Commit 5f3719f6 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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tracing: Update modules to persistent instances when loaded 

When a module is loaded and a persistent buffer is actively tracing, add
it to the list of modules in the persistent memory.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250305164609.469844721@goodmis.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 1bd25a6f

kernel/trace/trace.c

+27 −0
Original line number Diff line number Diff line
@@ -10087,6 +10087,32 @@ static void trace_module_remove_evals(struct module *mod) 
static inline void trace_module_remove_evals(struct module *mod) { }

#endif /* CONFIG_TRACE_EVAL_MAP_FILE */



static bool trace_array_active(struct trace_array *tr)

{

	if (tr->current_trace != &nop_trace)

		return true;



	/* 0 is no events, 1 is all disabled */

	return trace_events_enabled(tr, NULL) > 1;

}



static void trace_module_record(struct module *mod)

{

	struct trace_array *tr;



	list_for_each_entry(tr, &ftrace_trace_arrays, list) {

		/* Update any persistent trace array that has already been started */

		if ((tr->flags & (TRACE_ARRAY_FL_BOOT | TRACE_ARRAY_FL_LAST_BOOT)) ==

		    TRACE_ARRAY_FL_BOOT) {

			/* Only update if the trace array is active */

			if (trace_array_active(tr)) {

				guard(mutex)(&scratch_mutex);

				save_mod(mod, tr);

			}

		}

	}

}



static int trace_module_notify(struct notifier_block *self,

			       unsigned long val, void *data)

{
@@ -10095,6 +10121,7 @@ static int trace_module_notify(struct notifier_block *self, 
	switch (val) {

	case MODULE_STATE_COMING:

		trace_module_add_evals(mod);

		trace_module_record(mod);

		break;

	case MODULE_STATE_GOING:

		trace_module_remove_evals(mod);

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -786,6 +786,8 @@ extern void trace_find_cmdline(int pid, char comm[]); 
extern int trace_find_tgid(int pid);

extern void trace_event_follow_fork(struct trace_array *tr, bool enable);



extern int trace_events_enabled(struct trace_array *tr, const char *system);



#ifdef CONFIG_DYNAMIC_FTRACE

extern unsigned long ftrace_update_tot_cnt;

extern unsigned long ftrace_number_of_pages;

kernel/trace/trace_events.c

+28 −12
Original line number Diff line number Diff line
@@ -1818,28 +1818,28 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, 
	return cnt;

}



static ssize_t

system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,

		   loff_t *ppos)

/*

 * Returns:

 *   0 : no events exist?

 *   1 : all events are disabled

 *   2 : all events are enabled

 *   3 : some events are enabled and some are enabled

 */

int trace_events_enabled(struct trace_array *tr, const char *system)

{

	const char set_to_char[4] = { '?', '0', '1', 'X' };

	struct trace_subsystem_dir *dir = filp->private_data;

	struct event_subsystem *system = dir->subsystem;

	struct trace_event_call *call;

	struct trace_event_file *file;

	struct trace_array *tr = dir->tr;

	char buf[2];

	int set = 0;

	int ret;



	mutex_lock(&event_mutex);

	guard(mutex)(&event_mutex);



	list_for_each_entry(file, &tr->events, list) {

		call = file->event_call;

		if ((call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||

		    !trace_event_name(call) || !call->class || !call->class->reg)

			continue;



		if (system && strcmp(call->class->system, system->name) != 0)

		if (system && strcmp(call->class->system, system) != 0)

			continue;



		/*
@@ -1855,7 +1855,23 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt, 
		if (set == 3)

			break;

	}

	mutex_unlock(&event_mutex);



	return set;

}



static ssize_t

system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,

		   loff_t *ppos)

{

	const char set_to_char[4] = { '?', '0', '1', 'X' };

	struct trace_subsystem_dir *dir = filp->private_data;

	struct event_subsystem *system = dir->subsystem;

	struct trace_array *tr = dir->tr;

	char buf[2];

	int set;

	int ret;



	set = trace_events_enabled(tr, system ? system->name : NULL);



	buf[0] = set_to_char[set];

	buf[1] = '\n';