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llvm-project/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
Pavel Labath ca271f4ef5 [lldb-server/linux] Fix waitpid for multithreaded forks 
The lldb-server code is currently set up in a way that each
NativeProcess instance does its own waitpid handling. This works fine
for BSDs, where the code can do a waitpid(process_id), and get
information for all threads in that process.

The situation is trickier on linux, because waitpid(pid) will only
return information for the main thread of the process (one whose tid ==
pid). For this reason the linux code does a waitpid(-1), to get
information for all threads. This was fine while we were supporting just
a single process, but becomes a problem when we have multiple processes
as they end up stealing each others events.

There are two possible solutions to this problem:
- call waitpid(-1) centrally, and then dispatch the events to the
  appropriate process
- have each process call waitpid(tid) for all the threads it manages

This patch implements the second approach. Besides fitting better into
the existing design, it also has the added benefit of ensuring
predictable ordering for thread/process creation events (which come in
pairs -- one for the parent and one for the child). The first approach
OTOH, would make this ordering even more complicated since we would
have to keep the half-threads hanging in mid-air until we find the
process we should attach them to.

The downside to this approach is an increased number of syscalls (one
waitpid for each thread), but I think we're pretty far from optimizing
things like this, and so the cleanliness of the design is worth it.

The included test reproduces the circumstances which should demonstrate
the bug (which manifests as a hung test), but I have not been able to
get it to fail. The only place I've seen this failure modes are very
rare hangs in the thread sanitizer tests (tsan forks an addr2line
process to produce its error messages).

Differential Revision: https://reviews.llvm.org/D116372
2022-01-03 14:27:52 +01:00

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//===-- NativeProcessLinux.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 "NativeProcessLinux.h"
#include <cerrno>
#include <cstdint>
#include <cstring>
#include <unistd.h>
#include <fstream>
#include <mutex>
#include <sstream>
#include <string>
#include <unordered_map>
#include "NativeThreadLinux.h"
#include "Plugins/Process/POSIX/ProcessPOSIXLog.h"
#include "Plugins/Process/Utility/LinuxProcMaps.h"
#include "Procfs.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Host/Host.h"
#include "lldb/Host/HostProcess.h"
#include "lldb/Host/ProcessLaunchInfo.h"
#include "lldb/Host/PseudoTerminal.h"
#include "lldb/Host/ThreadLauncher.h"
#include "lldb/Host/common/NativeRegisterContext.h"
#include "lldb/Host/linux/Host.h"
#include "lldb/Host/linux/Ptrace.h"
#include "lldb/Host/linux/Uio.h"
#include "lldb/Host/posix/ProcessLauncherPosixFork.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/Target.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/Utility/State.h"
#include "lldb/Utility/Status.h"
#include "lldb/Utility/StringExtractor.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/Support/Errno.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Threading.h"
#include <linux/unistd.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/user.h>
#include <sys/wait.h>
#ifdef __aarch64__
#include <asm/hwcap.h>
#include <sys/auxv.h>
#endif
// Support hardware breakpoints in case it has not been defined
#ifndef TRAP_HWBKPT
#define TRAP_HWBKPT 4
#endif
#ifndef HWCAP2_MTE
#define HWCAP2_MTE (1 << 18)
#endif
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::process_linux;
using namespace llvm;
// Private bits we only need internally.
static bool ProcessVmReadvSupported() {
static bool is_supported;
static llvm::once_flag flag;
llvm::call_once(flag, [] {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
uint32_t source = 0x47424742;
uint32_t dest = 0;
struct iovec local, remote;
remote.iov_base = &source;
local.iov_base = &dest;
remote.iov_len = local.iov_len = sizeof source;
// We shall try if cross-process-memory reads work by attempting to read a
// value from our own process.
ssize_t res = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);
is_supported = (res == sizeof(source) && source == dest);
if (is_supported)
LLDB_LOG(log,
"Detected kernel support for process_vm_readv syscall. "
"Fast memory reads enabled.");
else
LLDB_LOG(log,
"syscall process_vm_readv failed (error: {0}). Fast memory "
"reads disabled.",
llvm::sys::StrError());
});
return is_supported;
}
static void MaybeLogLaunchInfo(const ProcessLaunchInfo &info) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
if (!log)
return;
if (const FileAction *action = info.GetFileActionForFD(STDIN_FILENO))
LLDB_LOG(log, "setting STDIN to '{0}'", action->GetFileSpec());
else
LLDB_LOG(log, "leaving STDIN as is");
if (const FileAction *action = info.GetFileActionForFD(STDOUT_FILENO))
LLDB_LOG(log, "setting STDOUT to '{0}'", action->GetFileSpec());
else
LLDB_LOG(log, "leaving STDOUT as is");
if (const FileAction *action = info.GetFileActionForFD(STDERR_FILENO))
LLDB_LOG(log, "setting STDERR to '{0}'", action->GetFileSpec());
else
LLDB_LOG(log, "leaving STDERR as is");
int i = 0;
for (const char **args = info.GetArguments().GetConstArgumentVector(); *args;
++args, ++i)
LLDB_LOG(log, "arg {0}: '{1}'", i, *args);
}
static void DisplayBytes(StreamString &s, void *bytes, uint32_t count) {
uint8_t *ptr = (uint8_t *)bytes;
const uint32_t loop_count = std::min<uint32_t>(DEBUG_PTRACE_MAXBYTES, count);
for (uint32_t i = 0; i < loop_count; i++) {
s.Printf("[%x]", *ptr);
ptr++;
}
}
static void PtraceDisplayBytes(int &req, void *data, size_t data_size) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
if (!log)
return;
StreamString buf;
switch (req) {
case PTRACE_POKETEXT: {
DisplayBytes(buf, &data, 8);
LLDB_LOGV(log, "PTRACE_POKETEXT {0}", buf.GetData());
break;
}
case PTRACE_POKEDATA: {
DisplayBytes(buf, &data, 8);
LLDB_LOGV(log, "PTRACE_POKEDATA {0}", buf.GetData());
break;
}
case PTRACE_POKEUSER: {
DisplayBytes(buf, &data, 8);
LLDB_LOGV(log, "PTRACE_POKEUSER {0}", buf.GetData());
break;
}
case PTRACE_SETREGS: {
DisplayBytes(buf, data, data_size);
LLDB_LOGV(log, "PTRACE_SETREGS {0}", buf.GetData());
break;
}
case PTRACE_SETFPREGS: {
DisplayBytes(buf, data, data_size);
LLDB_LOGV(log, "PTRACE_SETFPREGS {0}", buf.GetData());
break;
}
case PTRACE_SETSIGINFO: {
DisplayBytes(buf, data, sizeof(siginfo_t));
LLDB_LOGV(log, "PTRACE_SETSIGINFO {0}", buf.GetData());
break;
}
case PTRACE_SETREGSET: {
// Extract iov_base from data, which is a pointer to the struct iovec
DisplayBytes(buf, *(void **)data, data_size);
LLDB_LOGV(log, "PTRACE_SETREGSET {0}", buf.GetData());
break;
}
default: {}
}
}
static constexpr unsigned k_ptrace_word_size = sizeof(void *);
static_assert(sizeof(long) >= k_ptrace_word_size,
"Size of long must be larger than ptrace word size");
// Simple helper function to ensure flags are enabled on the given file
// descriptor.
static Status EnsureFDFlags(int fd, int flags) {
Status error;
int status = fcntl(fd, F_GETFL);
if (status == -1) {
error.SetErrorToErrno();
return error;
}
if (fcntl(fd, F_SETFL, status | flags) == -1) {
error.SetErrorToErrno();
return error;
}
return error;
}
// Public Static Methods
llvm::Expected<std::unique_ptr<NativeProcessProtocol>>
NativeProcessLinux::Factory::Launch(ProcessLaunchInfo &launch_info,
NativeDelegate &native_delegate,
MainLoop &mainloop) const {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
MaybeLogLaunchInfo(launch_info);
Status status;
::pid_t pid = ProcessLauncherPosixFork()
.LaunchProcess(launch_info, status)
.GetProcessId();
LLDB_LOG(log, "pid = {0:x}", pid);
if (status.Fail()) {
LLDB_LOG(log, "failed to launch process: {0}", status);
return status.ToError();
}
// Wait for the child process to trap on its call to execve.
int wstatus;
::pid_t wpid = llvm::sys::RetryAfterSignal(-1, ::waitpid, pid, &wstatus, 0);
assert(wpid == pid);
(void)wpid;
if (!WIFSTOPPED(wstatus)) {
LLDB_LOG(log, "Could not sync with inferior process: wstatus={1}",
WaitStatus::Decode(wstatus));
return llvm::make_error<StringError>("Could not sync with inferior process",
llvm::inconvertibleErrorCode());
}
LLDB_LOG(log, "inferior started, now in stopped state");
ProcessInstanceInfo Info;
if (!Host::GetProcessInfo(pid, Info)) {
return llvm::make_error<StringError>("Cannot get process architecture",
llvm::inconvertibleErrorCode());
}
// Set the architecture to the exe architecture.
