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Date: Mon, 30 May 2022 09:47:40 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Linyu Yuan <quic_linyyuan@...cinc.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Tom Zanussi <zanussi@...nel.org>,
Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>,
Tzvetomir Stoyanov (VMware) <tz.stoyanov@...il.com>
Subject: Re: [PATCH v2 1/2] tracing: auto generate event name when create a
group of events
Hi Linyu,
On Sun, 29 May 2022 11:34:53 +0800
Linyu Yuan <quic_linyyuan@...cinc.com> wrote:
> Currently when create a specific group of trace events,
> take kprobe event as example, user must use the following format:
> p:GRP/EVENT [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS],
> which means user must enter EVENT name, one example is: echo
> 'p:usb_gadget/config_usb_cfg_link config_usb_cfg_link $arg1' >>
> kprobe_events, it is not simple if there are too many entries
> because the event name is same as symbol name.
>
> This change allows user to specify no EVENT name, format changed as:
> p:GRP/ [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS],
> it will generate event name automatically and one example is:
> echo 'p:usb_gadget/ config_usb_cfg_link $arg1' >> kprobe_events.
>
> Signed-off-by: Linyu Yuan <quic_linyyuan@...cinc.com>
> ---
> v2: fix review comments in V1:
> change TP_ENAME_EMPTTY to TP_ENAME_EMPTY,
Thanks for update! And I think this return code is a bit redundant
because those cases can be rephrased as follows;
TP_ENAME_GROUP_EVENT : event != NULL && group != (default)
TP_ENAME_GROUP : event == NULL && group != (default)
TP_ENAME_EVENT : event != NULL && group == (default)
TP_ENAME_EMPTY : event == NULL && group == (default)
What about this (e.g. trace_kprobe.c)?
if (event) {
/* event and group will be updated in this function */
ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto parse_error;
}
if (!event) {
/* Make a new event name */
if (symbol)
snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
is_return ? 'r' : 'p', symbol, offset);
else
snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
is_return ? 'r' : 'p', addr);
sanitize_event_name(buf);
event = buf;
}
This makes the code clearer.
> add some space,
> document the macros return by traceprobe_parse_event_name(),
> updatea commit description.
>
> Documentation/trace/kprobetrace.rst | 8 ++++----
> Documentation/trace/uprobetracer.rst | 8 ++++----
> kernel/trace/trace_dynevent.c | 2 +-
> kernel/trace/trace_eprobe.c | 20 ++++++++++++--------
> kernel/trace/trace_kprobe.c | 19 ++++++++++++-------
> kernel/trace/trace_probe.c | 9 ++++++++-
> kernel/trace/trace_probe.h | 4 ++++
> kernel/trace/trace_uprobe.c | 15 ++++++++++-----
> 8 files changed, 55 insertions(+), 30 deletions(-)
>
> diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
> index b175d88..4274cc6 100644
> --- a/Documentation/trace/kprobetrace.rst
> +++ b/Documentation/trace/kprobetrace.rst
> @@ -28,10 +28,10 @@ Synopsis of kprobe_events
> -------------------------
> ::
>
> - p[:[GRP/]EVENT] [MOD:]SYM[+offs]|MEMADDR [FETCHARGS] : Set a probe
> - r[MAXACTIVE][:[GRP/]EVENT] [MOD:]SYM[+0] [FETCHARGS] : Set a return probe
> - p:[GRP/]EVENT] [MOD:]SYM[+0]%return [FETCHARGS] : Set a return probe
> - -:[GRP/]EVENT : Clear a probe
> + p[:[GRP/][EVENT]] [MOD:]SYM[+offs]|MEMADDR [FETCHARGS] : Set a probe
> + r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]SYM[+0] [FETCHARGS] : Set a return probe
> + p[:[GRP/][EVENT]] [MOD:]SYM[+0]%return [FETCHARGS] : Set a return probe
> + -:[GRP/][EVENT] : Clear a probe
Could you also update 'readme_msg' in kernel/trace/trace.c in this patch?
e.g.
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
"\t accepts: event-definitions (one definition per line)\n"
"\t Format: p[:[<group>/][<event>]] <place> [<args>]\n"
"\t r[maxactive][:[<group>/][<event>]] <place> [<args>]\n"
#ifdef CONFIG_HIST_TRIGGERS
"\t s:[synthetic/]<event> <field> [<field>]\n"
#endif
"\t e[:[<group>/][<event>]] <attached-group>.<attached-event> [<args>]\n"
"\t -:[<group>/]<event>\n"
And also, could you add *another patch* to update below testcases about
dynevent to ensure this feature is working?
tools/testing/selftests/ftrace/test.d/dynevent/add_remove_kprobe.tc
and tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
e.g.
if grep -q '\[<event>\]' README then
(add your test...)
fi
Thank you,
>
> GRP : Group name. If omitted, use "kprobes" for it.
