cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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kprobes-ftrace.c (1797B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Dynamic Ftrace based Kprobes Optimization
      4 *
      5 * Copyright (C) Hitachi Ltd., 2012
      6 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
      7 *		  IBM Corporation
      8 */
      9#include <linux/kprobes.h>
     10#include <linux/ptrace.h>
     11#include <linux/hardirq.h>
     12#include <linux/preempt.h>
     13#include <linux/ftrace.h>
     14
     15/* Ftrace callback handler for kprobes */
     16void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
     17			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
     18{
     19	struct kprobe *p;
     20	struct kprobe_ctlblk *kcb;
     21	struct pt_regs *regs;
     22	int bit;
     23
     24	bit = ftrace_test_recursion_trylock(nip, parent_nip);
     25	if (bit < 0)
     26		return;
     27
     28	regs = ftrace_get_regs(fregs);
     29	p = get_kprobe((kprobe_opcode_t *)nip);
     30	if (unlikely(!p) || kprobe_disabled(p))
     31		goto out;
     32
     33	kcb = get_kprobe_ctlblk();
     34	if (kprobe_running()) {
     35		kprobes_inc_nmissed_count(p);
     36	} else {
     37		/*
     38		 * On powerpc, NIP is *before* this instruction for the
     39		 * pre handler
     40		 */
     41		regs_add_return_ip(regs, -MCOUNT_INSN_SIZE);
     42
     43		__this_cpu_write(current_kprobe, p);
     44		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
     45		if (!p->pre_handler || !p->pre_handler(p, regs)) {
     46			/*
     47			 * Emulate singlestep (and also recover regs->nip)
     48			 * as if there is a nop
     49			 */
     50			regs_add_return_ip(regs, MCOUNT_INSN_SIZE);
     51			if (unlikely(p->post_handler)) {
     52				kcb->kprobe_status = KPROBE_HIT_SSDONE;
     53				p->post_handler(p, regs, 0);
     54			}
     55		}
     56		/*
     57		 * If pre_handler returns !0, it changes regs->nip. We have to
     58		 * skip emulating post_handler.
     59		 */
     60		__this_cpu_write(current_kprobe, NULL);
     61	}
     62out:
     63	ftrace_test_recursion_unlock(bit);
     64}
     65NOKPROBE_SYMBOL(kprobe_ftrace_handler);
     66
     67int arch_prepare_kprobe_ftrace(struct kprobe *p)
     68{
     69	p->ainsn.insn = NULL;
     70	p->ainsn.boostable = -1;
     71	return 0;
     72}