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 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        preempt_disable_notrace();
  30        p = get_kprobe((kprobe_opcode_t *)nip);
  31        if (unlikely(!p) || kprobe_disabled(p))
  32                goto out;
  33
  34        kcb = get_kprobe_ctlblk();
  35        if (kprobe_running()) {
  36                kprobes_inc_nmissed_count(p);
  37        } else {
  38                /*
  39                 * On powerpc, NIP is *before* this instruction for the
  40                 * pre handler
  41                 */
  42                regs_add_return_ip(regs, -MCOUNT_INSN_SIZE);
  43
  44                __this_cpu_write(current_kprobe, p);
  45                kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  46                if (!p->pre_handler || !p->pre_handler(p, regs)) {
  47                        /*
  48                         * Emulate singlestep (and also recover regs->nip)
  49                         * as if there is a nop
  50                         */
  51                        regs_add_return_ip(regs, MCOUNT_INSN_SIZE);
  52                        if (unlikely(p->post_handler)) {
  53                                kcb->kprobe_status = KPROBE_HIT_SSDONE;
  54                                p->post_handler(p, regs, 0);
  55                        }
  56                }
  57                /*
  58                 * If pre_handler returns !0, it changes regs->nip. We have to
  59                 * skip emulating post_handler.
  60                 */
  61                __this_cpu_write(current_kprobe, NULL);
  62        }
  63out:
  64        preempt_enable_notrace();
  65        ftrace_test_recursion_unlock(bit);
  66}
  67NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  68
  69int arch_prepare_kprobe_ftrace(struct kprobe *p)
  70{
  71        p->ainsn.insn = NULL;
  72        p->ainsn.boostable = -1;
  73        return 0;
  74}
  75