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// 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 pt_regs *regs)
{
struct kprobe *p;
struct kprobe_ctlblk *kcb;
int bit;
bit = ftrace_test_recursion_trylock(nip, parent_nip);
if (bit < 0)
return;
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;
}
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