[linux-block.git] / include / asm-generic / futex.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_GENERIC_FUTEX_H
#define _ASM_GENERIC_FUTEX_H

#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/errno.h>

#ifndef CONFIG_SMP
/*
 * The following implementation only for uniprocessor machines.
 * It relies on preempt_disable() ensuring mutual exclusion.
 *
 */

/**
 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
 *			  argument and comparison of the previous
 *			  futex value with another constant.
 *
 * @encoded_op:	encoded operation to execute
 * @uaddr:	pointer to user space address
 *
 * Return:
 * 0 - On success
 * -EFAULT - User access resulted in a page fault
 * -EAGAIN - Atomic operation was unable to complete due to contention
 * -ENOSYS - Operation not supported
 */
static inline int
arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
{
	int oldval, ret;
	u32 tmp;

	preempt_disable();

	ret = -EFAULT;
	if (unlikely(get_user(oldval, uaddr) != 0))
		goto out_pagefault_enable;

	ret = 0;
	tmp = oldval;

	switch (op) {
	case FUTEX_OP_SET:
		tmp = oparg;
		break;
	case FUTEX_OP_ADD:
		tmp += oparg;
		break;
	case FUTEX_OP_OR:
		tmp |= oparg;
		break;
	case FUTEX_OP_ANDN:
		tmp &= ~oparg;
		break;
	case FUTEX_OP_XOR:
		tmp ^= oparg;
		break;
	default:
		ret = -ENOSYS;
	}

	if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
		ret = -EFAULT;

out_pagefault_enable:
	preempt_enable();

	if (ret == 0)
		*oval = oldval;

	return ret;
}

/**
 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
 *				uaddr with newval if the current value is
 *				oldval.
 * @uval:	pointer to store content of @uaddr
 * @uaddr:	pointer to user space address
 * @oldval:	old value
 * @newval:	new value to store to @uaddr
 *
 * Return:
 * 0 - On success
 * -EFAULT - User access resulted in a page fault
 * -EAGAIN - Atomic operation was unable to complete due to contention
 * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
 */
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
			      u32 oldval, u32 newval)
{
	u32 val;

	preempt_disable();
	if (unlikely(get_user(val, uaddr) != 0)) {
		preempt_enable();
		return -EFAULT;
	}

	if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
		preempt_enable();
		return -EFAULT;
	}

	*uval = val;
	preempt_enable();

	return 0;
}

#else
static inline int
arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
{
	return -ENOSYS;
}

static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
			      u32 oldval, u32 newval)
{
	return -ENOSYS;
}

#endif /* CONFIG_SMP */
#endif
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
f8aaeace JD	2	#ifndef _ASM_GENERIC_FUTEX_H
	3	#define _ASM_GENERIC_FUTEX_H
	4
f8aaeace	5	#include <linux/futex.h>
730f412c	6	#include <linux/uaccess.h>
f8aaeace	7	#include <asm/errno.h>
f8aaeace	8
00f634bc LFT	9	#ifndef CONFIG_SMP
	10	/*
	11	* The following implementation only for uniprocessor machines.
f3dae07e	12	* It relies on preempt_disable() ensuring mutual exclusion.
00f634bc LFT	13	*
	14	*/
	15
	16	/**
30d6e0a4	17	* arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
00f634bc LFT	18	* argument and comparison of the previous
	19	* futex value with another constant.
	20	*
	21	* @encoded_op: encoded operation to execute
	22	* @uaddr: pointer to user space address
	23	*
	24	* Return:
	25	* 0 - On success
42750351 WD	26	* -EFAULT - User access resulted in a page fault
	27	* -EAGAIN - Atomic operation was unable to complete due to contention
	28	* -ENOSYS - Operation not supported
00f634bc LFT	29	*/
00f634bc LFT	30	static inline int
30d6e0a4	31	arch_futex_atomic_op_inuser(int op, u32 oparg, int oval, u32 __user uaddr)
00f634bc	32	{
00f634bc LFT	33	int oldval, ret;
	34	u32 tmp;
	35
f3dae07e	36	preempt_disable();
00f634bc LFT	37
	38	ret = -EFAULT;
	39	if (unlikely(get_user(oldval, uaddr) != 0))
	40	goto out_pagefault_enable;
	41
	42	ret = 0;
	43	tmp = oldval;
	44
	45	switch (op) {
	46	case FUTEX_OP_SET:
	47	tmp = oparg;
	48	break;
	49	case FUTEX_OP_ADD:
	50	tmp += oparg;
	51	break;
	52	case FUTEX_OP_OR:
	53	tmp \|= oparg;
	54	break;
	55	case FUTEX_OP_ANDN:
	56	tmp &= ~oparg;
	57	break;
	58	case FUTEX_OP_XOR:
	59	tmp ^= oparg;
	60	break;
	61	default:
	62	ret = -ENOSYS;
	63	}
	64
	65	if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
	66	ret = -EFAULT;
	67
	68	out_pagefault_enable:
f3dae07e	69	preempt_enable();
00f634bc	70
30d6e0a4 JS	71	if (ret == 0)
	72	*oval = oldval;
	73
00f634bc LFT	74	return ret;
	75	}
	76
	77	/**
	78	* futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
	79	* uaddr with newval if the current value is
	80	* oldval.
	81	* @uval: pointer to store content of @uaddr
	82	* @uaddr: pointer to user space address
	83	* @oldval: old value
	84	* @newval: new value to store to @uaddr
	85	*
	86	* Return:
	87	* 0 - On success
42750351 WD	88	* -EFAULT - User access resulted in a page fault
	89	* -EAGAIN - Atomic operation was unable to complete due to contention
	90	* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
00f634bc LFT	91	*/
	92	static inline int
	93	futex_atomic_cmpxchg_inatomic(u32 uval, u32 __user uaddr,
	94	u32 oldval, u32 newval)
	95	{
	96	u32 val;
	97
d9b9ff8c	98	preempt_disable();
fba7cd68 RP	99	if (unlikely(get_user(val, uaddr) != 0)) {
fba7cd68 RP	100	preempt_enable();
00f634bc	101	return -EFAULT;
fba7cd68	102	}
00f634bc	103
fba7cd68 RP	104	if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
fba7cd68 RP	105	preempt_enable();
00f634bc	106	return -EFAULT;
fba7cd68	107	}
00f634bc LFT	108
00f634bc LFT	109	*uval = val;
d9b9ff8c	110	preempt_enable();
00f634bc LFT	111
	112	return 0;
	113	}
	114
	115	#else
f8aaeace	116	static inline int
30d6e0a4	117	arch_futex_atomic_op_inuser(int op, u32 oparg, int oval, u32 __user uaddr)
f8aaeace	118	{
f9adc23e	119	return -ENOSYS;
f8aaeace JD	120	}
f8aaeace JD	121
e9056f13	122	static inline int
8d7718aa ML	123	futex_atomic_cmpxchg_inatomic(u32 uval, u32 __user uaddr,
8d7718aa ML	124	u32 oldval, u32 newval)
e9056f13 IM	125	{
	126	return -ENOSYS;
	127	}
	128
00f634bc	129	#endif /* CONFIG_SMP */
f8aaeace	130	#endif