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 (1544B)

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