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         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         }
  53 out:
  54         ftrace_test_recursion_unlock(bit);
  55 }
  56 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  57
  58 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  59 {
  60         p->ainsn.api.insn = NULL;
  61         return 0;
  62 }