arch/parisc/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_PARISC_FUTEX_H
   3 #define _ASM_PARISC_FUTEX_H
   4
   5 #ifdef __KERNEL__
   6
   7 #include <linux/futex.h>
   8 #include <linux/uaccess.h>
   9 #include <asm/atomic.h>
  10 #include <asm/errno.h>
  11
  12 /* The following has to match the LWS code in syscall.S.  We have
  13    sixteen four-word locks. */
  14
  15 static inline void
  16 _futex_spin_lock_irqsave(u32 __user *uaddr, unsigned long int *flags)
  17 {
  18         extern u32 lws_lock_start[];
  19         long index = ((long)uaddr & 0x3f8) >> 1;
  20         arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
  21         local_irq_save(*flags);
  22         arch_spin_lock(s);
  23 }
  24
  25 static inline void
  26 _futex_spin_unlock_irqrestore(u32 __user *uaddr, unsigned long int *flags)
  27 {
  28         extern u32 lws_lock_start[];
  29         long index = ((long)uaddr & 0x3f8) >> 1;
  30         arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
  31         arch_spin_unlock(s);
  32         local_irq_restore(*flags);
  33 }
  34
  35 static inline int
  36 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
  37 {
  38         unsigned long int flags;
  39         int oldval, ret;
  40         u32 tmp;
  41
  42         _futex_spin_lock_irqsave(uaddr, &flags);
  43
  44         ret = -EFAULT;
  45         if (unlikely(get_user(oldval, uaddr) != 0))
  46                 goto out_pagefault_enable;
  47
  48         ret = 0;
  49         tmp = oldval;
  50
  51         switch (op) {
  52         case FUTEX_OP_SET:
  53                 tmp = oparg;
  54                 break;
  55         case FUTEX_OP_ADD:
  56                 tmp += oparg;
  57                 break;
  58         case FUTEX_OP_OR:
  59                 tmp |= oparg;
  60                 break;
  61         case FUTEX_OP_ANDN:
  62                 tmp &= ~oparg;
  63                 break;
  64         case FUTEX_OP_XOR:
  65                 tmp ^= oparg;
  66                 break;
  67         default:
  68                 ret = -ENOSYS;
  69         }
  70
  71         if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
  72                 ret = -EFAULT;
  73
  74 out_pagefault_enable:
  75         _futex_spin_unlock_irqrestore(uaddr, &flags);
  76
  77         if (!ret)
  78                 *oval = oldval;
  79
  80         return ret;
  81 }
  82
  83 static inline int
  84 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  85                               u32 oldval, u32 newval)
  86 {
  87         u32 val;
  88         unsigned long flags;
  89
  90         /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
  91          * our gateway page, and causes no end of trouble...
  92          */
  93         if (uaccess_kernel() && !uaddr)
  94                 return -EFAULT;
  95
  96         if (!access_ok(uaddr, sizeof(u32)))
  97                 return -EFAULT;
  98
  99         /* HPPA has no cmpxchg in hardware and therefore the
 100          * best we can do here is use an array of locks. The
 101          * lock selected is based on a hash of the userspace
 102          * address. This should scale to a couple of CPUs.
 103          */
 104
 105         _futex_spin_lock_irqsave(uaddr, &flags);
 106         if (unlikely(get_user(val, uaddr) != 0)) {
 107                 _futex_spin_unlock_irqrestore(uaddr, &flags);
 108                 return -EFAULT;
 109         }
 110
 111         if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
 112                 _futex_spin_unlock_irqrestore(uaddr, &flags);
 113                 return -EFAULT;
 114         }
 115
 116         *uval = val;
 117         _futex_spin_unlock_irqrestore(uaddr, &flags);
 118
 119         return 0;
 120 }
 121
 122 #endif /*__KERNEL__*/
 123 #endif /*_ASM_PARISC_FUTEX_H*/