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Merged
DavidSpickett merged 3 commits into from
Dec 21, 2023
Merged

[lldb] add support for thread names on Windows #74731

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9383b8b
lldb: add support for thread names on Windows
oltolm Dec 1, 2023
89ea63c
[lldb] add unit test for Windows thread names
oltolm Dec 8, 2023
da9125b
lldb: cleanup Windows thread names
oltolm Dec 12, 2023
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31 changes: 31 additions & 0 deletions lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
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Expand Up @@ -15,6 +15,7 @@
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/State.h"
#include "llvm/Support/ConvertUTF.h"

#include "ProcessWindows.h"
#include "ProcessWindowsLog.h"
Expand All @@ -33,6 +34,9 @@
using namespace lldb;
using namespace lldb_private;

using GetThreadDescriptionFunctionPtr = HRESULT
WINAPI (*)(HANDLE hThread, PWSTR *ppszThreadDescription);

TargetThreadWindows::TargetThreadWindows(ProcessWindows &process,
const HostThread &thread)
: Thread(process, thread.GetNativeThread().GetThreadId()),
Expand Down Expand Up @@ -175,3 +179,30 @@ Status TargetThreadWindows::DoResume() {

return Status();
}

const char *TargetThreadWindows::GetName() {
Log *log = GetLog(LLDBLog::Thread);
HMODULE hModule = ::LoadLibraryW(L"Kernel32.dll");
if (hModule) {
auto GetThreadDescription =
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@compnerd compnerd Dec 12, 2023

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This should be pulled out into a lambda and store the lookup rather than re-evaluating it each time.

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@oltolm oltolm Dec 12, 2023

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done

reinterpret_cast<GetThreadDescriptionFunctionPtr>(
::GetProcAddress(hModule, "GetThreadDescription"));
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@clayborg clayborg Dec 7, 2023

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This code is only compiled on windows, why do we need to get the library handle manually and get the function pointer. Can't we just #include <processthreadsapi.h> and then call the function directly?

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@Fulgen301 Fulgen301 Dec 7, 2023 •
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The function was added in Windows 10 1607, which was also the only build (excluding Server 2016) where it isn't available in the header:

Windows Server 2016, Windows 10 LTSB 2016 and Windows 10 version 1607: GetThreadDescription is only available by Run Time Dynamic Linking in KernelBase.dll.

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@compnerd compnerd Dec 12, 2023

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If there is compatibility that we are concerned about, I think that we should consider falling back to more ... esoteric solutions.

__try {
  RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR), (ULONG_PTR*)&info);  
} __except (EXCEPTION_EXECUTE_HANDLER) {
}

Should be far more portable and is what VS also uses. This is documented at https://learn.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2015/debugger/how-to-set-a-thread-name-in-native-code?view=vs-2015&redirectedfrom=MSDN.

I would be okay with also raising the requirements to a newer version of Windows as 1607 is RS1 which makes it more than 8 years old at this point.

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@oltolm oltolm Dec 12, 2023

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You are talking about setting thread names, but I implemented getting a thread name from Windows.

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@compnerd compnerd Dec 13, 2023

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There is the set name below though.

LLDB_LOGF(log, "GetProcAddress: %p",
reinterpret_cast<void *>(GetThreadDescription));
if (GetThreadDescription) {
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@compnerd compnerd Dec 12, 2023

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An early out here would be nice to reduce indentation.

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@oltolm oltolm Dec 12, 2023

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done

PWSTR pszThreadName;
if (SUCCEEDED(GetThreadDescription(
m_host_thread.GetNativeThread().GetSystemHandle(),
&pszThreadName))) {
LLDB_LOGF(log, "GetThreadDescription: %ls", pszThreadName);
llvm::convertUTF16ToUTF8String(
llvm::ArrayRef(reinterpret_cast<char *>(pszThreadName),
wcslen(pszThreadName) * sizeof(wchar_t)),
m_name);
::LocalFree(pszThreadName);
}
}
}

return m_name.c_str();
}
2 changes: 2 additions & 0 deletions lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.h
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Expand Up @@ -34,6 +34,7 @@ class TargetThreadWindows : public lldb_private::Thread {
lldb::RegisterContextSP
CreateRegisterContextForFrame(StackFrame *frame) override;
bool CalculateStopInfo() override;
const char *GetName() override;

Status DoResume();

Expand All @@ -42,6 +43,7 @@ class TargetThreadWindows : public lldb_private::Thread {
private:
lldb::RegisterContextSP m_thread_reg_ctx_sp;
HostThread m_host_thread;
std::string m_name;
};
} // namespace lldb_private

