LXR linux/arch/powerpc/kernel/kprobes-ftrace.c

   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}
  64