kernel/arch/xtensa/include/asm/futex.h

   1 /*
   2  * Atomic futex routines
   3  *
   4  * Based on the PowerPC implementataion
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Copyright (C) 2013 TangoTec Ltd.
  11  *
  12  * Baruch Siach <baruch@tkos.co.il>
  13  */
  14
  15 #ifndef _ASM_XTENSA_FUTEX_H
  16 #define _ASM_XTENSA_FUTEX_H
  17
  18 #ifdef __KERNEL__
  19
  20 #include <linux/futex.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/errno.h>
  23
  24 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
  25         __asm__ __volatile(                             \
  26         "1:     l32i    %0, %2, 0\n"                    \
  27                 insn "\n"                               \
  28         "       wsr     %0, scompare1\n"                \
  29         "2:     s32c1i  %1, %2, 0\n"                    \
  30         "       bne     %1, %0, 1b\n"                   \
  31         "       movi    %1, 0\n"                        \
  32         "3:\n"                                          \
  33         "       .section .fixup,\"ax\"\n"               \
  34         "       .align 4\n"                             \
  35         "4:     .long   3b\n"                           \
  36         "5:     l32r    %0, 4b\n"                       \
  37         "       movi    %1, %3\n"                       \
  38         "       jx      %0\n"                           \
  39         "       .previous\n"                            \
  40         "       .section __ex_table,\"a\"\n"            \
  41         "       .long 1b,5b,2b,5b\n"                    \
  42         "       .previous\n"                            \
  43         : "=&r" (oldval), "=&r" (ret)                   \
  44         : "r" (uaddr), "I" (-EFAULT), "r" (oparg)       \
  45         : "memory")
  46
  47 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  48 {
  49         int op = (encoded_op >> 28) & 7;
  50         int cmp = (encoded_op >> 24) & 15;
  51         int oparg = (encoded_op << 8) >> 20;
  52         int cmparg = (encoded_op << 20) >> 20;
  53         int oldval = 0, ret;
  54         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  55                 oparg = 1 << oparg;
  56
  57         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  58                 return -EFAULT;
  59
  60 #if !XCHAL_HAVE_S32C1I
  61         return -ENOSYS;
  62 #endif
  63
  64         pagefault_disable();
  65
  66         switch (op) {
  67         case FUTEX_OP_SET:
  68                 __futex_atomic_op("mov %1, %4", ret, oldval, uaddr, oparg);
  69                 break;
  70         case FUTEX_OP_ADD:
  71                 __futex_atomic_op("add %1, %0, %4", ret, oldval, uaddr,
  72                                 oparg);
  73                 break;
  74         case FUTEX_OP_OR:
  75                 __futex_atomic_op("or %1, %0, %4", ret, oldval, uaddr,
  76                                 oparg);
  77                 break;
  78         case FUTEX_OP_ANDN:
  79                 __futex_atomic_op("and %1, %0, %4", ret, oldval, uaddr,
  80                                 ~oparg);
  81                 break;
  82         case FUTEX_OP_XOR:
  83                 __futex_atomic_op("xor %1, %0, %4", ret, oldval, uaddr,
  84                                 oparg);
  85                 break;
  86         default:
  87                 ret = -ENOSYS;
  88         }
  89
  90         pagefault_enable();
  91
  92         if (ret)
  93                 return ret;
  94
  95         switch (cmp) {
  96         case FUTEX_OP_CMP_EQ: return (oldval == cmparg);
  97         case FUTEX_OP_CMP_NE: return (oldval != cmparg);
  98         case FUTEX_OP_CMP_LT: return (oldval < cmparg);
  99         case FUTEX_OP_CMP_GE: return (oldval >= cmparg);
 100         case FUTEX_OP_CMP_LE: return (oldval <= cmparg);
 101         case FUTEX_OP_CMP_GT: return (oldval > cmparg);
 102         }
 103
 104         return -ENOSYS;
 105 }
 106
 107 static inline int
 108 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 109                               u32 oldval, u32 newval)
 110 {
 111         int ret = 0;
 112         u32 prev;
 113
 114         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 115                 return -EFAULT;
 116
 117 #if !XCHAL_HAVE_S32C1I
 118         return -ENOSYS;
 119 #endif
 120
 121         __asm__ __volatile__ (
 122         "       # futex_atomic_cmpxchg_inatomic\n"
 123         "1:     l32i    %1, %3, 0\n"
 124         "       mov     %0, %5\n"
 125         "       wsr     %1, scompare1\n"
 126         "2:     s32c1i  %0, %3, 0\n"
 127         "3:\n"
 128         "       .section .fixup,\"ax\"\n"
 129         "       .align 4\n"
 130         "4:     .long   3b\n"
 131         "5:     l32r    %1, 4b\n"
 132         "       movi    %0, %6\n"
 133         "       jx      %1\n"
 134         "       .previous\n"
 135         "       .section __ex_table,\"a\"\n"
 136         "       .long 1b,5b,2b,5b\n"
 137         "       .previous\n"
 138         : "+r" (ret), "=&r" (prev), "+m" (*uaddr)
 139         : "r" (uaddr), "r" (oldval), "r" (newval), "I" (-EFAULT)
 140         : "memory");
 141
 142         *uval = prev;
 143         return ret;
 144 }
 145
 146 #endif /* __KERNEL__ */
 147 #endif /* _ASM_XTENSA_FUTEX_H */