perf probe: Report possible permission error for map__load() failure

Report possible permission error including kptr_restrict setting
for map__load() failure. This can happen when non-superuser runs
perf probe.

With this patch, perf probe shows the following message.

 $ perf probe vfs_read
 Failed to load symbols from /proc/kallsyms
 Please ensure you can read the /proc/kallsyms symbol addresses.
 If the /proc/sys/kernel/kptr_restrict is '2', you can not read
 kernel symbol address even if you are a superuser. Please change
 it to '1'. If kptr_restrict is '1', the superuser can read the
 symbol addresses.
 In that case, please run this command again with sudo.
   Error: Failed to add events.

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/162282065877.448336.10047912688119745151.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions