62 lines
2.0 KiB
ArmAsm
62 lines
2.0 KiB
ArmAsm
/*******************************************************************************
|
|
|
|
Copyright(C) Jonas 'Sortie' Termansen 2012.
|
|
|
|
This file is part of Sortix.
|
|
|
|
Sortix is free software: you can redistribute it and/or modify it under the
|
|
terms of the GNU General Public License as published by the Free Software
|
|
Foundation, either version 3 of the License, or (at your option) any later
|
|
version.
|
|
|
|
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
|
|
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
|
|
details.
|
|
|
|
You should have received a copy of the GNU General Public License along with
|
|
Sortix. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
x86/interlock.s
|
|
Functions that perform non-atomic operations in an atomic manner.
|
|
|
|
*******************************************************************************/
|
|
|
|
.section .text
|
|
|
|
# Atomicly runs a function on a value and returns the unmodified value.
|
|
# ilret_t
|
|
# asm_interlocked_modify(unsigned long* val,
|
|
# unsigned long (*func)(unsigned long, unsigned long),
|
|
# unsigned long user);
|
|
.global asm_interlocked_modify
|
|
.type asm_interlocked_modify, @function
|
|
asm_interlocked_modify:
|
|
pushl %ebp
|
|
movl %esp, %ebp
|
|
pushl %ebx
|
|
asm_interlocked_modify_retry:
|
|
# Read the current value and calculate the replacement.
|
|
movl 20(%ebp), %ecx # user
|
|
movl 16(%ebp), %edx # func
|
|
movl 12(%ebp), %ebx # val
|
|
movl (%ebx), %ebx # *val
|
|
pushl %ecx
|
|
pushl %ebx
|
|
call *%edx
|
|
# Atomicly assign the replacement if the value is unchanged.
|
|
movl %eax, %edx # New value in %edx
|
|
movl %ebx, %eax # Old value in %eax
|
|
movl 8(%ebp), %ebx # val
|
|
cmpxchgl %edx, (%ebx)
|
|
# Retry if the value was modified by someone else.
|
|
jnz asm_interlocked_modify_retry
|
|
# According to the calling convention, the first parameter is secretly a
|
|
# pointer to where we store the result, the old value first, then the new.
|
|
movl 8(%ebp), %ebx
|
|
movl %eax, 0(%ebx)
|
|
movl %edx, 4(%ebx)
|
|
popl %ebx
|
|
leavel
|
|
retl $0x4
|