LXR linux/arch/riscv/kernel/probes/ftrace.c

   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        preempt_disable_notrace();
  19        p = get_kprobe((kprobe_opcode_t *)ip);
  20        if (unlikely(!p) || kprobe_disabled(p))
  21                goto out;
  22
  23        regs = ftrace_get_regs(fregs);
  24        kcb = get_kprobe_ctlblk();
  25        if (kprobe_running()) {
  26                kprobes_inc_nmissed_count(p);
  27        } else {
  28                unsigned long orig_ip = instruction_pointer(regs);
  29
  30                instruction_pointer_set(regs, ip);
  31
  32                __this_cpu_write(current_kprobe, p);
  33                kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  34                if (!p->pre_handler || !p->pre_handler(p, regs)) {
  35                        /*
  36                         * Emulate singlestep (and also recover regs->pc)
  37                         * as if there is a nop
  38                         */
  39                        instruction_pointer_set(regs,
  40                                (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  41                        if (unlikely(p->post_handler)) {
  42                                kcb->kprobe_status = KPROBE_HIT_SSDONE;
  43                                p->post_handler(p, regs, 0);
  44                        }
  45                        instruction_pointer_set(regs, orig_ip);
  46                }
  47
  48                /*
  49                 * If pre_handler returns !0, it changes regs->pc. We have to
  50                 * skip emulating post_handler.
  51                 */
  52                __this_cpu_write(current_kprobe, NULL);
  53        }
  54out:
  55        preempt_enable_notrace();
  56        ftrace_test_recursion_unlock(bit);
  57}
  58NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  59
  60int arch_prepare_kprobe_ftrace(struct kprobe *p)
  61{
  62        p->ainsn.api.insn = NULL;
  63        return 0;
  64}
  65