LLDB_LOG(log, "pid = {0:x}, detected architecture {1}", pid,
Info.GetArchitecture().GetArchitectureName());
status = SetDefaultPtraceOpts(pid);
if (status.Fail()) {
LLDB_LOG(log, "failed to set default ptrace options: {0}", status);
return status.ToError();
}
return std::unique_ptr<NativeProcessLinux>(new NativeProcessLinux(
pid, launch_info.GetPTY().ReleasePrimaryFileDescriptor(), native_delegate,
Info.GetArchitecture(), mainloop, {pid}));
}
llvm::Expected<std::unique_ptr<NativeProcessProtocol>>
NativeProcessLinux::Factory::Attach(
lldb::pid_t pid, NativeProcessProtocol::NativeDelegate &native_delegate,
MainLoop &mainloop) const {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "pid = {0:x}", pid);
// Retrieve the architecture for the running process.
ProcessInstanceInfo Info;
if (!Host::GetProcessInfo(pid, Info)) {
return llvm::make_error<StringError>("Cannot get process architecture",
llvm::inconvertibleErrorCode());
}
auto tids_or = NativeProcessLinux::Attach(pid);
if (!tids_or)
return tids_or.takeError();
return std::unique_ptr<NativeProcessLinux>(new NativeProcessLinux(
pid, -1, native_delegate, Info.GetArchitecture(), mainloop, *tids_or));
}
NativeProcessLinux::Extension
NativeProcessLinux::Factory::GetSupportedExtensions() const {
NativeProcessLinux::Extension supported =
Extension::multiprocess | Extension::fork | Extension::vfork |
Extension::pass_signals | Extension::auxv | Extension::libraries_svr4;
#ifdef __aarch64__
// At this point we do not have a process so read auxv directly.
if ((getauxval(AT_HWCAP2) & HWCAP2_MTE))
supported |= Extension::memory_tagging;
#endif
return supported;
}
// Public Instance Methods
NativeProcessLinux::NativeProcessLinux(::pid_t pid, int terminal_fd,
NativeDelegate &delegate,
const ArchSpec &arch, MainLoop &mainloop,
llvm::ArrayRef<::pid_t> tids)
: NativeProcessELF(pid, terminal_fd, delegate), m_arch(arch),
m_main_loop(mainloop), m_intel_pt_manager(pid) {
if (m_terminal_fd != -1) {
Status status = EnsureFDFlags(m_terminal_fd, O_NONBLOCK);
assert(status.Success());
}
Status status;
m_sigchld_handle = mainloop.RegisterSignal(
SIGCHLD, [this](MainLoopBase &) { SigchldHandler(); }, status);
assert(m_sigchld_handle && status.Success());
for (const auto &tid : tids) {
NativeThreadLinux &thread = AddThread(tid, /*resume*/ false);
ThreadWasCreated(thread);
}
// Let our process instance know the thread has stopped.
SetCurrentThreadID(tids[0]);
SetState(StateType::eStateStopped, false);
// Proccess any signals we received before installing our handler
SigchldHandler();
}
llvm::Expected<std::vector<::pid_t>> NativeProcessLinux::Attach(::pid_t pid) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
Status status;
// Use a map to keep track of the threads which we have attached/need to
// attach.
Host::TidMap tids_to_attach;
while (Host::FindProcessThreads(pid, tids_to_attach)) {
for (Host::TidMap::iterator it = tids_to_attach.begin();
it != tids_to_attach.end();) {
if (it->second == false) {
lldb::tid_t tid = it->first;
// Attach to the requested process.
// An attach will cause the thread to stop with a SIGSTOP.
if ((status = PtraceWrapper(PTRACE_ATTACH, tid)).Fail()) {
// No such thread. The thread may have exited. More error handling
// may be needed.
if (status.GetError() == ESRCH) {
it = tids_to_attach.erase(it);
continue;
}
return status.ToError();
}
int wpid =
llvm::sys::RetryAfterSignal(-1, ::waitpid, tid, nullptr, __WALL);
// Need to use __WALL otherwise we receive an error with errno=ECHLD At
// this point we should have a thread stopped if waitpid succeeds.
if (wpid < 0) {
// No such thread. The thread may have exited. More error handling
// may be needed.
if (errno == ESRCH) {
it = tids_to_attach.erase(it);
continue;
}
return llvm::errorCodeToError(
std::error_code(errno, std::generic_category()));
}
if ((status = SetDefaultPtraceOpts(tid)).Fail())
return status.ToError();
LLDB_LOG(log, "adding tid = {0}", tid);
it->second = true;
}
// move the loop forward
++it;
}
}
size_t tid_count = tids_to_attach.size();
if (tid_count == 0)
return llvm::make_error<StringError>("No such process",
llvm::inconvertibleErrorCode());
std::vector<::pid_t> tids;
tids.reserve(tid_count);
for (const auto &p : tids_to_attach)
tids.push_back(p.first);
return std::move(tids);
}
Status NativeProcessLinux::SetDefaultPtraceOpts(lldb::pid_t pid) {
long ptrace_opts = 0;
// Have the child raise an event on exit. This is used to keep the child in
// limbo until it is destroyed.
ptrace_opts |= PTRACE_O_TRACEEXIT;
// Have the tracer trace threads which spawn in the inferior process.
ptrace_opts |= PTRACE_O_TRACECLONE;
// Have the tracer notify us before execve returns (needed to disable legacy
// SIGTRAP generation)
ptrace_opts |= PTRACE_O_TRACEEXEC;
// Have the tracer trace forked children.
ptrace_opts |= PTRACE_O_TRACEFORK;
// Have the tracer trace vforks.
ptrace_opts |= PTRACE_O_TRACEVFORK;
// Have the tracer trace vfork-done in order to restore breakpoints after
// the child finishes sharing memory.
ptrace_opts |= PTRACE_O_TRACEVFORKDONE;
return PtraceWrapper(PTRACE_SETOPTIONS, pid, nullptr, (void *)ptrace_opts);
}
// Handles all waitpid events from the inferior process.
void NativeProcessLinux::MonitorCallback(NativeThreadLinux &thread,
WaitStatus status) {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS));
// Certain activities differ based on whether the pid is the tid of the main
// thread.
const bool is_main_thread = (thread.GetID() == GetID());
// Handle when the thread exits.
if (status.type == WaitStatus::Exit || status.type == WaitStatus::Signal) {
LLDB_LOG(log,
"got exit status({0}) , tid = {1} ({2} main thread), process "
"state = {3}",
status, thread.GetID(), is_main_thread ? "is" : "is not",
GetState());
// This is a thread that exited. Ensure we're not tracking it anymore.
StopTrackingThread(thread);
if (is_main_thread) {
// The main thread exited. We're done monitoring. Report to delegate.
SetExitStatus(status, true);
// Notify delegate that our process has exited.
SetState(StateType::eStateExited, true);
}
return;
}
siginfo_t info;
const auto info_err = GetSignalInfo(thread.GetID(), &info);
// Get details on the signal raised.
if (info_err.Success()) {
// We have retrieved the signal info. Dispatch appropriately.
if (info.si_signo == SIGTRAP)
MonitorSIGTRAP(info, thread);
else
MonitorSignal(info, thread);
} else {
if (info_err.GetError() == EINVAL) {
// This is a group stop reception for this tid. We can reach here if we
// reinject SIGSTOP, SIGSTP, SIGTTIN or SIGTTOU into the tracee,
// triggering the group-stop mechanism. Normally receiving these would
// stop the process, pending a SIGCONT. Simulating this state in a
// debugger is hard and is generally not needed (one use case is
// debugging background task being managed by a shell). For general use,
// it is sufficient to stop the process in a signal-delivery stop which
// happens before the group stop. This done by MonitorSignal and works
// correctly for all signals.
LLDB_LOG(log,
"received a group stop for pid {0} tid {1}. Transparent "
"handling of group stops not supported, resuming the "
"thread.",
GetID(), thread.GetID());
ResumeThread(thread, thread.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
} else {
// ptrace(GETSIGINFO) failed (but not due to group-stop).
