Re: [PATCH perf/core v5 11/15] perf probe: Accept %sdt and %cached event name

Hemant Kumar
2016-04-27T20:51:34Z

On 04/28/2016 12:08 AM, Masami Hiramatsu wrote:
> From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>
> To improbe usability, support %[PROVIDER:]SDTEVENT format to
> add new probes on SDT and cached events.
>
> e.g.
> ----
> # perf probe -x /lib/libc-2.17.so %lll_lock_wait_private
> Added new event:
> sdt_libc:lll_lock_wait_private (on %lll_lock_wait_private in
> /usr/lib/libc-2.17.so)
>
> You can now use it in all perf tools, such as:
>
> perf record -e sdt_libc:lll_lock_wait_private -aR sleep 1
>
> # perf probe -l | more
> sdt_libc:lll_lock_wait_private (on __lll_lock_wait_private+21
> in /usr/lib/libc-2.17.so)
> ----
>
> Note that this is not only for SDT events, but also normal
> events with event-name.
>
> e.g. define "myevent" on cache (-n doesn't add the real probe)
> ----
> # perf probe -x ./perf --cache -n --add 'myevent=dso__load $params'
> ----
> Reuse the "myevent" from cache as below.
> ----
> # perf probe -x ./perf %myevent
> ----
>
> TODO:
> Wildcard is not supported yet.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Acked-by: Hemant Kumar <hemant@linux.vnet.ibm.com>

