Update README.md

README.md

@@ -4,7 +4,7 @@
 On windows I was told it was "impossible to name your process something other then the executables name" so I figured I would go the extra mile and throw in some forward slashes into the name
 since you dont see that very often on windows.
 
-# How
+# how is this possible
 
 I copy the kernel pml4e's into the usermode part of the pml4. Windows has an amazing infrastructure/API that can be used to do much more then its been allowed. Lets take a look
 at ReadProcessMemory. ReadProcessMemory calls NtReadVirtualMemory which then calls MmCopyVirtualMemory. NtReadVirtualMemory does validation checks on addresses supplied from
@@ -30,3 +30,28 @@ copy the top 256 pml4e's into the bottom (usermode) part of the pml4, NtReadVirt
     v12 = (_QWORD *)a5;
   }
 ```
+
+# how do I use this
+
+Simply obtain the pid of `/proc/kmem` and then you can `OpenProcess` with `PROCESS_ALL_ACCESS`. You will be able to ReadProcessMemory and WriteProcessMemory, you will not
+be able to VirtualProtectEx, instead you can walk the paging tables since the self referencing pml4e is in usermode! You can scan for the self referencing pml4e or keep a 
+reference to the index it is located at. That is up to you!
+
+### address translation
+
+As stated in `how is this possible`, NtReadVirtualMemory is going to ensure that the addresses you are passing land below pml4e 256 (counting from 0 here). In order
+to still use windows api, you must call `nasa::kmem_ctx::translate`. `translate` is a static function that simply subtracts the pml4 index by 256 in order to give you the usermode mappings
+of the kernel memory which you can then use with ReadProcessMemory/WriteProcessMemory...
+
+```cpp
+	auto kmem_ctx::translate(std::uintptr_t kva) -> std::uintptr_t
+	{
+		virt_addr_t old_addr{ reinterpret_cast<void*>(kva) };
+		virt_addr_t new_addr{ NULL };
+		new_addr.pml4_index = old_addr.pml4_index - 255;
+		new_addr.pdpt_index = old_addr.pdpt_index;
+		new_addr.pd_index = old_addr.pd_index;
+		new_addr.pt_index = old_addr.pt_index;
+		return reinterpret_cast<std::uintptr_t>(new_addr.value);
+	}
+```