arch/arc/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4  *
   5  * Vineetg: August 2010: From Android kernel work
   6  */
   7
   8 #ifndef _ASM_FUTEX_H
   9 #define _ASM_FUTEX_H
  10
  11 #include <linux/futex.h>
  12 #include <linux/preempt.h>
  13 #include <linux/uaccess.h>
  14 #include <asm/errno.h>
  15
  16 #ifdef CONFIG_ARC_HAS_LLSC
  17
  18 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  19                                                         \
  20         smp_mb();                                       \
  21         __asm__ __volatile__(                           \
  22         "1:     llock   %1, [%2]                \n"     \
  23                 insn                            "\n"    \
  24         "2:     scond   %0, [%2]                \n"     \
  25         "       bnz     1b                      \n"     \
  26         "       mov %0, 0                       \n"     \
  27         "3:                                     \n"     \
  28         "       .section .fixup,\"ax\"          \n"     \
  29         "       .align  4                       \n"     \
  30         "4:     mov %0, %4                      \n"     \
  31         "       j   3b                          \n"     \
  32         "       .previous                       \n"     \
  33         "       .section __ex_table,\"a\"       \n"     \
  34         "       .align  4                       \n"     \
  35         "       .word   1b, 4b                  \n"     \
  36         "       .word   2b, 4b                  \n"     \
  37         "       .previous                       \n"     \
  38                                                         \
  39         : "=&r" (ret), "=&r" (oldval)                   \
  40         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  41         : "cc", "memory");                              \
  42         smp_mb()                                        \
  43
  44 #else   /* !CONFIG_ARC_HAS_LLSC */
  45
  46 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  47                                                         \
  48         smp_mb();                                       \
  49         __asm__ __volatile__(                           \
  50         "1:     ld      %1, [%2]                \n"     \
  51                 insn                            "\n"    \
  52         "2:     st      %0, [%2]                \n"     \
  53         "       mov %0, 0                       \n"     \
  54         "3:                                     \n"     \
  55         "       .section .fixup,\"ax\"          \n"     \
  56         "       .align  4                       \n"     \
  57         "4:     mov %0, %4                      \n"     \
  58         "       j   3b                          \n"     \
  59         "       .previous                       \n"     \
  60         "       .section __ex_table,\"a\"       \n"     \
  61         "       .align  4                       \n"     \
  62         "       .word   1b, 4b                  \n"     \
  63         "       .word   2b, 4b                  \n"     \
  64         "       .previous                       \n"     \
  65                                                         \
  66         : "=&r" (ret), "=&r" (oldval)                   \
  67         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  68         : "cc", "memory");                              \
  69         smp_mb()                                        \
  70
  71 #endif
  72
  73 static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
  74                 u32 __user *uaddr)
  75 {
  76         int oldval = 0, ret;
  77
  78         if (!access_ok(uaddr, sizeof(u32)))
  79                 return -EFAULT;
  80
  81 #ifndef CONFIG_ARC_HAS_LLSC
  82         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
  83 #endif
  84
  85         switch (op) {
  86         case FUTEX_OP_SET:
  87                 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  88                 break;
  89         case FUTEX_OP_ADD:
  90                 /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
  91                 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
  92                 break;
  93         case FUTEX_OP_OR:
  94                 __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
  95                 break;
  96         case FUTEX_OP_ANDN:
  97                 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
  98                 break;
  99         case FUTEX_OP_XOR:
 100                 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
 101                 break;
 102         default:
 103                 ret = -ENOSYS;
 104         }
 105
 106 #ifndef CONFIG_ARC_HAS_LLSC
 107         preempt_enable();
 108 #endif
 109
 110         if (!ret)
 111                 *oval = oldval;
 112
 113         return ret;
 114 }
 115
 116 /*
 117  * cmpxchg of futex (pagefaults disabled by caller)
 118  * Return 0 for success, -EFAULT otherwise
 119  */
 120 static inline int
 121 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
 122                               u32 newval)
 123 {
 124         int ret = 0;
 125         u32 existval;
 126
 127         if (!access_ok(uaddr, sizeof(u32)))
 128                 return -EFAULT;
 129
 130 #ifndef CONFIG_ARC_HAS_LLSC
 131         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
 132 #endif
 133         smp_mb();
 134
 135         __asm__ __volatile__(
 136 #ifdef CONFIG_ARC_HAS_LLSC
 137         "1:     llock   %1, [%4]                \n"
 138         "       brne    %1, %2, 3f              \n"
 139         "2:     scond   %3, [%4]                \n"
 140         "       bnz     1b                      \n"
 141 #else
 142         "1:     ld      %1, [%4]                \n"
 143         "       brne    %1, %2, 3f              \n"
 144         "2:     st      %3, [%4]                \n"
 145 #endif
 146         "3:     \n"
 147         "       .section .fixup,\"ax\"  \n"
 148         "4:     mov %0, %5      \n"
 149         "       j   3b  \n"
 150         "       .previous       \n"
 151         "       .section __ex_table,\"a\"       \n"
 152         "       .align  4       \n"
 153         "       .word   1b, 4b  \n"
 154         "       .word   2b, 4b  \n"
 155         "       .previous\n"
 156         : "+&r"(ret), "=&r"(existval)
 157         : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 158         : "cc", "memory");
 159
 160         smp_mb();
 161
 162 #ifndef CONFIG_ARC_HAS_LLSC
 163         preempt_enable();
 164 #endif
 165         *uval = existval;
 166         return ret;
 167 }
 168
 169 #endif