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tracing/boot: Add synthetic event support

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Add synthetic event node support to boot time tracing.
The synthetic event is a kind of event node, but the group
name is "synthetic".

 - ftrace.event.synthetic.EVENT.fields = FIELD[, FIELD2...]
   Defines new synthetic event with FIELDs. Each field should be
   "type varname".

The synthetic node requires "fields" string arraies, which defines
the fields as same as tracing/synth_events interface.

Link: http://lkml.kernel.org/r/157867241236.17873.12411615143321557709.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2020-01-11 01:06:52 +09:00 committed by Steven Rostedt (VMware)
parent 4d655281eb
commit 3fbe2d6e1f
2 changed files with 52 additions and 0 deletions
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47
kernel/trace/trace_boot.c
View File

@ -118,6 +118,50 @@ trace_boot_add_kprobe_event(struct xbc_node *node, const char *event)
}
#endif
#ifdef CONFIG_HIST_TRIGGERS
extern int synth_event_run_command(const char *command);
static int __init
trace_boot_add_synth_event(struct xbc_node *node, const char *event)
{
struct xbc_node *anode;
char buf[MAX_BUF_LEN], *q;
const char *p;
int len, delta, ret;
len = ARRAY_SIZE(buf);
delta = snprintf(buf, len, "%s", event);
if (delta >= len) {
pr_err("Event name is too long: %s\n", event);
return -E2BIG;
}
len -= delta; q = buf + delta;
xbc_node_for_each_array_value(node, "fields", anode, p) {
delta = snprintf(q, len, " %s;", p);
if (delta >= len) {
pr_err("fields string is too long: %s\n", p);
return -E2BIG;
}
len -= delta; q += delta;
}
ret = synth_event_run_command(buf);
if (ret < 0)
pr_err("Failed to add synthetic event: %s\n", buf);
return ret;
}
#else
static inline int __init
trace_boot_add_synth_event(struct xbc_node *node, const char *event)
{
pr_err("Synthetic event is not supported.\n");
return -ENOTSUPP;
}
#endif
static void __init
trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
struct xbc_node *enode)
@ -133,6 +177,9 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
if (!strcmp(group, "kprobes"))
if (trace_boot_add_kprobe_event(enode, event) < 0)
return;
if (!strcmp(group, "synthetic"))
if (trace_boot_add_synth_event(enode, event) < 0)
return;
mutex_lock(&event_mutex);
file = find_event_file(tr, group, event);

5
kernel/trace/trace_events_hist.c
View File

@ -1384,6 +1384,11 @@ static int create_or_delete_synth_event(int argc, char **argv)
return ret == -ECANCELED ? -EINVAL : ret;
}
int synth_event_run_command(const char *command)
{
return trace_run_command(command, create_or_delete_synth_event);
}
static int synth_event_create(int argc, const char **argv)
{
const char *name = argv[0];