vtop
====

::

   NAME
     vtop - virtual to physical

   SYNOPSIS
     vtop [-c [pid | taskp]] [-u|-k] address ...

   DESCRIPTION
     This command translates a user or kernel virtual address to its physical
     address.  Also displayed is the PTE translation, the vm_area_struct data
     for user virtual addresses, the mem_map page data associated with the
     physical page, and the swap location or file location if the page is
     not mapped.  The -u and -k options specify that the address is a user
     or kernel virtual address; -u and -k are not necessary on processors whose
     virtual addresses self-define themselves as user or kernel.  User addresses
     are translated with respect to the current context unless the -c option
     is used.  Kernel virtual addresses are translated using the swapper_pg_dir
     as the base page directory unless the -c option is used.

      -u                 The address is a user virtual address; only required
                         on processors with overlapping user and kernel virtual
                         address spaces.
      -k                 The address is a kernel virtual address; only required
                         on processors with overlapping user and kernel virtual
                         address spaces.
      -c [pid | taskp]   Translate the virtual address from the page directory
                         of the specified PID or hexadecimal task_struct pointer.
                         However, if this command is invoked from "foreach vtop",
                         the pid or taskp argument should NOT be entered; the
                         address will be translated using the page directory of
                         each task specified by "foreach".
      address            A hexadecimal user or kernel virtual address.

   EXAMPLES
     Translate user virtual address 80b4000:

       crash> vtop 80b4000
       VIRTUAL   PHYSICAL
       80b4000   660f000

       PAGE DIRECTORY: c37f0000
         PGD: c37f0080 => e0d067
         PMD: c37f0080 => e0d067
         PTE: c0e0d2d0 => 660f067
        PAGE: 660f000

         PTE    PHYSICAL  FLAGS
       660f067   660f000  (PRESENT|RW|USER|ACCESSED|DIRTY)

         VMA      START      END      FLAGS  FILE
       c773daa0   80b4000   810c000    77

         PAGE    PHYSICAL   INODE     OFFSET  CNT FLAGS
       c0393258   660f000         0     17000  1  uptodate

     Translate kernel virtual address c806e000, first using swapper_pg_dir
     as the page directory base, and secondly, using the page table base
     of PID 1359:

       crash> vtop c806e000
       VIRTUAL   PHYSICAL
       c806e000  2216000

       PAGE DIRECTORY: c0101000
         PGD: c0101c80 => 94063
         PMD: c0101c80 => 94063
         PTE: c00941b8 => 2216063
        PAGE: 2216000

         PTE    PHYSICAL  FLAGS
       2216063   2216000  (PRESENT|RW|ACCESSED|DIRTY)

         PAGE    PHYSICAL   INODE     OFFSET  CNT FLAGS
       c02e9370   2216000         0         0  1  

       crash> vtop -c 1359 c806e000
       VIRTUAL   PHYSICAL
       c806e000  2216000

       PAGE DIRECTORY: c5caf000
         PGD: c5cafc80 => 94063
         PMD: c5cafc80 => 94063
         PTE: c00941b8 => 2216063
        PAGE: 2216000

         PTE    PHYSICAL  FLAGS
       2216063   2216000  (PRESENT|RW|ACCESSED|DIRTY)

         PAGE    PHYSICAL   INODE     OFFSET  CNT FLAGS
       c02e9370   2216000         0         0  1  

     Determine swap location of user virtual address 40104000:

       crash> vtop 40104000
       VIRTUAL   PHYSICAL
       40104000  (not mapped)

       PAGE DIRECTORY: c40d8000
         PGD: c40d8400 => 6bbe067
         PMD: c40d8400 => 6bbe067
         PTE: c6bbe410 => 58bc00  

        PTE      SWAP     OFFSET
       58bc00  /dev/sda8   22716

         VMA      START      END     FLAGS  FILE
       c7200ae0  40104000  40b08000    73   

       SWAP: /dev/sda8  OFFSET: 22716