X86 Assembly Calling Convention

Published 2018-03-24

Calling Convention

总结一下关于汇编函数调用过程的知识。

References：

http://www.cs.virginia.edu/~evans/cs216/guides/x86.html https://en.wikibooks.org/wiki/X86_Assembly

Make a subrouting call

1. Before calling a subrouting, save the caller-saved registers (EAX, ECX, EDX).

2. Push the parameters onto the stack.

3. Use call instruction, places the retrun address onto stack, and branches to the subroutine code.

Callee prologue

1. Push old base pointer value, for restore it after subroutine.

push ebp
mov ebp, esp

2. Allocate local variables by make space on the stack. e.g.

sub esp, 12

3. Save the values of the callee-saved register push them onto stack (EBX, EDI, ESI).

Callee body proceed

Callee epilogue

1. Leave the return value in EAX.

2. Restore the old values of any callee-saved registers (EDI, ESI, EBX).

3. Deallocate local variables.

mov esp, ebp

4. Restore the caller's base pointer value by poping EBP from the stack.

5. Return to the caller by executing a return ret instruction, find and reomve the return address from the stack.

After subroutine return

1. Remove the parameters from stack.

2. Restore the contents of caller-saved registers (EAX, ECX, EDX)