Merge tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - New user_events interface. User space can register an event with the
   kernel describing the format of the event. Then it will receive a
   byte in a page mapping that it can check against. A privileged task
   can then enable that event like any other event, which will change
   the mapped byte to true, telling the user space application to start
   writing the event to the tracing buffer.

 - Add new "ftrace_boot_snapshot" kernel command line parameter. When
   set, the tracing buffer will be saved in the snapshot buffer at boot
   up when the kernel hands things over to user space. This will keep
   the traces that happened at boot up available even if user space boot
   up has tracing as well.

 - Have TRACE_EVENT_ENUM() also update trace event field type
   descriptions. Thus if a static array defines its size with an enum,
   the user space trace event parsers can still know how to parse that
   array.

 - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the
   TRACE_EVENT() macro, but will attach to an existing tracepoint. This
   will make one tracepoint be able to trace different content and not
   be stuck at only what the original TRACE_EVENT() macro exports.

 - Fixes to tracing error logging.

 - Better saving of cmdlines to PIDs when tracing (use the wakeup events
   for mapping).

* tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits)
  tracing: Have type enum modifications copy the strings
  user_events: Add trace event call as root for low permission cases
  tracing/user_events: Use alloc_pages instead of kzalloc() for register pages
  tracing: Add snapshot at end of kernel boot up
  tracing: Have TRACE_DEFINE_ENUM affect trace event types as well
  tracing: Fix strncpy warning in trace_events_synth.c
  user_events: Prevent dyn_event delete racing with ioctl add/delete
  tracing: Add TRACE_CUSTOM_EVENT() macro
  tracing: Move the defines to create TRACE_EVENTS into their own files
  tracing: Add sample code for custom trace events
  tracing: Allow custom events to be added to the tracefs directory
  tracing: Fix last_cmd_set() string management in histogram code
  user_events: Fix potential uninitialized pointer while parsing field
  tracing: Fix allocation of last_cmd in last_cmd_set()
  user_events: Add documentation file
  user_events: Add sample code for typical usage
  user_events: Add self-test for validator boundaries
  user_events: Add self-test for perf_event integration
  user_events: Add self-test for dynamic_events integration
  user_events: Add self-test for ftrace integration
  ...

