forked from ariadne/libucontext
101 lines
2.2 KiB
ArmAsm
101 lines
2.2 KiB
ArmAsm
/*
|
|
* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
|
|
*
|
|
* Permission to use, copy, modify, and/or distribute this software for any
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
* copyright notice and this permission notice appear in all copies.
|
|
*
|
|
* This software is provided 'as is' and without any warranty, express or
|
|
* implied. In no event shall the authors be liable for any damages arising
|
|
* from the use of this software.
|
|
*/
|
|
|
|
LOCALSZ = 2
|
|
|
|
#include "defs.h"
|
|
|
|
A3_OFF = FRAMESZ + (3 * REG_SZ)
|
|
|
|
/*
|
|
* Because we have to fiddle with $gp, we have to implement this in
|
|
* assembly rather than C. Annoying, that...
|
|
*/
|
|
|
|
ALIAS(makecontext, libucontext_makecontext)
|
|
|
|
FUNC(libucontext_makecontext)
|
|
PUSH_FRAME(libucontext_makecontext)
|
|
|
|
/* store $a3 through $a7 to the stack frame. */
|
|
sw $a3, A3_OFF($sp)
|
|
|
|
/* set $zero in the mcontext to 1. */
|
|
li $v0, 1
|
|
sw $v0, REG_OFFSET(0)($a0)
|
|
|
|
/* ensure the stack is aligned on a quad-word boundary. */
|
|
lw $t0, UCONTEXT_STACK_PTR($a0)
|
|
lw $t2, UCONTEXT_STACK_SIZE($a0)
|
|
addiu $t1, $sp, A3_OFF
|
|
addu $t0, $t2
|
|
and $t0, ALMASK
|
|
blez $a2, no_more_arguments
|
|
|
|
/* store register arguments. */
|
|
addiu $t2, $a0, MCONTEXT_GREGS + (4 * REG_SZ)
|
|
move $t3, $zero
|
|
|
|
store_register_arg:
|
|
addiu $t3, 1
|
|
lw $v1, ($t1)
|
|
addiu $t1, REG_SZ
|
|
sw $v1, ($t2)
|
|
addiu $t2, REG_SZ
|
|
bgeu $t3, $a2, no_more_arguments
|
|
bltu $t3, 4, store_register_arg
|
|
|
|
/* make room for stack arguments. */
|
|
subu $t2, $a2, $t3
|
|
sll $t2, 3
|
|
subu $t0, $t2
|
|
and $t0, ALMASK
|
|
|
|
/* store stack arguments. */
|
|
move $t2, $t0
|
|
|
|
store_stack_arg:
|
|
addiu $t3, 1
|
|
lw $v1, ($t1)
|
|
addiu $t1, REG_SZ
|
|
sw $v1, ($t2)
|
|
addiu $t2, REG_SZ
|
|
bltu $t3, $a2, store_stack_arg
|
|
|
|
no_more_arguments:
|
|
/* make room for $a0-$a3 storage */
|
|
addiu $t0, -(4 * REG_SZ)
|
|
|
|
/* trampoline setup. */
|
|
la $t9, libucontext_trampoline
|
|
|
|
/* copy link pointer as $s0... */
|
|
lw $v1, UCONTEXT_UC_LINK($a0)
|
|
sw $v1, REG_OFFSET(16)($a0)
|
|
|
|
/* set our $sp */
|
|
sw $t0, REG_OFFSET(29)($a0)
|
|
|
|
/* $gp is copied as $s1 */
|
|
sw $gp, REG_OFFSET(17)($a0)
|
|
|
|
/* set our $ra */
|
|
sw $t9, REG_OFFSET(31)($a0)
|
|
|
|
/* set our $pc */
|
|
sw $a1, MCONTEXT_PC($a0)
|
|
|
|
POP_FRAME(libucontext_makecontext)
|
|
|
|
jr $ra
|
|
END(libucontext_makecontext)
|