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 */
   6 void 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
  13         p = get_kprobe((kprobe_opcode_t *)ip);
  14         if (unlikely(!p) || kprobe_disabled(p))
  15                 return;
  16
  17         regs = ftrace_get_regs(fregs);
  18         kcb = get_kprobe_ctlblk();
  19         if (kprobe_running()) {
  20                 kprobes_inc_nmissed_count(p);
  21         } else {
  22                 unsigned long orig_ip = instruction_pointer(regs);
  23
  24                 instruction_pointer_set(regs, ip);
  25
  26                 __this_cpu_write(current_kprobe, p);
  27                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  28                 if (!p->pre_handler || !p->pre_handler(p, regs)) {
  29                         /*
  30                          * Emulate singlestep (and also recover regs->pc)
  31                          * as if there is a nop
  32                          */
  33                         instruction_pointer_set(regs,
  34                                 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  35                         if (unlikely(p->post_handler)) {
  36                                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
  37                                 p->post_handler(p, regs, 0);
  38                         }
  39                         instruction_pointer_set(regs, orig_ip);
  40                 }
  41
  42                 /*
  43                  * If pre_handler returns !0, it changes regs->pc. We have to
  44                  * skip emulating post_handler.
  45                  */
  46                 __this_cpu_write(current_kprobe, NULL);
  47         }
  48 }
  49 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  50
  51 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  52 {
  53         p->ainsn.api.insn = NULL;
  54         return 0;
  55 }