platform_bionic/libc/arch-arm/bionic/atomics_arm.S
Kenny Root 420878c690 Add function marks and size indications
Add a macro to annotate function end and start using both ENTRY and END
for each function. This allows valgrind (and presumably other debugging
tools) to use the debug symbols to trace the functions.

Change-Id: I5f09cef8e22fb356eb6f5cee952b031e567599b6
2011-02-17 09:07:25 -08:00

236 lines
6.5 KiB
ArmAsm

/*
* 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/asm.h>
#include <machine/cpu-features.h>
#define FUTEX_WAIT 0
#define FUTEX_WAKE 1
#if defined(__ARM_HAVE_LDREX_STREX)
/*
* ===========================================================================
* ARMv6+ implementation
* ===========================================================================
*/
/* r0(addr) -> r0(old) */
ENTRY(__atomic_dec)
mov r1, r0 @ copy addr so we don't clobber it
1: ldrex r0, [r1] @ load current value into r0
sub r2, r0, #1 @ generate new value into r2
strex r3, r2, [r1] @ try to store new value; result in r3
cmp r3, #0 @ success?
bxeq lr @ yes, return
b 1b @ no, retry
END(__atomic_dec)
/* r0(addr) -> r0(old) */
ENTRY(__atomic_inc)
mov r1, r0
1: ldrex r0, [r1]
add r2, r0, #1
strex r3, r2, [r1]
cmp r3, #0
bxeq lr
b 1b
END(__atomic_inc)
/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
ENTRY(__atomic_cmpxchg)
1: mov ip, #2 @ ip=2 means "new != old"
ldrex r3, [r2] @ load current value into r3
teq r0, r3 @ new == old?
strexeq ip, r1, [r2] @ yes, try store, set ip to 0 or 1
teq ip, #1 @ strex failure?
beq 1b @ yes, retry
mov r0, ip @ return 0 on success, 2 on failure
bx lr
END(__atomic_cmpxchg)
/* r0(new) r1(addr) -> r0(old) */
ENTRY(__atomic_swap)
1: ldrex r2, [r1]
strex r3, r0, [r1]
teq r3, #0
bne 1b
mov r0, r2
bx lr
END(__atomic_swap)
#else /*not defined __ARM_HAVE_LDREX_STREX*/
/*
* ===========================================================================
* Pre-ARMv6 implementation
* ===========================================================================
*/
/* int __kernel_cmpxchg(int oldval, int newval, int* ptr) */
.equ kernel_cmpxchg, 0xFFFF0FC0
.equ kernel_atomic_base, 0xFFFF0FFF
/* r0(addr) -> r0(old) */
ENTRY(__atomic_dec)
.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
END(__atomic_dec)
/* r0(addr) -> r0(old) */
ENTRY(__atomic_inc)
.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
END(__atomic_inc)
/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
ENTRY(__atomic_cmpxchg)
.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
END(__atomic_cmpxchg)
/* r0(new) r1(addr) -> r0(old) */
ENTRY(__atomic_swap)
swp r0, r0, [r1]
bx lr
END(__atomic_swap)
#endif /*not defined __ARM_HAVE_LDREX_STREX*/
/* __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__
ENTRY(__futex_syscall3)
stmdb sp!, {r4, r7}
.save {r4, r7}
ldr r7, =__NR_futex
swi #0
ldmia sp!, {r4, r7}
bx lr
END(__futex_syscall3)
ENTRY(__futex_wait)
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
END(__futex_wait)
ENTRY(__futex_wake)
.save {r4, r7}
stmdb sp!, {r4, r7}
mov r2, r1
mov r1, #FUTEX_WAKE
ldr r7, =__NR_futex
swi #0
ldmia sp!, {r4, r7}
bx lr
END(__futex_wake)
#else
ENTRY(__futex_syscall3)
swi #__NR_futex
bx lr
END(__futex_syscall3)
ENTRY(__futex_wait)
mov r3, r2
mov r2, r1
mov r1, #FUTEX_WAIT
swi #__NR_futex
bx lr
END(__futex_wait)
ENTRY(__futex_wake)
mov r2, r1
mov r1, #FUTEX_WAKE
swi #__NR_futex
bx lr
END(__futex_wake)
#endif
ENTRY(__futex_syscall4)
b __futex_syscall3
END(__futex_syscall4)