Notes on Type Layouts and ABIs in Rust - Faultlore PDF 5. Calling conventions - Agner itself satisfy calling convention ABI. Fastcall is the calling convention for x64 Windows. When talking about calling conventions you will hear about something called the "Application Binary Interface" (ABI). By maintaining a known stack alignment at the entry of functions, the compiler can safely use the more efficientmovdqa to save the nonvolatile registers rather than using the . This calling convention is used for calling C++ non-static member functions. Windows uses a four-register fastcall calling convention by default. Reversing the x64 calling convention · Low Level Pleasure x64 Calling Conventions. Calling Conventions for x64 ASM - social.msdn.microsoft.com Smashing the Stack in the 21st Century :: Jon Gjengset Functions that allocate stack space, call other functions, save non-volatile registers or use exception handling are called " frame functions "; other functions are called " leaf functions ".. Frame functions use an area on the stack called a " stack frame " and have a defined prologue in which this is set up. When calling a subroutine, the stack pointer (RSP) must be aligned on a 16-byte boundary (a multiple of 16).The CALL instruction pushes an 8-byte return address on the stack, so the calling program must . Microsoft x64; 1.2. On the other hand, if you had callee clean and variable-sized home space, you would have to push an extra dummy parameter for half of the functions, just so that the stack stayed aligned. Fastcall is the default calling convention on X64 where in the first 4 parameters are passed via the registers RCX, RDX, R8, R9. In the generic procedure call standard, all function arguments passed on the stack consume slots in multiples of 8 bytes. Linux x64 Calling Convention: Stack Frame - Red Teaming Experiments In computer science, a calling convention is an implementation-level (low-level) scheme for how subroutines receive parameters from their caller and how they return a result. In the Microsoft x64 calling convention, it is the caller's responsibility to allocate 32 bytes of "shadow space" on the stack right before calling the .