// A return value of ESRCH means the thread/process is no longer on the
// system, so it was killed somehow outside of our control. Either way,
// we can't do anything with it anymore.
// Stop tracking the metadata for the thread since it's entirely off the
// system now.
StopTrackingThread(thread);
LLDB_LOG(log,
"GetSignalInfo failed: {0}, tid = {1}, status = {2}, "
"status = {3}, main_thread = {4}",
info_err, thread.GetID(), status, status, is_main_thread);
if (is_main_thread) {
// Notify the delegate - our process is not available but appears to
// have been killed outside our control. Is eStateExited the right
// exit state in this case?
SetExitStatus(status, true);
SetState(StateType::eStateExited, true);
} else {
// This thread was pulled out from underneath us. Anything to do here?
// Do we want to do an all stop?
LLDB_LOG(log,
"pid {0} tid {1} non-main thread exit occurred, didn't "
"tell delegate anything since thread disappeared out "
"from underneath us",
GetID(), thread.GetID());
}
}
}
}
void NativeProcessLinux::WaitForCloneNotification(::pid_t pid) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
// The PID is not tracked yet, let's wait for it to appear.
int status = -1;
LLDB_LOG(log,
"received clone event for pid {0}. pid not tracked yet, "
"waiting for it to appear...",
pid);
::pid_t wait_pid =
llvm::sys::RetryAfterSignal(-1, ::waitpid, pid, &status, __WALL);
// It's theoretically possible to get other events if the entire process was
// SIGKILLed before we got a chance to check this. In that case, we'll just
// clean everything up when we get the process exit event.
LLDB_LOG(log,
"waitpid({0}, &status, __WALL) => {1} (errno: {2}, status = {3})",
pid, wait_pid, errno, WaitStatus::Decode(status));
}
void NativeProcessLinux::MonitorSIGTRAP(const siginfo_t &info,
NativeThreadLinux &thread) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
const bool is_main_thread = (thread.GetID() == GetID());
assert(info.si_signo == SIGTRAP && "Unexpected child signal!");
switch (info.si_code) {
case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
case (SIGTRAP | (PTRACE_EVENT_CLONE << 8)): {
// This can either mean a new thread or a new process spawned via
// clone(2) without SIGCHLD or CLONE_VFORK flag. Note that clone(2)
// can also cause PTRACE_EVENT_FORK and PTRACE_EVENT_VFORK if one
// of these flags are passed.
unsigned long event_message = 0;
if (GetEventMessage(thread.GetID(), &event_message).Fail()) {
LLDB_LOG(log,
"pid {0} received clone() event but GetEventMessage failed "
"so we don't know the new pid/tid",
thread.GetID());
ResumeThread(thread, thread.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
} else {
MonitorClone(thread, event_message, info.si_code >> 8);
}
break;
}
case (SIGTRAP | (PTRACE_EVENT_EXEC << 8)): {
LLDB_LOG(log, "received exec event, code = {0}", info.si_code ^ SIGTRAP);
// Exec clears any pending notifications.
m_pending_notification_tid = LLDB_INVALID_THREAD_ID;
// Remove all but the main thread here. Linux fork creates a new process
// which only copies the main thread.
LLDB_LOG(log, "exec received, stop tracking all but main thread");
llvm::erase_if(m_threads, [&](std::unique_ptr<NativeThreadProtocol> &t) {
return t->GetID() != GetID();
});
assert(m_threads.size() == 1);
auto *main_thread = static_cast<NativeThreadLinux *>(m_threads[0].get());
SetCurrentThreadID(main_thread->GetID());
main_thread->SetStoppedByExec();
// Tell coordinator about about the "new" (since exec) stopped main thread.
ThreadWasCreated(*main_thread);
// Let our delegate know we have just exec'd.
NotifyDidExec();
// Let the process know we're stopped.
StopRunningThreads(main_thread->GetID());
break;
}
case (SIGTRAP | (PTRACE_EVENT_EXIT << 8)): {
// The inferior process or one of its threads is about to exit. We don't
// want to do anything with the thread so we just resume it. In case we
// want to implement "break on thread exit" functionality, we would need to
// stop here.
unsigned long data = 0;
if (GetEventMessage(thread.GetID(), &data).Fail())
data = -1;
LLDB_LOG(log,
"received PTRACE_EVENT_EXIT, data = {0:x}, WIFEXITED={1}, "
"WIFSIGNALED={2}, pid = {3}, main_thread = {4}",
data, WIFEXITED(data), WIFSIGNALED(data), thread.GetID(),
is_main_thread);
StateType state = thread.GetState();
if (!StateIsRunningState(state)) {
// Due to a kernel bug, we may sometimes get this stop after the inferior
// gets a SIGKILL. This confuses our state tracking logic in
// ResumeThread(), since normally, we should not be receiving any ptrace
// events while the inferior is stopped. This makes sure that the
// inferior is resumed and exits normally.
state = eStateRunning;
}
ResumeThread(thread, state, LLDB_INVALID_SIGNAL_NUMBER);
break;
}
case (SIGTRAP | (PTRACE_EVENT_VFORK_DONE << 8)): {
if (bool(m_enabled_extensions & Extension::vfork)) {
thread.SetStoppedByVForkDone();
StopRunningThreads(thread.GetID());
}
else
ResumeThread(thread, thread.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
break;
}
case 0:
case TRAP_TRACE: // We receive this on single stepping.
case TRAP_HWBKPT: // We receive this on watchpoint hit
{
// If a watchpoint was hit, report it
uint32_t wp_index;
Status error = thread.GetRegisterContext().GetWatchpointHitIndex(
wp_index, (uintptr_t)info.si_addr);
if (error.Fail())
LLDB_LOG(log,
"received error while checking for watchpoint hits, pid = "
"{0}, error = {1}",
thread.GetID(), error);
if (wp_index != LLDB_INVALID_INDEX32) {
MonitorWatchpoint(thread, wp_index);
break;
}
// If a breakpoint was hit, report it
uint32_t bp_index;
error = thread.GetRegisterContext().GetHardwareBreakHitIndex(
bp_index, (uintptr_t)info.si_addr);
if (error.Fail())
LLDB_LOG(log, "received error while checking for hardware "
"breakpoint hits, pid = {0}, error = {1}",
thread.GetID(), error);
if (bp_index != LLDB_INVALID_INDEX32) {
MonitorBreakpoint(thread);
break;
}
// Otherwise, report step over
MonitorTrace(thread);
break;
}
case SI_KERNEL:
#if defined __mips__
// For mips there is no special signal for watchpoint So we check for
// watchpoint in kernel trap
{
// If a watchpoint was hit, report it
uint32_t wp_index;
Status error = thread.GetRegisterContext().GetWatchpointHitIndex(
wp_index, LLDB_INVALID_ADDRESS);
if (error.Fail())
LLDB_LOG(log,
"received error while checking for watchpoint hits, pid = "
"{0}, error = {1}",
thread.GetID(), error);
if (wp_index != LLDB_INVALID_INDEX32) {
MonitorWatchpoint(thread, wp_index);
break;
}
}
// NO BREAK
#endif
case TRAP_BRKPT:
MonitorBreakpoint(thread);
break;
case SIGTRAP:
case (SIGTRAP | 0x80):
LLDB_LOG(
log,
"received unknown SIGTRAP stop event ({0}, pid {1} tid {2}, resuming",
info.si_code, GetID(), thread.GetID());
// Ignore these signals until we know more about them.
ResumeThread(thread, thread.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
break;
default:
LLDB_LOG(log, "received unknown SIGTRAP stop event ({0}, pid {1} tid {2}",
info.si_code, GetID(), thread.GetID());
MonitorSignal(info, thread);
break;
}
}
void NativeProcessLinux::MonitorTrace(NativeThreadLinux &thread) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "received trace event, pid = {0}", thread.GetID());
// This thread is currently stopped.
thread.SetStoppedByTrace();
StopRunningThreads(thread.GetID());
}
void NativeProcessLinux::MonitorBreakpoint(NativeThreadLinux &thread) {
Log *log(
GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_BREAKPOINTS));
LLDB_LOG(log, "received breakpoint event, pid = {0}", thread.GetID());
// Mark the thread as stopped at breakpoint.
thread.SetStoppedByBreakpoint();
FixupBreakpointPCAsNeeded(thread);
if (m_threads_stepping_with_breakpoint.find(thread.GetID()) !=
m_threads_stepping_with_breakpoint.end())
thread.SetStoppedByTrace();
StopRunningThreads(thread.GetID());
}
void NativeProcessLinux::MonitorWatchpoint(NativeThreadLinux &thread,
uint32_t wp_index) {
Log *log(
GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_WATCHPOINTS));
LLDB_LOG(log, "received watchpoint event, pid = {0}, wp_index = {1}",
thread.GetID(), wp_index);
// Mark the thread as stopped at watchpoint. The address is at
// (lldb::addr_t)info->si_addr if we need it.
thread.SetStoppedByWatchpoint(wp_index);
// We need to tell all other running threads before we notify the delegate
// about this stop.
