return_address.c 1.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * arch/arm64/kernel/return_address.c
  4. *
  5. * Copyright (C) 2013 Linaro Limited
  6. * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
  7. */
  8. #include <linux/export.h>
  9. #include <linux/ftrace.h>
  10. #include <linux/kprobes.h>
  11. #include <asm/stack_pointer.h>
  12. #include <asm/stacktrace.h>
  13. struct return_address_data {
  14. unsigned int level;
  15. void *addr;
  16. };
  17. static bool save_return_addr(void *d, unsigned long pc)
  18. {
  19. struct return_address_data *data = d;
  20. if (!data->level) {
  21. data->addr = (void *)pc;
  22. return false;
  23. } else {
  24. --data->level;
  25. return true;
  26. }
  27. }
  28. NOKPROBE_SYMBOL(save_return_addr);
  29. void *return_address(unsigned int level)
  30. {
  31. struct return_address_data data;
  32. struct stackframe frame;
  33. data.level = level + 2;
  34. data.addr = NULL;
  35. start_backtrace(&frame,
  36. (unsigned long)__builtin_frame_address(0),
  37. (unsigned long)return_address);
  38. walk_stackframe(current, &frame, save_return_addr, &data);
  39. if (!data.level)
  40. return data.addr;
  41. else
  42. return NULL;
  43. }
  44. EXPORT_SYMBOL_GPL(return_address);
  45. NOKPROBE_SYMBOL(return_address);