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Commit f7fa6ef0 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
Browse files

kprobes: cleanup to separate probe-able check 

Separate probe-able address checking code from
register_kprobe().

Link: http://lkml.kernel.org/r/20120605102820.27845.90133.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 72ef3794

kernel/kprobes.c

+45 −37
Original line number Diff line number Diff line
@@ -1313,67 +1313,80 @@ static inline int check_kprobe_rereg(struct kprobe *p) 
	return ret;

}



int __kprobes register_kprobe(struct kprobe *p)

static __kprobes int check_kprobe_address_safe(struct kprobe *p,

					       struct module **probed_mod)

{

	int ret = 0;

	struct kprobe *old_p;

	struct module *probed_mod;

	kprobe_opcode_t *addr;



	addr = kprobe_addr(p);

	if (IS_ERR(addr))

		return PTR_ERR(addr);

	p->addr = addr;



	ret = check_kprobe_rereg(p);

	if (ret)

		return ret;



	jump_label_lock();

	preempt_disable();



	/* Ensure it is not in reserved area nor out of text */

	if (!kernel_text_address((unsigned long) p->addr) ||

	    in_kprobes_functions((unsigned long) p->addr) ||

	    ftrace_text_reserved(p->addr, p->addr) ||

	    jump_label_text_reserved(p->addr, p->addr)) {

		ret = -EINVAL;

		goto cannot_probe;

		goto out;

	}



	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */

	p->flags &= KPROBE_FLAG_DISABLED;



	/*

	 * Check if are we probing a module.

	 */

	probed_mod = __module_text_address((unsigned long) p->addr);

	if (probed_mod) {

		/* Return -ENOENT if fail. */

		ret = -ENOENT;

	/* Check if are we probing a module */

	*probed_mod = __module_text_address((unsigned long) p->addr);

	if (*probed_mod) {

		/*

		 * We must hold a refcount of the probed module while updating

		 * its code to prohibit unexpected unloading.

		 */

		if (unlikely(!try_module_get(probed_mod)))

			goto cannot_probe;

		if (unlikely(!try_module_get(*probed_mod))) {

			ret = -ENOENT;

			goto out;

		}



		/*

		 * If the module freed .init.text, we couldn't insert

		 * kprobes in there.

		 */

		if (within_module_init((unsigned long)p->addr, probed_mod) &&

		    probed_mod->state != MODULE_STATE_COMING) {

			module_put(probed_mod);

			goto cannot_probe;

		if (within_module_init((unsigned long)p->addr, *probed_mod) &&

		    (*probed_mod)->state != MODULE_STATE_COMING) {

			module_put(*probed_mod);

			*probed_mod = NULL;

			ret = -ENOENT;

		}

		/* ret will be updated by following code */

	}

out:

	preempt_enable();

	jump_label_unlock();



	return ret;

}



int __kprobes register_kprobe(struct kprobe *p)

{

	int ret;

	struct kprobe *old_p;

	struct module *probed_mod;

	kprobe_opcode_t *addr;



	/* Adjust probe address from symbol */

	addr = kprobe_addr(p);

	if (IS_ERR(addr))

		return PTR_ERR(addr);

	p->addr = addr;



	ret = check_kprobe_rereg(p);

	if (ret)

		return ret;



	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */

	p->flags &= KPROBE_FLAG_DISABLED;

	p->nmissed = 0;

	INIT_LIST_HEAD(&p->list);

	mutex_lock(&kprobe_mutex);



	ret = check_kprobe_address_safe(p, &probed_mod);

	if (ret)

		return ret;



	mutex_lock(&kprobe_mutex);

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



	get_online_cpus();	/* For avoiding text_mutex deadlock. */
@@ -1410,11 +1423,6 @@ int __kprobes register_kprobe(struct kprobe *p) 
		module_put(probed_mod);



	return ret;



cannot_probe:

	preempt_enable();

	jump_label_unlock();

	return ret;

}

EXPORT_SYMBOL_GPL(register_kprobe);