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 CONFIG_SMP
 10/*
 11 * The following implementation only for uniprocessor machines.
 12 * It relies on preempt_disable() ensuring mutual exclusion.
 13 *
 14 */
 15
 16/**
 17 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
 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 * -EFAULT - User access resulted in a page fault
 27 * -EAGAIN - Atomic operation was unable to complete due to contention
 28 * -ENOSYS - Operation not supported
 29 */
 30static inline int
 31arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 32{
 33	int oldval, ret;
 34	u32 tmp;
 
 
 
 
 
 35
 36	preempt_disable();
 37	pagefault_disable();
 38
 39	ret = -EFAULT;
 40	if (unlikely(get_user(oldval, uaddr) != 0))
 41		goto out_pagefault_enable;
 42
 43	ret = 0;
 44	tmp = oldval;
 45
 46	switch (op) {
 47	case FUTEX_OP_SET:
 48		tmp = oparg;
 49		break;
 50	case FUTEX_OP_ADD:
 51		tmp += oparg;
 52		break;
 53	case FUTEX_OP_OR:
 54		tmp |= oparg;
 55		break;
 56	case FUTEX_OP_ANDN:
 57		tmp &= ~oparg;
 58		break;
 59	case FUTEX_OP_XOR:
 60		tmp ^= oparg;
 61		break;
 62	default:
 63		ret = -ENOSYS;
 64	}
 65
 66	if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
 67		ret = -EFAULT;
 68
 69out_pagefault_enable:
 70	pagefault_enable();
 71	preempt_enable();
 72
 73	if (ret == 0)
 74		*oval = oldval;
 75
 76	return ret;
 77}
 78
 79/**
 80 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
 81 *				uaddr with newval if the current value is
 82 *				oldval.
 83 * @uval:	pointer to store content of @uaddr
 84 * @uaddr:	pointer to user space address
 85 * @oldval:	old value
 86 * @newval:	new value to store to @uaddr
 87 *
 88 * Return:
 89 * 0 - On success
 90 * -EFAULT - User access resulted in a page fault
 91 * -EAGAIN - Atomic operation was unable to complete due to contention
 92 * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
 93 */
 94static inline int
 95futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 96			      u32 oldval, u32 newval)
 97{
 98	u32 val;
 99
100	preempt_disable();
101	if (unlikely(get_user(val, uaddr) != 0)) {
102		preempt_enable();
103		return -EFAULT;
 
 
 
 
 
 
104	}
105
106	if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
107		preempt_enable();
108		return -EFAULT;
109	}
110
111	*uval = val;
112	preempt_enable();
113
114	return 0;
115}
116
117#else
118static inline int
119arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
120{
121	return -ENOSYS;
122}
123
124static inline int
125futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
126			      u32 oldval, u32 newval)
127{
128	return -ENOSYS;
129}
130
131#endif /* CONFIG_SMP */
132#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