> EVENT : Event name. If omitted, the event name is generated
> diff --git a/Documentation/trace/uprobetracer.rst b/Documentation/trace/uprobetracer.rst
> index a8e5938..3a1797d7 100644
> --- a/Documentation/trace/uprobetracer.rst
> +++ b/Documentation/trace/uprobetracer.rst
> @@ -26,10 +26,10 @@ Synopsis of uprobe_tracer
> -------------------------
> ::
>
> - p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a uprobe
> - r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
> - p[:[GRP/]EVENT] PATH:OFFSET%return [FETCHARGS] : Set a return uprobe (uretprobe)
> - -:[GRP/]EVENT : Clear uprobe or uretprobe event
> + p[:[GRP/][EVENT]] PATH:OFFSET [FETCHARGS] : Set a uprobe
> + r[:[GRP/][EVENT]] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
> + p[:[GRP/][EVENT]] PATH:OFFSET%return [FETCHARGS] : Set a return uprobe (uretprobe)
> + -:[GRP/][EVENT] : Clear uprobe or uretprobe event
>
> GRP : Group name. If omitted, "uprobes" is the default value.
> EVENT : Event name. If omitted, the event name is generated based
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index e34e8182..033248d 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -101,7 +101,7 @@ int dyn_event_release(const char *raw_command, struct dyn_event_operations *type
> event = p + 1;
> *p = '\0';
> }
> - if (event[0] == '\0') {
> + if (!system && event[0] == '\0') {
> ret = -EINVAL;
> goto out;
> }
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index 7d44785..13cd7fc 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -125,6 +125,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> * We match the following:
> * event only - match all eprobes with event name
> * system and event only - match all system/event probes
> + * system only - match all system probes
> *
> * The below has the above satisfied with more arguments:
> *
> @@ -143,7 +144,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> return false;
>
> /* Must match the event name */
> - if (strcmp(trace_probe_name(&ep->tp), event) != 0)
> + if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
> return false;
>
> /* No arguments match all */
> @@ -848,7 +849,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> {
> /*
> * Argument syntax:
> - * e[:[GRP/]ENAME] SYSTEM.EVENT [FETCHARGS]
> + * e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS]
> * Fetch args:
> * <name>=$<field>[:TYPE]
> */
> @@ -858,6 +859,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> struct trace_eprobe *ep = NULL;
> char buf1[MAX_EVENT_NAME_LEN];
> char buf2[MAX_EVENT_NAME_LEN];
> + char grp_buf[MAX_EVENT_NAME_LEN];
> int ret = 0;
> int i;
>
> @@ -866,14 +868,17 @@ static int __trace_eprobe_create(int argc, const char *argv[])
>
> trace_probe_log_init("event_probe", argc, argv);
>
> + ret = TP_ENAME_EMPTY;
> event = strchr(&argv[0][1], ':');
> if (event) {
> event++;
> - ret = traceprobe_parse_event_name(&event, &group, buf1,
> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> event - argv[0]);
> - if (ret)
> + if (ret < 0)
> goto parse_error;
> - } else {
> + }
> +
> + if (ret == TP_ENAME_EMPTY || ret == TP_ENAME_GROUP) {
> strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
> sanitize_event_name(buf1);
> event = buf1;
> @@ -882,9 +887,8 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> goto parse_error;
>
> sys_event = argv[1];
> - ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
> - sys_event - argv[1]);
> - if (ret || !sys_name)
> + ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
> + if (ret != TP_ENAME_GROUP_EVENT)
> goto parse_error;
> if (!is_good_name(sys_event) || !is_good_name(sys_name))
> goto parse_error;
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 47cebef..55822b6 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -163,7 +163,8 @@ static bool trace_kprobe_match(const char *system, const char *event,
> {
> struct trace_kprobe *tk = to_trace_kprobe(ev);
>
> - return strcmp(trace_probe_name(&tk->tp), event) == 0 &&
> + return (event[0] == '\0' ||
> + strcmp(trace_probe_name(&tk->tp), event) == 0) &&
> (!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
> trace_kprobe_match_command_head(tk, argc, argv);
> }
> @@ -708,11 +709,11 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> /*
> * Argument syntax:
> * - Add kprobe:
> - * p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