StopRunningThreads(thread.GetID());
}
void NativeProcessLinux::MonitorSignal(const siginfo_t &info,
NativeThreadLinux &thread) {
const int signo = info.si_signo;
const bool is_from_llgs = info.si_pid == getpid();
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
// POSIX says that process behaviour is undefined after it ignores a SIGFPE,
// SIGILL, SIGSEGV, or SIGBUS *unless* that signal was generated by a kill(2)
// or raise(3). Similarly for tgkill(2) on Linux.
//
// IOW, user generated signals never generate what we consider to be a
// "crash".
//
// Similarly, ACK signals generated by this monitor.
// Handle the signal.
LLDB_LOG(log,
"received signal {0} ({1}) with code {2}, (siginfo pid = {3}, "
"waitpid pid = {4})",
Host::GetSignalAsCString(signo), signo, info.si_code,
thread.GetID());
// Check for thread stop notification.
if (is_from_llgs && (info.si_code == SI_TKILL) && (signo == SIGSTOP)) {
// This is a tgkill()-based stop.
LLDB_LOG(log, "pid {0} tid {1}, thread stopped", GetID(), thread.GetID());
// Check that we're not already marked with a stop reason. Note this thread
// really shouldn't already be marked as stopped - if we were, that would
// imply that the kernel signaled us with the thread stopping which we
// handled and marked as stopped, and that, without an intervening resume,
// we received another stop. It is more likely that we are missing the
// marking of a run state somewhere if we find that the thread was marked
// as stopped.
const StateType thread_state = thread.GetState();
if (!StateIsStoppedState(thread_state, false)) {
// An inferior thread has stopped because of a SIGSTOP we have sent it.
// Generally, these are not important stops and we don't want to report
// them as they are just used to stop other threads when one thread (the
// one with the *real* stop reason) hits a breakpoint (watchpoint,
// etc...). However, in the case of an asynchronous Interrupt(), this
// *is* the real stop reason, so we leave the signal intact if this is
// the thread that was chosen as the triggering thread.
if (m_pending_notification_tid != LLDB_INVALID_THREAD_ID) {
if (m_pending_notification_tid == thread.GetID())
thread.SetStoppedBySignal(SIGSTOP, &info);
else
thread.SetStoppedWithNoReason();
SetCurrentThreadID(thread.GetID());
SignalIfAllThreadsStopped();
} else {
// We can end up here if stop was initiated by LLGS but by this time a
// thread stop has occurred - maybe initiated by another event.
Status error = ResumeThread(thread, thread.GetState(), 0);
if (error.Fail())
LLDB_LOG(log, "failed to resume thread {0}: {1}", thread.GetID(),
error);
}
} else {
LLDB_LOG(log,
"pid {0} tid {1}, thread was already marked as a stopped "
"state (state={2}), leaving stop signal as is",
GetID(), thread.GetID(), thread_state);
SignalIfAllThreadsStopped();
}
// Done handling.
return;
}
// Check if debugger should stop at this signal or just ignore it and resume
// the inferior.
if (m_signals_to_ignore.contains(signo)) {
ResumeThread(thread, thread.GetState(), signo);
return;
}
// This thread is stopped.
LLDB_LOG(log, "received signal {0}", Host::GetSignalAsCString(signo));
thread.SetStoppedBySignal(signo, &info);
// Send a stop to the debugger after we get all other threads to stop.
StopRunningThreads(thread.GetID());
}
bool NativeProcessLinux::MonitorClone(NativeThreadLinux &parent,
lldb::pid_t child_pid, int event) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "parent_tid={0}, child_pid={1}, event={2}", parent.GetID(),
child_pid, event);
WaitForCloneNotification(child_pid);
switch (event) {
case PTRACE_EVENT_CLONE: {
// PTRACE_EVENT_CLONE can either mean a new thread or a new process.
// Try to grab the new process' PGID to figure out which one it is.
// If PGID is the same as the PID, then it's a new process. Otherwise,
// it's a thread.
auto tgid_ret = getPIDForTID(child_pid);
if (tgid_ret != child_pid) {
// A new thread should have PGID matching our process' PID.
assert(!tgid_ret || tgid_ret.getValue() == GetID());
NativeThreadLinux &child_thread = AddThread(child_pid, /*resume*/ true);
ThreadWasCreated(child_thread);
// Resume the parent.
ResumeThread(parent, parent.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
break;
}
}
LLVM_FALLTHROUGH;
case PTRACE_EVENT_FORK:
case PTRACE_EVENT_VFORK: {
bool is_vfork = event == PTRACE_EVENT_VFORK;
std::unique_ptr<NativeProcessLinux> child_process{new NativeProcessLinux(
static_cast<::pid_t>(child_pid), m_terminal_fd, m_delegate, m_arch,
m_main_loop, {static_cast<::pid_t>(child_pid)})};
if (!is_vfork)
child_process->m_software_breakpoints = m_software_breakpoints;
Extension expected_ext = is_vfork ? Extension::vfork : Extension::fork;
if (bool(m_enabled_extensions & expected_ext)) {
m_delegate.NewSubprocess(this, std::move(child_process));
// NB: non-vfork clone() is reported as fork
parent.SetStoppedByFork(is_vfork, child_pid);
StopRunningThreads(parent.GetID());
} else {
child_process->Detach();
ResumeThread(parent, parent.GetState(), LLDB_INVALID_SIGNAL_NUMBER);
}
break;
}
default:
llvm_unreachable("unknown clone_info.event");
}
return true;
}
bool NativeProcessLinux::SupportHardwareSingleStepping() const {
if (m_arch.GetMachine() == llvm::Triple::arm || m_arch.IsMIPS())
return false;
return true;
}
Status NativeProcessLinux::Resume(const ResumeActionList &resume_actions) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "pid {0}", GetID());
bool software_single_step = !SupportHardwareSingleStepping();
if (software_single_step) {
for (const auto &thread : m_threads) {
assert(thread && "thread list should not contain NULL threads");
const ResumeAction *const action =
resume_actions.GetActionForThread(thread->GetID(), true);
if (action == nullptr)
continue;
if (action->state == eStateStepping) {
Status error = SetupSoftwareSingleStepping(
static_cast<NativeThreadLinux &>(*thread));
if (error.Fail())
return error;
}
}
}
for (const auto &thread : m_threads) {
assert(thread && "thread list should not contain NULL threads");
const ResumeAction *const action =
resume_actions.GetActionForThread(thread->GetID(), true);
if (action == nullptr) {
LLDB_LOG(log, "no action specified for pid {0} tid {1}", GetID(),
thread->GetID());
continue;
}
LLDB_LOG(log, "processing resume action state {0} for pid {1} tid {2}",
action->state, GetID(), thread->GetID());
switch (action->state) {
case eStateRunning:
case eStateStepping: {
// Run the thread, possibly feeding it the signal.
const int signo = action->signal;
ResumeThread(static_cast<NativeThreadLinux &>(*thread), action->state,
signo);
break;
}
case eStateSuspended:
case eStateStopped:
llvm_unreachable("Unexpected state");
default:
return Status("NativeProcessLinux::%s (): unexpected state %s specified "
"for pid %" PRIu64 ", tid %" PRIu64,
__FUNCTION__, StateAsCString(action->state), GetID(),
thread->GetID());
}
}
return Status();
}
Status NativeProcessLinux::Halt() {
Status error;
if (kill(GetID(), SIGSTOP) != 0)
error.SetErrorToErrno();
return error;
}
Status NativeProcessLinux::Detach() {
Status error;
// Stop monitoring the inferior.
m_sigchld_handle.reset();
// Tell ptrace to detach from the process.
if (GetID() == LLDB_INVALID_PROCESS_ID)
return error;
for (const auto &thread : m_threads) {
Status e = Detach(thread->GetID());
if (e.Fail())
error =
e; // Save the error, but still attempt to detach from other threads.
