[FIX] Flush kretprobe instances after last put_task

Remove rp_inst from kretprobe_inst_table when task has died

Change-Id: I97e8b7209e22f70c5c8ff3afc55704aa3ddfa87e
Signed-off-by: Vyacheslav Cherkashin <v.cherkashin@samsung.com>

diff --git a/kprobe/swap_kprobes.c b/kprobe/swap_kprobes.c
index d080dd5..ece1f7f 100644 (file)
--- a/kprobe/swap_kprobes.c
+++ b/kprobe/swap_kprobes.c
@@ -1091,6 +1091,41 @@ static int swap_disarm_krp_inst(struct kretprobe_instance *ri)
        return retval;
 }
 
+static void krp_inst_flush(struct task_struct *task)
+{
+       unsigned long flags;
+       struct kretprobe_instance *ri;
+       struct hlist_node *tmp;
+       struct hlist_head *head;
+       DECLARE_NODE_PTR_FOR_HLIST(node);
+
+       spin_lock_irqsave(&kretprobe_lock, flags);
+       head = kretprobe_inst_table_head(task);
+       swap_hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+               if (ri->task == task) {
+                       printk("task[%u %u %s]: flush krp_inst, ret_addr=%p\n",
+                               task->tgid, task->pid, task->comm,
+                               ri->ret_addr);
+                       recycle_rp_inst(ri);
+               }
+       }
+       spin_unlock_irqrestore(&kretprobe_lock, flags);
+}
+
+static int put_task_handler(struct kprobe *p, struct pt_regs *regs)
+{
+       struct task_struct *t = (struct task_struct *)swap_get_karg(regs, 0);
+
+       /* task has died */
+       krp_inst_flush(t);
+
+       return 0;
+}
+
+static struct kprobe put_task_kp = {
+       .pre_handler = put_task_handler,
+};
+
 static int init_module_deps(void)
 {
        int ret;
@@ -1131,6 +1166,11 @@ static int once(void)
        if (module_alloc == NULL)
                goto not_found;
 
+       sym = "__put_task_struct";
+       put_task_kp.addr = (void *)swap_ksyms(sym);
+       if (put_task_kp.addr == NULL)
+               goto not_found;
+
        ret = init_module_deps();
        if (ret)
                return ret;
@@ -1153,14 +1193,27 @@ not_found:
 
 static int init_kprobes(void)
 {
+       int ret;
+
        init_sm();
        atomic_set(&kprobe_count, 0);
 
-       return swap_arch_init_kprobes();
+       ret = swap_arch_init_kprobes();
+       if (ret)
+               return ret;
+
+       ret = swap_register_kprobe(&put_task_kp);
+       if (ret) {
+               swap_arch_exit_kprobes();
+               return ret;
+       }
+
+       return 0;
 }
 
 static void exit_kprobes(void)
 {
+       swap_unregister_kprobe(&put_task_kp);
        swap_arch_exit_kprobes();
        exit_sm();
 }