arch/csky/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         int bit;
  10         bool lr_saver = false;
  11         struct kprobe *p;
  12         struct kprobe_ctlblk *kcb;
  13         struct pt_regs *regs;
  14
  15         if (unlikely(kprobe_ftrace_disabled))
  16                 return;
  17
  18         bit = ftrace_test_recursion_trylock(ip, parent_ip);
  19         if (bit < 0)
  20                 return;
  21
  22         regs = ftrace_get_regs(fregs);
  23         p = get_kprobe((kprobe_opcode_t *)ip);
  24         if (!p) {
  25                 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
  26                 if (unlikely(!p) || kprobe_disabled(p))
  27                         goto out;
  28                 lr_saver = true;
  29         }
  30
  31         kcb = get_kprobe_ctlblk();
  32         if (kprobe_running()) {
  33                 kprobes_inc_nmissed_count(p);
  34         } else {
  35                 unsigned long orig_ip = instruction_pointer(regs);
  36
  37                 if (lr_saver)
  38                         ip -= MCOUNT_INSN_SIZE;
  39                 instruction_pointer_set(regs, ip);
  40                 __this_cpu_write(current_kprobe, p);
  41                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  42                 if (!p->pre_handler || !p->pre_handler(p, regs)) {
  43                         /*
  44                          * Emulate singlestep (and also recover regs->pc)
  45                          * as if there is a nop
  46                          */
  47                         instruction_pointer_set(regs,
  48                                 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  49                         if (unlikely(p->post_handler)) {
  50                                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
  51                                 p->post_handler(p, regs, 0);
  52                         }
  53                         instruction_pointer_set(regs, orig_ip);
  54                 }
  55                 /*
  56                  * If pre_handler returns !0, it changes regs->pc. We have to
  57                  * skip emulating post_handler.
  58                  */
  59                 __this_cpu_write(current_kprobe, NULL);
  60         }
  61 out:
  62         ftrace_test_recursion_unlock(bit);
  63 }
  64 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  65
  66 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  67 {
  68         p->ainsn.api.insn = NULL;
  69         return 0;
  70 }