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Commit 0490cd1f authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes: Reuse unused kprobe 



Reuse unused (waiting for unoptimizing and no user handler)
kprobe on given address instead of returning -EBUSY for
registering a new kprobe.

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20101203095416.2961.39080.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6274de49

kernel/kprobes.c

+30 −2
Original line number Diff line number Diff line
@@ -692,6 +692,27 @@ static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force) 
	}

}



/* Cancel unoptimizing for reusing */

static void reuse_unused_kprobe(struct kprobe *ap)

{

	struct optimized_kprobe *op;



	BUG_ON(!kprobe_unused(ap));

	/*

	 * Unused kprobe MUST be on the way of delayed unoptimizing (means

	 * there is still a relative jump) and disabled.

	 */

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

	if (unlikely(list_empty(&op->list)))

		printk(KERN_WARNING "Warning: found a stray unused "

			"aggrprobe@%p\n", ap->addr);

	/* Enable the probe again */

	ap->flags &= ~KPROBE_FLAG_DISABLED;

	/* Optimize it again (remove from op->list) */

	BUG_ON(!kprobe_optready(ap));

	optimize_kprobe(ap);

}



/* Remove optimized instructions */

static void __kprobes kill_optimized_kprobe(struct kprobe *p)

{
@@ -872,6 +893,13 @@ static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt) 
#define kprobe_disarmed(p)			kprobe_disabled(p)

#define wait_for_kprobe_optimizer()		do {} while (0)



/* There should be no unused kprobes can be reused without optimization */

static void reuse_unused_kprobe(struct kprobe *ap)

{

	printk(KERN_ERR "Error: There should be no unused kprobe here.\n");

	BUG_ON(kprobe_unused(ap));

}



static __kprobes void free_aggr_kprobe(struct kprobe *p)

{

	arch_remove_kprobe(p);
@@ -1173,8 +1201,8 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, 
			return -ENOMEM;

		init_aggr_kprobe(ap, orig_p);

	} else if (kprobe_unused(ap))

		/* Busy to die */

		return -EBUSY;

		/* This probe is going to die. Rescue it */

		reuse_unused_kprobe(ap);



	if (kprobe_gone(ap)) {

		/*