Expand Down
2 changes: 2 additions & 0 deletions lldb/unittests/Thread/CMakeLists.txt
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Expand Up @@ -11,5 +11,7 @@ add_lldb_unittest(ThreadTests
lldbInterpreter
lldbBreakpoint
lldbPluginPlatformLinux
lldbPluginPlatformWindows
lldbPluginProcessWindowsCommon
)

71 changes: 71 additions & 0 deletions lldb/unittests/Thread/ThreadTest.cpp
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Expand Up @@ -8,9 +8,20 @@

#include "lldb/Target/Thread.h"
#include "Plugins/Platform/Linux/PlatformLinux.h"
#include <thread>
#ifdef _WIN32
#include "lldb/Host/windows/HostThreadWindows.h"
#include "lldb/Host/windows/windows.h"

#include "Plugins/Platform/Windows/PlatformWindows.h"
#include "Plugins/Process/Windows/Common/LocalDebugDelegate.h"
#include "Plugins/Process/Windows/Common/ProcessWindows.h"
#include "Plugins/Process/Windows/Common/TargetThreadWindows.h"
#endif
#include "lldb/Core/Debugger.h"
#include "lldb/Host/FileSystem.h"
#include "lldb/Host/HostInfo.h"
#include "lldb/Host/HostThread.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Utility/ArchSpec.h"
Expand All @@ -21,14 +32,33 @@ using namespace lldb_private::repro;
using namespace lldb;

namespace {

#ifdef _WIN32
using SetThreadDescriptionFunctionPtr = HRESULT
WINAPI (*)(HANDLE hThread, PCWSTR lpThreadDescription);

static SetThreadDescriptionFunctionPtr SetThreadName;
#endif

class ThreadTest : public ::testing::Test {
public:
void SetUp() override {
FileSystem::Initialize();
HostInfo::Initialize();
#ifdef _WIN32
HMODULE hModule = ::LoadLibraryW(L"Kernel32.dll");
if (hModule) {
SetThreadName = reinterpret_cast<SetThreadDescriptionFunctionPtr>(
::GetProcAddress(hModule, "SetThreadDescription"));
}
PlatformWindows::Initialize();
#endif
platform_linux::PlatformLinux::Initialize();
}
void TearDown() override {
#ifdef _WIN32
PlatformWindows::Terminate();
#endif
platform_linux::PlatformLinux::Terminate();
HostInfo::Terminate();
FileSystem::Terminate();
Expand Down Expand Up @@ -88,6 +118,47 @@ TargetSP CreateTarget(DebuggerSP &debugger_sp, ArchSpec &arch) {
return target_sp;
}

#ifdef _WIN32
std::shared_ptr<TargetThreadWindows>
CreateWindowsThread(const ProcessWindowsSP &process_sp, std::thread &t) {
HostThread host_thread((lldb::thread_t)t.native_handle());
ThreadSP thread_sp =
std::make_shared<TargetThreadWindows>(*process_sp.get(), host_thread);
return std::static_pointer_cast<TargetThreadWindows>(thread_sp);
}

TEST_F(ThreadTest, GetThreadDescription) {
if (!SetThreadName)
return;

ArchSpec arch(HostInfo::GetArchitecture());
Platform::SetHostPlatform(PlatformWindows::CreateInstance(true, &arch));

DebuggerSP debugger_sp = Debugger::CreateInstance();
ASSERT_TRUE(debugger_sp);

TargetSP target_sp = CreateTarget(debugger_sp, arch);
ASSERT_TRUE(target_sp);

ListenerSP listener_sp(Listener::MakeListener("dummy"));
auto process_sp = std::static_pointer_cast<ProcessWindows>(
ProcessWindows::CreateInstance(target_sp, listener_sp, nullptr, false));
ASSERT_TRUE(process_sp);

std::thread t([]() {});
auto thread_sp = CreateWindowsThread(process_sp, t);
DWORD tid = thread_sp->GetHostThread().GetNativeThread().GetThreadId();
HANDLE hThread = ::OpenThread(THREAD_SET_LIMITED_INFORMATION, FALSE, tid);
ASSERT_TRUE(hThread);

SetThreadName(hThread, L"thread name");
::CloseHandle(hThread);
ASSERT_STREQ(thread_sp->GetName(), "thread name");

t.join();
}
#endif

TEST_F(ThreadTest, SetStopInfo) {
ArchSpec arch("powerpc64-pc-linux");

Expand Down