| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Dynamic Ftrace based Kprobes Optimization |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright (C) Hitachi Ltd., 2012 |
| 19 | */ |
| 20 | #include <linux/kprobes.h> |
| 21 | #include <linux/ptrace.h> |
| 22 | #include <linux/hardirq.h> |
| 23 | #include <linux/preempt.h> |
| 24 | #include <linux/ftrace.h> |
| 25 | |
| 26 | #include "common.h" |
| 27 | |
| 28 | /* Ftrace callback handler for kprobes -- called under preepmt disabed */ |
| 29 | void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, |
| 30 | struct ftrace_ops *ops, struct pt_regs *regs) |
| 31 | { |
| 32 | struct kprobe *p; |
| 33 | struct kprobe_ctlblk *kcb; |
| 34 | |
| 35 | /* Preempt is disabled by ftrace */ |
| 36 | p = get_kprobe((kprobe_opcode_t *)ip); |
| 37 | if (unlikely(!p) || kprobe_disabled(p)) |
| 38 | return; |
| 39 | |
| 40 | kcb = get_kprobe_ctlblk(); |
| 41 | if (kprobe_running()) { |
| 42 | kprobes_inc_nmissed_count(p); |
| 43 | } else { |
| 44 | unsigned long orig_ip = regs->ip; |
| 45 | /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ |
| 46 | regs->ip = ip + sizeof(kprobe_opcode_t); |
| 47 | |
| 48 | __this_cpu_write(current_kprobe, p); |
| 49 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 50 | if (!p->pre_handler || !p->pre_handler(p, regs)) { |
| 51 | /* |
| 52 | * Emulate singlestep (and also recover regs->ip) |
| 53 | * as if there is a 5byte nop |
| 54 | */ |
| 55 | regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE; |
| 56 | if (unlikely(p->post_handler)) { |
| 57 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 58 | p->post_handler(p, regs, 0); |
| 59 | } |
| 60 | regs->ip = orig_ip; |
| 61 | } |
| 62 | /* |
| 63 | * If pre_handler returns !0, it changes regs->ip. We have to |
| 64 | * skip emulating post_handler. |
| 65 | */ |
| 66 | __this_cpu_write(current_kprobe, NULL); |
| 67 | } |
| 68 | } |
| 69 | NOKPROBE_SYMBOL(kprobe_ftrace_handler); |
| 70 | |
| 71 | int arch_prepare_kprobe_ftrace(struct kprobe *p) |
| 72 | { |
| 73 | p->ainsn.insn = NULL; |
| 74 | p->ainsn.boostable = false; |
| 75 | return 0; |
| 76 | } |