tracing/kprobes: Support perf-style return probe
Support perf-style return probe ("SYMBOL%return") for kprobe events.
This will allow boot-time tracing user to define a return probe event.
Link: https://lkml.kernel.org/r/159972813535.428528.4437029657208468954.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f8e4692..9d46415 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -718,6 +718,9 @@ static int trace_kprobe_create(int argc, const char *argv[])
* p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe:
* r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
+ * Or
+ * p:[GRP/]EVENT] [MOD:]KSYM[+0]%return [FETCHARGS]
+ *
* Fetch args:
* $retval : fetch return value
* $stack : fetch stack address
@@ -747,7 +750,6 @@ static int trace_kprobe_create(int argc, const char *argv[])
switch (argv[0][0]) {
case 'r':
is_return = true;
- flags |= TPARG_FL_RETURN;
break;
case 'p':
break;
@@ -805,12 +807,26 @@ static int trace_kprobe_create(int argc, const char *argv[])
symbol = kstrdup(argv[1], GFP_KERNEL);
if (!symbol)
return -ENOMEM;
+
+ tmp = strchr(symbol, '%');
+ if (tmp) {
+ if (!strcmp(tmp, "%return")) {
+ *tmp = '\0';
+ is_return = true;
+ } else {
+ trace_probe_log_err(tmp - symbol, BAD_ADDR_SUFFIX);
+ goto parse_error;
+ }
+ }
+
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret || offset < 0 || offset > UINT_MAX) {
trace_probe_log_err(0, BAD_PROBE_ADDR);
goto parse_error;
}
+ if (is_return)
+ flags |= TPARG_FL_RETURN;
if (kprobe_on_func_entry(NULL, symbol, offset))
flags |= TPARG_FL_FENTRY;
if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {