LXR linux/arch/arc/include/asm/futex.h

   1/*
   2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * Vineetg: August 2010: From Android kernel work
   9 */
  10
  11#ifndef _ASM_FUTEX_H
  12#define _ASM_FUTEX_H
  13
  14#include <linux/futex.h>
  15#include <linux/preempt.h>
  16#include <linux/uaccess.h>
  17#include <asm/errno.h>
  18
  19#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  20                                                        \
  21        __asm__ __volatile__(                           \
  22        "1:     ld  %1, [%2]                    \n"     \
  23                insn                            "\n"    \
  24        "2:     st  %0, [%2]                    \n"     \
  25        "       mov %0, 0                       \n"     \
  26        "3:                                     \n"     \
  27        "       .section .fixup,\"ax\"          \n"     \
  28        "       .align  4                       \n"     \
  29        "4:     mov %0, %4                      \n"     \
  30        "       b   3b                          \n"     \
  31        "       .previous                       \n"     \
  32        "       .section __ex_table,\"a\"       \n"     \
  33        "       .align  4                       \n"     \
  34        "       .word   1b, 4b                  \n"     \
  35        "       .word   2b, 4b                  \n"     \
  36        "       .previous                       \n"     \
  37                                                        \
  38        : "=&r" (ret), "=&r" (oldval)                   \
  39        : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  40        : "cc", "memory")
  41
  42static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  43{
  44        int op = (encoded_op >> 28) & 7;
  45        int cmp = (encoded_op >> 24) & 15;
  46        int oparg = (encoded_op << 8) >> 20;
  47        int cmparg = (encoded_op << 20) >> 20;
  48        int oldval = 0, ret;
  49
  50        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  51                oparg = 1 << oparg;
  52
  53        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  54                return -EFAULT;
  55
  56        pagefault_disable();    /* implies preempt_disable() */
  57
  58        switch (op) {
  59        case FUTEX_OP_SET:
  60                __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  61                break;
  62        case FUTEX_OP_ADD:
  63                __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
  64                break;
  65        case FUTEX_OP_OR:
  66                __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
  67                break;
  68        case FUTEX_OP_ANDN:
  69                __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
  70                break;
  71        case FUTEX_OP_XOR:
  72                __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
  73                break;
  74        default:
  75                ret = -ENOSYS;
  76        }
  77
  78        pagefault_enable();     /* subsumes preempt_enable() */
  79
  80        if (!ret) {
  81                switch (cmp) {
  82                case FUTEX_OP_CMP_EQ:
  83                        ret = (oldval == cmparg);
  84                        break;
  85                case FUTEX_OP_CMP_NE:
  86                        ret = (oldval != cmparg);
  87                        break;
  88                case FUTEX_OP_CMP_LT:
  89                        ret = (oldval < cmparg);
  90                        break;
  91                case FUTEX_OP_CMP_GE:
  92                        ret = (oldval >= cmparg);
  93                        break;
  94                case FUTEX_OP_CMP_LE:
  95                        ret = (oldval <= cmparg);
  96                        break;
  97                case FUTEX_OP_CMP_GT:
  98                        ret = (oldval > cmparg);
  99                        break;
 100                default:
 101                        ret = -ENOSYS;
 102                }
 103        }
 104        return ret;
 105}
 106
 107/* Compare-xchg with preemption disabled.
 108 *  Notes:
 109 *      -Best-Effort: Exchg happens only if compare succeeds.
 110 *          If compare fails, returns; leaving retry/looping to upper layers
 111 *      -successful cmp-xchg: return orig value in @addr (same as cmp val)
 112 *      -Compare fails: return orig value in @addr
 113 *      -user access r/w fails: return -EFAULT
 114 */
 115static inline int
 116futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
 117                                        u32 newval)
 118{
 119        u32 val;
 120
 121        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 122                return -EFAULT;
 123
 124        pagefault_disable();    /* implies preempt_disable() */
 125
 126        /* TBD : can use llock/scond */
 127        __asm__ __volatile__(
 128        "1:     ld    %0, [%3]  \n"
 129        "       brne  %0, %1, 3f        \n"
 130        "2:     st    %2, [%3]  \n"
 131        "3:     \n"
 132        "       .section .fixup,\"ax\"  \n"
 133        "4:     mov %0, %4      \n"
 134        "       b   3b  \n"
 135        "       .previous       \n"
 136        "       .section __ex_table,\"a\"       \n"
 137        "       .align  4       \n"
 138        "       .word   1b, 4b  \n"
 139        "       .word   2b, 4b  \n"
 140        "       .previous\n"
 141        : "=&r"(val)
 142        : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 143        : "cc", "memory");
 144
 145        pagefault_enable();     /* subsumes preempt_enable() */
 146
 147        *uval = val;
 148        return val;
 149}
 150
 151#endif
 152