> ---
> tools/perf/Documentation/perf-probe.txt | 3 +
> tools/perf/util/probe-event.c | 78 ++++++++++++++++++++++---------
> tools/perf/util/probe-event.h | 1
> tools/perf/util/probe-file.c | 9 ++++
> 4 files changed, 69 insertions(+), 22 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
> index 7a258e9..43523be 100644
> --- a/tools/perf/Documentation/perf-probe.txt
> +++ b/tools/perf/Documentation/perf-probe.txt
> @@ -151,6 +151,8 @@ Probe points are defined by following syntax.
> 3) Define event based on source file with lazy pattern
> [[GROUP:]EVENT=]SRC;PTN [ARG ...]
>
> + 4) Pre-defined SDT events
> + %[PROVIDER:]SDTEVENT
>
> 'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. You can also specify a group name by 'GROUP', if omitted, set 'probe' is used for kprobe and 'probe_<bin>' is used for uprobe.
> Note that using existing group name can conflict with other events. Especially, using the group name reserved for kernel modules can hide embedded events in the
> @@ -158,6 +160,7 @@ modules.
> 'FUNC' specifies a probed function name, and it may have one of the following options; '+OFFS' is the offset from function entry address in bytes, ':RLN' is the relative-line number from function entry line, and '%return' means that it probes function return. And ';PTN' means lazy matching pattern (see LAZY MATCHING). Note that ';PTN' must be the end of the probe point definition. In addition, '@SRC' specifies a source file which has that function.
> It is also possible to specify a probe point by the source line number or lazy matching by using 'SRC:ALN' or 'SRC;PTN' syntax, where 'SRC' is the source file path, ':ALN' is the line number and ';PTN' is the lazy matching pattern.
> 'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
> +'SDTEVENT' and 'PROVIDER' is the pre-defined event name which is defined by user SDT (Statically Defined Tracing) or the pre-cached probes with event name.
>
> PROBE ARGUMENT
> --------------
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index b2c6a4a..1a9ea2b 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1199,6 +1199,34 @@ err:
> return err;
> }
>
> +static int parse_perf_probe_event_name(char **arg, struct perf_probe_event *pev)
> +{
> + char *ptr;
> +
> + ptr = strchr(*arg, ':');
> + if (ptr) {
> + *ptr = '\0';
> + if (!is_c_func_name(*arg))
> + goto ng_name;
> + pev->group = strdup(*arg);
> + if (!pev->group)
> + return -ENOMEM;
> + *arg = ptr + 1;
> + } else
> + pev->group = NULL;
> + if (!is_c_func_name(*arg)) {
> +ng_name:
> + semantic_error("%s is bad for event name -it must "
> + "follow C symbol-naming rule.\n", *arg);
> + return -EINVAL;
> + }
> + pev->event = strdup(*arg);
> + if (pev->event == NULL)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> /* Parse probepoint definition. */
> static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> {
> @@ -1206,38 +1234,43 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> char *ptr, *tmp;
> char c, nc = 0;
> bool file_spec = false;
> + int ret;
> +
> /*
> * <Syntax>
> * perf probe [GRP:][EVENT=]SRC[:LN|;PTN]
> * perf probe [GRP:][EVENT=]FUNC[@SRC][+OFFS|%return|:LN|;PAT]
> + * perf probe %[GRP:]SDT_EVENT
> */
> if (!arg)
> return -EINVAL;
>
> + if (arg[0] == '%') {
> + pev->sdt = true;
> + arg++;
> + }
> +
> ptr = strpbrk(arg, ";=@+%");
> - if (ptr && *ptr == '=') { /* Event name */
> - *ptr = '\0';
> - tmp = ptr + 1;
> - ptr = strchr(arg, ':');
> + if (pev->sdt) {
> if (ptr) {
> - *ptr = '\0';
> - if (!is_c_func_name(arg))
> - goto not_fname;
> - pev->group = strdup(arg);
> - if (!pev->group)
> - return -ENOMEM;
> - arg = ptr + 1;
> - } else
> - pev->group = NULL;
> - if (!is_c_func_name(arg)) {
> -not_fname:
> - semantic_error("%s is bad for event name -it must "
> - "follow C symbol-naming rule.\n", arg);
> + semantic_error("%s must contain only an SDT event name.\n", arg);
> return -EINVAL;
> }
> - pev->event = strdup(arg);
> - if (pev->event == NULL)
> - return -ENOMEM;
> + ret = parse_perf_probe_event_name(&arg, pev);
> + if (ret == 0) {
> + if (asprintf(&pev->point.function, "%%%s", pev->event) < 0)
> + ret = -errno;
> + }
> + return ret;
> + }
> +
> + if (ptr && *ptr == '=') { /* Event name */
> + *ptr = '\0';
> + tmp = ptr + 1;
> + ret = parse_perf_probe_event_name(&arg, pev);
> + if (ret < 0)
> + return ret;
> +
> arg = tmp;
> }
>
> @@ -2849,7 +2882,8 @@ static int find_probe_trace_events_from_cache(struct perf_probe_event *pev,
> pev->point.function);
> }
> if (!entry) {
> - ret = 0;
> + /* SDT must be in the cache */
> + ret = pev->sdt ? -ENOENT : 0;
> goto out;
> }
>
> @@ -2888,7 +2922,7 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
> {
> int ret;
>
> - if (!pev->group) {
> + if (!pev->group && !pev->sdt) {
> /* Set group name if not given */
> if (!pev->uprobes) {
> pev->group = strdup(PERFPROBE_GROUP);
> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> index c451223..2a23efe 100644
> --- a/tools/perf/util/probe-event.h
> +++ b/tools/perf/util/probe-event.h
> @@ -85,6 +85,7 @@ struct perf_probe_event {
> char *group; /* Group name */
> struct perf_probe_point point; /* Probe point */
> int nargs; /* Number of arguments */
> + bool sdt; /* SDT/cached event flag */
> bool uprobes; /* Uprobe event flag */
> char *target; /* Target binary */
> struct perf_probe_arg *args; /* Arguments */
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index c10a647..ee560dd 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -529,6 +529,15 @@ probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)
> return NULL;
>
> list_for_each_entry(entry, &pcache->list, list) {
> + if (pev->sdt) {
> + if (entry->pev.event &&
> + streql(entry->pev.event, pev->event) &&
> + (!pev->group ||
> + streql(entry->pev.group, pev->group)))
> + goto found;
> +
> + continue;
> + }
> /* Hit if same event name or same command-string */
> if ((pev->event &&
> (streql(entry->pev.group, pev->group) &&
>

--
Thanks,
Hemant Kumar