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I'm trying to develop understanding of Assembly language. I understand that when function creates stack frame, it pushes current EBP, than copies stack pointer value to the EBP. First (and only) function parameter is accessed by EBP + 8. But why 8? Next value after pushed EBP is logically offset 4. I read many webpages, but it seems I don't understand this part.

Inline
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1 Answers1

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The "missing" DWORD is the return address. The call stack looks like:

ebp     : saved ebp
ebp + 4 : return address
ebp + 8 : pushed parameter

And then if the function uses local variables, since stack space is (typically) reserved for those after the stack frame, they are referenced as ebp - xx:

ebp - 8 : second local
ebp - 4 : first local
ebp     : saved ebp
ebp + 4 : return address
ebp + 8 : pushed parameter
DocMax
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  • Thank you. I focused on the wrong part (read about calling conventions, but forgot basic thing) – Inline Mar 13 '17 at 19:12
  • Is worth mentioning that the stack in this question grows downward that's why you substrate local variables from ebp which were pushed after arguments and return address. – Cholthi Paul Ttiopic Mar 15 '18 at 19:18