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
19 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
22 #include <linux/kprobes.h>
23 #include <linux/ptrace.h>
24 #include <linux/hardirq.h>
25 #include <linux/preempt.h>
26 #include <linux/ftrace.h>
28 static nokprobe_inline
29 int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
30 struct kprobe_ctlblk *kcb, unsigned long orig_nip)
33 * Emulate singlestep (and also recover regs->nip)
34 * as if there is a nop
36 regs->nip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
37 if (unlikely(p->post_handler)) {
38 kcb->kprobe_status = KPROBE_HIT_SSDONE;
39 p->post_handler(p, regs, 0);
41 __this_cpu_write(current_kprobe, NULL);
47 int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
48 struct kprobe_ctlblk *kcb)
51 return __skip_singlestep(p, regs, kcb, 0);
55 NOKPROBE_SYMBOL(skip_singlestep);
57 /* Ftrace callback handler for kprobes */
58 void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
59 struct ftrace_ops *ops, struct pt_regs *regs)
62 struct kprobe_ctlblk *kcb;
65 /* Disable irq for emulating a breakpoint and avoiding preempt */
66 local_irq_save(flags);
70 p = get_kprobe((kprobe_opcode_t *)nip);
71 if (unlikely(!p) || kprobe_disabled(p))
74 kcb = get_kprobe_ctlblk();
75 if (kprobe_running()) {
76 kprobes_inc_nmissed_count(p);
78 unsigned long orig_nip = regs->nip;
81 * On powerpc, NIP is *before* this instruction for the
84 regs->nip -= MCOUNT_INSN_SIZE;
86 __this_cpu_write(current_kprobe, p);
87 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
88 if (!p->pre_handler || !p->pre_handler(p, regs))
89 __skip_singlestep(p, regs, kcb, orig_nip);
92 * If pre_handler returns !0, it sets regs->nip and
93 * resets current kprobe. In this case, we still need
94 * to restore irq, but not preemption.
96 local_irq_restore(flags);
101 preempt_enable_no_resched();
102 local_irq_restore(flags);
104 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
106 int arch_prepare_kprobe_ftrace(struct kprobe *p)
108 p->ainsn.insn = NULL;
109 p->ainsn.boostable = -1;