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llvm-project/lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp

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//===-- ProcessDebugger.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 "ProcessDebugger.h"
// Windows includes
#include "lldb/Host/windows/windows.h"
#include <psapi.h>
#include "lldb/Host/FileSystem.h"
#include "lldb/Host/HostNativeProcessBase.h"
#include "lldb/Host/HostProcess.h"
#include "lldb/Host/HostThread.h"
#include "lldb/Host/ProcessLaunchInfo.h"
#include "lldb/Target/MemoryRegionInfo.h"
#include "lldb/Target/Process.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/Error.h"
#include "DebuggerThread.h"
#include "ExceptionRecord.h"
#include "ProcessWindowsLog.h"
using namespace lldb;
using namespace lldb_private;
static DWORD ConvertLldbToWinApiProtect(uint32_t protect) {
// We also can process a read / write permissions here, but if the debugger
// will make later a write into the allocated memory, it will fail. To get
// around it is possible inside DoWriteMemory to remember memory permissions,
// allow write, write and restore permissions, but for now we process only
// the executable permission.
//
// TODO: Process permissions other than executable
if (protect & ePermissionsExecutable)
return PAGE_EXECUTE_READWRITE;
return PAGE_READWRITE;
}
// The Windows page protection bits are NOT independent masks that can be
// bitwise-ORed together. For example, PAGE_EXECUTE_READ is not (PAGE_EXECUTE
// | PAGE_READ). To test for an access type, it's necessary to test for any of
// the bits that provide that access type.
static bool IsPageReadable(uint32_t protect) {
return (protect & PAGE_NOACCESS) == 0;
}
static bool IsPageWritable(uint32_t protect) {
return (protect & (PAGE_EXECUTE_READWRITE | PAGE_EXECUTE_WRITECOPY |
PAGE_READWRITE | PAGE_WRITECOPY)) != 0;
}
static bool IsPageExecutable(uint32_t protect) {
return (protect & (PAGE_EXECUTE | PAGE_EXECUTE_READ | PAGE_EXECUTE_READWRITE |
PAGE_EXECUTE_WRITECOPY)) != 0;
}
namespace lldb_private {
ProcessDebugger::~ProcessDebugger() {}
lldb::pid_t ProcessDebugger::GetDebuggedProcessId() const {
if (m_session_data)
return m_session_data->m_debugger->GetProcess().GetProcessId();
return LLDB_INVALID_PROCESS_ID;
}
Status ProcessDebugger::DetachProcess() {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
DebuggerThreadSP debugger_thread;
{
// Acquire the lock only long enough to get the DebuggerThread.
// StopDebugging() will trigger a call back into ProcessDebugger which will
// also acquire the lock. Thus we have to release the lock before calling
// StopDebugging().
llvm::sys::ScopedLock lock(m_mutex);
if (!m_session_data) {
LLDB_LOG(log, "there is no active session.");
return Status();
}
debugger_thread = m_session_data->m_debugger;
}
Status error;
LLDB_LOG(log, "detaching from process {0}.",
debugger_thread->GetProcess().GetNativeProcess().GetSystemHandle());
error = debugger_thread->StopDebugging(false);
// By the time StopDebugging returns, there is no more debugger thread, so
// we can be assured that no other thread will race for the session data.
m_session_data.reset();
return error;
}
Status ProcessDebugger::LaunchProcess(ProcessLaunchInfo &launch_info,
DebugDelegateSP delegate) {
// Even though m_session_data is accessed here, it is before a debugger
// thread has been kicked off. So there's no race conditions, and it
// shouldn't be necessary to acquire the mutex.
