Stack alignment in x64 assembly

Question

how is the value of 28h (decimal 40) that is subtracted from rsp calculated in the following:

    option casemap:none

    includel         


        

Answer 1

I had stumbled upon the same case. Tried lurker answer and was fine. Later added some code(by the way, i'm using my own compiler) and got problems.

The problem was that the shadow space address was ending with 8 on the stack. When the shadow space address was ending with 0 ("Stack aligned on 16 bytes"), the call was OK. Adding 8 bytes will crash the app in my last case.