Arnaldo Carvalho de Melo d8fc764d0b perf bpf: Add probe() helper to reduce kprobes boilerplate
So that kprobe definitions become:

  int probe(function, variables)(void *ctx, int err, var1, var2, ...)

The existing 5sec.c, got converted and goes from:

  SEC("func=hrtimer_nanosleep rqtp->tv_sec")
  int func(void *ctx, int err, long sec)
  {
  }

To:

  int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec)
  {
  }

If we decide to add tv_nsec as well, then it becomes:

  $ cat tools/perf/examples/bpf/5sec.c
  #include <bpf.h>

  int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
  {
	  return sec == 5;
  }

  license(GPL);
  $

And if we run it, system wide as before and run some 'sleep' with values
for the tv_nsec field, we get:

  # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c
     0.000 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9811b5f0) tv_sec=5 tv_nsec=100000000
  9641.650 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9811b5f0) tv_sec=5 tv_nsec=123450001
  ^C#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-1v9r8f6ds5av0w9pcwpeknyl@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-05-15 14:31:24 -03:00
2018-04-26 09:02:01 -06:00
2018-05-13 10:28:53 -07:00
2018-01-06 10:59:44 -07:00
2018-05-05 23:05:31 +02:00
2018-04-15 17:21:30 -07:00
2017-11-17 17:45:29 -08:00
2018-05-13 16:15:17 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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