The message does not indicate the possibility that the symbol is not
found because the file does not exist.

Before:

  $ perf record -e intel_pt//u --filter 'filter strcmp / strcpy @ foo ' ls
  Symbol 'strcmp' not found.
  Note that symbols must be functions.
  Failed to parse address filter: 'filter strcmp / strcpy @ foo '
  Filter format is: filter|start|stop|tracestop <start symbol or address> [/ <end symbol or size>] [@<file name>]
  Where multiple filters are separated by space or comma.

After:

  $ perf record -e intel_pt//u --filter 'filter strcmp / strcpy @ foo ' ls
  File 'foo' not found or has no symbols.
  Symbol 'strcmp' not found.
  Note that symbols must be functions.
  Failed to parse address filter: 'filter strcmp / strcpy @ foo '
  Filter format is: filter|start|stop|tracestop <start symbol or address> [/ <end symbol or size>] [@<file name>]
  Where multiple filters are separated by space or comma.
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lkml.kernel.org/n/tip-dvngzxd0jkplzw1ary69dilb@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>