arch_atomic_s390.h

   1 #ifndef _ARCH_ATOMIC_S390_H
   2 #define _ARCH_ATOMIC_S390_H
   3
   4 /*
   5  * Atomic exchange operations for the S390 architecture.
   6  *
   7  * Copyright (C) 2009 Novell, Inc.
   8  * Author: Jan Blunck <jblunck@suse.de>
   9  *
  10  * This is taken from the Principles of Operation Appendix A "Conditional
  11  * Swapping Instructions (CS, CDS)".
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms of the GNU Lesser General Public License version 2.1 as
  15  * published by the Free  Software Foundation.
  16  */
  17
  18 #ifndef __SIZEOF_LONG__
  19 #ifdef __s390x__
  20 #define __SIZEOF_LONG__ 8
  21 #else
  22 #define __SIZEOF_LONG__ 4
  23 #endif
  24 #endif
  25
  26 #ifndef BITS_PER_LONG
  27 #define BITS_PER_LONG   (__SIZEOF_LONG__ * 8)
  28 #endif
  29
  30 #ifndef _INCLUDE_API_H
  31
  32 static inline __attribute__((always_inline))
  33 unsigned int atomic_exchange_32(volatile unsigned int *addr, unsigned int val)
  34 {
  35         unsigned int result;
  36
  37         __asm__ __volatile__(
  38                 "0:     cs %0,%2,%1\n"
  39                 "       brc 4,0b\n"
  40                 : "=&r"(result), "=m" (*addr)
  41                 : "r"(val), "m" (*addr)
  42                 : "memory", "cc");
  43
  44         return result;
  45 }
  46
  47 #if (BITS_PER_LONG == 64)
  48
  49 static inline __attribute__((always_inline))
  50 unsigned long atomic_exchange_64(volatile unsigned long *addr,
  51                                  unsigned long val)
  52 {
  53         unsigned long result;
  54
  55         __asm__ __volatile__(
  56                 "0:     csg %0,%2,%1\n"
  57                 "       brc 4,0b\n"
  58                 : "=&r"(result), "=m" (*addr)
  59                 : "r"(val), "m" (*addr)
  60                 : "memory", "cc");
  61
  62         return result;
  63 }
  64
  65 #endif
  66
  67 static inline __attribute__((always_inline))
  68 unsigned long _atomic_exchange(volatile void *addr, unsigned long val, int len)
  69 {
  70         switch (len) {
  71         case 4:
  72                 return atomic_exchange_32(addr, val);
  73 #if (BITS_PER_LONG == 64)
  74         case 8:
  75                 return atomic_exchange_64(addr, val);
  76 #endif
  77         default:
  78                 __asm__ __volatile__(".long     0xd00d00");
  79         }
  80
  81         return 0;
  82 }
  83
  84 #define xchg(addr, v)                                                   \
  85         (__typeof__(*(addr))) _atomic_exchange((addr), (unsigned long)(v), \
  86                                                sizeof(*(addr)))
  87
  88 #endif /* #ifndef _INCLUDE_API_H */
  89
  90 #endif /* ARCH_ATOMIC_S390_H */