Viewing file:  futex.h (2.59 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* 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 futex_atomic_cmpxchg_inatomic
#ifndef CONFIG_SMP
/*
* The following implementation only for uniprocessor machines.
* It relies on preempt_disable() ensuring mutual exclusion.
*
*/
#define futex_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval) \
futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval)
#define arch_futex_atomic_op_inuser(op, oparg, oval, uaddr) \
futex_atomic_op_inuser_local(op, oparg, oval, uaddr)
#endif /* CONFIG_SMP */
#endif
/**
* futex_atomic_op_inuser_local() - 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
futex_atomic_op_inuser_local(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_local() - 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
*/
static inline int
futex_atomic_cmpxchg_inatomic_local(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;
}
#endif
|