Commit 88cefd99 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
Browse files

ftrace: Show subops in enabled_functions 

The function graph infrastructure uses subops of the function tracer.
These are not shown in enabled_functions. Add a "subops:" section to the
enabled_functions line to show what functions are attached via subops. If
the subops is from the function_graph infrastructure, then show the entry
and return callbacks that are attached.

Here's an example of the output:

schedule_on_each_cpu (1)                tramp: 0xffffffffc03ef000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60     subops: {ent:trace_graph_entry+0x0/0x20 ret:trace_graph_return+0x0/0x150}

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250410153830.5d97f108@gandalf.local.home


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 54c53dfd

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -328,6 +328,7 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops); 
 * DIRECT - Used by the direct ftrace_ops helper for direct functions

 *            (internal ftrace only, should not be used by others)

 * SUBOP  - Is controlled by another op in field managed.

 * GRAPH  - Is a component of the fgraph_ops structure

 */

enum {

	FTRACE_OPS_FL_ENABLED			= BIT(0),
@@ -349,6 +350,7 @@ enum { 
	FTRACE_OPS_FL_PERMANENT                 = BIT(16),

	FTRACE_OPS_FL_DIRECT			= BIT(17),

	FTRACE_OPS_FL_SUBOP			= BIT(18),

	FTRACE_OPS_FL_GRAPH			= BIT(19),

};



#ifndef CONFIG_DYNAMIC_FTRACE_WITH_ARGS

kernel/trace/fgraph.c

+2 −0
Original line number Diff line number Diff line
@@ -1382,6 +1382,8 @@ int register_ftrace_graph(struct fgraph_ops *gops) 
	/* Always save the function, and reset at unregistering */

	gops->saved_func = gops->entryfunc;



	gops->ops.flags |= FTRACE_OPS_FL_GRAPH;



	ret = ftrace_startup_subops(&graph_ops, &gops->ops, command);

	if (!ret)

		fgraph_array[i] = gops;

kernel/trace/ftrace.c

+38 −0
Original line number Diff line number Diff line
@@ -4373,6 +4373,42 @@ static inline int print_rec(struct seq_file *m, unsigned long ip) 
}

#endif



static void print_subops(struct seq_file *m, struct ftrace_ops *ops, struct dyn_ftrace *rec)

{

	struct ftrace_ops *subops;

	bool first = true;



	list_for_each_entry(subops, &ops->subop_list, list) {

		if (!((subops->flags & FTRACE_OPS_FL_ENABLED) &&

		      hash_contains_ip(rec->ip, subops->func_hash)))

			continue;

		if (first) {

			seq_printf(m, "\tsubops:");

			first = false;

		}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

		if (subops->flags & FTRACE_OPS_FL_GRAPH) {

			struct fgraph_ops *gops;



			gops = container_of(subops, struct fgraph_ops, ops);

			seq_printf(m, " {ent:%pS ret:%pS}",

				   (void *)gops->entryfunc,

				   (void *)gops->retfunc);

			continue;

		}

#endif

		if (subops->trampoline) {

			seq_printf(m, " {%pS (%pS)}",

				   (void *)subops->trampoline,

				   (void *)subops->func);

			add_trampoline_func(m, subops, rec);

		} else {

			seq_printf(m, " {%pS}",

				   (void *)subops->func);

		}

	}

}



static int t_show(struct seq_file *m, void *v)

{

	struct ftrace_iterator *iter = m->private;
@@ -4425,6 +4461,7 @@ static int t_show(struct seq_file *m, void *v) 
						   (void *)ops->trampoline,

						   (void *)ops->func);

					add_trampoline_func(m, ops, rec);

					print_subops(m, ops, rec);

					ops = ftrace_find_tramp_ops_next(rec, ops);

				} while (ops);

			} else
@@ -4437,6 +4474,7 @@ static int t_show(struct seq_file *m, void *v) 
			if (ops) {

				seq_printf(m, "\tops: %pS (%pS)",

					   ops, ops->func);

				print_subops(m, ops, rec);

			} else {

				seq_puts(m, "\tops: ERROR!");

			}