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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_PARISC_FUTEX_H
#define _ASM_PARISC_FUTEX_H
#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/atomic.h>
#include <asm/errno.h>
/* The following has to match the LWS code in syscall.S. We have
* 256 four-word locks. We use bits 20-27 of the futex virtual
* address for the hash index.
*/
static inline unsigned long _futex_hash_index(unsigned long ua)
{
return (ua >> 2) & 0x3fc;
}
static inline void
_futex_spin_lock_irqsave(arch_spinlock_t *s, unsigned long *flags)
{
local_irq_save(*flags);
arch_spin_lock(s);
}
static inline void
_futex_spin_unlock_irqrestore(arch_spinlock_t *s, unsigned long *flags)
{
arch_spin_unlock(s);
local_irq_restore(*flags);
}
static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
{
extern u32 lws_lock_start[];
unsigned long ua = (unsigned long)uaddr;
arch_spinlock_t *s;
unsigned long flags;
int oldval, ret;
u32 tmp;
s = (arch_spinlock_t *)&lws_lock_start[_futex_hash_index(ua)];
_futex_spin_lock_irqsave(s, &flags);
/* Return -EFAULT if we encounter a page fault or COW break */
if (unlikely(get_user(oldval, uaddr) != 0)) {
ret = -EFAULT;
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;
goto out_pagefault_enable;
}
if (unlikely(put_user(tmp, uaddr) != 0))
ret = -EFAULT;
out_pagefault_enable:
_futex_spin_unlock_irqrestore(s, &flags);
if (!ret)
*oval = oldval;
return ret;
}
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
extern u32 lws_lock_start[];
unsigned long ua = (unsigned long)uaddr;
arch_spinlock_t *s;
u32 val;
unsigned long flags;
/* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
* our gateway page, and causes no end of trouble...
*/
if (uaccess_kernel() && !uaddr)
return -EFAULT;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
/* HPPA has no cmpxchg in hardware and therefore the
* best we can do here is use an array of locks. The
* lock selected is based on a hash of the virtual
* address of the futex. This should scale to a couple
* of CPUs.
*/
s = (arch_spinlock_t *)&lws_lock_start[_futex_hash_index(ua)];
_futex_spin_lock_irqsave(s, &flags);
if (unlikely(get_user(val, uaddr) != 0)) {
_futex_spin_unlock_irqrestore(s, &flags);
return -EFAULT;
}
if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
_futex_spin_unlock_irqrestore(s, &flags);
return -EFAULT;
}
*uval = val;
_futex_spin_unlock_irqrestore(s, &flags);
return 0;
}
#endif /*_ASM_PARISC_FUTEX_H*/
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