Add user_events support for the native runtime events (#102523)

Author: davmason

THIRD-PARTY-NOTICES.TXT

@@ -115,6 +115,33 @@ Altered source versions must be plainly marked as such, and must not be misrepre
 
 This notice may not be removed or altered from any source distribution.
 
+License notice for LinuxTracepoints
+-----------------------------------
+
+https://github.com/microsoft/LinuxTracepoints/blob/main/LICENSE
+
+Copyright (c) Microsoft Corporation.
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE
+
 License notice for Mono
 -------------------------------
 

docs/design/features/user-events.md

@@ -0,0 +1,20 @@
+# user_events support in the runtime
+
+Historically only kernelspace code was allowed to emit events in the Linux kernel, meaning that programs like Perf could only collect system events. Over the years various libraries such as LTTng have been created to allow userspace applications to write to the same trace as the kernel code. The runtime has supported LTTng since very early on, but LTTng has some limitations that are problematic. LTTng requires that all providers and events are known at compile time rather than runtime, and has also recently broken their ABI in a way that is difficult to recover from.
+
+Starting with kernel version 6.4 the user_events feature is available. user_events allows userspace applications to write events to the same traces as kernel events but does not have the limitations of LTTng. It allows dynamic event creation at runtime and has a stable ABI. For this reason we are adding support for user_events to the runtime in .net 9.
+
+# Limitations
+
+Currently the support for user_events is experimental and does not support managed EventSources, it only supports native runtime events such as JIT, GC, class loads, etc.
+
+# How to enable
+
+The support for user_events is off by default and can be enabled in one of two ways.
+
+1. Setting the `DOTNET_EnableUserEvents` environment variable to the value `1`.
+2. Setting the `System.Diagnostics.Tracing.UserEvents` configuration value to `true` in either your project file or in your `runtimeconfig.json` file.
+
+# Format
+
+The events are written with the EventHeader format specified at https://github.com/microsoft/LinuxTracepoints/blob/main/libeventheader-tracepoint/include/eventheader/eventheader.h

src/coreclr/dlls/mscoree/coreclr/CMakeLists.txt

@@ -174,6 +174,14 @@ if(FEATURE_EVENT_TRACE)
     endif(CLR_CMAKE_HOST_UNIX)
 endif(FEATURE_EVENT_TRACE)
 
+if(FEATURE_PERFTRACING)
+    if(CLR_CMAKE_TARGET_LINUX)
+        list(APPEND CORECLR_LIBRARIES
+            usereventsprovider
+        )
+    endif(CLR_CMAKE_TARGET_LINUX)
+endif(FEATURE_PERFTRACING)
+
 if(FEATURE_MERGE_JIT_AND_ENGINE)
     set(CLRJIT_STATIC clrjit_static)
 endif(FEATURE_MERGE_JIT_AND_ENGINE)

src/coreclr/inc/clrconfigvalues.h

@@ -690,6 +690,11 @@ RETAIL_CONFIG_DWORD_INFO(INTERNAL_EventPipeProcNumbers, W("EventPipeProcNumbers"
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_EventPipeOutputStreaming, W("EventPipeOutputStreaming"), 1, "Enable/disable streaming for trace file set in DOTNET_EventPipeOutputPath.  Non-zero values enable streaming.")
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_EventPipeEnableStackwalk, W("EventPipeEnableStackwalk"), 1, "Set to 0 to disable collecting stacks for EventPipe events.")
 
