tracing/boot: Add per-event settings

Add per-event settings for boottime tracing. User can set filter,
actions and enable on each event on boot. The event entries are
under ftrace.event.GROUP.EVENT node (note that the option key
includes event's group name and event name.) This supports below
configs.

 - ftrace.event.GROUP.EVENT.enable
   Enables GROUP:EVENT tracing.

 - ftrace.event.GROUP.EVENT.filter = FILTER
   Set FILTER rule to the GROUP:EVENT.

 - ftrace.event.GROUP.EVENT.actions = ACTION[, ACTION2...]
   Set ACTIONs to the GROUP:EVENT.

For example,

  ftrace.event.sched.sched_process_exec {
                filter = "pid < 128"
		enable
  }

this will enable tracing "sched:sched_process_exec" event
with "pid < 128" filter.

Link: http://lkml.kernel.org/r/157867238942.17873.11177628789184546198.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 4b41310184dff9ae098fde9e83faf3c73d3e9305..37524031533e1fc222f96ea4f569eb5176d95c0a 100644 (file)
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -56,6 +56,7 @@ trace_boot_set_ftrace_options(struct trace_array *tr, struct xbc_node *node)
 
 #ifdef CONFIG_EVENT_TRACING
 extern int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
+extern int trigger_process_regex(struct trace_event_file *file, char *buff);
 
 static void __init
 trace_boot_enable_events(struct trace_array *tr, struct xbc_node *node)
@@ -74,8 +75,66 @@ trace_boot_enable_events(struct trace_array *tr, struct xbc_node *node)
                        pr_err("Failed to enable event: %s\n", p);
        }
 }
+
+static void __init
+trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
+                         struct xbc_node *enode)
+{
+       struct trace_event_file *file;
+       struct xbc_node *anode;
+       char buf[MAX_BUF_LEN];
+       const char *p, *group, *event;
+
+       group = xbc_node_get_data(gnode);
+       event = xbc_node_get_data(enode);
+
+       mutex_lock(&event_mutex);
+       file = find_event_file(tr, group, event);
+       if (!file) {
+               pr_err("Failed to find event: %s:%s\n", group, event);
+               goto out;
+       }
+
+       p = xbc_node_find_value(enode, "filter", NULL);
+       if (p && *p != '\0') {
+               if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
+                       pr_err("filter string is too long: %s\n", p);
+               else if (apply_event_filter(file, buf) < 0)
+                       pr_err("Failed to apply filter: %s\n", buf);
+       }
+
+       xbc_node_for_each_array_value(enode, "actions", anode, p) {
+               if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
+                       pr_err("action string is too long: %s\n", p);
+               else if (trigger_process_regex(file, buf) < 0)
+                       pr_err("Failed to apply an action: %s\n", buf);
+       }
+
+       if (xbc_node_find_value(enode, "enable", NULL)) {
+               if (trace_event_enable_disable(file, 1, 0) < 0)
+                       pr_err("Failed to enable event node: %s:%s\n",
+                               group, event);
+       }
+out:
+       mutex_unlock(&event_mutex);
+}
+
+static void __init
+trace_boot_init_events(struct trace_array *tr, struct xbc_node *node)
+{
+       struct xbc_node *gnode, *enode;
+
+       node = xbc_node_find_child(node, "event");
+       if (!node)
+               return;
+       /* per-event key starts with "event.GROUP.EVENT" */
+       xbc_node_for_each_child(node, gnode)
+               xbc_node_for_each_child(gnode, enode)
+                       trace_boot_init_one_event(tr, gnode, enode);
+}
 #else
 #define trace_boot_enable_events(tr, node) do {} while (0)
+#define trace_boot_init_events(tr, node) do {} while (0)
 #endif
 
 static void __init
@@ -104,6 +163,7 @@ static int __init trace_boot_init(void)
                return 0;
 
        trace_boot_set_ftrace_options(tr, trace_node);
+       trace_boot_init_events(tr, trace_node);
        trace_boot_enable_events(tr, trace_node);
        trace_boot_enable_tracer(tr, trace_node);
 

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 2cd53ca21b515f620873572845a8e591ae44a968..d8ada4c6f3f7c21da10cca44baf3fccdbdf9d805 100644 (file)
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -213,7 +213,7 @@ static int event_trigger_regex_open(struct inode *inode, struct file *file)
        return ret;
 }
 
-static int trigger_process_regex(struct trace_event_file *file, char *buff)
+int trigger_process_regex(struct trace_event_file *file, char *buff)
 {
        char *command, *next = buff;
        struct event_command *p;