LXR linux/arch/tile/kernel/futex

   1/*
   2 * Copyright 2011 Tilera Corporation. All Rights Reserved.
   3 *
   4 *   This program is free software; you can redistribute it and/or
   5 *   modify it under the terms of the GNU General Public License
   6 *   as published by the Free Software Foundation, version 2.
   7 *
   8 *   This program is distributed in the hope that it will be useful, but
   9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11 *   NON INFRINGEMENT.  See the GNU General Public License for
  12 *   more details.
  13 *
  14 * Atomically access user memory, but use MMU to avoid propagating
  15 * kernel exceptions.
  16 */
  17
  18#include <linux/linkage.h>
  19#include <asm/errno.h>
  20#include <asm/futex.h>
  21#include <asm/page.h>
  22#include <asm/processor.h>
  23
  24/*
  25 * Provide a set of atomic memory operations supporting <asm/futex.h>.
  26 *
  27 * r0: user address to manipulate
  28 * r1: new value to write, or for cmpxchg, old value to compare against
  29 * r2: (cmpxchg only) new value to write
  30 *
  31 * Return __get_user struct, r0 with value, r1 with error.
  32 */
  33#define FUTEX_OP(name, ...) \
  34STD_ENTRY(futex_##name)                 \
  35        __VA_ARGS__;                    \
  36        {                               \
  37         move   r1, zero;               \
  38         jrp    lr                      \
  39        };                              \
  40        STD_ENDPROC(futex_##name);      \
  41        .pushsection __ex_table,"a";    \
  42        .quad 1b, get_user_fault;       \
  43        .popsection
  44
  45        .pushsection .fixup,"ax"
  46get_user_fault:
  47        { movei r1, -EFAULT; jrp lr }
  48        ENDPROC(get_user_fault)
  49        .popsection
  50
  51FUTEX_OP(cmpxchg, mtspr CMPEXCH_VALUE, r1; 1: cmpexch4 r0, r0, r2)
  52FUTEX_OP(set, 1: exch4 r0, r0, r1)
  53FUTEX_OP(add, 1: fetchadd4 r0, r0, r1)
  54FUTEX_OP(or, 1: fetchor4 r0, r0, r1)
  55FUTEX_OP(andn, nor r1, r1, zero; 1: fetchand4 r0, r0, r1)
  56