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, %w7\n"                                             \
  29 "3:\n"                                                                  \
  30 "       dmb     ish\n"                                                  \
  31 "       .pushsection .fixup,\"ax\"\n"                                   \
  32 "       .align  2\n"                                                    \
  33 "4:     mov     %w0, %w6\n"                                             \
  34 "       b       3b\n"                                                   \
  35 "       .popsection\n"                                                  \
  36         _ASM_EXTABLE(1b, 4b)                                            \
  37         _ASM_EXTABLE(2b, 4b)                                            \
  38         : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),      \
  39           "+r" (loops)                                                  \
  40         : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN)                   \
  41         : "memory");                                                    \
  42         uaccess_disable_privileged();                                   \
  43 } while (0)
  44
  45 static inline int
  46 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
  47 {
  48         int oldval = 0, ret, tmp;
  49         u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
  50
  51         if (!access_ok(_uaddr, sizeof(u32)))
  52                 return -EFAULT;
  53
  54         switch (op) {
  55         case FUTEX_OP_SET:
  56                 __futex_atomic_op("mov  %w3, %w5",
  57                                   ret, oldval, uaddr, tmp, oparg);
  58                 break;
  59         case FUTEX_OP_ADD:
  60                 __futex_atomic_op("add  %w3, %w1, %w5",
  61                                   ret, oldval, uaddr, tmp, oparg);
  62                 break;
  63         case FUTEX_OP_OR:
  64                 __futex_atomic_op("orr  %w3, %w1, %w5",
  65                                   ret, oldval, uaddr, tmp, oparg);
  66                 break;
  67         case FUTEX_OP_ANDN:
  68                 __futex_atomic_op("and  %w3, %w1, %w5",
  69                                   ret, oldval, uaddr, tmp, ~oparg);
  70                 break;
  71         case FUTEX_OP_XOR:
  72                 __futex_atomic_op("eor  %w3, %w1, %w5",
  73                                   ret, oldval, uaddr, tmp, oparg);
  74                 break;
  75         default:
  76                 ret = -ENOSYS;
  77         }
  78
  79         if (!ret)
  80                 *oval = oldval;
  81
  82         return ret;
  83 }
  84
  85 static inline int
  86 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
  87                               u32 oldval, u32 newval)
  88 {
  89         int ret = 0;
  90         unsigned int loops = FUTEX_MAX_LOOPS;
  91         u32 val, tmp;
  92         u32 __user *uaddr;
  93
  94         if (!access_ok(_uaddr, sizeof(u32)))
  95                 return -EFAULT;
  96
  97         uaddr = __uaccess_mask_ptr(_uaddr);
  98         uaccess_enable_privileged();
  99         asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 100 "       prfm    pstl1strm, %2\n"
 101 "1:     ldxr    %w1, %2\n"
 102 "       sub     %w3, %w1, %w5\n"
 103 "       cbnz    %w3, 4f\n"
 104 "2:     stlxr   %w3, %w6, %2\n"
 105 "       cbz     %w3, 3f\n"
 106 "       sub     %w4, %w4, %w3\n"
 107 "       cbnz    %w4, 1b\n"
 108 "       mov     %w0, %w8\n"
 109 "3:\n"
 110 "       dmb     ish\n"
 111 "4:\n"
 112 "       .pushsection .fixup,\"ax\"\n"
 113 "5:     mov     %w0, %w7\n"
 114 "       b       4b\n"
 115 "       .popsection\n"
 116         _ASM_EXTABLE(1b, 5b)
 117         _ASM_EXTABLE(2b, 5b)
 118         : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
 119         : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
 120         : "memory");
 121         uaccess_disable_privileged();
 122
 123         if (!ret)
 124                 *uval = val;
 125
 126         return ret;
 127 }
 128
 129 #endif /* __ASM_FUTEX_H */