1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Dynamic Ftrace based Kprobes Optimization
5 * Copyright (C) Hitachi Ltd., 2012
6 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
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>
15 /* Ftrace callback handler for kprobes */
16 void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
17 struct ftrace_ops *ops, struct ftrace_regs *fregs)
20 struct kprobe_ctlblk *kcb;
24 bit = ftrace_test_recursion_trylock(nip, parent_nip);
28 regs = ftrace_get_regs(fregs);
29 p = get_kprobe((kprobe_opcode_t *)nip);
30 if (unlikely(!p) || kprobe_disabled(p))
33 kcb = get_kprobe_ctlblk();
34 if (kprobe_running()) {
35 kprobes_inc_nmissed_count(p);
38 * On powerpc, NIP is *before* this instruction for the
41 regs_add_return_ip(regs, -MCOUNT_INSN_SIZE);
43 __this_cpu_write(current_kprobe, p);
44 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
45 if (!p->pre_handler || !p->pre_handler(p, regs)) {
47 * Emulate singlestep (and also recover regs->nip)
48 * as if there is a nop
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);
57 * If pre_handler returns !0, it changes regs->nip. We have to
58 * skip emulating post_handler.
60 __this_cpu_write(current_kprobe, NULL);
63 ftrace_test_recursion_unlock(bit);
65 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
67 int arch_prepare_kprobe_ftrace(struct kprobe *p)
70 p->ainsn.boostable = -1;