From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>, Jonathan Corbet <corbet@lwn.net>
Cc: mhiramat@kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCH v2 4/6] tracing/kprobes: Support perf-style return probe
Date: Tue, 1 Sep 2020 16:57:10 +0900 [thread overview]
Message-ID: <159894703070.1478826.15755889933157654537.stgit@devnote2> (raw)
In-Reply-To: <159894698993.1478826.2813843560314595660.stgit@devnote2>
Support perf-style return probe ("SYMBOL%return") in kprobe events.
This will allow boot-time tracing user to define a return probe event.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/trace/trace_kprobe.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index aefb6065b508..391361b67c8f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -709,6 +709,18 @@ static inline void sanitize_event_name(char *name)
*name = '_';
}
+static inline bool split_return_suffix(char *symbol)
+{
+ char *p = strchr(symbol, '%');
+
+ if (p && !strcmp(p, "%return")) {
+ *p = '\0';
+ return true;
+ }
+
+ return false;
+}
+
static int trace_kprobe_create(int argc, const char *argv[])
{
/*
@@ -717,6 +729,9 @@ 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
@@ -746,7 +761,6 @@ 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;
@@ -804,12 +818,17 @@ static int trace_kprobe_create(int argc, const char *argv[])
symbol = kstrdup(argv[1], GFP_KERNEL);
if (!symbol)
return -ENOMEM;
+
+ is_return = split_return_suffix(symbol) || is_return;
+
/* 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)) {
next prev parent reply other threads:[~2020-09-01 7:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 7:56 [PATCH v2 0/6] tracing/boot: Add new options for tracing specific period Masami Hiramatsu
2020-09-01 7:56 ` [PATCH v2 1/6] kprobes: tracing/kprobes: Fix to kill kprobes on initmem after boot Masami Hiramatsu
2020-09-01 7:56 ` [PATCH v2 2/6] tracing/boot: Add per-instance tracing_on option support Masami Hiramatsu
2020-09-01 7:57 ` [PATCH v2 3/6] Documentation: tracing: Add tracing_on option to boot-time tracer Masami Hiramatsu
2020-09-01 7:57 ` Masami Hiramatsu [this message]
2020-09-10 0:49 ` [PATCH v2 4/6] tracing/kprobes: Support perf-style return probe Masami Hiramatsu
2020-09-01 7:57 ` [PATCH v2 5/6] Documentation: tracing: Add %return suffix description Masami Hiramatsu
2020-09-01 7:57 ` [PATCH v2 6/6] Documentation: tracing: boot: Add an example of tracing function-calls Masami Hiramatsu
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