}
m_intel_pt_manager.Clear();
return error;
}
Status NativeProcessLinux::Signal(int signo) {
Status error;
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "sending signal {0} ({1}) to pid {1}", signo,
Host::GetSignalAsCString(signo), GetID());
if (kill(GetID(), signo))
error.SetErrorToErrno();
return error;
}
Status NativeProcessLinux::Interrupt() {
// Pick a running thread (or if none, a not-dead stopped thread) as the
// chosen thread that will be the stop-reason thread.
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
NativeThreadProtocol *running_thread = nullptr;
NativeThreadProtocol *stopped_thread = nullptr;
LLDB_LOG(log, "selecting running thread for interrupt target");
for (const auto &thread : m_threads) {
// If we have a running or stepping thread, we'll call that the target of
// the interrupt.
const auto thread_state = thread->GetState();
if (thread_state == eStateRunning || thread_state == eStateStepping) {
running_thread = thread.get();
break;
} else if (!stopped_thread && StateIsStoppedState(thread_state, true)) {
// Remember the first non-dead stopped thread. We'll use that as a
// backup if there are no running threads.
stopped_thread = thread.get();
}
}
if (!running_thread && !stopped_thread) {
Status error("found no running/stepping or live stopped threads as target "
"for interrupt");
LLDB_LOG(log, "skipping due to error: {0}", error);
return error;
}
NativeThreadProtocol *deferred_signal_thread =
running_thread ? running_thread : stopped_thread;
LLDB_LOG(log, "pid {0} {1} tid {2} chosen for interrupt target", GetID(),
running_thread ? "running" : "stopped",
deferred_signal_thread->GetID());
StopRunningThreads(deferred_signal_thread->GetID());
return Status();
}
Status NativeProcessLinux::Kill() {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "pid {0}", GetID());
Status error;
switch (m_state) {
case StateType::eStateInvalid:
case StateType::eStateExited:
case StateType::eStateCrashed:
case StateType::eStateDetached:
case StateType::eStateUnloaded:
// Nothing to do - the process is already dead.
LLDB_LOG(log, "ignored for PID {0} due to current state: {1}", GetID(),
m_state);
return error;
case StateType::eStateConnected:
case StateType::eStateAttaching:
case StateType::eStateLaunching:
case StateType::eStateStopped:
case StateType::eStateRunning:
case StateType::eStateStepping:
case StateType::eStateSuspended:
// We can try to kill a process in these states.
break;
}
if (kill(GetID(), SIGKILL) != 0) {
error.SetErrorToErrno();
return error;
}
return error;
}
Status NativeProcessLinux::GetMemoryRegionInfo(lldb::addr_t load_addr,
MemoryRegionInfo &range_info) {
// FIXME review that the final memory region returned extends to the end of
// the virtual address space,
// with no perms if it is not mapped.
// Use an approach that reads memory regions from /proc/{pid}/maps. Assume
// proc maps entries are in ascending order.
// FIXME assert if we find differently.
if (m_supports_mem_region == LazyBool::eLazyBoolNo) {
// We're done.
return Status("unsupported");
}
Status error = PopulateMemoryRegionCache();
if (error.Fail()) {
return error;
}
lldb::addr_t prev_base_address = 0;
// FIXME start by finding the last region that is <= target address using
// binary search. Data is sorted.
// There can be a ton of regions on pthreads apps with lots of threads.
for (auto it = m_mem_region_cache.begin(); it != m_mem_region_cache.end();
++it) {
MemoryRegionInfo &proc_entry_info = it->first;
// Sanity check assumption that /proc/{pid}/maps entries are ascending.
assert((proc_entry_info.GetRange().GetRangeBase() >= prev_base_address) &&
"descending /proc/pid/maps entries detected, unexpected");
prev_base_address = proc_entry_info.GetRange().GetRangeBase();
UNUSED_IF_ASSERT_DISABLED(prev_base_address);
// If the target address comes before this entry, indicate distance to next
// region.
if (load_addr < proc_entry_info.GetRange().GetRangeBase()) {
range_info.GetRange().SetRangeBase(load_addr);
range_info.GetRange().SetByteSize(
proc_entry_info.GetRange().GetRangeBase() - load_addr);
range_info.SetReadable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetWritable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetExecutable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetMapped(MemoryRegionInfo::OptionalBool::eNo);
return error;
} else if (proc_entry_info.GetRange().Contains(load_addr)) {
// The target address is within the memory region we're processing here.
range_info = proc_entry_info;
return error;
}
// The target memory address comes somewhere after the region we just
// parsed.
}
// If we made it here, we didn't find an entry that contained the given
// address. Return the load_addr as start and the amount of bytes betwwen
// load address and the end of the memory as size.
range_info.GetRange().SetRangeBase(load_addr);
range_info.GetRange().SetRangeEnd(LLDB_INVALID_ADDRESS);
range_info.SetReadable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetWritable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetExecutable(MemoryRegionInfo::OptionalBool::eNo);
range_info.SetMapped(MemoryRegionInfo::OptionalBool::eNo);
return error;
}
Status NativeProcessLinux::PopulateMemoryRegionCache() {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
// If our cache is empty, pull the latest. There should always be at least
// one memory region if memory region handling is supported.
if (!m_mem_region_cache.empty()) {
LLDB_LOG(log, "reusing {0} cached memory region entries",
m_mem_region_cache.size());
return Status();
}
Status Result;
LinuxMapCallback callback = [&](llvm::Expected<MemoryRegionInfo> Info) {
if (Info) {
FileSpec file_spec(Info->GetName().GetCString());
FileSystem::Instance().Resolve(file_spec);
m_mem_region_cache.emplace_back(*Info, file_spec);
return true;
}
Result = Info.takeError();
m_supports_mem_region = LazyBool::eLazyBoolNo;
LLDB_LOG(log, "failed to parse proc maps: {0}", Result);
return false;
};
// Linux kernel since 2.6.14 has /proc/{pid}/smaps
// if CONFIG_PROC_PAGE_MONITOR is enabled
auto BufferOrError = getProcFile(GetID(), "smaps");
if (BufferOrError)
ParseLinuxSMapRegions(BufferOrError.get()->getBuffer(), callback);
else {
BufferOrError = getProcFile(GetID(), "maps");
if (!BufferOrError) {
m_supports_mem_region = LazyBool::eLazyBoolNo;
return BufferOrError.getError();
}
ParseLinuxMapRegions(BufferOrError.get()->getBuffer(), callback);
}
if (Result.Fail())
return Result;
if (m_mem_region_cache.empty()) {
// No entries after attempting to read them. This shouldn't happen if
// /proc/{pid}/maps is supported. Assume we don't support map entries via
// procfs.
m_supports_mem_region = LazyBool::eLazyBoolNo;
LLDB_LOG(log,
"failed to find any procfs maps entries, assuming no support "
"for memory region metadata retrieval");
return Status("not supported");
}
LLDB_LOG(log, "read {0} memory region entries from /proc/{1}/maps",
m_mem_region_cache.size(), GetID());
// We support memory retrieval, remember that.
m_supports_mem_region = LazyBool::eLazyBoolYes;
return Status();
}
void NativeProcessLinux::DoStopIDBumped(uint32_t newBumpId) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log, "newBumpId={0}", newBumpId);
LLDB_LOG(log, "clearing {0} entries from memory region cache",
m_mem_region_cache.size());
m_mem_region_cache.clear();
}
llvm::Expected<uint64_t>
NativeProcessLinux::Syscall(llvm::ArrayRef<uint64_t> args) {
PopulateMemoryRegionCache();
auto region_it = llvm::find_if(m_mem_region_cache, [](const auto &pair) {
return pair.first.GetExecutable() == MemoryRegionInfo::eYes;
});
if (region_it == m_mem_region_cache.end())
return llvm::createStringError(llvm::inconvertibleErrorCode(),
"No executable memory region found!");
addr_t exe_addr = region_it->first.GetRange().GetRangeBase();
NativeThreadLinux &thread = *GetThreadByID(GetID());
assert(thread.GetState() == eStateStopped);
NativeRegisterContextLinux &reg_ctx = thread.GetRegisterContext();
NativeRegisterContextLinux::SyscallData syscall_data =
*reg_ctx.GetSyscallData();
DataBufferSP registers_sp;
if (llvm::Error Err = reg_ctx.ReadAllRegisterValues(registers_sp).ToError())
return std::move(Err);
auto restore_regs = llvm::make_scope_exit(
[&] { reg_ctx.WriteAllRegisterValues(registers_sp); });
llvm::SmallVector<uint8_t, 8> memory(syscall_data.Insn.size());
size_t bytes_read;
if (llvm::Error Err =
ReadMemory(exe_addr, memory.data(), memory.size(), bytes_read)
.ToError()) {
return std::move(Err);
}
auto restore_mem = llvm::make_scope_exit(
[&] { WriteMemory(exe_addr, memory.data(), memory.size(), bytes_read); });
if (llvm::Error Err = reg_ctx.SetPC(exe_addr).ToError())
return std::move(Err);
for (const auto &zip : llvm::zip_first(args, syscall_data.Args)) {
if (llvm::Error Err =
reg_ctx
.WriteRegisterFromUnsigned(std::get<1>(zip), std::get<0>(zip))
.ToError()) {
return std::move(Err);
}
}
if (llvm::Error Err = WriteMemory(exe_addr, syscall_data.Insn.data(),
syscall_data.Insn.size(), bytes_read)
.ToError())
return std::move(Err);
m_mem_region_cache.clear();
// With software single stepping the syscall insn buffer must also include a
// trap instruction to stop the process.
