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Commit 25764288 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
Browse files

kprobes: Move locks into appropriate functions 

Break a big critical region into fine-grained pieces at
registering kprobe path. This helps us to solve circular
locking dependency when introducing ftrace-based kprobes.

Link: http://lkml.kernel.org/r/20120605102826.27845.81689.stgit@localhost.localdomain



Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f7fa6ef0

kernel/kprobes.c

+42 −21
Original line number Diff line number Diff line
@@ -759,20 +759,28 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p) 
	struct kprobe *ap;

	struct optimized_kprobe *op;



	/* For preparing optimization, jump_label_text_reserved() is called */

	jump_label_lock();

	mutex_lock(&text_mutex);



	ap = alloc_aggr_kprobe(p);

	if (!ap)

		return;

		goto out;



	op = container_of(ap, struct optimized_kprobe, kp);

	if (!arch_prepared_optinsn(&op->optinsn)) {

		/* If failed to setup optimizing, fallback to kprobe */

		arch_remove_optimized_kprobe(op);

		kfree(op);

		return;

		goto out;

	}



	init_aggr_kprobe(ap, p);

	optimize_kprobe(ap);

	optimize_kprobe(ap);	/* This just kicks optimizer thread */



out:

	mutex_unlock(&text_mutex);

	jump_label_unlock();

}



#ifdef CONFIG_SYSCTL
@@ -1144,12 +1152,6 @@ static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p) 
	if (p->post_handler && !ap->post_handler)

		ap->post_handler = aggr_post_handler;



	if (kprobe_disabled(ap) && !kprobe_disabled(p)) {

		ap->flags &= ~KPROBE_FLAG_DISABLED;

		if (!kprobes_all_disarmed)

			/* Arm the breakpoint again. */

			__arm_kprobe(ap);

	}

	return 0;

}
@@ -1189,11 +1191,22 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, 
	int ret = 0;

	struct kprobe *ap = orig_p;



	/* For preparing optimization, jump_label_text_reserved() is called */

	jump_label_lock();

	/*

	 * Get online CPUs to avoid text_mutex deadlock.with stop machine,

	 * which is invoked by unoptimize_kprobe() in add_new_kprobe()

	 */

	get_online_cpus();

	mutex_lock(&text_mutex);



	if (!kprobe_aggrprobe(orig_p)) {

		/* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */

		ap = alloc_aggr_kprobe(orig_p);

		if (!ap)

			return -ENOMEM;

		if (!ap) {

			ret = -ENOMEM;

			goto out;

		}

		init_aggr_kprobe(ap, orig_p);

	} else if (kprobe_unused(ap))

		/* This probe is going to die. Rescue it */
@@ -1213,7 +1226,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, 
			 * free aggr_probe. It will be used next time, or

			 * freed by unregister_kprobe.

			 */

			return ret;

			goto out;



		/* Prepare optimized instructions if possible. */

		prepare_optimized_kprobe(ap);
@@ -1228,7 +1241,20 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, 


	/* Copy ap's insn slot to p */

	copy_kprobe(ap, p);

	return add_new_kprobe(ap, p);

	ret = add_new_kprobe(ap, p);



out:

	mutex_unlock(&text_mutex);

	put_online_cpus();

	jump_label_unlock();



	if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {

		ap->flags &= ~KPROBE_FLAG_DISABLED;

		if (!kprobes_all_disarmed)

			/* Arm the breakpoint again. */

			arm_kprobe(ap);

	}

	return ret;

}



static int __kprobes in_kprobes_functions(unsigned long addr)
@@ -1387,10 +1413,6 @@ int __kprobes register_kprobe(struct kprobe *p) 
		return ret;



	mutex_lock(&kprobe_mutex);

	jump_label_lock(); /* needed to call jump_label_text_reserved() */



	get_online_cpus();	/* For avoiding text_mutex deadlock. */

	mutex_lock(&text_mutex);



	old_p = get_kprobe(p->addr);

	if (old_p) {
@@ -1399,7 +1421,9 @@ int __kprobes register_kprobe(struct kprobe *p) 
		goto out;

	}



	mutex_lock(&text_mutex);	/* Avoiding text modification */

	ret = arch_prepare_kprobe(p);

	mutex_unlock(&text_mutex);

	if (ret)

		goto out;
@@ -1408,15 +1432,12 @@ int __kprobes register_kprobe(struct kprobe *p) 
		       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);



	if (!kprobes_all_disarmed && !kprobe_disabled(p))

		__arm_kprobe(p);

		arm_kprobe(p);



	/* Try to optimize kprobe */

	try_to_optimize_kprobe(p);



out:

	mutex_unlock(&text_mutex);

	put_online_cpus();

	jump_label_unlock();

	mutex_unlock(&kprobe_mutex);



	if (probed_mod)