arch/riscv/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (c) 2006  Ralf Baechle (ralf@linux-mips.org)
   4  * Copyright (c) 2018  Jim Wilson (jimw@sifive.com)
   5  */
   6
   7 #ifndef _ASM_RISCV_FUTEX_H
   8 #define _ASM_RISCV_FUTEX_H
   9
  10 #include <linux/futex.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/errno.h>
  13 #include <asm/asm.h>
  14 #include <asm/asm-extable.h>
  15
  16 /* We don't even really need the extable code, but for now keep it simple */
  17 #ifndef CONFIG_MMU
  18 #define __enable_user_access()          do { } while (0)
  19 #define __disable_user_access()         do { } while (0)
  20 #endif
  21
  22 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
  23 {                                                               \
  24         __enable_user_access();                                 \
  25         __asm__ __volatile__ (                                  \
  26         "1:     " insn "                                \n"     \
  27         "2:                                             \n"     \
  28         _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r])                  \
  29         : [r] "+r" (ret), [ov] "=&r" (oldval),                  \
  30           [u] "+m" (*uaddr)                                     \
  31         : [op] "Jr" (oparg)                                     \
  32         : "memory");                                            \
  33         __disable_user_access();                                \
  34 }
  35
  36 static inline int
  37 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
  38 {
  39         int oldval = 0, ret = 0;
  40
  41         if (!access_ok(uaddr, sizeof(u32)))
  42                 return -EFAULT;
  43
  44         switch (op) {
  45         case FUTEX_OP_SET:
  46                 __futex_atomic_op("amoswap.w.aqrl %[ov],%z[op],%[u]",
  47                                   ret, oldval, uaddr, oparg);
  48                 break;
  49         case FUTEX_OP_ADD:
  50                 __futex_atomic_op("amoadd.w.aqrl %[ov],%z[op],%[u]",
  51                                   ret, oldval, uaddr, oparg);
  52                 break;
  53         case FUTEX_OP_OR:
  54                 __futex_atomic_op("amoor.w.aqrl %[ov],%z[op],%[u]",
  55                                   ret, oldval, uaddr, oparg);
  56                 break;
  57         case FUTEX_OP_ANDN:
  58                 __futex_atomic_op("amoand.w.aqrl %[ov],%z[op],%[u]",
  59                                   ret, oldval, uaddr, ~oparg);
  60                 break;
  61         case FUTEX_OP_XOR:
  62                 __futex_atomic_op("amoxor.w.aqrl %[ov],%z[op],%[u]",
  63                                   ret, oldval, uaddr, oparg);
  64                 break;
  65         default:
  66                 ret = -ENOSYS;
  67         }
  68
  69         if (!ret)
  70                 *oval = oldval;
  71
  72         return ret;
  73 }
  74
  75 static inline int
  76 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  77                               u32 oldval, u32 newval)
  78 {
  79         int ret = 0;
  80         u32 val;
  81         uintptr_t tmp;
  82
  83         if (!access_ok(uaddr, sizeof(u32)))
  84                 return -EFAULT;
  85
  86         __enable_user_access();
  87         __asm__ __volatile__ (
  88         "1:     lr.w.aqrl %[v],%[u]                     \n"
  89         "       bne %[v],%z[ov],3f                      \n"
  90         "2:     sc.w.aqrl %[t],%z[nv],%[u]              \n"
  91         "       bnez %[t],1b                            \n"
  92         "3:                                             \n"
  93                 _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r])  \
  94                 _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r])  \
  95         : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
  96         : [ov] "Jr" (oldval), [nv] "Jr" (newval)
  97         : "memory");
  98         __disable_user_access();
  99
 100         *uval = val;
 101         return ret;
 102 }
 103
 104 #endif /* _ASM_RISCV_FUTEX_H */