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