On Tue, 1 Sep 2020 16:57:10 +0900
Masami Hiramatsu <mhira...@kernel.org> wrote:
> Support perf-style return probe ("SYMBOL%return") in kprobe events.
> This will allow boot-time tracing user to define a return probe event.
>
Hmm, I think I should add this for uprobe event too.
I'll update the series.
Thank you,
> Signed-off-by: Masami Hiramatsu <mhira...@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)) {
>
--
Masami Hiramatsu <mhira...@kernel.org>
