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Commit 059053a2 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes: Don't check the ->break_handler() in generic kprobes code 



Don't check the ->break_handler() from the core kprobes code,
because it was only used by jprobes which got removed.

( In followup patches we'll remove the remaining calls in low level
  arch handlers as well and remove the callback altogether. )

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arch@vger.kernel.org
Link: https://lore.kernel.org/lkml/152942462686.15209.6324404940493598980.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e9bf11a5

Documentation/kprobes.txt

+1 −1
Original line number Diff line number Diff line
@@ -262,7 +262,7 @@ is optimized, that modification is ignored. Thus, if you want to 
tweak the kernel's execution path, you need to suppress optimization,

using one of the following techniques:



- Specify an empty function for the kprobe's post_handler or break_handler.

- Specify an empty function for the kprobe's post_handler.



or

kernel/kprobes.c

+5 −34
Original line number Diff line number Diff line
@@ -627,8 +627,8 @@ static void optimize_kprobe(struct kprobe *p) 
	    (kprobe_disabled(p) || kprobes_all_disarmed))

		return;



	/* Both of break_handler and post_handler are not supported. */

	if (p->break_handler || p->post_handler)

	/* kprobes with post_handler can not be optimized */

	if (p->post_handler)

		return;



	op = container_of(p, struct optimized_kprobe, kp);
@@ -1116,20 +1116,6 @@ static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, 
}

NOKPROBE_SYMBOL(aggr_fault_handler);



static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)

{

	struct kprobe *cur = __this_cpu_read(kprobe_instance);

	int ret = 0;



	if (cur && cur->break_handler) {

		if (cur->break_handler(cur, regs))

			ret = 1;

	}

	reset_kprobe_instance();

	return ret;

}

NOKPROBE_SYMBOL(aggr_break_handler);



/* Walks the list and increments nmissed count for multiprobe case */

void kprobes_inc_nmissed_count(struct kprobe *p)

{
@@ -1270,23 +1256,14 @@ static void cleanup_rp_inst(struct kretprobe *rp) 
}

NOKPROBE_SYMBOL(cleanup_rp_inst);



/*

* Add the new probe to ap->list. Fail if this is the

* second break_handler at the address

*/

/* Add the new probe to ap->list */

static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)

{

	BUG_ON(kprobe_gone(ap) || kprobe_gone(p));



	if (p->break_handler || p->post_handler)

	if (p->post_handler)

		unoptimize_kprobe(ap, true);	/* Fall back to normal kprobe */



	if (p->break_handler) {

		if (ap->break_handler)

			return -EEXIST;

		list_add_tail_rcu(&p->list, &ap->list);

		ap->break_handler = aggr_break_handler;

	} else

	list_add_rcu(&p->list, &ap->list);

	if (p->post_handler && !ap->post_handler)

		ap->post_handler = aggr_post_handler;
@@ -1310,8 +1287,6 @@ static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) 
	/* We don't care the kprobe which has gone. */

	if (p->post_handler && !kprobe_gone(p))

		ap->post_handler = aggr_post_handler;

	if (p->break_handler && !kprobe_gone(p))

		ap->break_handler = aggr_break_handler;



	INIT_LIST_HEAD(&ap->list);

	INIT_HLIST_NODE(&ap->hlist);
@@ -1706,8 +1681,6 @@ static int __unregister_kprobe_top(struct kprobe *p) 
		goto disarmed;

	else {

		/* If disabling probe has special handlers, update aggrprobe */

		if (p->break_handler && !kprobe_gone(p))

			ap->break_handler = NULL;

		if (p->post_handler && !kprobe_gone(p)) {

			list_for_each_entry_rcu(list_p, &ap->list, list) {

				if ((list_p != p) && (list_p->post_handler))
@@ -1911,7 +1884,6 @@ int register_kretprobe(struct kretprobe *rp) 
	rp->kp.pre_handler = pre_handler_kretprobe;

	rp->kp.post_handler = NULL;

	rp->kp.fault_handler = NULL;

	rp->kp.break_handler = NULL;



	/* Pre-allocate memory for max kretprobe instances */

	if (rp->maxactive <= 0) {
@@ -2034,7 +2006,6 @@ static void kill_kprobe(struct kprobe *p) 
		list_for_each_entry_rcu(kp, &p->list, list)

			kp->flags |= KPROBE_FLAG_GONE;

		p->post_handler = NULL;

		p->break_handler = NULL;

		kill_optimized_kprobe(p);

	}

	/*