/*
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* Dynamic Ftrace based Kprobes Optimization
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) Hitachi Ltd., 2012
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*/
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#include <linux/kprobes.h>
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#include <linux/ptrace.h>
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#include <linux/hardirq.h>
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#include <linux/preempt.h>
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#include <linux/ftrace.h>
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#include "common.h"
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/* Ftrace callback handler for kprobes -- called under preepmt disabed */
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void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *ops, struct pt_regs *regs)
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{
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struct kprobe *p;
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struct kprobe_ctlblk *kcb;
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/* Preempt is disabled by ftrace */
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p = get_kprobe((kprobe_opcode_t *)ip);
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if (unlikely(!p) || kprobe_disabled(p))
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return;
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kcb = get_kprobe_ctlblk();
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if (kprobe_running()) {
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kprobes_inc_nmissed_count(p);
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} else {
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unsigned long orig_ip = regs->ip;
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/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
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regs->ip = ip + sizeof(kprobe_opcode_t);
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__this_cpu_write(current_kprobe, p);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (!p->pre_handler || !p->pre_handler(p, regs)) {
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/*
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* Emulate singlestep (and also recover regs->ip)
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* as if there is a 5byte nop
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*/
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regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
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if (unlikely(p->post_handler)) {
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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p->post_handler(p, regs, 0);
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}
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regs->ip = orig_ip;
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}
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/*
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* If pre_handler returns !0, it changes regs->ip. We have to
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* skip emulating post_handler.
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*/
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__this_cpu_write(current_kprobe, NULL);
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}
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}
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NOKPROBE_SYMBOL(kprobe_ftrace_handler);
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int arch_prepare_kprobe_ftrace(struct kprobe *p)
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{
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p->ainsn.insn = NULL;
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p->ainsn.boostable = false;
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return 0;
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}
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