最近做opengl模拟器的时候，需要从用户虚拟地址得到实际的物理地址，在网上找到一个不错的参考（http://www.eefocus.com/html/09-05/71993s.shtml），稍微修改了一下（用current替代了find_task_by_pid.

   
   
   
   
    
    
    
    
    
  1. #include  
    2. 
    
    
    
    
  2. #include  
    3. 
    
    
    
    
  3. #include  
    4. 
    
    
    
    
  4. #include  
    5. 
    
    
    
    
  5.  
    6. 
    
    
    
    
  6. static int v2p(unsigned long va) 
    7. 
    
    
    
    
  7. { 
    8. 
    
    
    
    
  8.     unsigned long pa = 0; 
    9. 
    
    
    
    
  9.     struct task_struct *pcb_tmp; 
    10. 
    
    
    
    
  10.     pgd_t *pgd_tmp = NULL; 
    11. 
    
    
    
    
  11.     pud_t *pud_tmp = NULL; 
    12. 
    
    
    
    
  12.     pmd_t *pmd_tmp = NULL; 
    13. 
    
    
    
    
  13.     pte_t *pte_tmp = NULL; 
    14. 
    
    
    
    
  14.  
    15. 
    
    
    
    
  15.     printk(KERN_INFO"PAGE_OFFSET = 0x%lx\n",PAGE_OFFSET); 
    16. 
    
    
    
    
  16.     printk(KERN_INFO"PGDIR_SHIFT = %d\n",PGDIR_SHIFT); 
    17. 
    
    
    
    
  17.     printk(KERN_INFO"PUD_SHIFT = %d\n",PUD_SHIFT); 
    18. 
    
    
    
    
  18.     printk(KERN_INFO"PMD_SHIFT = %d\n",PMD_SHIFT); 
    19. 
    
    
    
    
  19.     printk(KERN_INFO"PAGE_SHIFT = %d\n",PAGE_SHIFT); 
    20. 
    
    
    
    
  20.  
    21. 
    
    
    
    
  21.     printk(KERN_INFO"PTRS_PER_PGD = %d\n",PTRS_PER_PGD); 
    22. 
    
    
    
    
  22.     printk(KERN_INFO"PTRS_PER_PUD = %d\n",PTRS_PER_PUD); 
    23. 
    
    
    
    
  23.     printk(KERN_INFO"PTRS_PER_PMD = %d\n",PTRS_PER_PMD); 
    24. 
    
    
    
    
  24.     printk(KERN_INFO"PTRS_PER_PTE = %d\n",PTRS_PER_PTE); 
    25. 
    
    
    
    
  25.  
    26. 
    
    
    
    
  26.     printk(KERN_INFO"PAGE_MASK = 0x%lx\n",PAGE_MASK); 
    27. 
    
    
    
    
  27.  
    28. 
    
    
    
    
  28.     pcb_tmp = current; 
    29. 
    
    
    
    
  29.     printk(KERN_INFO"pgd = 0x%p\n",pcb_tmp->mm->pgd); 
    30. 
    
    
    
    
  30.     if(!find_vma(pcb_tmp->mm,va)){ 
    31. 
    
    
    
    
  31.                     printk(KERN_INFO"virt_addr 0x%lx not available.\n",va); 
    32. 
    
    
    
    
  32.                     return 0; 
    33. 
    
    
    
    
  33.     } 
    34. 
    
    
    
    
  34.     pgd_tmp = pgd_offset(pcb_tmp->mm,va); 
    35. 
    
    
    
    
  35.     printk(KERN_INFO"pgd_tmp = 0x%p\n",pgd_tmp); 
    36. 
    
    
    
    
  36.     printk(KERN_INFO"pgd_val(*pgd_tmp) = 0x%lx\n",pgd_val(*pgd_tmp)); 
    37. 
    
    
    
    
  37.     if(pgd_none(*pgd_tmp)){ 
    38. 
    
    
    
    
  38.                     printk(KERN_INFO"Not mapped in pgd.\n");                 
    39. 
    
    
    
    
  39.                     return 0; 
    40. 
    
    
    
    
  40.     } 
    41. 
    
    
    
    
  41.     pud_tmp = pud_offset(pgd_tmp,va); 
    42. 
    
    
    
    
  42.     printk(KERN_INFO"pud_tmp = 0x%p\n",pud_tmp); 
    43. 
    
    
    
    
  43.     printk(KERN_INFO"pud_val(*pud_tmp) = 0x%lx\n",pud_val(*pud_tmp)); 
    44. 
    
    
    
    
  44.     if(pud_none(*pud_tmp)){ 
    45. 
    
    
    
    
  45.                     printk(KERN_INFO"Not mapped in pud.\n"); 
    46. 
    
    
    
    
  46.                     return 0; 
    47. 
    
    
    
    
  47.     } 
    48. 
    
    
    
    
  48.     pmd_tmp = pmd_offset(pud_tmp,va); 
    49. 
    
    
    
    
  49.     printk(KERN_INFO"pmd_tmp = 0x%p\n",pmd_tmp); 
    50. 
    
    
    
    
  50.     printk(KERN_INFO"pmd_val(*pmd_tmp) = 0x%lx\n",pmd_val(*pmd_tmp)); 
    51. 
    
    
    
    
  51.     if(pmd_none(*pmd_tmp)){ 
    52. 
    
    
    
    
  52.                     printk(KERN_INFO"Not mapped in pmd.\n"); 
    53. 
    
    
    
    
  53.                     return 0; 
    54. 
    
    
    
    
  54.     } 
    55. 
    
    
    
    
  55.  
    56. 
    
    
    
    
  56.     pte_tmp = pte_offset_kernel(pmd_tmp,va); 
    57. 
    
    
    
    
  57.  
    58. 
    
    
    
    
  58.     printk(KERN_INFO"pte_tmp = 0x%p\n",pte_tmp); 
    59. 
    
    
    
    
  59.     printk(KERN_INFO"pte_val(*pte_tmp) = 0x%lx\n",pte_val(*pte_tmp)); 
    60. 
    
    
    
    
  60.     if(pte_none(*pte_tmp)){ 
    61. 
    
    
    
    
  61.                     printk(KERN_INFO"Not mapped in pte.\n"); 
    62. 
    
    
    
    
  62.                     return 0; 
    63. 
    
    
    
    
  63.     } 
    64. 
    
    
    
    
  64.     if(!pte_present(*pte_tmp)){ 
    65. 
    
    
    
    
  65.                     printk(KERN_INFO"pte not in RAM.\n"); 
    66. 
    
    
    
    
  66.                     return 0; 
    67. 
    
    
    
    
  67.     } 
    68. 
    
    
    
    
  68.     pa = (pte_val(*pte_tmp) & PAGE_MASK) |(va & ~PAGE_MASK); 
    69. 
    
    
    
    
  69.     printk(KERN_INFO"virt_addr 0x%lx in RAM is 0x%lx .\n",va,pa); 
    70. 
    
    
    
    
  70.     printk(KERN_INFO"contect in 0x%lx is 0x%lx\n",pa, 
    71. 
    
    
    
    
  71.                     *(unsigned long *)((char *)pa + PAGE_OFFSET)); 
    72. 
    
    
    
    
  72.                                                                                                      
    73. 
    
    
    
    
  73.     return 0; 
    74. 
    
    
    
    
  74. } 
    75.