> + * p[:[GRP/][EVENT]] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
> * - Add kretprobe:
> - * r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
> + * r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]KSYM[+0] [FETCHARGS]
> * Or
> - * p:[GRP/]EVENT] [MOD:]KSYM[+0]%return [FETCHARGS]
> + * p[:[GRP/][EVENT]] [MOD:]KSYM[+0]%return [FETCHARGS]
> *
> * Fetch args:
> * $retval : fetch return value
> @@ -739,6 +740,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> long offset = 0;
> void *addr = NULL;
> char buf[MAX_EVENT_NAME_LEN];
> + char grp_buf[MAX_EVENT_NAME_LEN];
> unsigned int flags = TPARG_FL_KERNEL;
>
> switch (argv[0][0]) {
> @@ -832,12 +834,15 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> }
>
> trace_probe_log_set_index(0);
> + ret = TP_ENAME_EMPTY;
> if (event) {
> - ret = traceprobe_parse_event_name(&event, &group, buf,
> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> event - argv[0]);
> - if (ret)
> + if (ret < 0)
> goto parse_error;
> - } else {
> + }
> +
> + if (ret == TP_ENAME_EMPTY || ret == TP_ENAME_GROUP) {
> /* Make a new event name */
> if (symbol)
> snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 80863c6..7fd50ab 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -257,6 +257,9 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> }
> len = strlen(event);
> if (len == 0) {
> + if (slash)
> + return TP_ENAME_GROUP;
> +
> trace_probe_log_err(offset, NO_EVENT_NAME);
> return -EINVAL;
> } else if (len > MAX_EVENT_NAME_LEN) {
> @@ -267,7 +270,11 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> trace_probe_log_err(offset, BAD_EVENT_NAME);
> return -EINVAL;
> }
> - return 0;
> +
> + if (slash)
> + return TP_ENAME_GROUP_EVENT;
> +
> + return TP_ENAME_EVENT;
> }
>
> #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 92cc149..7390669 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -364,6 +364,10 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
> extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
> int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> char *buf, int offset);
> +#define TP_ENAME_GROUP_EVENT 0 /* GRP/EVENT format, user defined group and event name */
> +#define TP_ENAME_EVENT 1 /* EVENT format, user defined event name, default group */
> +#define TP_ENAME_GROUP 2 /* GRP/ format, user defined group name, auto event name */
> +#define TP_ENAME_EMPTY 3 /* default group and auto event name */
>
> enum probe_print_type {
> PROBE_PRINT_NORMAL,
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 9711589..bc32361 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -312,7 +312,8 @@ static bool trace_uprobe_match(const char *system, const char *event,
> {
> struct trace_uprobe *tu = to_trace_uprobe(ev);
>
> - return strcmp(trace_probe_name(&tu->tp), event) == 0 &&
> + return (event[0] == '\0' ||
> + strcmp(trace_probe_name(&tu->tp), event) == 0) &&
> (!system || strcmp(trace_probe_group_name(&tu->tp), system) == 0) &&
> trace_uprobe_match_command_head(tu, argc, argv);
> }
> @@ -532,7 +533,7 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
>
> /*
> * Argument syntax:
> - * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET[%return][(REF)] [FETCHARGS]
> + * - Add uprobe: p|r[:[GRP/][EVENT]] PATH:OFFSET[%return][(REF)] [FETCHARGS]
> */
> static int __trace_uprobe_create(int argc, const char **argv)
> {
> @@ -540,6 +541,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
> const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
> char *arg, *filename, *rctr, *rctr_end, *tmp;
> char buf[MAX_EVENT_NAME_LEN];
> + char grp_buf[MAX_EVENT_NAME_LEN];
> enum probe_print_type ptype;
> struct path path;
> unsigned long offset, ref_ctr_offset;
> @@ -644,12 +646,15 @@ static int __trace_uprobe_create(int argc, const char **argv)
>
> /* setup a probe */
> trace_probe_log_set_index(0);
> + ret = TP_ENAME_EMPTY;
> if (event) {
> - ret = traceprobe_parse_event_name(&event, &group, buf,
> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> event - argv[0]);
> - if (ret)
> + if (ret < 0)
> goto fail_address_parse;
> - } else {
> + }
> +
> + if (ret == TP_ENAME_EMPTY || ret == TP_ENAME_GROUP) {
> char *tail;
> char *ptr;
>
> --
> 2.7.4
>
--
Masami Hiramatsu (Google) <mhiramat@...nel.org>
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