arch/csky/kernel/probes/ftrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/kprobes.h>
   4
   5 int arch_check_ftrace_location(struct kprobe *p)
   6 {
   7         if (ftrace_location((unsigned long)p->addr))
   8                 p->flags |= KPROBE_FLAG_FTRACE;
   9         return 0;
  10 }
  11
  12 /* Ftrace callback handler for kprobes -- called under preepmt disabed */
  13 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
  14                            struct ftrace_ops *ops, struct pt_regs *regs)
  15 {
  16         int bit;
  17         bool lr_saver = false;
  18         struct kprobe *p;
  19         struct kprobe_ctlblk *kcb;
  20
  21         bit = ftrace_test_recursion_trylock();
  22         if (bit < 0)
  23                 return;
  24
  25         preempt_disable_notrace();
  26         p = get_kprobe((kprobe_opcode_t *)ip);
  27         if (!p) {
  28                 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
  29                 if (unlikely(!p) || kprobe_disabled(p))
  30                         goto out;
  31                 lr_saver = true;
  32         }
  33
  34         kcb = get_kprobe_ctlblk();
  35         if (kprobe_running()) {
  36                 kprobes_inc_nmissed_count(p);
  37         } else {
  38                 unsigned long orig_ip = instruction_pointer(regs);
  39
  40                 if (lr_saver)
  41                         ip -= MCOUNT_INSN_SIZE;
  42                 instruction_pointer_set(regs, ip);
  43                 __this_cpu_write(current_kprobe, p);
  44                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  45                 if (!p->pre_handler || !p->pre_handler(p, regs)) {
  46                         /*
  47                          * Emulate singlestep (and also recover regs->pc)
  48                          * as if there is a nop
  49                          */
  50                         instruction_pointer_set(regs,
  51                                 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  52                         if (unlikely(p->post_handler)) {
  53                                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
  54                                 p->post_handler(p, regs, 0);
  55                         }
  56                         instruction_pointer_set(regs, orig_ip);
  57                 }
  58                 /*
  59                  * If pre_handler returns !0, it changes regs->pc. We have to
  60                  * skip emulating post_handler.
  61                  */
  62                 __this_cpu_write(current_kprobe, NULL);
  63         }
  64 out:
  65         preempt_enable_notrace();
  66         ftrace_test_recursion_unlock(bit);
  67 }
  68 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  69
  70 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  71 {
  72         p->ainsn.api.insn = NULL;
  73         return 0;
  74 }