arch/arm64/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2012 ARM Ltd.
   4  */
   5 #ifndef __ASM_FUTEX_H
   6 #define __ASM_FUTEX_H
   7
   8 #include <linux/futex.h>
   9 #include <linux/uaccess.h>
  10
  11 #include <asm/errno.h>
  12
  13 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
  14
  15 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  16 do {                                                                    \
  17         unsigned int loops = FUTEX_MAX_LOOPS;                           \
  18                                                                         \
  19         uaccess_enable_privileged();                                    \
  20         asm volatile(                                                   \
  21 "       prfm    pstl1strm, %2\n"                                        \
  22 "1:     ldxr    %w1, %2\n"                                              \
  23         insn "\n"                                                       \
  24 "2:     stlxr   %w0, %w3, %2\n"                                         \
  25 "       cbz     %w0, 3f\n"                                              \
  26 "       sub     %w4, %w4, %w0\n"                                        \
  27 "       cbnz    %w4, 1b\n"                                              \
  28 "       mov     %w0, %w6\n"                                             \
  29 "3:\n"                                                                  \
  30 "       dmb     ish\n"                                                  \
  31         _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0)                           \
  32         _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0)                           \
  33         : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),      \
  34           "+r" (loops)                                                  \
  35         : "r" (oparg), "Ir" (-EAGAIN)                                   \
  36         : "memory");                                                    \
  37         uaccess_disable_privileged();                                   \
  38 } while (0)
  39
  40 static inline int
  41 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
  42 {
  43         int oldval = 0, ret, tmp;
  44         u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
  45
  46         if (!access_ok(_uaddr, sizeof(u32)))
  47                 return -EFAULT;
  48
  49         switch (op) {
  50         case FUTEX_OP_SET:
  51                 __futex_atomic_op("mov  %w3, %w5",
  52                                   ret, oldval, uaddr, tmp, oparg);
  53                 break;
  54         case FUTEX_OP_ADD:
  55                 __futex_atomic_op("add  %w3, %w1, %w5",
  56                                   ret, oldval, uaddr, tmp, oparg);
  57                 break;
  58         case FUTEX_OP_OR:
  59                 __futex_atomic_op("orr  %w3, %w1, %w5",
  60                                   ret, oldval, uaddr, tmp, oparg);
  61                 break;
  62         case FUTEX_OP_ANDN:
  63                 __futex_atomic_op("and  %w3, %w1, %w5",
  64                                   ret, oldval, uaddr, tmp, ~oparg);
  65                 break;
  66         case FUTEX_OP_XOR:
  67                 __futex_atomic_op("eor  %w3, %w1, %w5",
  68                                   ret, oldval, uaddr, tmp, oparg);
  69                 break;
  70         default:
  71                 ret = -ENOSYS;
  72         }
  73
  74         if (!ret)
  75                 *oval = oldval;
  76
  77         return ret;
  78 }
  79
  80 static inline int
  81 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
  82                               u32 oldval, u32 newval)
  83 {
  84         int ret = 0;
  85         unsigned int loops = FUTEX_MAX_LOOPS;
  86         u32 val, tmp;
  87         u32 __user *uaddr;
  88
  89         if (!access_ok(_uaddr, sizeof(u32)))
  90                 return -EFAULT;
  91
  92         uaddr = __uaccess_mask_ptr(_uaddr);
  93         uaccess_enable_privileged();
  94         asm volatile("// futex_atomic_cmpxchg_inatomic\n"
  95 "       prfm    pstl1strm, %2\n"
  96 "1:     ldxr    %w1, %2\n"
  97 "       sub     %w3, %w1, %w5\n"
  98 "       cbnz    %w3, 4f\n"
  99 "2:     stlxr   %w3, %w6, %2\n"
 100 "       cbz     %w3, 3f\n"
 101 "       sub     %w4, %w4, %w3\n"
 102 "       cbnz    %w4, 1b\n"
 103 "       mov     %w0, %w7\n"
 104 "3:\n"
 105 "       dmb     ish\n"
 106 "4:\n"
 107         _ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0)
 108         _ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0)
 109         : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
 110         : "r" (oldval), "r" (newval), "Ir" (-EAGAIN)
 111         : "memory");
 112         uaccess_disable_privileged();
 113
 114         if (!ret)
 115                 *uval = val;
 116
 117         return ret;
 118 }
 119
 120 #endif /* __ASM_FUTEX_H */