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tracing/kprobe: Add multi-probe per event support

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Add multi-probe per one event support to kprobe events.
User can define several different probes on one trace event
if those events have same "event signature",
e.g.

  # echo p:testevent _do_fork > kprobe_events
  # echo p:testevent fork_idle >> kprobe_events
  # kprobe_events
  p:kprobes/testevent _do_fork
  p:kprobes/testevent fork_idle

The event signature is defined by kprobe type (retprobe or not),
the number of args, argument names, and argument types.

Note that this only support appending method. Delete event
operation will delete all probes on the event.

Link: http://lkml.kernel.org/r/156095686913.28024.9357292202316540742.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu
2019-06-20 00:07:49 +09:00
committed by Steven Rostedt (VMware)
parent 30199137c8
commit ca89bc071d
4 changed files with 111 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
kernel/trace/trace_kprobe.c
View File

@@ -492,6 +492,10 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk)
/* Unregister a trace_probe and probe_event */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* If other probes are on the event, just unregister kprobe */
if (trace_probe_has_sibling(&tk->tp))
goto unreg;
/* Enabled event can not be unregistered */
if (trace_probe_is_enabled(&tk->tp))
return -EBUSY;
@@ -500,12 +504,38 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk)
if (unregister_kprobe_event(tk))
return -EBUSY;
unreg:
__unregister_trace_kprobe(tk);
dyn_event_remove(&tk->devent);
trace_probe_unlink(&tk->tp);
return 0;
}
static int append_trace_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to)
{
int ret;
/* Append to existing event */
ret = trace_probe_append(&tk->tp, &to->tp);
if (ret)
return ret;
/* Register k*probe */
ret = __register_trace_kprobe(tk);
if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
ret = 0;
}
if (ret)
trace_probe_unlink(&tk->tp);
else
dyn_event_add(&tk->devent);
return ret;
}
/* Register a trace_probe and probe_event */
static int register_trace_kprobe(struct trace_kprobe *tk)
{
@@ -514,14 +544,24 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
mutex_lock(&event_mutex);
/* Delete old (same name) event if exist */
old_tk = find_trace_kprobe(trace_probe_name(&tk->tp),
trace_probe_group_name(&tk->tp));
if (old_tk) {
ret = unregister_trace_kprobe(old_tk);
if (ret < 0)
goto end;
free_trace_kprobe(old_tk);
if (trace_kprobe_is_return(tk) != trace_kprobe_is_return(old_tk)) {
trace_probe_log_set_index(0);
trace_probe_log_err(0, DIFF_PROBE_TYPE);
ret = -EEXIST;
} else {
ret = trace_probe_compare_arg_type(&tk->tp, &old_tk->tp);
if (ret) {
/* Note that argument starts index = 2 */
trace_probe_log_set_index(ret + 1);
trace_probe_log_err(0, DIFF_ARG_TYPE);
ret = -EEXIST;
} else
ret = append_trace_kprobe(tk, old_tk);
}
goto end;
}
/* Register new event */
@@ -755,7 +795,7 @@ static int trace_kprobe_create(int argc, const char *argv[])
trace_probe_log_err(0, BAD_INSN_BNDRY);
else if (ret == -ENOENT)
trace_probe_log_err(0, BAD_PROBE_ADDR);
else if (ret != -ENOMEM)
else if (ret != -ENOMEM && ret != -EEXIST)
trace_probe_log_err(0, FAIL_REG_PROBE);
goto error;
}