Commit 36721656 authored by mao, bibo's avatar mao, bibo Committed by Linus Torvalds
Browse files

[PATCH] Kprobe: multi kprobe posthandler for booster 



If there are multi kprobes on the same probepoint, there will be one extra
aggr_kprobe on the head of kprobe list.  The aggr_kprobe has
aggr_post_handler/aggr_break_handler whether the other kprobe
post_hander/break_handler is NULL or not.  This patch modifies this, only
when there is one or more kprobe in the list whose post_handler is not
NULL, post_handler of aggr_kprobe will be set as aggr_post_handler.

[soshima@redhat.com: !CONFIG_PREEMPT fix]
Signed-off-by: default avatarbibo, mao <bibo.mao@intel.com>
Cc: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp>
Cc: Hideo Aoki <haoki@redhat.com>
Signed-off-by: default avatarSatoshi Oshima <soshima@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 585deaca

arch/i386/kernel/kprobes.c

+5 −11
Original line number Diff line number Diff line
@@ -259,7 +259,9 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
	struct kprobe_ctlblk *kcb;

#ifdef CONFIG_PREEMPT

	unsigned pre_preempt_count = preempt_count();

#endif /* CONFIG_PREEMPT */

#else

	unsigned pre_preempt_count = 1;

#endif



	addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
@@ -336,22 +338,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
		/* handler has already set things up, so skip ss setup */

		return 1;



	if (p->ainsn.boostable == 1 &&

#ifdef CONFIG_PREEMPT

	    !(pre_preempt_count) && /*

				       * This enables booster when the direct

				       * execution path aren't preempted.

				       */

#endif /* CONFIG_PREEMPT */

	    !p->post_handler && !p->break_handler ) {

ss_probe:

	if (pre_preempt_count && p->ainsn.boostable == 1 && !p->post_handler){

		/* Boost up -- we can execute copied instructions directly */

		reset_current_kprobe();

		regs->eip = (unsigned long)p->ainsn.insn;

		preempt_enable_no_resched();

		return 1;

	}



ss_probe:

	prepare_singlestep(p, regs);

	kcb->kprobe_status = KPROBE_HIT_SS;

	return 1;

kernel/kprobes.c

+24 −8
Original line number Diff line number Diff line
@@ -368,16 +368,15 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) 
*/

static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)

{

        struct kprobe *kp;



	if (p->break_handler) {

		list_for_each_entry_rcu(kp, &old_p->list, list) {

			if (kp->break_handler)

		if (old_p->break_handler)

			return -EEXIST;

		}

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

		old_p->break_handler = aggr_break_handler;

	} else

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

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

		old_p->post_handler = aggr_post_handler;

	return 0;

}
@@ -390,8 +389,10 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) 
	copy_kprobe(p, ap);

	ap->addr = p->addr;

	ap->pre_handler = aggr_pre_handler;

	ap->post_handler = aggr_post_handler;

	ap->fault_handler = aggr_fault_handler;

	if (p->post_handler)

		ap->post_handler = aggr_post_handler;

	if (p->break_handler)

		ap->break_handler = aggr_break_handler;



	INIT_LIST_HEAD(&ap->list);
@@ -536,6 +537,21 @@ valid_p: 
			kfree(old_p);

		}

		arch_remove_kprobe(p);

	} else {

		mutex_lock(&kprobe_mutex);

		if (p->break_handler)

			old_p->break_handler = NULL;

		if (p->post_handler){

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

				if (list_p->post_handler){

					cleanup_p = 2;

					break;

				}

			}

			if (cleanup_p == 0)

				old_p->post_handler = NULL;

		}

		mutex_unlock(&kprobe_mutex);

	}

}

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