diff options
Diffstat (limited to 'arch/x86/kernel/kprobes/ftrace.c')
| -rw-r--r-- | arch/x86/kernel/kprobes/ftrace.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c new file mode 100644 index 000000000000..23ef5c556f06 --- /dev/null +++ b/arch/x86/kernel/kprobes/ftrace.c | |||
| @@ -0,0 +1,93 @@ | |||
| 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 | static int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, | ||
| 29 | struct kprobe_ctlblk *kcb) | ||
| 30 | { | ||
| 31 | /* | ||
| 32 | * Emulate singlestep (and also recover regs->ip) | ||
| 33 | * as if there is a 5byte nop | ||
| 34 | */ | ||
| 35 | regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE; | ||
| 36 | if (unlikely(p->post_handler)) { | ||
| 37 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | ||
| 38 | p->post_handler(p, regs, 0); | ||
| 39 | } | ||
| 40 | __this_cpu_write(current_kprobe, NULL); | ||
| 41 | return 1; | ||
| 42 | } | ||
| 43 | |||
| 44 | int __kprobes skip_singlestep(struct kprobe *p, struct pt_regs *regs, | ||
| 45 | struct kprobe_ctlblk *kcb) | ||
| 46 | { | ||
| 47 | if (kprobe_ftrace(p)) | ||
| 48 | return __skip_singlestep(p, regs, kcb); | ||
| 49 | else | ||
| 50 | return 0; | ||
| 51 | } | ||
| 52 | |||
| 53 | /* Ftrace callback handler for kprobes */ | ||
| 54 | void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, | ||
| 55 | struct ftrace_ops *ops, struct pt_regs *regs) | ||
| 56 | { | ||
| 57 | struct kprobe *p; | ||
| 58 | struct kprobe_ctlblk *kcb; | ||
| 59 | unsigned long flags; | ||
| 60 | |||
| 61 | /* Disable irq for emulating a breakpoint and avoiding preempt */ | ||
| 62 | local_irq_save(flags); | ||
| 63 | |||
| 64 | p = get_kprobe((kprobe_opcode_t *)ip); | ||
| 65 | if (unlikely(!p) || kprobe_disabled(p)) | ||
| 66 | goto end; | ||
| 67 | |||
| 68 | kcb = get_kprobe_ctlblk(); | ||
| 69 | if (kprobe_running()) { | ||
| 70 | kprobes_inc_nmissed_count(p); | ||
| 71 | } else { | ||
| 72 | /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ | ||
| 73 | regs->ip = ip + sizeof(kprobe_opcode_t); | ||
| 74 | |||
| 75 | __this_cpu_write(current_kprobe, p); | ||
| 76 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | ||
| 77 | if (!p->pre_handler || !p->pre_handler(p, regs)) | ||
| 78 | __skip_singlestep(p, regs, kcb); | ||
| 79 | /* | ||
| 80 | * If pre_handler returns !0, it sets regs->ip and | ||
| 81 | * resets current kprobe. | ||
| 82 | */ | ||
| 83 | } | ||
| 84 | end: | ||
| 85 | local_irq_restore(flags); | ||
| 86 | } | ||
| 87 | |||
| 88 | int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p) | ||
| 89 | { | ||
| 90 | p->ainsn.insn = NULL; | ||
| 91 | p->ainsn.boostable = -1; | ||
| 92 | return 0; | ||
| 93 | } | ||