perf probe: Support adding probes on offline kernel modules

perf probe: Support adding probes on offline kernel modules

Support adding probes on offline kernel modules. This enables
perf-probe to trace kernel-module init functions via perf-probe.
If user gives the path of module with -m option, perf-probe
expects the module is offline.
This feature works with --add, --funcs, and --vars.

E.g)
 # perf probe -m /lib/modules/`uname -r`/kernel/fs/btrfs/btrfs.ko \
   -a "extent_io_init:5 extent_state_cache"
 Add new events:
   probe:extent_io_init (on extent_io_init:5 with extent_state_cache)
   probe:extent_io_init_1 (on extent_io_init:5 with extent_state_cache)

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

         perf record -e probe:extent_io_init_1 -aR sleep 1

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20110627072751.6528.10230.stgit@fedora15
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>