1 files changed, 49 insertions, 9 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1fbf466a29aa..64aab081153b 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -47,11 +47,17 @@
 
 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
+static atomic_t kprobe_count;
 
 DEFINE_MUTEX(kprobe_mutex);             /* Protects kprobe_table */
 DEFINE_SPINLOCK(kretprobe_lock);        /* Protects kretprobe_inst_table */
 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
 
+static struct notifier_block kprobe_page_fault_nb = {
+        .notifier_call = kprobe_exceptions_notify,
+        .priority = 0x7fffffff /* we need to notified first */
+};
+
 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 /*
  * kprobe->ainsn.insn points to the copy of the instruction to be
@@ -368,16 +374,15 @@ 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)
-                                return -EEXIST;
-                }
+                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;
 }
 
@@ -390,9 +395,11 @@ 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;
-        ap->break_handler = aggr_break_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);
         list_add_rcu(&p->list, &ap->list);
@@ -464,6 +471,8 @@ static int __kprobes __register_kprobe(struct kprobe *p,
         old_p = get_kprobe(p->addr);
         if (old_p) {
                 ret = register_aggr_kprobe(old_p, p);
+                if (!ret)
+                        atomic_inc(&kprobe_count);
                 goto out;
         }
 
@@ -474,6 +483,10 @@ static int __kprobes __register_kprobe(struct kprobe *p,
         hlist_add_head_rcu(&p->hlist,
                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 
+        if (atomic_add_return(1, &kprobe_count) == \
+                                (ARCH_INACTIVE_KPROBE_COUNT + 1))
+                register_page_fault_notifier(&kprobe_page_fault_nb);
+
         arch_arm_kprobe(p);
 
 out:
@@ -536,14 +549,40 @@ 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);
         }
+
+        /* Call unregister_page_fault_notifier()
+         * if no probes are active
+         */
+        mutex_lock(&kprobe_mutex);
+        if (atomic_add_return(-1, &kprobe_count) == \
+                                ARCH_INACTIVE_KPROBE_COUNT)
+                unregister_page_fault_notifier(&kprobe_page_fault_nb);
+        mutex_unlock(&kprobe_mutex);
+        return;
 }
 
 static struct notifier_block kprobe_exceptions_nb = {
         .notifier_call = kprobe_exceptions_notify,
-        .priority = 0x7fffffff /* we need to notified first */
+        .priority = 0x7fffffff /* we need to be notified first */
 };
 
+
 int __kprobes register_jprobe(struct jprobe *jp)
 {
         /* Todo: Verify probepoint is a function entry point */
@@ -652,6 +691,7 @@ static int __init init_kprobes(void)
                 INIT_HLIST_HEAD(&kprobe_table[i]);
                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
         }
+        atomic_set(&kprobe_count, 0);
 
         err = arch_init_kprobes();
         if (!err)