libfringe/src/init.s

40 lines
929 B
ArmAsm

// Copyright (c) 2015, edef <edef@edef.eu>
// See LICENSE file that comes with this distribution.
/// initialise a new context
/// arguments: rdi: stack pointer,
/// rsi: function pointer,
/// rdx, data pointer
/// rcx, stack limit
// switch to the fresh stack
xchg %rsp, %rdi
// save the function pointer, data pointer, and stack limit, respectively
pushq %rsi
pushq %rdx
pushq %rcx
// save the return address, control flow continues at label 1
call 1f
// we arrive here once this context is reactivated (see swap.s)
// restore the stack limit, data pointer, and function pointer, respectively
popq %fs:0x70
popq %rdi
popq %rax
// initialise the frame pointer
movq $$0, %rbp
// call the function pointer with the data pointer (rdi is the first argument)
call *%rax
// crash if it ever returns
ud2
1:
// save our neatly-setup new stack
xchg %rsp, %rdi
// back into Rust-land we go