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POPage translation of process code section in Linux. Why does the Page Table Entry get 0 for some pages?
 

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  1. POPage translation of process code section in Linux. Why does the Page Table Entry get 0 for some pages?
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    <p>For some reason, I need to translate the virtual address of the code section to physical address. I did following experiment: </p> <ol> <li><p>I get the virtual address from the start_code and end_code in mm_struct of process A, which are the initial address and final address of the executable code. </p></li> <li><p>I get the CR3 of process A. </p></li> <li><p>I translate the virtual address to physical address page by page. For example, there are 10 pages for code section in process A. I will translate 10 virtual address of each beginning of the page. </p></li> <li><p>I found out some pages will get Page Table Entry(PTE) == 0.Some pages could successfully translate to a physical address. </p></li> <li><p>I tried Firefox and Minicom as my Process, and both of them will get into situation. </p></li> </ol> <p>I guess my question is: could anyone explain to me why PTE == 0? Does it mean these pages have been swap out to disk? If this is the case, how can I find these pages?</p> <p>Thanks for any input!!</p>
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    1. USFengwei Zhang
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    1. COIs this in kernel mode (like from a convention device driver) or user mode?
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      1. USwallyk
    2. COThanks for your asking. Actually, this neither in kernel mode nor user mode. I am doing forensics on another computer. Assume I have a memory dump 4G file, CR3 of process A, start_code and end_code (virtual address) of process A. I need to find out the executable code of process A.
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      1. POPage translation of process code section in Linux. Why does the Page Table Entry get 0 for some pages?
      1. USFengwei Zhang
 

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