1 files changed, 221 insertions, 0 deletions

diff --git a/include/trace/trace_custom_events.h b/include/trace/trace_custom_events.h
new file mode 100644
index 000000000000..b567c7202339
--- /dev/null
+++ b/include/trace/trace_custom_events.h
@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This is similar to the trace_events.h file, but is to only
+ * create custom trace events to be attached to existing tracepoints.
+ * Where as the TRACE_EVENT() macro (from trace_events.h) will create
+ * both the trace event and the tracepoint it will attach the event to,
+ * TRACE_CUSTOM_EVENT() is to create only a custom version of an existing
+ * trace event (created by TRACE_EVENT() or DEFINE_EVENT()), and will
+ * be placed in the "custom" system.
+ */
+
+#include <linux/trace_events.h>
+
+/* All custom events are placed in the custom group */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM custom
+
+#ifndef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR TRACE_SYSTEM
+#endif
+
+/* The init stage creates the system string and enum mappings */
+
+#include "stages/init.h"
+
+#undef TRACE_CUSTOM_EVENT
+#define TRACE_CUSTOM_EVENT(name, proto, args, tstruct, assign, print) \
+	DECLARE_CUSTOM_EVENT_CLASS(name,			      \
+			     PARAMS(proto),		       \
+			     PARAMS(args),		       \
+			     PARAMS(tstruct),		       \
+			     PARAMS(assign),		       \
+			     PARAMS(print));		       \
+	DEFINE_CUSTOM_EVENT(name, name, PARAMS(proto), PARAMS(args));
+
+/* Stage 1 creates the structure of the recorded event layout */
+
+#include "stages/stage1_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(name, proto, args, tstruct, assign, print) \
+	struct trace_custom_event_raw_##name {				\
+		struct trace_entry	ent;				\
+		tstruct							\
+		char			__data[];			\
+	};								\
+									\
+	static struct trace_event_class custom_event_class_##name;
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)	\
+	static struct trace_event_call	__used			\
+	__attribute__((__aligned__(4))) custom_event_##name
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 2 creates the custom class */
+
+#include "stages/stage2_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
+	struct trace_custom_event_data_offsets_##call {			\
+		tstruct;						\
+	};
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 3 create the way to print the custom event */
+
+#include "stages/stage3_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static notrace enum print_line_t					\
+trace_custom_raw_output_##call(struct trace_iterator *iter, int flags,	\
+			struct trace_event *trace_event)		\
+{									\
+	struct trace_seq *s = &iter->seq;				\
+	struct trace_seq __maybe_unused *p = &iter->tmp_seq;		\
+	struct trace_custom_event_raw_##call *field;			\
+	int ret;							\
+									\
+	field = (typeof(field))iter->ent;				\
+									\
+	ret = trace_raw_output_prep(iter, trace_event);			\
+	if (ret != TRACE_TYPE_HANDLED)					\
+		return ret;						\
+									\
+	trace_event_printf(iter, print);				\
+									\
+	return trace_handle_return(s);					\
+}									\
+static struct trace_event_functions trace_custom_event_type_funcs_##call = { \
+	.trace			= trace_custom_raw_output_##call,	\
+};
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 4 creates the offset layout for the fields */
+
+#include "stages/stage4_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, func, print)	\
+static struct trace_event_fields trace_custom_event_fields_##call[] = {	\
+	tstruct								\
+	{} };
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 5 creates the helper function for dynamic fields */
+
+#include "stages/stage5_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static inline notrace int trace_custom_event_get_offsets_##call(	\
+	struct trace_custom_event_data_offsets_##call *__data_offsets, proto) \
+{									\
+	int __data_size = 0;						\
+	int __maybe_unused __item_length;				\
+	struct trace_custom_event_raw_##call __maybe_unused *entry;	\
+									\
+	tstruct;							\
+									\
+	return __data_size;						\
+}
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 6 creates the probe function that records the event */
+
+#include "stages/stage6_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+									\
+static notrace void							\
+trace_custom_event_raw_event_##call(void *__data, proto)		\
+{									\
+	struct trace_event_file *trace_file = __data;			\
+	struct trace_custom_event_data_offsets_##call __maybe_unused __data_offsets; \
+	struct trace_event_buffer fbuffer;				\
+	struct trace_custom_event_raw_##call *entry;			\
+	int __data_size;						\
+									\
+	if (trace_trigger_soft_disabled(trace_file))			\
+		return;							\
+									\
+	__data_size = trace_custom_event_get_offsets_##call(&__data_offsets, args); \
+									\
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,	\
+				 sizeof(*entry) + __data_size);		\
+									\
+	if (!entry)							\
+		return;							\
+									\
+	tstruct								\
+									\
+	{ assign; }							\
+									\
+	trace_event_buffer_commit(&fbuffer);				\
+}
+/*
+ * The ftrace_test_custom_probe is compiled out, it is only here as a build time check
+ * to make sure that if the tracepoint handling changes, the ftrace probe will
+ * fail to compile unless it too is updated.
+ */
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, call, proto, args)		\
+static inline void ftrace_test_custom_probe_##call(void)		\
+{									\
+	check_trace_callback_type_##call(trace_custom_event_raw_event_##template); \
+}
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 7 creates the actual class and event structure for the custom event */
+
+#include "stages/stage7_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static char custom_print_fmt_##call[] = print;					\
+static struct trace_event_class __used __refdata custom_event_class_##call = { \
+	.system			= TRACE_SYSTEM_STRING,			\
+	.fields_array		= trace_custom_event_fields_##call,		\
+	.fields			= LIST_HEAD_INIT(custom_event_class_##call.fields),\
+	.raw_init		= trace_event_raw_init,			\
+	.probe			= trace_custom_event_raw_event_##call,	\
+	.reg			= trace_event_reg,			\
+};
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, call, proto, args)		\
+									\
+static struct trace_event_call __used custom_event_##call = {		\
+	.name			= #call,				\
+	.class			= &custom_event_class_##template,	\
+	.event.funcs		= &trace_custom_event_type_funcs_##template, \
+	.print_fmt		= custom_print_fmt_##template,		\
+	.flags			= TRACE_EVENT_FL_CUSTOM,		\
+};									\
+static inline int trace_custom_event_##call##_update(struct tracepoint *tp) \
+{									\
+	if (tp->name && strcmp(tp->name, #call) == 0) {			\
+		custom_event_##call.tp = tp;				\
+		custom_event_##call.flags = TRACE_EVENT_FL_TRACEPOINT;	\
+		return 1;						\
+	}								\
+	return 0;							\
+}									\
+static struct trace_event_call __used					\
+__section("_ftrace_events") *__custom_event_##call = &custom_event_##call
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)