LXR linux/arch/mips/lib/uncached.c

   1/*
   2 * This file is subject to the terms and conditions of the GNU General Public
   3 * License.  See the file "COPYING" in the main directory of this archive
   4 * for more details.
   5 *
   6 * Copyright (C) 2005 Thiemo Seufer
   7 * Copyright (C) 2005  MIPS Technologies, Inc.  All rights reserved.
   8 *      Author: Maciej W. Rozycki <macro@mips.com>
   9 */
  10
  11
  12#include <asm/addrspace.h>
  13#include <asm/bug.h>
  14#include <asm/cacheflush.h>
  15
  16#ifndef CKSEG2
  17#define CKSEG2 CKSSEG
  18#endif
  19#ifndef TO_PHYS_MASK
  20#define TO_PHYS_MASK -1
  21#endif
  22
  23/*
  24 * FUNC is executed in one of the uncached segments, depending on its
  25 * original address as follows:
  26 *
  27 * 1. If the original address is in CKSEG0 or CKSEG1, then the uncached
  28 *    segment used is CKSEG1.
  29 * 2. If the original address is in XKPHYS, then the uncached segment
  30 *    used is XKPHYS(2).
  31 * 3. Otherwise it's a bug.
  32 *
  33 * The same remapping is done with the stack pointer.  Stack handling
  34 * works because we don't handle stack arguments or more complex return
  35 * values, so we can avoid sharing the same stack area between a cached
  36 * and the uncached mode.
  37 */
  38unsigned long run_uncached(void *func)
  39{
  40        register long sp __asm__("$sp");
  41        register long ret __asm__("$2");
  42        long lfunc = (long)func, ufunc;
  43        long usp;
  44
  45        if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
  46                usp = CKSEG1ADDR(sp);
  47#ifdef CONFIG_64BIT
  48        else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0, 0) &&
  49                 (long long)sp < (long long)PHYS_TO_XKPHYS(8, 0))
  50                usp = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
  51                                     XKPHYS_TO_PHYS((long long)sp));
  52#endif
  53        else {
  54                BUG();
  55                usp = sp;
  56        }
  57        if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2)
  58                ufunc = CKSEG1ADDR(lfunc);
  59#ifdef CONFIG_64BIT
  60        else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0, 0) &&
  61                 (long long)lfunc < (long long)PHYS_TO_XKPHYS(8, 0))
  62                ufunc = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
  63                                       XKPHYS_TO_PHYS((long long)lfunc));
  64#endif
  65        else {
  66                BUG();
  67                ufunc = lfunc;
  68        }
  69
  70        __asm__ __volatile__ (
  71                "       move    $16, $sp\n"
  72                "       move    $sp, %1\n"
  73                "       jalr    %2\n"
  74                "       move    $sp, $16"
  75                : "=r" (ret)
  76                : "r" (usp), "r" (ufunc)
  77                : "$16", "$31");
  78
  79        return ret;
  80}
  81