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
Status result;
FileSpec working_dir = launch_info.GetWorkingDirectory();
namespace fs = llvm::sys::fs;
if (working_dir) {
FileSystem::Instance().Resolve(working_dir);
if (!FileSystem::Instance().IsDirectory(working_dir)) {
result.SetErrorStringWithFormat("No such file or directory: %s",
working_dir.GetCString());
return result;
}
}
if (!launch_info.GetFlags().Test(eLaunchFlagDebug)) {
StreamString stream;
stream.Printf("ProcessDebugger unable to launch '%s'. ProcessDebugger can "
"only be used for debug launches.",
launch_info.GetExecutableFile().GetPath().c_str());
std::string message = stream.GetString().str();
result.SetErrorString(message.c_str());
LLDB_LOG(log, "error: {0}", message);
return result;
}
bool stop_at_entry = launch_info.GetFlags().Test(eLaunchFlagStopAtEntry);
m_session_data.reset(new ProcessWindowsData(stop_at_entry));
m_session_data->m_debugger.reset(new DebuggerThread(delegate));
DebuggerThreadSP debugger = m_session_data->m_debugger;
// Kick off the DebugLaunch asynchronously and wait for it to complete.
result = debugger->DebugLaunch(launch_info);
if (result.Fail()) {
LLDB_LOG(log, "failed launching '{0}'. {1}",
launch_info.GetExecutableFile().GetPath(), result);
return result;
}
HostProcess process;
Status error = WaitForDebuggerConnection(debugger, process);
if (error.Fail()) {
LLDB_LOG(log, "failed launching '{0}'. {1}",
launch_info.GetExecutableFile().GetPath(), error);
return error;
}
LLDB_LOG(log, "successfully launched '{0}'",
launch_info.GetExecutableFile().GetPath());
// We've hit the initial stop. If eLaunchFlagsStopAtEntry was specified, the
// private state should already be set to eStateStopped as a result of
// hitting the initial breakpoint. If it was not set, the breakpoint should
// have already been resumed from and the private state should already be
// eStateRunning.
launch_info.SetProcessID(process.GetProcessId());
return result;
}
Status ProcessDebugger::AttachProcess(lldb::pid_t pid,
const ProcessAttachInfo &attach_info,
DebugDelegateSP delegate) {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
m_session_data.reset(
new ProcessWindowsData(!attach_info.GetContinueOnceAttached()));
DebuggerThreadSP debugger(new DebuggerThread(delegate));
m_session_data->m_debugger = debugger;
DWORD process_id = static_cast<DWORD>(pid);
Status error = debugger->DebugAttach(process_id, attach_info);
if (error.Fail()) {
LLDB_LOG(
log,
"encountered an error occurred initiating the asynchronous attach. {0}",
error);
return error;
}
HostProcess process;
error = WaitForDebuggerConnection(debugger, process);
if (error.Fail()) {
LLDB_LOG(log,
"encountered an error waiting for the debugger to connect. {0}",
error);
return error;
}
LLDB_LOG(log, "successfully attached to process with pid={0}", process_id);
// We've hit the initial stop. If eLaunchFlagsStopAtEntry was specified, the
// private state should already be set to eStateStopped as a result of
// hitting the initial breakpoint. If it was not set, the breakpoint should
// have already been resumed from and the private state should already be
// eStateRunning.
return error;
}
Status ProcessDebugger::DestroyProcess(const lldb::StateType state) {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
DebuggerThreadSP debugger_thread;
{
// Acquire this lock inside an inner scope, only long enough to get the
// DebuggerThread. StopDebugging() will trigger a call back into
// ProcessDebugger which will acquire the lock again, so we need to not
// deadlock.
llvm::sys::ScopedLock lock(m_mutex);
if (!m_session_data) {
LLDB_LOG(log, "warning: state = {0}, but there is no active session.",
state);
return Status();
}
debugger_thread = m_session_data->m_debugger;
}
Status error;
if (state != eStateExited && state != eStateDetached) {
LLDB_LOG(
log, "Shutting down process {0}.",
debugger_thread->GetProcess().GetNativeProcess().GetSystemHandle());
error = debugger_thread->StopDebugging(true);
// By the time StopDebugging returns, there is no more debugger thread, so
// we can be assured that no other thread will race for the session data.
