/* * Dynamic Ftrace based Kprobes Optimization * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright (C) Hitachi Ltd., 2012 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> * IBM Corporation */ #include <linux/kprobes.h> #include <linux/ptrace.h> #include <linux/hardirq.h> #include <linux/preempt.h> #include <linux/ftrace.h> /* Ftrace callback handler for kprobes */ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, struct ftrace_ops *ops, struct pt_regs *regs) { struct kprobe *p; struct kprobe_ctlblk *kcb; p = get_kprobe((kprobe_opcode_t *)nip); if (unlikely(!p) || kprobe_disabled(p)) return; kcb = get_kprobe_ctlblk(); if (kprobe_running()) { kprobes_inc_nmissed_count(p); } else { /* * On powerpc, NIP is *before* this instruction for the * pre handler */ regs->nip -= MCOUNT_INSN_SIZE; __this_cpu_write(current_kprobe, p); kcb->kprobe_status = KPROBE_HIT_ACTIVE; if (!p->pre_handler || !p->pre_handler(p, regs)) { /* * Emulate singlestep (and also recover regs->nip) * as if there is a nop */ regs->nip += MCOUNT_INSN_SIZE; if (unlikely(p->post_handler)) { kcb->kprobe_status = KPROBE_HIT_SSDONE; p->post_handler(p, regs, 0); } } /* * If pre_handler returns !0, it changes regs->nip. We have to * skip emulating post_handler. */ __this_cpu_write(current_kprobe, NULL); } } NOKPROBE_SYMBOL(kprobe_ftrace_handler); int arch_prepare_kprobe_ftrace(struct kprobe *p) { p->ainsn.insn = NULL; p->ainsn.boostable = -1; return 0; }