity for thread %" PRIx64
        ": %s",
        __FUNCTION__, m_tid, error.AsCString());
  }
}

void NativeThreadLinux::MaybeCleanupSingleStepWorkaround() {
  if (!SingleStepWorkaroundNeeded())
    return;

  if (sched_setaffinity(static_cast<::pid_t>(m_tid), sizeof m_original_cpu_set,
                        &m_original_cpu_set) != 0) {
    Error error(errno, eErrorTypePOSIX);
    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
    log->Printf(
        "NativeThreadLinux::%s Unable to reset cpu affinity for thread %" PRIx64
        ": %s",
        __FUNCTION__, m_tid, error.AsCString());
  }
}

Error NativeThreadLinux::SingleStep(uint32_t signo) {
  const StateType new_state = StateType::eStateStepping;
  MaybeLogStateChange(new_state);
  m_state = new_state;
  m_stop_info.reason = StopReason::eStopReasonNone;

  MaybePrepareSingleStepWorkaround();

  intptr_t data = 0;
  if (signo != LLDB_INVALID_SIGNAL_NUMBER)
    data = signo;

  // If hardware single-stepping is not supported, we just do a continue. The
  // breakpoint on the
  // next instruction has been setup in NativeProcessLinux::Resume.
  return NativeProcessLinux::PtraceWrapper(
      GetProcess().SupportHardwareSingleStepping() ? PTRACE_SINGLESTEP
                                                   : PTRACE_CONT,
      m_tid, nullptr, reinterpret_cast<void *>(data));
}

void NativeThreadLinux::SetStoppedBySignal(uint32_t signo,
                                           const siginfo_t *info) {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
  if (log)
    log->Printf("NativeThreadLinux::%s called with signal 0x%02" PRIx32,
                __FUNCTION__, signo);

  SetStopped();

  m_stop_info.reason = StopReason::eStopReasonSignal;
  m_stop_info.details.signal.signo = signo;

  m_stop_description.clear();
  if (info) {
    switch (signo) {
    case SIGSEGV:
    case SIGBUS:
    case SIGFPE:
    case SIGILL:
      // In case of MIPS64 target, SI_KERNEL is generated for invalid 64bit
      // address.
      const auto reason =
          (info->si_signo == SIGBUS && info->si_code == SI_KERNEL)
              ? CrashReason::eInvalidAddress
              : GetCrashReason(*info);
      m_stop_description = GetCrashReasonString(
          reason, reinterpret_cast<uintptr_t>(info->si_addr));
      break;
    }
  }
}

bool NativeThreadLinux::IsStopped(int *signo) {
  if (!StateIsStoppedState(m_state, false))
    return false;

  // If we are stopped by a signal, return the signo.
  if (signo && m_state == StateType::eStateStopped &&
      m_stop_info.reason == StopReason::eStopReasonSignal) {
    *signo = m_stop_info.details.signal.signo;
  }

  // Regardless, we are stopped.
  return true;
}

void NativeThreadLinux::SetStopped() {
  if (m_state == StateType::eStateStepping)
    MaybeCleanupSingleStepWorkaround();

  const StateType new_state = StateType::eStateStopped;
  MaybeLogStateChange(new_state);
  m_state = new_state;
  m_stop_description.clear();
}

void NativeThreadLinux::SetStoppedByExec() {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
  if (log)
    log->Printf("NativeThreadLinux::%s()", __FUNCTION__);

  SetStopped();

  m_stop_info.reason = StopReason::eStopReasonExec;
  m_stop_info.details.signal.signo = SIGSTOP;
}

void NativeThreadLinux::SetStoppedByBreakpoint() {
  SetStopped();

  m_stop_info.reason = StopReason::eStopReasonBreakpoint;
  m_stop_info.details.signal.signo = SIGTRAP;
  m_stop_description.clear();
}

void NativeThreadLinux::SetStoppedByWatchpoint(uint32_t wp_index) {
  SetStopped();

  lldbassert(wp_index != LLDB_INVALID_INDEX32 && "wp_index cannot be invalid");

  std::ostringstream ostr;
  ostr << GetRegisterContext()->GetWatchpointAddress(wp_index) << " ";
  ostr << wp_index;

  /*
   * MIPS: Last 3bits of the watchpoint address are masked by the kernel. For
   * example:
   * 'n' is at 0x120010d00 and 'm' is 0x120010d04. When a watchpoint is set at
   * 'm', then
   * watch exception is generated even when 'n' is read/written. To handle this
   * case,
   * find the base address of the load/store instruction and append it in the
   * stop-info
   * packet.
  */
  ostr << " " << GetRegisterContext()->GetWatchpointHitAddress(wp_index);

  m_stop_description = ostr.str();

  m_stop_info.reason = StopReason::eStopReasonWatchpoint;
  m_stop_info.details.signal.signo = SIGTRAP;
}

bool NativeThreadLinux::IsStoppedAtBreakpoint() {
  return GetState() == StateType::eStateStopped &&
         m_stop_info.reason == StopReason::eStopReasonBreakpoint;
}

bool NativeThreadLinux::IsStoppedAtWatchpoint() {
  return GetState() == StateType::eStateStopped &&
         m_stop_info.reason == StopReason::eStopReasonWatchpoint;
}

void NativeThreadLinux::SetStoppedByTrace() {
  SetStopped();

  m_stop_info.reason = StopReason::eStopReasonTrace;
  m_stop_info.details.signal.signo = SIGTRAP;
}

void NativeThreadLinux::SetStoppedWithNoReason() {
  SetStopped();

  m_stop_info.reason = StopReason::eStopReasonNone;
  m_stop_info.details.signal.signo = 0;
}

void NativeThreadLinux::SetExited() {
  const StateType new_state = StateType::eStateExited;
  MaybeLogStateChange(new_state);
  m_state = new_state;

  m_stop_info.reason = StopReason::eStopReasonThreadExiting;
}

Error NativeThreadLinux::RequestStop() {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));

  NativeProcessLinux &process = GetProcess();

  lldb::pid_t pid = process.GetID();
  lldb::tid_t tid = GetID();

  if (log)
    log->Printf("NativeThreadLinux::%s requesting thread stop(pid: %" PRIu64
                ", tid: %" PRIu64 ")",
                __FUNCTION__, pid, tid);

  Error err;
  errno = 0;
  if (::tgkill(pid, tid, SIGSTOP) != 0) {
    err.SetErrorToErrno();
    if (log)
      log->Printf("NativeThreadLinux::%s tgkill(%" PRIu64 ", %" PRIu64
                  ", SIGSTOP) failed: %s",
                  __FUNCTION__, pid, tid, err.AsCString());
  }

  return err;
}

void NativeThreadLinux::MaybeLogStateChange(lldb::StateType new_state) {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
  // If we're not logging, we're done.
  if (!log)
    return;

  // If this is a state change to the same state, we're done.
  lldb::StateType old_state = m_state;
  if (new_state == old_state)
    return;

  NativeProcessProtocolSP m_process_sp = m_process_wp.lock();
  lldb::pid_t pid =
      m_process_sp ? m_process_sp->GetID() : LLDB_INVALID_PROCESS_ID;

  // Log it.
  log->Printf("NativeThreadLinux: thread (pid=%" PRIu64 ", tid=%" PRIu64
              ") changing from state %s to %s",
              pid, GetID(), StateAsCString(old_state),
              StateAsCString(new_state));
}

NativeProcessLinux &NativeThreadLinux::GetProcess() {
  auto process_sp = std::static_pointer_cast<NativeProcessLinux>(
      NativeThreadProtocol::GetProcess());
  assert(process_sp);
  return *process_sp;
}