arch/riscv/kernel/ftrace.c

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C) 2013 Linaro Limited
   4  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
   5  * Copyright (C) 2017 Andes Technology Corporation
   6  */
   7
   8 #include <linux/ftrace.h>
   9
  10 /*
  11  * Most of this file is copied from arm64.
  12  */
  13 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
  14                            unsigned long frame_pointer)
  15 {
  16         unsigned long return_hooker = (unsigned long)&return_to_handler;
  17         unsigned long old;
  18         struct ftrace_graph_ent trace;
  19         int err;
  20
  21         if (unlikely(atomic_read(&current->tracing_graph_pause)))
  22                 return;
  23
  24         /*
  25          * We don't suffer access faults, so no extra fault-recovery assembly
  26          * is needed here.
  27          */
  28         old = *parent;
  29
  30         trace.func = self_addr;
  31         trace.depth = current->curr_ret_stack + 1;
  32
  33         if (!ftrace_graph_entry(&trace))
  34                 return;
  35
  36         err = ftrace_push_return_trace(old, self_addr, &trace.depth,
  37                                        frame_pointer, NULL);
  38         if (err == -EBUSY)
  39                 return;
  40         *parent = return_hooker;
  41 }