[PATCH v4 2/3] tracing: auto generate event name when create a group of events

From: Linyu Yuan
Date: Thu Jun 02 2022 - 08:11:22 EST

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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@xxxxxxxxxxx>
---
v2: fix review comments in V1:
change TP_ENAME_EMPTTY to TP_ENAME_EMPTY,
add some space,
document the macros return by traceprobe_parse_event_name(),
updatea commit description.
v3: remove TP_ENAME_* macro which suggest by Masami Hiramatsu,
allow generate event name from SYSTEM/EVENT for eprobe.
v4: no change

Documentation/trace/kprobetrace.rst | 8 ++++----
Documentation/trace/uprobetracer.rst | 8 ++++----
kernel/trace/trace.c | 8 ++++----
kernel/trace/trace_dynevent.c | 2 +-
kernel/trace/trace_eprobe.c | 21 ++++++++++++---------
kernel/trace/trace_kprobe.c | 16 ++++++++++------
kernel/trace/trace_probe.c | 6 ++++++
kernel/trace/trace_uprobe.c | 12 ++++++++----
8 files changed, 49 insertions(+), 32 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

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.c b/kernel/trace/trace.c
index f400800b..76274c6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5575,13 +5575,13 @@ static const char readme_msg[] =
#endif
#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"
+ "\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"
+ "\t e[:[<group>/][<event>]] <attached-group>.<attached-event> [<args>]\n"
+ "\t -:[<group>/][<event>]\n"
#ifdef CONFIG_KPROBE_EVENTS
"\t place: [<module>:]<symbol>[+<offset>]|<memaddr>\n"
"place (kretprobe): [<module>:]<symbol>[+<offset>]%return|<memaddr>\n"
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 076b447..1549966 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 17d64e3..be9a94d 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 gbuf[MAX_EVENT_NAME_LEN];
int ret = 0;
int i;

@@ -869,22 +871,23 @@ static int __trace_eprobe_create(int argc, const char *argv[])
event = strchr(&argv[0][1], ':');
if (event) {
event++;
- ret = traceprobe_parse_event_name(&event, &group, buf1,
+ ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto parse_error;
- } else {
- strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
- sanitize_event_name(buf1);
- event = buf1;
}

sys_event = argv[1];
- ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
- sys_event - argv[1]);
+ ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
if (ret || !sys_name)
goto parse_error;

+ if (!event) {
+ snprintf(buf1, MAX_EVENT_NAME_LEN, "%s_%s", sys_name, sys_event);
+ sanitize_event_name(buf1);
+ event = buf1;
+ }
+
mutex_lock(&event_mutex);
event_call = find_and_get_event(sys_name, sys_event);
ep = alloc_event_probe(group, event, event_call, argc - 2);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 9350733..2c36a71 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 gbuf[MAX_EVENT_NAME_LEN];
unsigned int flags = TPARG_FL_KERNEL;

switch (argv[0][0]) {
@@ -833,11 +835,13 @@ static int __trace_kprobe_create(int argc, const char *argv[])

trace_probe_log_set_index(0);
if (event) {
- ret = traceprobe_parse_event_name(&event, &group, buf,
+ ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto parse_error;
- } else {
+ }
+
+ if (!event) {
/* 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..b788183 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -257,6 +257,11 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
}
len = strlen(event);
if (len == 0) {
+ if (slash) {
+ *pevent = NULL;
+ return 0;
+ }
+
trace_probe_log_err(offset, NO_EVENT_NAME);
return -EINVAL;
} else if (len > MAX_EVENT_NAME_LEN) {
@@ -267,6 +272,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
trace_probe_log_err(offset, BAD_EVENT_NAME);
return -EINVAL;
}
+
return 0;
}

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 9711589..5af0e85 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 gbuf[MAX_EVENT_NAME_LEN];
enum probe_print_type ptype;
struct path path;
unsigned long offset, ref_ctr_offset;
@@ -645,11 +647,13 @@ static int __trace_uprobe_create(int argc, const char **argv)
/* setup a probe */
trace_probe_log_set_index(0);
if (event) {
- ret = traceprobe_parse_event_name(&event, &group, buf,
+ ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto fail_address_parse;
- } else {
+ }
+
+ if (!event) {
char *tail;
char *ptr;

--
2.7.4

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