/arch/i386/kernel/sysenter.c

https://bitbucket.org/evzijst/gittest · C · 65 lines · 42 code · 12 blank · 11 comment · 1 complexity · bc213c217721410d95fb153afc8f17fb MD5 · raw file 

    

  1. /*
    2. 

  2.  * linux/arch/i386/kernel/sysenter.c
    3. 

  3.  *
    4. 

  4.  * (C) Copyright 2002 Linus Torvalds
    5. 

  5.  *
    6. 

  6.  * This file contains the needed initializations to support sysenter.
    7. 

  7.  */
    8. 

  8. 

  9. #include <linux/init.h>
    10. 

  10. #include <linux/smp.h>
    11. 

  11. #include <linux/thread_info.h>
    12. 

  12. #include <linux/sched.h>
    13. 

  13. #include <linux/gfp.h>
    14. 

  14. #include <linux/string.h>
    15. 

  15. #include <linux/elf.h>
    16. 

  16. 

  17. #include <asm/cpufeature.h>
    18. 

  18. #include <asm/msr.h>
    19. 

  19. #include <asm/pgtable.h>
    20. 

  20. #include <asm/unistd.h>
    21. 

  21. 

  22. extern asmlinkage void sysenter_entry(void);
    23. 

  23. 

  24. void enable_sep_cpu(void *info)
    25. 

  25. {
    26. 

  26. 	int cpu = get_cpu();
    27. 

  27. 	struct tss_struct *tss = &per_cpu(init_tss, cpu);
    28. 

  28. 

  29. 	tss->ss1 = __KERNEL_CS;
    30. 

  30. 	tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
    31. 

  31. 	wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
    32. 

  32. 	wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0);
    33. 

  33. 	wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
    34. 

  34. 	put_cpu();	
    35. 

  35. }
    36. 

  36. 

  37. /*
    38. 

  38.  * These symbols are defined by vsyscall.o to mark the bounds
    39. 

  39.  * of the ELF DSO images included therein.
    40. 

  40.  */
    41. 

  41. extern const char vsyscall_int80_start, vsyscall_int80_end;
    42. 

  42. extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
    43. 

  43. 

  44. static int __init sysenter_setup(void)
    45. 

  45. {
    46. 

  46. 	void *page = (void *)get_zeroed_page(GFP_ATOMIC);
    47. 

  47. 

  48. 	__set_fixmap(FIX_VSYSCALL, __pa(page), PAGE_READONLY_EXEC);
    49. 

  49. 

  50. 	if (!boot_cpu_has(X86_FEATURE_SEP)) {
    51. 

  51. 		memcpy(page,
    52. 

  52. 		       &vsyscall_int80_start,
    53. 

  53. 		       &vsyscall_int80_end - &vsyscall_int80_start);
    54. 

  54. 		return 0;
    55. 

  55. 	}
    56. 

  56. 

  57. 	memcpy(page,
    58. 

  58. 	       &vsyscall_sysenter_start,
    59. 

  59. 	       &vsyscall_sysenter_end - &vsyscall_sysenter_start);
    60. 

  60. 

  61. 	on_each_cpu(enable_sep_cpu, NULL, 1, 1);
    62. 

  62. 	return 0;
    63. 

  63. }
    64. 

  64. 

  65. __initcall(sysenter_setup);
    66.