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        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}
  73