int req = SupportHardwareSingleStepping() ? PTRACE_SINGLESTEP : PTRACE_CONT;
if (llvm::Error Err =
PtraceWrapper(req, thread.GetID(), nullptr, nullptr).ToError())
return std::move(Err);
int status;
::pid_t wait_pid = llvm::sys::RetryAfterSignal(-1, ::waitpid, thread.GetID(),
&status, __WALL);
if (wait_pid == -1) {
return llvm::errorCodeToError(
std::error_code(errno, std::generic_category()));
}
assert((unsigned)wait_pid == thread.GetID());
uint64_t result = reg_ctx.ReadRegisterAsUnsigned(syscall_data.Result, -ESRCH);
// Values larger than this are actually negative errno numbers.
uint64_t errno_threshold =
(uint64_t(-1) >> (64 - 8 * m_arch.GetAddressByteSize())) - 0x1000;
if (result > errno_threshold) {
return llvm::errorCodeToError(
std::error_code(-result & 0xfff, std::generic_category()));
}
return result;
}
llvm::Expected<addr_t>
NativeProcessLinux::AllocateMemory(size_t size, uint32_t permissions) {
llvm::Optional<NativeRegisterContextLinux::MmapData> mmap_data =
GetCurrentThread()->GetRegisterContext().GetMmapData();
if (!mmap_data)
return llvm::make_error<UnimplementedError>();
unsigned prot = PROT_NONE;
assert((permissions & (ePermissionsReadable | ePermissionsWritable |
ePermissionsExecutable)) == permissions &&
"Unknown permission!");
if (permissions & ePermissionsReadable)
prot |= PROT_READ;
if (permissions & ePermissionsWritable)
prot |= PROT_WRITE;
if (permissions & ePermissionsExecutable)
prot |= PROT_EXEC;
llvm::Expected<uint64_t> Result =
Syscall({mmap_data->SysMmap, 0, size, prot, MAP_ANONYMOUS | MAP_PRIVATE,
uint64_t(-1), 0});
if (Result)
m_allocated_memory.try_emplace(*Result, size);
return Result;
}
llvm::Error NativeProcessLinux::DeallocateMemory(lldb::addr_t addr) {
llvm::Optional<NativeRegisterContextLinux::MmapData> mmap_data =
GetCurrentThread()->GetRegisterContext().GetMmapData();
if (!mmap_data)
return llvm::make_error<UnimplementedError>();
auto it = m_allocated_memory.find(addr);
if (it == m_allocated_memory.end())
return llvm::createStringError(llvm::errc::invalid_argument,
"Memory not allocated by the debugger.");
llvm::Expected<uint64_t> Result =
Syscall({mmap_data->SysMunmap, addr, it->second});
if (!Result)
return Result.takeError();
m_allocated_memory.erase(it);
return llvm::Error::success();
}
Status NativeProcessLinux::ReadMemoryTags(int32_t type, lldb::addr_t addr,
size_t len,
std::vector<uint8_t> &tags) {
llvm::Expected<NativeRegisterContextLinux::MemoryTaggingDetails> details =
GetCurrentThread()->GetRegisterContext().GetMemoryTaggingDetails(type);
if (!details)
return Status(details.takeError());
// Ignore 0 length read
if (!len)
return Status();
// lldb will align the range it requests but it is not required to by
// the protocol so we'll do it again just in case.
// Remove non address bits too. Ptrace calls may work regardless but that
// is not a guarantee.
MemoryTagManager::TagRange range(details->manager->RemoveNonAddressBits(addr),
len);
range = details->manager->ExpandToGranule(range);
// Allocate enough space for all tags to be read
size_t num_tags = range.GetByteSize() / details->manager->GetGranuleSize();
tags.resize(num_tags * details->manager->GetTagSizeInBytes());
struct iovec tags_iovec;
uint8_t *dest = tags.data();
lldb::addr_t read_addr = range.GetRangeBase();
// This call can return partial data so loop until we error or
// get all tags back.
while (num_tags) {
tags_iovec.iov_base = dest;
tags_iovec.iov_len = num_tags;
Status error = NativeProcessLinux::PtraceWrapper(
details->ptrace_read_req, GetID(), reinterpret_cast<void *>(read_addr),
static_cast<void *>(&tags_iovec), 0, nullptr);
if (error.Fail()) {
// Discard partial reads
tags.resize(0);
return error;
}
size_t tags_read = tags_iovec.iov_len;
assert(tags_read && (tags_read <= num_tags));
dest += tags_read * details->manager->GetTagSizeInBytes();
read_addr += details->manager->GetGranuleSize() * tags_read;
num_tags -= tags_read;
}
return Status();
}
Status NativeProcessLinux::WriteMemoryTags(int32_t type, lldb::addr_t addr,
size_t len,
const std::vector<uint8_t> &tags) {
llvm::Expected<NativeRegisterContextLinux::MemoryTaggingDetails> details =
GetCurrentThread()->GetRegisterContext().GetMemoryTaggingDetails(type);
if (!details)
return Status(details.takeError());
// Ignore 0 length write
if (!len)
return Status();
// lldb will align the range it requests but it is not required to by
// the protocol so we'll do it again just in case.
// Remove non address bits too. Ptrace calls may work regardless but that
// is not a guarantee.
MemoryTagManager::TagRange range(details->manager->RemoveNonAddressBits(addr),
len);
range = details->manager->ExpandToGranule(range);
// Not checking number of tags here, we may repeat them below
llvm::Expected<std::vector<lldb::addr_t>> unpacked_tags_or_err =
details->manager->UnpackTagsData(tags);
if (!unpacked_tags_or_err)
return Status(unpacked_tags_or_err.takeError());
llvm::Expected<std::vector<lldb::addr_t>> repeated_tags_or_err =
details->manager->RepeatTagsForRange(*unpacked_tags_or_err, range);
if (!repeated_tags_or_err)
return Status(repeated_tags_or_err.takeError());
// Repack them for ptrace to use
llvm::Expected<std::vector<uint8_t>> final_tag_data =
details->manager->PackTags(*repeated_tags_or_err);
if (!final_tag_data)
return Status(final_tag_data.takeError());
struct iovec tags_vec;
uint8_t *src = final_tag_data->data();
lldb::addr_t write_addr = range.GetRangeBase();
// unpacked tags size because the number of bytes per tag might not be 1
size_t num_tags = repeated_tags_or_err->size();
// This call can partially write tags, so we loop until we
// error or all tags have been written.
while (num_tags > 0) {
tags_vec.iov_base = src;
tags_vec.iov_len = num_tags;
Status error = NativeProcessLinux::PtraceWrapper(
details->ptrace_write_req, GetID(),
reinterpret_cast<void *>(write_addr), static_cast<void *>(&tags_vec), 0,
nullptr);
if (error.Fail()) {
// Don't attempt to restore the original values in the case of a partial
// write
return error;
}
size_t tags_written = tags_vec.iov_len;
assert(tags_written && (tags_written <= num_tags));
src += tags_written * details->manager->GetTagSizeInBytes();
write_addr += details->manager->GetGranuleSize() * tags_written;
num_tags -= tags_written;
}
return Status();
}
size_t NativeProcessLinux::UpdateThreads() {
// The NativeProcessLinux monitoring threads are always up to date with
// respect to thread state and they keep the thread list populated properly.
