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[Fu-hau Hsu]

Dear friends:

 I have a question about memory protection. I appreciate any suggestion. 
 Thank you so much.

    Given a virtual address, how can we know whether this address contains
    an executable code? If there is a method that can be used to answer
    the above question, is there any exception for this method?

    PS:
    (a)Could we get the result by checking the VM_EXECUTABLE attribute of
    the vm_flags of the vm_area_struct for the memory area that contains    
    that address? If yes, does this apply to x86 architecture?

    (b) Could information in vm_page_prot of vm_area_struct or in
        struct mem_map_t help? If yes, which attribute and how?

  Best Regards,

FuHau