/* * 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 */ #include <linux/kprobes.h> #include <linux/ptrace.h> #include <linux/hardirq.h> #include <linux/preempt.h> #include <linux/ftrace.h> #include "common.h" static nokprobe_inline int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { /* * Emulate singlestep (and also recover regs->ip) * as if there is a 5byte nop */ regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE; if (unlikely(p->post_handler)) { kcb->kprobe_status = KPROBE_HIT_SSDONE; p->post_handler(p, regs, 0); } __this_cpu_write(current_kprobe, NULL); return 1; } int skip_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { if (kprobe_ftrace(p)) return __skip_singlestep(p, regs, kcb); else return 0; } NOKPROBE_SYMBOL(skip_singlestep); /* Ftrace callback handler for kprobes */ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct pt_regs *regs) { struct kprobe *p; struct kprobe_ctlblk *kcb; unsigned long flags; /* Disable irq for emulating a breakpoint and avoiding preempt */ local_irq_save(flags); p = get_kprobe((kprobe_opcode_t *)ip); if (unlikely(!p) || kprobe_disabled(p)) goto end; kcb = get_kprobe_ctlblk(); if (kprobe_running()) { kprobes_inc_nmissed_count(p); } else { /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ regs->ip = ip + sizeof(kprobe_opcode_t); __this_cpu_write(current_kprobe, p); kcb->kprobe_status = KPROBE_HIT_ACTIVE; if (!p->pre_handler || !p->pre_handler(p, regs)) __skip_singlestep(p, regs, kcb); /* * If pre_handler returns !0, it sets regs->ip and * resets current kprobe. */ } end: local_irq_restore(flags); } NOKPROBE_SYMBOL(kprobe_ftrace_handler); int arch_prepare_kprobe_ftrace(struct kprobe *p) { p->ainsn.insn = NULL; p->ainsn.boostable = -1; return 0; }