// All this method needs to do is return the thread count.
return m_threads.size();
}
Status NativeProcessLinux::SetBreakpoint(lldb::addr_t addr, uint32_t size,
bool hardware) {
if (hardware)
return SetHardwareBreakpoint(addr, size);
else
return SetSoftwareBreakpoint(addr, size);
}
Status NativeProcessLinux::RemoveBreakpoint(lldb::addr_t addr, bool hardware) {
if (hardware)
return RemoveHardwareBreakpoint(addr);
else
return NativeProcessProtocol::RemoveBreakpoint(addr);
}
llvm::Expected<llvm::ArrayRef<uint8_t>>
NativeProcessLinux::GetSoftwareBreakpointTrapOpcode(size_t size_hint) {
// The ARM reference recommends the use of 0xe7fddefe and 0xdefe but the
// linux kernel does otherwise.
static const uint8_t g_arm_opcode[] = {0xf0, 0x01, 0xf0, 0xe7};
static const uint8_t g_thumb_opcode[] = {0x01, 0xde};
switch (GetArchitecture().GetMachine()) {
case llvm::Triple::arm:
switch (size_hint) {
case 2:
return llvm::makeArrayRef(g_thumb_opcode);
case 4:
return llvm::makeArrayRef(g_arm_opcode);
default:
return llvm::createStringError(llvm::inconvertibleErrorCode(),
"Unrecognised trap opcode size hint!");
}
default:
return NativeProcessProtocol::GetSoftwareBreakpointTrapOpcode(size_hint);
}
}
Status NativeProcessLinux::ReadMemory(lldb::addr_t addr, void *buf, size_t size,
size_t &bytes_read) {
if (ProcessVmReadvSupported()) {
// The process_vm_readv path is about 50 times faster than ptrace api. We
// want to use this syscall if it is supported.
const ::pid_t pid = GetID();
struct iovec local_iov, remote_iov;
local_iov.iov_base = buf;
local_iov.iov_len = size;
remote_iov.iov_base = reinterpret_cast<void *>(addr);
remote_iov.iov_len = size;
bytes_read = process_vm_readv(pid, &local_iov, 1, &remote_iov, 1, 0);
const bool success = bytes_read == size;
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
LLDB_LOG(log,
"using process_vm_readv to read {0} bytes from inferior "
"address {1:x}: {2}",
size, addr, success ? "Success" : llvm::sys::StrError(errno));
if (success)
return Status();
// else the call failed for some reason, let's retry the read using ptrace
// api.
}
unsigned char *dst = static_cast<unsigned char *>(buf);
size_t remainder;
long data;
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_MEMORY));
LLDB_LOG(log, "addr = {0}, buf = {1}, size = {2}", addr, buf, size);
for (bytes_read = 0; bytes_read < size; bytes_read += remainder) {
Status error = NativeProcessLinux::PtraceWrapper(
PTRACE_PEEKDATA, GetID(), (void *)addr, nullptr, 0, &data);
if (error.Fail())
return error;
remainder = size - bytes_read;
remainder = remainder > k_ptrace_word_size ? k_ptrace_word_size : remainder;
// Copy the data into our buffer
memcpy(dst, &data, remainder);
LLDB_LOG(log, "[{0:x}]:{1:x}", addr, data);
addr += k_ptrace_word_size;
dst += k_ptrace_word_size;
}
return Status();
}
Status NativeProcessLinux::WriteMemory(lldb::addr_t addr, const void *buf,
size_t size, size_t &bytes_written) {
const unsigned char *src = static_cast<const unsigned char *>(buf);
size_t remainder;
Status error;
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_MEMORY));
LLDB_LOG(log, "addr = {0}, buf = {1}, size = {2}", addr, buf, size);
for (bytes_written = 0; bytes_written < size; bytes_written += remainder) {
remainder = size - bytes_written;
remainder = remainder > k_ptrace_word_size ? k_ptrace_word_size : remainder;
if (remainder == k_ptrace_word_size) {
unsigned long data = 0;
memcpy(&data, src, k_ptrace_word_size);
LLDB_LOG(log, "[{0:x}]:{1:x}", addr, data);
error = NativeProcessLinux::PtraceWrapper(PTRACE_POKEDATA, GetID(),
(void *)addr, (void *)data);
if (error.Fail())
return error;
} else {
unsigned char buff[8];
size_t bytes_read;
error = ReadMemory(addr, buff, k_ptrace_word_size, bytes_read);
if (error.Fail())
return error;
memcpy(buff, src, remainder);
size_t bytes_written_rec;
error = WriteMemory(addr, buff, k_ptrace_word_size, bytes_written_rec);
if (error.Fail())
return error;
LLDB_LOG(log, "[{0:x}]:{1:x} ({2:x})", addr, *(const unsigned long *)src,
*(unsigned long *)buff);
}
addr += k_ptrace_word_size;
src += k_ptrace_word_size;
}
return error;
}
Status NativeProcessLinux::GetSignalInfo(lldb::tid_t tid, void *siginfo) {
return PtraceWrapper(PTRACE_GETSIGINFO, tid, nullptr, siginfo);
}
Status NativeProcessLinux::GetEventMessage(lldb::tid_t tid,
unsigned long *message) {
return PtraceWrapper(PTRACE_GETEVENTMSG, tid, nullptr, message);
}
Status NativeProcessLinux::Detach(lldb::tid_t tid) {
if (tid == LLDB_INVALID_THREAD_ID)
return Status();
return PtraceWrapper(PTRACE_DETACH, tid);
}
bool NativeProcessLinux::HasThreadNoLock(lldb::tid_t thread_id) {
for (const auto &thread : m_threads) {
assert(thread && "thread list should not contain NULL threads");
if (thread->GetID() == thread_id) {
// We have this thread.
return true;
}
}
// We don't have this thread.
return false;
}
void NativeProcessLinux::StopTrackingThread(NativeThreadLinux &thread) {
Log *const log = ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD);
lldb::tid_t thread_id = thread.GetID();
LLDB_LOG(log, "tid: {0}", thread_id);
auto it = llvm::find_if(m_threads, [&](const auto &thread_up) {
return thread_up.get() == &thread;
});
assert(it != m_threads.end());
m_threads.erase(it);
NotifyTracersOfThreadDestroyed(thread_id);
SignalIfAllThreadsStopped();
}
Status NativeProcessLinux::NotifyTracersOfNewThread(lldb::tid_t tid) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD));
Status error(m_intel_pt_manager.OnThreadCreated(tid));
if (error.Fail())
LLDB_LOG(log, "Failed to trace a new thread with intel-pt, tid = {0}. {1}",
tid, error.AsCString());
return error;
}
Status NativeProcessLinux::NotifyTracersOfThreadDestroyed(lldb::tid_t tid) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD));
Status error(m_intel_pt_manager.OnThreadDestroyed(tid));
if (error.Fail())
LLDB_LOG(log,
"Failed to stop a destroyed thread with intel-pt, tid = {0}. {1}",
tid, error.AsCString());
return error;
}
NativeThreadLinux &NativeProcessLinux::AddThread(lldb::tid_t thread_id,
bool resume) {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD));
LLDB_LOG(log, "pid {0} adding thread with tid {1}", GetID(), thread_id);
assert(!HasThreadNoLock(thread_id) &&
"attempted to add a thread by id that already exists");
// If this is the first thread, save it as the current thread
if (m_threads.empty())
SetCurrentThreadID(thread_id);
m_threads.push_back(std::make_unique<NativeThreadLinux>(*this, thread_id));
NativeThreadLinux &thread =
static_cast<NativeThreadLinux &>(*m_threads.back());
Status tracing_error = NotifyTracersOfNewThread(thread.GetID());
if (tracing_error.Fail()) {
thread.SetStoppedByProcessorTrace(tracing_error.AsCString());
StopRunningThreads(thread.GetID());
} else if (resume)
ResumeThread(thread, eStateRunning, LLDB_INVALID_SIGNAL_NUMBER);
else
thread.SetStoppedBySignal(SIGSTOP);
return thread;
}
Status NativeProcessLinux::GetLoadedModuleFileSpec(const char *module_path,
FileSpec &file_spec) {
Status error = PopulateMemoryRegionCache();
if (error.Fail())
return error;
FileSpec module_file_spec(module_path);
FileSystem::Instance().Resolve(module_file_spec);
file_spec.Clear();
for (const auto &it : m_mem_region_cache) {
if (it.second.GetFilename() == module_file_spec.GetFilename()) {
file_spec = it.second;
return Status();
}
}
return Status("Module file (%s) not found in /proc/%" PRIu64 "/maps file!",
module_file_spec.GetFilename().AsCString(), GetID());
}
Status NativeProcessLinux::GetFileLoadAddress(const llvm::StringRef &file_name,
lldb::addr_t &load_addr) {
load_addr = LLDB_INVALID_ADDRESS;
Status error = PopulateMemoryRegionCache();
if (error.Fail())
return error;
FileSpec file(file_name);
for (const auto &it : m_mem_region_cache) {
if (it.second == file) {
load_addr = it.first.GetRange().GetRangeBase();
return Status();
}
}
return Status("No load address found for specified file.");
}
NativeThreadLinux *NativeProcessLinux::GetThreadByID(lldb::tid_t tid) {
return static_cast<NativeThreadLinux *>(
NativeProcessProtocol::GetThreadByID(tid));
}
NativeThreadLinux *NativeProcessLinux::GetCurrentThread() {
return static_cast<NativeThreadLinux *>(
NativeProcessProtocol::GetCurrentThread());
}
Status NativeProcessLinux::ResumeThread(NativeThreadLinux &thread,
lldb::StateType state, int signo) {
Log *const log = ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD);
LLDB_LOG(log, "tid: {0}", thread.GetID());
// Before we do the resume below, first check if we have a pending stop
// notification that is currently waiting for all threads to stop. This is
// potentially a buggy situation since we're ostensibly waiting for threads
// to stop before we send out the pending notification, and here we are
// resuming one before we send out the pending stop notification.
