elf_aux.c 1.8 KB

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  1. /*
  2. * arch/um/kernel/elf_aux.c
  3. *
  4. * Scan the Elf auxiliary vector provided by the host to extract
  5. * information about vsyscall-page, etc.
  6. *
  7. * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
  8. * Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com)
  9. */
  10. #include <elf.h>
  11. #include <stddef.h>
  12. #include "init.h"
  13. #include "elf_user.h"
  14. #include "mem_user.h"
  15. #if ELF_CLASS == ELFCLASS32
  16. typedef Elf32_auxv_t elf_auxv_t;
  17. #else
  18. typedef Elf64_auxv_t elf_auxv_t;
  19. #endif
  20. char * elf_aux_platform;
  21. long elf_aux_hwcap;
  22. unsigned long vsyscall_ehdr;
  23. unsigned long vsyscall_end;
  24. unsigned long __kernel_vsyscall;
  25. __init void scan_elf_aux( char **envp)
  26. {
  27. long page_size = 0;
  28. elf_auxv_t * auxv;
  29. while ( *envp++ != NULL) ;
  30. for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
  31. switch ( auxv->a_type ) {
  32. case AT_SYSINFO:
  33. __kernel_vsyscall = auxv->a_un.a_val;
  34. break;
  35. case AT_SYSINFO_EHDR:
  36. vsyscall_ehdr = auxv->a_un.a_val;
  37. /* See if the page is under TASK_SIZE */
  38. if (vsyscall_ehdr < (unsigned long) envp)
  39. vsyscall_ehdr = 0;
  40. break;
  41. case AT_HWCAP:
  42. elf_aux_hwcap = auxv->a_un.a_val;
  43. break;
  44. case AT_PLATFORM:
  45. /* elf.h removed the pointer elements from
  46. * a_un, so we have to use a_val, which is
  47. * all that's left.
  48. */
  49. elf_aux_platform = (char *) auxv->a_un.a_val;
  50. break;
  51. case AT_PAGESZ:
  52. page_size = auxv->a_un.a_val;
  53. break;
  54. }
  55. }
  56. if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
  57. ! elf_aux_hwcap || ! elf_aux_platform ||
  58. ! page_size || (vsyscall_ehdr % page_size) ) {
  59. __kernel_vsyscall = 0;
  60. vsyscall_ehdr = 0;
  61. elf_aux_hwcap = 0;
  62. elf_aux_platform = "i586";
  63. }
  64. else {
  65. vsyscall_end = vsyscall_ehdr + page_size;
  66. }
  67. }