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         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         }
  54 out:
  55         preempt_enable_notrace();
  56         ftrace_test_recursion_unlock(bit);
  57 }
  58 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  59
  60 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  61 {
  62         p->ainsn.api.insn = NULL;
  63         return 0;
  64 }