if (m_pending_notification_tid != LLDB_INVALID_THREAD_ID) {
LLDB_LOG(log,
"about to resume tid {0} per explicit request but we have a "
"pending stop notification (tid {1}) that is actively "
"waiting for this thread to stop. Valid sequence of events?",
thread.GetID(), m_pending_notification_tid);
}
// Request a resume. We expect this to be synchronous and the system to
// reflect it is running after this completes.
switch (state) {
case eStateRunning: {
const auto resume_result = thread.Resume(signo);
if (resume_result.Success())
SetState(eStateRunning, true);
return resume_result;
}
case eStateStepping: {
const auto step_result = thread.SingleStep(signo);
if (step_result.Success())
SetState(eStateRunning, true);
return step_result;
}
default:
LLDB_LOG(log, "Unhandled state {0}.", state);
llvm_unreachable("Unhandled state for resume");
}
}
//===----------------------------------------------------------------------===//
void NativeProcessLinux::StopRunningThreads(const lldb::tid_t triggering_tid) {
Log *const log = ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD);
LLDB_LOG(log, "about to process event: (triggering_tid: {0})",
triggering_tid);
m_pending_notification_tid = triggering_tid;
// Request a stop for all the thread stops that need to be stopped and are
// not already known to be stopped.
for (const auto &thread : m_threads) {
if (StateIsRunningState(thread->GetState()))
static_cast<NativeThreadLinux *>(thread.get())->RequestStop();
}
SignalIfAllThreadsStopped();
LLDB_LOG(log, "event processing done");
}
void NativeProcessLinux::SignalIfAllThreadsStopped() {
if (m_pending_notification_tid == LLDB_INVALID_THREAD_ID)
return; // No pending notification. Nothing to do.
for (const auto &thread_sp : m_threads) {
if (StateIsRunningState(thread_sp->GetState()))
return; // Some threads are still running. Don't signal yet.
}
// We have a pending notification and all threads have stopped.
Log *log(
GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_BREAKPOINTS));
// Clear any temporary breakpoints we used to implement software single
// stepping.
for (const auto &thread_info : m_threads_stepping_with_breakpoint) {
Status error = RemoveBreakpoint(thread_info.second);
if (error.Fail())
LLDB_LOG(log, "pid = {0} remove stepping breakpoint: {1}",
thread_info.first, error);
}
m_threads_stepping_with_breakpoint.clear();
// Notify the delegate about the stop
SetCurrentThreadID(m_pending_notification_tid);
SetState(StateType::eStateStopped, true);
m_pending_notification_tid = LLDB_INVALID_THREAD_ID;
}
void NativeProcessLinux::ThreadWasCreated(NativeThreadLinux &thread) {
Log *const log = ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD);
LLDB_LOG(log, "tid: {0}", thread.GetID());
if (m_pending_notification_tid != LLDB_INVALID_THREAD_ID &&
StateIsRunningState(thread.GetState())) {
// We will need to wait for this new thread to stop as well before firing
// the notification.
thread.RequestStop();
}
}
void NativeProcessLinux::SigchldHandler() {
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
// Threads can appear or disappear as a result of event processing, so gather
// the events upfront.
llvm::DenseMap<lldb::tid_t, WaitStatus> tid_events;
for (const auto &thread_up : m_threads) {
int status = -1;
::pid_t wait_pid =
llvm::sys::RetryAfterSignal(-1, ::waitpid, thread_up->GetID(), &status,
__WALL | __WNOTHREAD | WNOHANG);
if (wait_pid == 0)
continue; // Nothing to do for this thread.
if (wait_pid == -1) {
Status error(errno, eErrorTypePOSIX);
LLDB_LOG(log, "waitpid({0}, &status, _) failed: {1}", thread_up->GetID(),
error);
continue;
}
assert(wait_pid == static_cast<::pid_t>(thread_up->GetID()));
WaitStatus wait_status = WaitStatus::Decode(status);
LLDB_LOG(log, "waitpid({0}) got status = {1}", thread_up->GetID(),
wait_status);
tid_events.try_emplace(thread_up->GetID(), wait_status);
}
for (auto &KV : tid_events) {
LLDB_LOG(log, "processing {0}({1}) ...", KV.first, KV.second);
NativeThreadLinux *thread = GetThreadByID(KV.first);
if (thread) {
MonitorCallback(*thread, KV.second);
} else {
// This can happen if one of the events is an main thread exit.
LLDB_LOG(log, "... but the thread has disappeared");
}
}
}
// Wrapper for ptrace to catch errors and log calls. Note that ptrace sets
// errno on error because -1 can be a valid result (i.e. for PTRACE_PEEK*)
Status NativeProcessLinux::PtraceWrapper(int req, lldb::pid_t pid, void *addr,
void *data, size_t data_size,
long *result) {
Status error;
long int ret;
Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
PtraceDisplayBytes(req, data, data_size);
errno = 0;
if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
ret = ptrace(static_cast<__ptrace_request>(req), static_cast<::pid_t>(pid),
*(unsigned int *)addr, data);
else
ret = ptrace(static_cast<__ptrace_request>(req), static_cast<::pid_t>(pid),
addr, data);
if (ret == -1)
error.SetErrorToErrno();
if (result)
*result = ret;
LLDB_LOG(log, "ptrace({0}, {1}, {2}, {3}, {4})={5:x}", req, pid, addr, data,
data_size, ret);
PtraceDisplayBytes(req, data, data_size);
if (error.Fail())
LLDB_LOG(log, "ptrace() failed: {0}", error);
return error;
}
llvm::Expected<TraceSupportedResponse> NativeProcessLinux::TraceSupported() {
if (IntelPTManager::IsSupported())
return TraceSupportedResponse{"intel-pt", "Intel Processor Trace"};
return NativeProcessProtocol::TraceSupported();
}
Error NativeProcessLinux::TraceStart(StringRef json_request, StringRef type) {
if (type == "intel-pt") {
if (Expected<TraceIntelPTStartRequest> request =
json::parse<TraceIntelPTStartRequest>(json_request,
"TraceIntelPTStartRequest")) {
std::vector<lldb::tid_t> process_threads;
for (auto &thread : m_threads)
process_threads.push_back(thread->GetID());
return m_intel_pt_manager.TraceStart(*request, process_threads);
} else
return request.takeError();
}
return NativeProcessProtocol::TraceStart(json_request, type);
}
Error NativeProcessLinux::TraceStop(const TraceStopRequest &request) {
if (request.type == "intel-pt")
return m_intel_pt_manager.TraceStop(request);
return NativeProcessProtocol::TraceStop(request);
}
Expected<json::Value> NativeProcessLinux::TraceGetState(StringRef type) {
if (type == "intel-pt")
return m_intel_pt_manager.GetState();
return NativeProcessProtocol::TraceGetState(type);
}
Expected<std::vector<uint8_t>> NativeProcessLinux::TraceGetBinaryData(
const TraceGetBinaryDataRequest &request) {
if (request.type == "intel-pt")
return m_intel_pt_manager.GetBinaryData(request);
return NativeProcessProtocol::TraceGetBinaryData(request);
}
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