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 #ifdef __KERNEL__
   9
  10 #include <linux/futex.h>
  11 #include <linux/uaccess.h>
  12
  13 #include <asm/errno.h>
  14
  15 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
  16
  17 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  18 do {                                                                    \
  19         unsigned int loops = FUTEX_MAX_LOOPS;                           \
  20                                                                         \
  21         uaccess_enable();                                               \
  22         asm volatile(                                                   \
  23 "       prfm    pstl1strm, %2\n"                                        \
  24 "1:     ldxr    %w1, %2\n"                                              \
  25         insn "\n"                                                       \
  26 "2:     stlxr   %w0, %w3, %2\n"                                         \
  27 "       cbz     %w0, 3f\n"                                              \
  28 "       sub     %w4, %w4, %w0\n"                                        \
  29 "       cbnz    %w4, 1b\n"                                              \
  30 "       mov     %w0, %w7\n"                                             \
  31 "3:\n"                                                                  \
  32 "       dmb     ish\n"                                                  \
  33 "       .pushsection .fixup,\"ax\"\n"                                   \
  34 "       .align  2\n"                                                    \
  35 "4:     mov     %w0, %w6\n"                                             \
  36 "       b       3b\n"                                                   \
  37 "       .popsection\n"                                                  \
  38         _ASM_EXTABLE(1b, 4b)                                            \
  39         _ASM_EXTABLE(2b, 4b)                                            \
  40         : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),      \
  41           "+r" (loops)                                                  \
  42         : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN)                   \
  43         : "memory");                                                    \
  44         uaccess_disable();                                              \
  45 } while (0)
  46
  47 static inline int
  48 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
  49 {
  50         int oldval = 0, ret, tmp;
  51         u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
  52
  53         pagefault_disable();
  54
  55         switch (op) {
  56         case FUTEX_OP_SET:
  57                 __futex_atomic_op("mov  %w3, %w5",
  58                                   ret, oldval, uaddr, tmp, oparg);
  59                 break;
  60         case FUTEX_OP_ADD:
  61                 __futex_atomic_op("add  %w3, %w1, %w5",
  62                                   ret, oldval, uaddr, tmp, oparg);
  63                 break;
  64         case FUTEX_OP_OR:
  65                 __futex_atomic_op("orr  %w3, %w1, %w5",
  66                                   ret, oldval, uaddr, tmp, oparg);
  67                 break;
  68         case FUTEX_OP_ANDN:
  69                 __futex_atomic_op("and  %w3, %w1, %w5",
  70                                   ret, oldval, uaddr, tmp, ~oparg);
  71                 break;
  72         case FUTEX_OP_XOR:
  73                 __futex_atomic_op("eor  %w3, %w1, %w5",
  74                                   ret, oldval, uaddr, tmp, oparg);
  75                 break;
  76         default:
  77                 ret = -ENOSYS;
  78         }
  79
  80         pagefault_enable();
  81
  82         if (!ret)
  83                 *oval = oldval;
  84
  85         return ret;
  86 }
  87
  88 static inline int
  89 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
  90                               u32 oldval, u32 newval)
  91 {
  92         int ret = 0;
  93         unsigned int loops = FUTEX_MAX_LOOPS;
  94         u32 val, tmp;
  95         u32 __user *uaddr;
  96
  97         if (!access_ok(_uaddr, sizeof(u32)))
  98                 return -EFAULT;
  99
 100         uaddr = __uaccess_mask_ptr(_uaddr);
 101         uaccess_enable();
 102         asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 103 "       prfm    pstl1strm, %2\n"
 104 "1:     ldxr    %w1, %2\n"
 105 "       sub     %w3, %w1, %w5\n"
 106 "       cbnz    %w3, 4f\n"
 107 "2:     stlxr   %w3, %w6, %2\n"
 108 "       cbz     %w3, 3f\n"
 109 "       sub     %w4, %w4, %w3\n"
 110 "       cbnz    %w4, 1b\n"
 111 "       mov     %w0, %w8\n"
 112 "3:\n"
 113 "       dmb     ish\n"
 114 "4:\n"
 115 "       .pushsection .fixup,\"ax\"\n"
 116 "5:     mov     %w0, %w7\n"
 117 "       b       4b\n"
 118 "       .popsection\n"
 119         _ASM_EXTABLE(1b, 5b)
 120         _ASM_EXTABLE(2b, 5b)
 121         : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
 122         : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
 123         : "memory");
 124         uaccess_disable();
 125
 126         if (!ret)
 127                 *uval = val;
 128
 129         return ret;
 130 }
 131
 132 #endif /* __KERNEL__ */
 133 #endif /* __ASM_FUTEX_H */