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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/mips/lib/uncached.c
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/*

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 * This file is subject to the terms and conditions of the GNU General Public

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 * License.  See the file "COPYING" in the main directory of this archive

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 * for more details.

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 *

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 * Copyright (C) 2005 Thiemo Seufer

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 * Copyright (C) 2005  MIPS Technologies, Inc.	All rights reserved.

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 *	Author: Maciej W. Rozycki <[email protected]>

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 */

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#include <asm/addrspace.h>

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#include <asm/bug.h>

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#include <asm/cacheflush.h>

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#ifndef CKSEG2

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#define CKSEG2 CKSSEG

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#endif

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#ifndef TO_PHYS_MASK

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#define TO_PHYS_MASK -1

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#endif

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/*

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 * FUNC is executed in one of the uncached segments, depending on its

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 * original address as follows:

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 *

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 * 1. If the original address is in CKSEG0 or CKSEG1, then the uncached

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 *    segment used is CKSEG1.

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 * 2. If the original address is in XKPHYS, then the uncached segment

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 *    used is XKPHYS(2).

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 * 3. Otherwise it's a bug.

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 *

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 * The same remapping is done with the stack pointer.  Stack handling

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 * works because we don't handle stack arguments or more complex return

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 * values, so we can avoid sharing the same stack area between a cached

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 * and the uncached mode.

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 */

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unsigned long run_uncached(void *func)

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{

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	register long ret __asm__("$2");

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	long lfunc = (long)func, ufunc;

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	long usp;

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	long sp;

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	__asm__("move %0, $sp" : "=r" (sp));

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	if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)

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		usp = CKSEG1ADDR(sp);

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#ifdef CONFIG_64BIT

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	else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0, 0) &&

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		 (long long)sp < (long long)PHYS_TO_XKPHYS(8, 0))

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		usp = PHYS_TO_XKPHYS(K_CALG_UNCACHED,

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				     XKPHYS_TO_PHYS((long long)sp));

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#endif

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	else {

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		BUG();

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		usp = sp;

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	}

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	if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2)

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		ufunc = CKSEG1ADDR(lfunc);

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#ifdef CONFIG_64BIT

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	else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0, 0) &&

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		 (long long)lfunc < (long long)PHYS_TO_XKPHYS(8, 0))

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		ufunc = PHYS_TO_XKPHYS(K_CALG_UNCACHED,

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				       XKPHYS_TO_PHYS((long long)lfunc));

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#endif

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	else {

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		BUG();

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		ufunc = lfunc;

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	}

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	__asm__ __volatile__ (

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		"	move	$16, $sp\n"

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		"	move	$sp, %1\n"

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		"	jalr	%2\n"

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		"	move	$sp, $16"

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		: "=r" (ret)

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		: "r" (usp), "r" (ufunc)

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		: "$16", "$31");

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	return ret;

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}

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