perf probe: Provide clearer message permission error for tracefs access

Report permission error for the tracefs open and rewrite whole the error
message code around it.

You'll see a hint according to what you want to do with perf probe as
below.

  $ perf probe -l
  No permission to read tracefs.
  Please try 'sudo mount -o remount,mode=755 /sys/kernel/tracing/'
    Error: Failed to show event list.

  $ perf probe -d \*
  No permission to write tracefs.
  Please run this command again with sudo.
    Error: Failed to delete events.

This also fixes -ENOTSUP checking for mounting tracefs/debugfs.
Actually open returns -ENOENT in that case and we have to check it with
current mount point list. If we unmount debugfs and tracefs perf probe
shows correct message as below.

  $ perf probe -l
  Debugfs or tracefs is not mounted
  Please try 'sudo mount -t tracefs nodev /sys/kernel/tracing/'
    Error: Failed to show event list.

Signed-off-by: Masami Hiramatsu <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Link: http://lore.kernel.org/lkml/162299456839.503471.13863002017089255222.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions