1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Dynamic Ftrace based Kprobes Optimization
 4 *
 5 * Copyright (C) Hitachi Ltd., 2012
 6 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
 7 *		  IBM Corporation
 8 */
 9#include <linux/kprobes.h>
10#include <linux/ptrace.h>
11#include <linux/hardirq.h>
12#include <linux/preempt.h>
13#include <linux/ftrace.h>
14
15/* Ftrace callback handler for kprobes */
16void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
17			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
18{
19	struct kprobe *p;
20	struct kprobe_ctlblk *kcb;
21	struct pt_regs *regs;
22	int bit;
23
24	bit = ftrace_test_recursion_trylock(nip, parent_nip);
25	if (bit < 0)
26		return;
27
28	regs = ftrace_get_regs(fregs);
29	p = get_kprobe((kprobe_opcode_t *)nip);
30	if (unlikely(!p) || kprobe_disabled(p))
31		goto out;
32
33	kcb = get_kprobe_ctlblk();
34	if (kprobe_running()) {
35		kprobes_inc_nmissed_count(p);
36	} else {
37		/*
38		 * On powerpc, NIP is *before* this instruction for the
39		 * pre handler
40		 */
41		regs_add_return_ip(regs, -MCOUNT_INSN_SIZE);
42
43		__this_cpu_write(current_kprobe, p);
44		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
45		if (!p->pre_handler || !p->pre_handler(p, regs)) {
46			/*
47			 * Emulate singlestep (and also recover regs->nip)
48			 * as if there is a nop
49			 */
50			regs_add_return_ip(regs, MCOUNT_INSN_SIZE);
51			if (unlikely(p->post_handler)) {
52				kcb->kprobe_status = KPROBE_HIT_SSDONE;
53				p->post_handler(p, regs, 0);
54			}
55		}
56		/*
57		 * If pre_handler returns !0, it changes regs->nip. We have to
58		 * skip emulating post_handler.
59		 */
60		__this_cpu_write(current_kprobe, NULL);
61	}
62out:
63	ftrace_test_recursion_unlock(bit);
64}
65NOKPROBE_SYMBOL(kprobe_ftrace_handler);
66
67int arch_prepare_kprobe_ftrace(struct kprobe *p)
68{
69	p->ainsn.insn = NULL;
70	p->ainsn.boostable = -1;
71	return 0;
72}

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Dynamic Ftrace based Kprobes Optimization
 4 *
 5 * Copyright (C) Hitachi Ltd., 2012
 6 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
 7 *		  IBM Corporation
 8 */
 9#include <linux/kprobes.h>
10#include <linux/ptrace.h>
11#include <linux/hardirq.h>
12#include <linux/preempt.h>
13#include <linux/ftrace.h>
14
15/* Ftrace callback handler for kprobes */
16void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
17			   struct ftrace_ops *ops, struct pt_regs *regs)
18{
19	struct kprobe *p;
20	struct kprobe_ctlblk *kcb;
 
 
21
 
 
 
 
 
22	p = get_kprobe((kprobe_opcode_t *)nip);
23	if (unlikely(!p) || kprobe_disabled(p))
24		return;
25
26	kcb = get_kprobe_ctlblk();
27	if (kprobe_running()) {
28		kprobes_inc_nmissed_count(p);
29	} else {
30		/*
31		 * On powerpc, NIP is *before* this instruction for the
32		 * pre handler
33		 */
34		regs->nip -= MCOUNT_INSN_SIZE;
35
36		__this_cpu_write(current_kprobe, p);
37		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
38		if (!p->pre_handler || !p->pre_handler(p, regs)) {
39			/*
40			 * Emulate singlestep (and also recover regs->nip)
41			 * as if there is a nop
42			 */
43			regs->nip += MCOUNT_INSN_SIZE;
44			if (unlikely(p->post_handler)) {
45				kcb->kprobe_status = KPROBE_HIT_SSDONE;
46				p->post_handler(p, regs, 0);
47			}
48		}
49		/*
50		 * If pre_handler returns !0, it changes regs->nip. We have to
51		 * skip emulating post_handler.
52		 */
53		__this_cpu_write(current_kprobe, NULL);
54	}
 
 
55}
56NOKPROBE_SYMBOL(kprobe_ftrace_handler);
57
58int arch_prepare_kprobe_ftrace(struct kprobe *p)
59{
60	p->ainsn.insn = NULL;
61	p->ainsn.boostable = -1;
62	return 0;
63}