73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Dynamic Ftrace based Kprobes Optimization
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*
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* Copyright (C) Hitachi Ltd., 2012
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* Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
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* IBM Corporation
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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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/* Ftrace callback handler for kprobes */
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void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
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struct ftrace_ops *ops, struct ftrace_regs *fregs)
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{
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struct kprobe *p;
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struct kprobe_ctlblk *kcb;
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struct pt_regs *regs;
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int bit;
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bit = ftrace_test_recursion_trylock(nip, parent_nip);
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if (bit < 0)
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return;
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regs = ftrace_get_regs(fregs);
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p = get_kprobe((kprobe_opcode_t *)nip);
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if (unlikely(!p) || kprobe_disabled(p))
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goto out;
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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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/*
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* On powerpc, NIP is *before* this instruction for the
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* pre handler
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*/
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regs_add_return_ip(regs, -MCOUNT_INSN_SIZE);
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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->nip)
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* as if there is a nop
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*/
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regs_add_return_ip(regs, 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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}
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/*
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* If pre_handler returns !0, it changes regs->nip. 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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out:
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ftrace_test_recursion_unlock(bit);
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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 = -1;
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return 0;
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}
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