Calling Conventions for AARCH64

• sp contains the stack pointer,
• lr (link register) contains the return address,
• fp contains the frame pointer,
• r19 to r28 are callee-saved and must be reset to their original state before returning, and
• r0 to r7 are used to store the arguments and results of a subroutine.

Additionally:

• The stack must always be quad-word aligned, i.e. sp mod 16 == 0.

Prologue

1. push the value of lr onto the stack,
2. push the value of fp onto the stack, then
3. read the current value of sp into fp.

stp fp, lr, [sp, -16]!
mov fp, sp

Epilogue

ldp fp, lr, [sp], #16