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Date: Mon, 30 May 2022 09:28:23 +0800
From: Linyu Yuan <quic_linyyuan@...cinc.com>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
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
On 5/30/2022 8:47 AM, Masami Hiramatsu (Google) wrote:
> 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.
good idea, will follow it.
>
>> 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"
sure.
>
> 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
thanks, will do it.
>
>
> 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
>>
>
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