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 disabled */
  13 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
  14                            struct ftrace_ops *ops, struct ftrace_regs *fregs)
  15 {
  16         int bit;
  17         bool lr_saver = false;
  18         struct kprobe *p;
  19         struct kprobe_ctlblk *kcb;
  20         struct pt_regs *regs;
  21
  22         bit = ftrace_test_recursion_trylock(ip, parent_ip);
  23         if (bit < 0)
  24                 return;
  25
  26         regs = ftrace_get_regs(fregs);
  27         preempt_disable_notrace();
  28         p = get_kprobe((kprobe_opcode_t *)ip);
  29         if (!p) {
  30                 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
  31                 if (unlikely(!p) || kprobe_disabled(p))
  32                         goto out;
  33                 lr_saver = true;
  34         }
  35
  36         kcb = get_kprobe_ctlblk();
  37         if (kprobe_running()) {
  38                 kprobes_inc_nmissed_count(p);
  39         } else {
  40                 unsigned long orig_ip = instruction_pointer(regs);
  41
  42                 if (lr_saver)
  43                         ip -= MCOUNT_INSN_SIZE;
  44                 instruction_pointer_set(regs, ip);
  45                 __this_cpu_write(current_kprobe, p);
  46                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
  47                 if (!p->pre_handler || !p->pre_handler(p, regs)) {
  48                         /*
  49                          * Emulate singlestep (and also recover regs->pc)
  50                          * as if there is a nop
  51                          */
  52                         instruction_pointer_set(regs,
  53                                 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
  54                         if (unlikely(p->post_handler)) {
  55                                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
  56                                 p->post_handler(p, regs, 0);
  57                         }
  58                         instruction_pointer_set(regs, orig_ip);
  59                 }
  60                 /*
  61                  * If pre_handler returns !0, it changes regs->pc. We have to
  62                  * skip emulating post_handler.
  63                  */
  64                 __this_cpu_write(current_kprobe, NULL);
  65         }
  66 out:
  67         preempt_enable_notrace();
  68         ftrace_test_recursion_unlock(bit);
  69 }
  70 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
  71
  72 int arch_prepare_kprobe_ftrace(struct kprobe *p)
  73 {
  74         p->ainsn.api.insn = NULL;
  75         return 0;
  76 }