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 #include <asm/dwarf.h>
  11
  12 #ifdef CONFIG_DWARF_UNWINDER
  13
  14 void *return_address(unsigned int depth)
  15 {
  16         struct dwarf_frame *frame;
  17         unsigned long ra;
  18         int i;
  19
  20         for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
  21                 struct dwarf_frame *tmp;
  22
  23                 tmp = dwarf_unwind_stack(ra, frame);
  24                 if (!tmp)
  25                         return NULL;
  26
  27                 if (frame)
  28                         dwarf_free_frame(frame);
  29
  30                 frame = tmp;
  31
  32                 if (!frame || !frame->return_addr)
  33                         break;
  34
  35                 ra = frame->return_addr;
  36         }
  37
  38         /* Failed to unwind the stack to the specified depth. */
  39         WARN_ON(i != depth + 1);
  40
  41         if (frame)
  42                 dwarf_free_frame(frame);
  43
  44         return (void *)ra;
  45 }
  46
  47 #else
  48
  49 void *return_address(unsigned int depth)
  50 {
  51         return NULL;
  52 }
  53
  54 #endif
  55
  56 EXPORT_SYMBOL_GPL(return_address);