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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ftrace.c (1804B)

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