[mirror_ubuntu-bionic-kernel.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
 * <0 - On error
 */
static inline int
arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
{
	int oldval, ret;
	u32 tmp;

	preempt_disable();
	pagefault_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:
	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
 * <0 - On error
 */
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)
{
	int oldval = 0, ret;

	pagefault_disable();

	switch (op) {
	case FUTEX_OP_SET:
	case FUTEX_OP_ADD:
	case FUTEX_OP_OR:
	case FUTEX_OP_ANDN:
	case FUTEX_OP_XOR:
	default:
		ret = -ENOSYS;
	}

	pagefault_enable();

	if (!ret)
		*oval = oldval;

	return ret;
}

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
	26	* <0 - On error
	27	*/
	28	static inline int
30d6e0a4	29	arch_futex_atomic_op_inuser(int op, u32 oparg, int oval, u32 __user uaddr)
00f634bc	30	{
00f634bc LFT	31	int oldval, ret;
	32	u32 tmp;
	33
f3dae07e	34	preempt_disable();
00f634bc LFT	35	pagefault_disable();
	36
	37	ret = -EFAULT;
	38	if (unlikely(get_user(oldval, uaddr) != 0))
	39	goto out_pagefault_enable;
	40
	41	ret = 0;
	42	tmp = oldval;
	43
	44	switch (op) {
	45	case FUTEX_OP_SET:
	46	tmp = oparg;
	47	break;
	48	case FUTEX_OP_ADD:
	49	tmp += oparg;
	50	break;
	51	case FUTEX_OP_OR:
	52	tmp \|= oparg;
	53	break;
	54	case FUTEX_OP_ANDN:
	55	tmp &= ~oparg;
	56	break;
	57	case FUTEX_OP_XOR:
	58	tmp ^= oparg;
	59	break;
	60	default:
	61	ret = -ENOSYS;
	62	}
	63
	64	if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
	65	ret = -EFAULT;
	66
	67	out_pagefault_enable:
	68	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
	88	* <0 - On error
	89	*/
	90	static inline int
	91	futex_atomic_cmpxchg_inatomic(u32 uval, u32 __user uaddr,
	92	u32 oldval, u32 newval)
	93	{
	94	u32 val;
	95
d9b9ff8c	96	preempt_disable();
fba7cd68 RP	97	if (unlikely(get_user(val, uaddr) != 0)) {
fba7cd68 RP	98	preempt_enable();
00f634bc	99	return -EFAULT;
fba7cd68	100	}
00f634bc	101
fba7cd68 RP	102	if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
fba7cd68 RP	103	preempt_enable();
00f634bc	104	return -EFAULT;
fba7cd68	105	}
00f634bc LFT	106
00f634bc LFT	107	*uval = val;
d9b9ff8c	108	preempt_enable();
00f634bc LFT	109
	110	return 0;
	111	}
	112
	113	#else
f8aaeace	114	static inline int
30d6e0a4	115	arch_futex_atomic_op_inuser(int op, u32 oparg, int oval, u32 __user uaddr)
f8aaeace	116	{
f8aaeace	117	int oldval = 0, ret;
f8aaeace	118
a866374a	119	pagefault_disable();
f8aaeace JD	120
	121	switch (op) {
	122	case FUTEX_OP_SET:
	123	case FUTEX_OP_ADD:
	124	case FUTEX_OP_OR:
	125	case FUTEX_OP_ANDN:
	126	case FUTEX_OP_XOR:
	127	default:
	128	ret = -ENOSYS;
	129	}
	130
a866374a	131	pagefault_enable();
f8aaeace	132
30d6e0a4 JS	133	if (!ret)
	134	*oval = oldval;
	135
f8aaeace JD	136	return ret;
	137	}
	138
e9056f13	139	static inline int
8d7718aa ML	140	futex_atomic_cmpxchg_inatomic(u32 uval, u32 __user uaddr,
8d7718aa ML	141	u32 oldval, u32 newval)
e9056f13 IM	142	{
	143	return -ENOSYS;
	144	}
	145
00f634bc	146	#endif /* CONFIG_SMP */
f8aaeace	147	#endif