2 * Dynamic Ftrace based Kprobes Optimization
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 * Copyright (C) Hitachi Ltd., 2012
20 #include <linux/kprobes.h>
21 #include <linux/ptrace.h>
22 #include <linux/hardirq.h>
23 #include <linux/preempt.h>
24 #include <linux/ftrace.h>
28 /* Ftrace callback handler for kprobes -- called under preepmt disabed */
29 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
30 struct ftrace_ops *ops, struct pt_regs *regs)
33 struct kprobe_ctlblk *kcb;
35 /* Preempt is disabled by ftrace */
36 p = get_kprobe((kprobe_opcode_t *)ip);
37 if (unlikely(!p) || kprobe_disabled(p))
40 kcb = get_kprobe_ctlblk();
41 if (kprobe_running()) {
42 kprobes_inc_nmissed_count(p);
44 unsigned long orig_ip = regs->ip;
45 /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
46 regs->ip = ip + sizeof(kprobe_opcode_t);
48 __this_cpu_write(current_kprobe, p);
49 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
50 if (!p->pre_handler || !p->pre_handler(p, regs)) {
52 * Emulate singlestep (and also recover regs->ip)
53 * as if there is a 5byte nop
55 regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
56 if (unlikely(p->post_handler)) {
57 kcb->kprobe_status = KPROBE_HIT_SSDONE;
58 p->post_handler(p, regs, 0);
63 * If pre_handler returns !0, it changes regs->ip. We have to
64 * skip emulating post_handler.
66 __this_cpu_write(current_kprobe, NULL);
69 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
71 int arch_prepare_kprobe_ftrace(struct kprobe *p)
74 p->ainsn.boostable = false;