summaryrefslogtreecommitdiff
path: root/kernel/kprobes.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r--kernel/kprobes.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 507f26e7ae7c..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
@@ -465,6 +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;
}
@@ -475,6 +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:
@@ -553,6 +565,16 @@ valid_p:
}
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 = {
@@ -560,10 +582,6 @@ static struct notifier_block kprobe_exceptions_nb = {
.priority = 0x7fffffff /* we need to be notified first */
};
-static struct notifier_block kprobe_page_fault_nb = {
- .notifier_call = kprobe_exceptions_notify,
- .priority = 0x7fffffff /* we need to notified first */
-};
int __kprobes register_jprobe(struct jprobe *jp)
{
@@ -673,14 +691,12 @@ 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)
err = register_die_notifier(&kprobe_exceptions_nb);
- if (!err)
- err = register_page_fault_notifier(&kprobe_page_fault_nb);
-
return err;
}