m_session_data.reset();
} else {
error.SetErrorStringWithFormat("cannot destroy process %" PRIx64
" while state = %d",
GetDebuggedProcessId(), state);
LLDB_LOG(log, "error: {0}", error);
}
return error;
}
Status ProcessDebugger::HaltProcess(bool &caused_stop) {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
Status error;
llvm::sys::ScopedLock lock(m_mutex);
caused_stop = ::DebugBreakProcess(m_session_data->m_debugger->GetProcess()
.GetNativeProcess()
.GetSystemHandle());
if (!caused_stop) {
error.SetError(::GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "DebugBreakProcess failed with error {0}", error);
}
return error;
}
Status ProcessDebugger::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
size_t &bytes_read) {
Status error;
bytes_read = 0;
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_MEMORY);
llvm::sys::ScopedLock lock(m_mutex);
if (!m_session_data) {
error.SetErrorString(
"cannot read, there is no active debugger connection.");
LLDB_LOG(log, "error: {0}", error);
return error;
}
LLDB_LOG(log, "attempting to read {0} bytes from address {1:x}", size,
vm_addr);
HostProcess process = m_session_data->m_debugger->GetProcess();
void *addr = reinterpret_cast<void *>(vm_addr);
SIZE_T num_of_bytes_read = 0;
if (!::ReadProcessMemory(process.GetNativeProcess().GetSystemHandle(), addr,
buf, size, &num_of_bytes_read)) {
// Reading from the process can fail for a number of reasons - set the
// error code and make sure that the number of bytes read is set back to 0
// because in some scenarios the value of bytes_read returned from the API
// is garbage.
error.SetError(GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "reading failed with error: {0}", error);
} else {
bytes_read = num_of_bytes_read;
}
return error;
}
Status ProcessDebugger::WriteMemory(lldb::addr_t vm_addr, const void *buf,
size_t size, size_t &bytes_written) {
Status error;
bytes_written = 0;
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_MEMORY);
llvm::sys::ScopedLock lock(m_mutex);
LLDB_LOG(log, "attempting to write {0} bytes into address {1:x}", size,
vm_addr);
if (!m_session_data) {
error.SetErrorString(
"cannot write, there is no active debugger connection.");
LLDB_LOG(log, "error: {0}", error);
return error;
}
HostProcess process = m_session_data->m_debugger->GetProcess();
void *addr = reinterpret_cast<void *>(vm_addr);
SIZE_T num_of_bytes_written = 0;
lldb::process_t handle = process.GetNativeProcess().GetSystemHandle();
if (::WriteProcessMemory(handle, addr, buf, size, &num_of_bytes_written)) {
FlushInstructionCache(handle, addr, num_of_bytes_written);
bytes_written = num_of_bytes_written;
} else {
error.SetError(GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "writing failed with error: {0}", error);
}
return error;
}
Status ProcessDebugger::AllocateMemory(size_t size, uint32_t permissions,
lldb::addr_t &addr) {
Status error;
addr = LLDB_INVALID_ADDRESS;
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_MEMORY);
llvm::sys::ScopedLock lock(m_mutex);
LLDB_LOG(log, "attempting to allocate {0} bytes with permissions {1}", size,
permissions);
if (!m_session_data) {
error.SetErrorString(
"cannot allocate, there is no active debugger connection");
LLDB_LOG(log, "error: {0}", error);
return error;
}
HostProcess process = m_session_data->m_debugger->GetProcess();
lldb::process_t handle = process.GetNativeProcess().GetSystemHandle();
auto protect = ConvertLldbToWinApiProtect(permissions);
auto result = ::VirtualAllocEx(handle, nullptr, size, MEM_COMMIT, protect);
if (!result) {
error.SetError(GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "allocating failed with error: {0}", error);
} else {
addr = reinterpret_cast<addr_t>(result);
}
return error;
}
Status ProcessDebugger::DeallocateMemory(lldb::addr_t vm_addr) {
Status result;
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_MEMORY);
llvm::sys::ScopedLock lock(m_mutex);
LLDB_LOG(log, "attempting to deallocate bytes at address {0}", vm_addr);
if (!m_session_data) {
