LXR linux/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
  47static 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
 107static inline int
 108futex_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 */
 148