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

 
 1#ifndef _ASM_GENERIC_FUTEX_H
 2#define _ASM_GENERIC_FUTEX_H
 3
 4#include <linux/futex.h>
 5#include <linux/uaccess.h>
 6#include <asm/errno.h>
 7
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 8static inline int
 9futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
10{
11	int op = (encoded_op >> 28) & 7;
12	int cmp = (encoded_op >> 24) & 15;
13	int oparg = (encoded_op << 8) >> 20;
14	int cmparg = (encoded_op << 20) >> 20;
15	int oldval = 0, ret;
16	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
17		oparg = 1 << oparg;
18
19	if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32)))
20		return -EFAULT;
 
 
 
21
22	pagefault_disable();
 
23
24	switch (op) {
25	case FUTEX_OP_SET:
 
 
26	case FUTEX_OP_ADD:
 
 
27	case FUTEX_OP_OR:
 
 
28	case FUTEX_OP_ANDN:
 
 
29	case FUTEX_OP_XOR:
 
 
30	default:
31		ret = -ENOSYS;
32	}
33
34	pagefault_enable();
 
 
 
 
 
 
 
35
36	if (!ret) {
37		switch (cmp) {
38		case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
39		case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
40		case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
41		case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
42		case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
43		case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
44		default: ret = -ENOSYS;
45		}
46	}
47	return ret;
48}
49
 
 
 
 
 
 
 
 
 
 
 
 
 
 
50static inline int
51futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
52			      u32 oldval, u32 newval)
53{
54	return -ENOSYS;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
55}
56
57#endif