| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Dynamic Ftrace based Kprobes Optimization |
| * |
| * 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 ftrace_regs *fregs) |
| { |
| struct kprobe *p; |
| struct kprobe_ctlblk *kcb; |
| struct pt_regs *regs; |
| int bit; |
| |
| bit = ftrace_test_recursion_trylock(nip, parent_nip); |
| if (bit < 0) |
| return; |
| |
| regs = ftrace_get_regs(fregs); |
| preempt_disable_notrace(); |
| p = get_kprobe((kprobe_opcode_t *)nip); |
| if (unlikely(!p) || kprobe_disabled(p)) |
| goto out; |
| |
| 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); |
| } |
| out: |
| preempt_enable_notrace(); |
| ftrace_test_recursion_unlock(bit); |
| } |
| NOKPROBE_SYMBOL(kprobe_ftrace_handler); |
| |
| int arch_prepare_kprobe_ftrace(struct kprobe *p) |
| { |
| p->ainsn.insn = NULL; |
| p->ainsn.boostable = -1; |
| return 0; |
| } |