trace: Add user-space event tracing/injection

Subject: trace: Add user-space event tracing/injection
From: Ingo Molnar <mingo@elte.hu>
Date: Wed Nov 17 10:11:53 CET 2010

This feature (suggested by Darren Hart and Pekka Engberg) allows user-space
programs to print trace events in a very simple and self-contained way:

#include <sys/prctl.h>
#include <string.h>

#define PR_TASK_PERF_USER_TRACE 35

int main(void)
{
char *msg = "Hello World!\n";

prctl(PR_TASK_PERF_USER_TRACE, msg, strlen(msg));

return 0;
}

These show up in 'trace' output as:

$ trace report
#
# trace events of 'sleep 1':
#
testit/ 6006 ( 0.002 ms): <"Hello World!">
testit/ 6006 ( 0.002 ms): <"Hello World!">

Suggested-by: Darren Hart <dvhart@linux.intel.com>
Suggested-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/prctl.h       |    2 ++
include/trace/events/user.h |   32 ++++++++++++++++++++++++++++++++
kernel/sys.c                |   23 +++++++++++++++++++++++
kernel/trace/trace_events.c |   34 +++++++++++-----------------------
tools/perf/builtin-trace.c  |   41 +++++++++++++++++++++++++++++++++++++++++
5 files changed, 109 insertions(+), 23 deletions(-)