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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/linux-syscalls.h>
#include <machine/cpu-features.h>
.global __atomic_cmpxchg
.type __atomic_cmpxchg, %function
.global __atomic_swap
.type __atomic_swap, %function
.global __atomic_dec
.type __atomic_dec, %function
.global __atomic_inc
.type __atomic_inc, %function
#define FUTEX_WAIT 0
#define FUTEX_WAKE 1
#if 1
.equ kernel_cmpxchg, 0xFFFF0FC0
.equ kernel_atomic_base, 0xFFFF0FFF
__atomic_dec:
.fnstart
.save {r4, lr}
stmdb sp!, {r4, lr}
mov r2, r0
1: @ atomic_dec
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
sub r1, r0, #1
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
add r0, r1, #1
ldmia sp!, {r4, lr}
bx lr
.fnend
__atomic_inc:
.fnstart
.save {r4, lr}
stmdb sp!, {r4, lr}
mov r2, r0
1: @ atomic_inc
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
add r1, r0, #1
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
sub r0, r1, #1
ldmia sp!, {r4, lr}
bx lr
.fnend
/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
__atomic_cmpxchg:
.fnstart
.save {r4, lr}
stmdb sp!, {r4, lr}
mov r4, r0 /* r4 = save oldvalue */
1: @ atomic_cmpxchg
mov r3, #kernel_atomic_base
add lr, pc, #4
mov r0, r4 /* r0 = oldvalue */
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcs 2f /* swap was made. we're good, return. */
ldr r3, [r2] /* swap not made, see if it's because *ptr!=oldvalue */
cmp r3, r4
beq 1b
2: @ atomic_cmpxchg
ldmia sp!, {r4, lr}
bx lr
.fnend
#else
#define KUSER_CMPXCHG 0xffffffc0
/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
__atomic_cmpxchg:
stmdb sp!, {r4, lr}
mov r4, r0 /* r4 = save oldvalue */
1: add lr, pc, #4
mov r0, r4 /* r0 = oldvalue */
mov pc, #KUSER_CMPXCHG
bcs 2f /* swap was made. we're good, return. */
ldr r3, [r2] /* swap not made, see if it's because *ptr!=oldvalue */
cmp r3, r4
beq 1b
2: ldmia sp!, {r4, lr}
bx lr
/* r0(addr) -> r0(old) */
__atomic_dec:
stmdb sp!, {r4, lr}
mov r2, r0 /* address */
1: ldr r0, [r2] /* oldvalue */
add lr, pc, #4
sub r1, r0, #1 /* newvalue = oldvalue - 1 */
mov pc, #KUSER_CMPXCHG
bcc 1b /* no swap, try again until we get it right */
mov r0, ip /* swapped, return the old value */
ldmia sp!, {r4, lr}
bx lr
/* r0(addr) -> r0(old) */
__atomic_inc:
stmdb sp!, {r4, lr}
mov r2, r0 /* address */
1: ldr r0, [r2] /* oldvalue */
add lr, pc, #4
add r1, r0, #1 /* newvalue = oldvalue + 1 */
mov pc, #KUSER_CMPXCHG
bcc 1b /* no swap, try again until we get it right */
mov r0, ip /* swapped, return the old value */
ldmia sp!, {r4, lr}
bx lr
#endif
/* r0(new) r1(addr) -> r0(old) */
/* replaced swp instruction with ldrex/strex for ARMv6 & ARMv7 */
__atomic_swap:
#if defined (__ARM_HAVE_LDREX_STREX)
1: ldrex r2, [r1]
strex r3, r0, [r1]
teq r3, #0
bne 1b
mov r0, r2
mcr p15, 0, r0, c7, c10, 5 /* or, use dmb */
#else
swp r0, r0, [r1]
#endif
bx lr
/* __futex_wait(*ftx, val, *timespec) */
/* __futex_wake(*ftx, counter) */
/* __futex_syscall3(*ftx, op, val) */
/* __futex_syscall4(*ftx, op, val, *timespec) */
.global __futex_wait
.type __futex_wait, %function
.global __futex_wake
.type __futex_wake, %function
.global __futex_syscall3
.type __futex_syscall3, %function
.global __futex_syscall4
.type __futex_syscall4, %function
#if __ARM_EABI__
__futex_syscall3:
.fnstart
stmdb sp!, {r4, r7}
.save {r4, r7}
ldr r7, =__NR_futex
swi #0
ldmia sp!, {r4, r7}
bx lr
.fnend
__futex_wait:
.fnstart
stmdb sp!, {r4, r7}
.save {r4, r7}
mov r3, r2
mov r2, r1
mov r1, #FUTEX_WAIT
ldr r7, =__NR_futex
swi #0
ldmia sp!, {r4, r7}
bx lr
.fnend
__futex_wake:
stmdb sp!, {r4, r7}
mov r2, r1
mov r1, #FUTEX_WAKE
ldr r7, =__NR_futex
swi #0
ldmia sp!, {r4, r7}
bx lr
#else
__futex_syscall3:
swi #__NR_futex
bx lr
__futex_wait:
mov r3, r2
mov r2, r1
mov r1, #FUTEX_WAIT
swi #__NR_futex
bx lr
__futex_wake:
mov r2, r1
mov r1, #FUTEX_WAKE
swi #__NR_futex
bx lr
#endif
__futex_syscall4:
b __futex_syscall3
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