result.SetErrorString(
"cannot deallocate, there is no active debugger connection");
LLDB_LOG(log, "error: {0}", result);
return result;
}
HostProcess process = m_session_data->m_debugger->GetProcess();
lldb::process_t handle = process.GetNativeProcess().GetSystemHandle();
if (!::VirtualFreeEx(handle, reinterpret_cast<LPVOID>(vm_addr), 0,
MEM_RELEASE)) {
result.SetError(GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "deallocating failed with error: {0}", result);
}
return result;
}
Status ProcessDebugger::GetMemoryRegionInfo(lldb::addr_t vm_addr,
MemoryRegionInfo &info) {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_MEMORY);
Status error;
llvm::sys::ScopedLock lock(m_mutex);
info.Clear();
if (!m_session_data) {
error.SetErrorString(
"GetMemoryRegionInfo called with no debugging session.");
LLDB_LOG(log, "error: {0}", error);
return error;
}
HostProcess process = m_session_data->m_debugger->GetProcess();
lldb::process_t handle = process.GetNativeProcess().GetSystemHandle();
if (handle == nullptr || handle == LLDB_INVALID_PROCESS) {
error.SetErrorString(
"GetMemoryRegionInfo called with an invalid target process.");
LLDB_LOG(log, "error: {0}", error);
return error;
}
LLDB_LOG(log, "getting info for address {0:x}", vm_addr);
void *addr = reinterpret_cast<void *>(vm_addr);
MEMORY_BASIC_INFORMATION mem_info = {};
SIZE_T result = ::VirtualQueryEx(handle, addr, &mem_info, sizeof(mem_info));
if (result == 0) {
if (::GetLastError() == ERROR_INVALID_PARAMETER) {
// ERROR_INVALID_PARAMETER is returned if VirtualQueryEx is called with
// an address past the highest accessible address. We should return a
// range from the vm_addr to LLDB_INVALID_ADDRESS
info.GetRange().SetRangeBase(vm_addr);
info.GetRange().SetRangeEnd(LLDB_INVALID_ADDRESS);
info.SetReadable(MemoryRegionInfo::eNo);
info.SetExecutable(MemoryRegionInfo::eNo);
info.SetWritable(MemoryRegionInfo::eNo);
info.SetMapped(MemoryRegionInfo::eNo);
return error;
} else {
error.SetError(::GetLastError(), eErrorTypeWin32);
LLDB_LOG(log,
"VirtualQueryEx returned error {0} while getting memory "
"region info for address {1:x}",
error, vm_addr);
return error;
}
}
// Protect bits are only valid for MEM_COMMIT regions.
if (mem_info.State == MEM_COMMIT) {
const bool readable = IsPageReadable(mem_info.Protect);
const bool executable = IsPageExecutable(mem_info.Protect);
const bool writable = IsPageWritable(mem_info.Protect);
info.SetReadable(readable ? MemoryRegionInfo::eYes : MemoryRegionInfo::eNo);
info.SetExecutable(executable ? MemoryRegionInfo::eYes
: MemoryRegionInfo::eNo);
info.SetWritable(writable ? MemoryRegionInfo::eYes : MemoryRegionInfo::eNo);
} else {
info.SetReadable(MemoryRegionInfo::eNo);
info.SetExecutable(MemoryRegionInfo::eNo);
info.SetWritable(MemoryRegionInfo::eNo);
}
// AllocationBase is defined for MEM_COMMIT and MEM_RESERVE but not MEM_FREE.
if (mem_info.State != MEM_FREE) {
info.GetRange().SetRangeBase(
reinterpret_cast<addr_t>(mem_info.AllocationBase));
info.GetRange().SetRangeEnd(reinterpret_cast<addr_t>(mem_info.BaseAddress) +
mem_info.RegionSize);
info.SetMapped(MemoryRegionInfo::eYes);
} else {
// In the unmapped case we need to return the distance to the next block of
// memory. VirtualQueryEx nearly does that except that it gives the
// distance from the start of the page containing vm_addr.
SYSTEM_INFO data;
::GetSystemInfo(&data);
DWORD page_offset = vm_addr % data.dwPageSize;
info.GetRange().SetRangeBase(vm_addr);
info.GetRange().SetByteSize(mem_info.RegionSize - page_offset);
info.SetMapped(MemoryRegionInfo::eNo);
}
error.SetError(::GetLastError(), eErrorTypeWin32);
LLDB_LOGV(log,
"Memory region info for address {0}: readable={1}, "
"executable={2}, writable={3}",
vm_addr, info.GetReadable(), info.GetExecutable(),
info.GetWritable());
return error;
}
void ProcessDebugger::OnExitProcess(uint32_t exit_code) {
// If the process exits before any initial stop then notify the debugger
// of the error otherwise WaitForDebuggerConnection() will be blocked.
