arch/sh/kernel/return_address.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * arch/sh/kernel/return_address.c
   4  *
   5  * Copyright (C) 2009  Matt Fleming
   6  * Copyright (C) 2009  Paul Mundt
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10
  11 #include <asm/dwarf.h>
  12 #include <asm/ftrace.h>
  13
  14 #ifdef CONFIG_DWARF_UNWINDER
  15
  16 void *return_address(unsigned int depth)
  17 {
  18         struct dwarf_frame *frame;
  19         unsigned long ra;
  20         int i;
  21
  22         for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
  23                 struct dwarf_frame *tmp;
  24
  25                 tmp = dwarf_unwind_stack(ra, frame);
  26                 if (!tmp)
  27                         return NULL;
  28
  29                 if (frame)
  30                         dwarf_free_frame(frame);
  31
  32                 frame = tmp;
  33
  34                 if (!frame || !frame->return_addr)
  35                         break;
  36
  37                 ra = frame->return_addr;
  38         }
  39
  40         /* Failed to unwind the stack to the specified depth. */
  41         WARN_ON(i != depth + 1);
  42
  43         if (frame)
  44                 dwarf_free_frame(frame);
  45
  46         return (void *)ra;
  47 }
  48
  49 #else
  50
  51 void *return_address(unsigned int depth)
  52 {
  53         return NULL;
  54 }
  55
  56 #endif
  57
  58 EXPORT_SYMBOL_GPL(return_address);