So now we can use:

  # perf trace -e pkey_*
   532.784 ( 0.006 ms): pkey/16018 pkey_alloc(init_val: DISABLE_WRITE) = -1 EINVAL Invalid argument
   532.795 ( 0.004 ms): pkey/16018 pkey_mprotect(start: 0x7f380d0a6000, len: 4096, prot: READ|WRITE, pkey: -1) = 0
   532.801 ( 0.002 ms): pkey/16018 pkey_free(pkey: -1                ) = -1 EINVAL Invalid argument
  ^C[root@jouet ~]#

Or '-e epoll*', '-e *msg*', etc.

Combining syscall names with perf events, tracepoints, etc, continues to
be valid, i.e. this is possible:

  # perf probe -L sys_nanosleep
  <SyS_nanosleep@/home/acme/git/linux/kernel/time/hrtimer.c:0>
      0  SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
                        struct timespec __user *, rmtp)
         {
                struct timespec64 tu;

      5         if (get_timespec64(&tu, rqtp))
      6                 return -EFAULT;

                if (!timespec64_valid(&tu))
      9                 return -EINVAL;

     11         current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
     12         current->restart_block.nanosleep.rmtp = rmtp;
     13         return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
         }

  # perf probe my_probe="sys_nanosleep:12 rmtp"
  Added new event:
    probe:my_probe       (on sys_nanosleep:12 with rmtp)

  You can now use it in all perf tools, such as:

	perf record -e probe:my_probe -aR sleep 1

  #
  # perf trace -e probe:my_probe/max-stack=5/,*sleep sleep 1
     0.427 ( 0.003 ms): sleep/16690 nanosleep(rqtp: 0x7ffefc245090) ...
     0.430 (         ): probe:my_probe:(ffffffffbd112923) rmtp=0)
                                       sys_nanosleep ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       return_from_SYSCALL_64 ([kernel.kallsyms])
                                       __nanosleep_nocancel (/usr/lib64/libc-2.25.so)
     0.427 (1000.208 ms): sleep/16690  ... [continued]: nanosleep()) = 0
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-elycoi8wy6y0w9dkj7ox1mzz@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>