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         "       .literal_position\n"                    \
  36         "5:     movi    %0, 3b\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 arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
  48                 u32 __user *uaddr)
  49 {
  50         int oldval = 0, ret;
  51
  52 #if !XCHAL_HAVE_S32C1I
  53         return -ENOSYS;
  54 #endif
  55
  56         pagefault_disable();
  57
  58         switch (op) {
  59         case FUTEX_OP_SET:
  60                 __futex_atomic_op("mov %1, %4", ret, oldval, uaddr, oparg);
  61                 break;
  62         case FUTEX_OP_ADD:
  63                 __futex_atomic_op("add %1, %0, %4", ret, oldval, uaddr,
  64                                 oparg);
  65                 break;
  66         case FUTEX_OP_OR:
  67                 __futex_atomic_op("or %1, %0, %4", ret, oldval, uaddr,
  68                                 oparg);
  69                 break;
  70         case FUTEX_OP_ANDN:
  71                 __futex_atomic_op("and %1, %0, %4", ret, oldval, uaddr,
  72                                 ~oparg);
  73                 break;
  74         case FUTEX_OP_XOR:
  75                 __futex_atomic_op("xor %1, %0, %4", ret, oldval, uaddr,
  76                                 oparg);
  77                 break;
  78         default:
  79                 ret = -ENOSYS;
  80         }
  81
  82         pagefault_enable();
  83
  84         if (!ret)
  85                 *oval = oldval;
  86
  87         return ret;
  88 }
  89
  90 static inline int
  91 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  92                               u32 oldval, u32 newval)
  93 {
  94         int ret = 0;
  95
  96         if (!access_ok(uaddr, sizeof(u32)))
  97                 return -EFAULT;
  98
  99 #if !XCHAL_HAVE_S32C1I
 100         return -ENOSYS;
 101 #endif
 102
 103         __asm__ __volatile__ (
 104         "       # futex_atomic_cmpxchg_inatomic\n"
 105         "       wsr     %5, scompare1\n"
 106         "1:     s32c1i  %1, %4, 0\n"
 107         "       s32i    %1, %6, 0\n"
 108         "2:\n"
 109         "       .section .fixup,\"ax\"\n"
 110         "       .align 4\n"
 111         "       .literal_position\n"
 112         "4:     movi    %1, 2b\n"
 113         "       movi    %0, %7\n"
 114         "       jx      %1\n"
 115         "       .previous\n"
 116         "       .section __ex_table,\"a\"\n"
 117         "       .long 1b,4b\n"
 118         "       .previous\n"
 119         : "+r" (ret), "+r" (newval), "+m" (*uaddr), "+m" (*uval)
 120         : "r" (uaddr), "r" (oldval), "r" (uval), "I" (-EFAULT)
 121         : "memory");
 122
 123         return ret;
 124 }
 125
 126 #endif /* __KERNEL__ */
 127 #endif /* _ASM_XTENSA_FUTEX_H */