+//
+// UserEvents
+//
+RETAIL_CONFIG_DWORD_INFO(INTERNAL_EnableUserEvents, W("EnableUserEvents"), 0, "Enable/disable writing events to user_events.  Non-zero values enable tracing.")
+
 #ifdef FEATURE_AUTO_TRACE
 RETAIL_CONFIG_DWORD_INFO_EX(INTERNAL_AutoTrace_N_Tracers, W("AutoTrace_N_Tracers"), 0, "", CLRConfig::LookupOptions::ParseIntegerAsBase10)
 RETAIL_CONFIG_STRING_INFO(INTERNAL_AutoTrace_Command, W("AutoTrace_Command"), "")

src/coreclr/inc/eventtracebase.h

@@ -121,12 +121,15 @@ enum EtwGCSettingFlags
 
 #define ETW_TRACING_INITIALIZED(RegHandle) (TRUE)
 #define ETW_EVENT_ENABLED(Context, EventDescriptor) (EventPipeHelper::IsEnabled(Context, EventDescriptor.Level, EventDescriptor.Keyword) || \
-        (XplatEventLogger::IsKeywordEnabled(Context, EventDescriptor.Level, EventDescriptor.Keyword)))
+        (XplatEventLogger::IsKeywordEnabled(Context, EventDescriptor.Level, EventDescriptor.Keyword)) || \
+        (UserEventsHelper::IsEnabled(Context, EventDescriptor.Level, EventDescriptor.Keyword)))
 #define ETW_CATEGORY_ENABLED(Context, Level, Keyword) (EventPipeHelper::IsEnabled(Context, Level, Keyword) || \
-        (XplatEventLogger::IsKeywordEnabled(Context, Level, Keyword)))
+        (XplatEventLogger::IsKeywordEnabled(Context, Level, Keyword)) || \
+        (UserEventsHelper::IsEnabled(Context, Level, Keyword)))
 #define ETW_TRACING_ENABLED(Context, EventDescriptor) (EventEnabled##EventDescriptor())
 #define ETW_TRACING_CATEGORY_ENABLED(Context, Level, Keyword) (EventPipeHelper::IsEnabled(Context, Level, Keyword) || \
-        (XplatEventLogger::IsKeywordEnabled(Context, Level, Keyword)))
+        (XplatEventLogger::IsKeywordEnabled(Context, Level, Keyword)) || \
+        (UserEventsHelper::IsEnabled(Context, Level, Keyword)))
 #define ETW_PROVIDER_ENABLED(ProviderSymbol) (TRUE)
 #else //defined(FEATURE_PERFTRACING)
 #define ETW_INLINE
@@ -651,6 +654,13 @@ class EventPipeHelper
     static bool Enabled();
     static bool IsEnabled(DOTNET_TRACE_CONTEXT Context, UCHAR Level, ULONGLONG Keyword);
 };
+
+class UserEventsHelper
+{
+public:
+    static bool Enabled();
+    static bool IsEnabled(DOTNET_TRACE_CONTEXT Context, UCHAR Level, ULONGLONG Keyword);
+};
 #endif // defined(FEATURE_PERFTRACING)
 
 #endif // FEATURE_EVENT_TRACE

src/coreclr/scripts/genEventPipe.py

@@ -1,3 +1,9 @@
+#
+## Licensed to the .NET Foundation under one or more agreements.
+## The .NET Foundation licenses this file to you under the MIT license.
+#
+#
+
 from __future__ import print_function
 from genEventing import *
 from genLttngProvider import *
@@ -1189,16 +1195,6 @@ def generateEventPipeImplFiles(
         etwmanifest, eventpipe_directory, extern, target_cpp, runtimeFlavor, inclusionList, exclusionList, dryRun):
     tree = DOM.parse(etwmanifest)
 
-    # Find the src directory starting with the assumption that
-    # A) It is named 'src'
-    # B) This script lives in it
-    src_dirname = os.path.dirname(__file__)
-    while os.path.basename(src_dirname) != "src":
-        src_dirname = os.path.dirname(src_dirname)
-
-        if os.path.basename(src_dirname) == "":
-            raise IOError("Could not find the Core CLR 'src' directory")
-
     for providerNode in tree.getElementsByTagName('provider'):
         providerName = providerNode.getAttribute('name')
         if not includeProvider(providerName, runtimeFlavor):