tracing/kprobes: Add symbol counting check when module loads

tracing/kprobes: Add symbol counting check when module loads

Currently, kprobe event checks whether the target symbol name is unique
or not, so that it does not put a probe on an unexpected place. But this
skips the check if the target is on a module because the module may not
be loaded.

To fix this issue, this patch checks the number of probe target symbols
in a target module when the module is loaded. If the probe is not on the
unique name symbols in the module, it will be rejected at that point.

Note that the symbol which has a unique name in the target module,
it will be accepted even if there are same-name symbols in the
kernel or other modules,

Link: https://lore.kernel.org/all/172016348553.99543.2834679315611882137.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>