// An example of this issue is when a process fails to load a dependent DLL.
if (m_session_data && !m_session_data->m_initial_stop_received) {
Status error(exit_code, eErrorTypeWin32);
OnDebuggerError(error, 0);
}
}
void ProcessDebugger::OnDebuggerConnected(lldb::addr_t image_base) {}
ExceptionResult
ProcessDebugger::OnDebugException(bool first_chance,
const ExceptionRecord &record) {
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EXCEPTION);
llvm::sys::ScopedLock lock(m_mutex);
// FIXME: Without this check, occasionally when running the test suite
// there is an issue where m_session_data can be null. It's not clear how
// this could happen but it only surfaces while running the test suite. In
// order to properly diagnose this, we probably need to first figure allow the
// test suite to print out full lldb logs, and then add logging to the process
// plugin.
if (!m_session_data) {
LLDB_LOG(log,
"Debugger thread reported exception {0:x} at address {1:x}, but "
"there is no session.",
record.GetExceptionCode(), record.GetExceptionAddress());
return ExceptionResult::SendToApplication;
}
ExceptionResult result = ExceptionResult::SendToApplication;
if ((record.GetExceptionCode() == EXCEPTION_BREAKPOINT ||
record.GetExceptionCode() ==
0x4000001FL /*WOW64 STATUS_WX86_BREAKPOINT*/) &&
!m_session_data->m_initial_stop_received) {
// Handle breakpoints at the first chance.
result = ExceptionResult::BreakInDebugger;
LLDB_LOG(
log,
"Hit loader breakpoint at address {0:x}, setting initial stop event.",
record.GetExceptionAddress());
m_session_data->m_initial_stop_received = true;
::SetEvent(m_session_data->m_initial_stop_event);
}
return result;
}
void ProcessDebugger::OnCreateThread(const HostThread &thread) {
// Do nothing by default
}
void ProcessDebugger::OnExitThread(lldb::tid_t thread_id, uint32_t exit_code) {
// Do nothing by default
}
void ProcessDebugger::OnLoadDll(const ModuleSpec &module_spec,
lldb::addr_t module_addr) {
// Do nothing by default
}
void ProcessDebugger::OnUnloadDll(lldb::addr_t module_addr) {
// Do nothing by default
}
void ProcessDebugger::OnDebugString(const std::string &string) {}
void ProcessDebugger::OnDebuggerError(const Status &error, uint32_t type) {
llvm::sys::ScopedLock lock(m_mutex);
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
if (m_session_data->m_initial_stop_received) {
// This happened while debugging. Do we shutdown the debugging session,
// try to continue, or do something else?
LLDB_LOG(log,
"Error {0} occurred during debugging. Unexpected behavior "
"may result. {1}",
error.GetError(), error);
} else {
// If we haven't actually launched the process yet, this was an error
// launching the process. Set the internal error and signal the initial
// stop event so that the DoLaunch method wakes up and returns a failure.
m_session_data->m_launch_error = error;
::SetEvent(m_session_data->m_initial_stop_event);
LLDB_LOG(log,
"Error {0} occurred launching the process before the initial "
"stop. {1}",
error.GetError(), error);
return;
}
}
Status ProcessDebugger::WaitForDebuggerConnection(DebuggerThreadSP debugger,
HostProcess &process) {
Status result;
Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS |
WINDOWS_LOG_BREAKPOINTS);
LLDB_LOG(log, "Waiting for loader breakpoint.");
// Block this function until we receive the initial stop from the process.
if (::WaitForSingleObject(m_session_data->m_initial_stop_event, INFINITE) ==
WAIT_OBJECT_0) {
LLDB_LOG(log, "hit loader breakpoint, returning.");
process = debugger->GetProcess();
return m_session_data->m_launch_error;
} else
return Status(::GetLastError(), eErrorTypeWin32);
}
} // namespace lldb_private
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