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 disabed */
   6 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
   7                            struct ftrace_ops *ops, struct ftrace_regs *regs)
   8 {
   9         struct kprobe *p;
  10         struct kprobe_ctlblk *kcb;
  11
  12         p = get_kprobe((kprobe_opcode_t *)ip);
  13         if (unlikely(!p) || kprobe_disabled(p))
  14                 return;
  15
  16         kcb = get_kprobe_ctlblk();
  17         if (kprobe_running()) {
  18                 kprobes_inc_nmissed_count(p);
  19         } else {
  20                 unsigned long orig_ip = instruction_pointer(&(regs->regs));
  21
  22                 instruction_pointer_set(&(regs->regs), ip);
  23
  24                 __this_cpu_write(current_kprobe, p);
  25                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  26                 if (!p->pre_handler || !p->pre_handler(p, &(regs->regs))) {
  27                         /*
  28                          * Emulate singlestep (and also recover regs->pc)
  29                          * as if there is a nop
  30                          */
  31                         instruction_pointer_set(&(regs->regs),
  32                                 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  33                         if (unlikely(p->post_handler)) {
  34                                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
  35                                 p->post_handler(p, &(regs->regs), 0);
  36                         }
  37                         instruction_pointer_set(&(regs->regs), orig_ip);
  38                 }
  39
  40                 /*
  41                  * If pre_handler returns !0, it changes regs->pc. We have to
  42                  * skip emulating post_handler.
  43                  */
  44                 __this_cpu_write(current_kprobe, NULL);
  45         }
  46 }
  47 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  48
  49 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  50 {
  51         p->ainsn.api.insn = NULL;
  52         return 0;
  53 }