Linux下获取虚拟地址对应的物理地址的方法

首先摘录如下URL对pagemap的描述。

https://www.kernel.org/doc/Documentation/vm/pagemap.txt

 * /proc/pid/pagemap.  This file lets a userspace process find out which
   physical frame each virtual page is mapped to.  It contains one 64-bit
   value for each virtual page, containing the following data (from
   fs/proc/task_mmu.c, above pagemap_read):


    * Bits 0-54  page frame number (PFN) if present
    * Bits 0-4   swap type if swapped
    * Bits 5-54  swap offset if swapped
    * Bit  55    pte is soft-dirty (see Documentation/vm/soft-dirty.txt)
    * Bits 56-60 zero
    * Bit  61    page is file-page or shared-anon
    * Bit  62