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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/microblaze/mm/mmu_context.c
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/*

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 * This file contains the routines for handling the MMU.

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 *

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 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.

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 *

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 *  Derived from arch/ppc/mm/4xx_mmu.c:

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 *  -- paulus

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 *

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 *  Derived from arch/ppc/mm/init.c:

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 *    Copyright (C) 1995-1996 Gary Thomas ([email protected])

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 *

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 *  Modifications by Paul Mackerras (PowerMac) ([email protected])

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 *  and Cort Dougan (PReP) ([email protected])

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 *    Copyright (C) 1996 Paul Mackerras

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 *  Amiga/APUS changes by Jesper Skov ([email protected]).

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 *

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 *  Derived from "arch/i386/mm/init.c"

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 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds

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 *

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 *  This program is free software; you can redistribute it and/or

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 *  modify it under the terms of the GNU General Public License

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 *  as published by the Free Software Foundation; either version

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 *  2 of the License, or (at your option) any later version.

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 *

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 */

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#include <linux/mm.h>

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#include <linux/init.h>

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#include <asm/tlbflush.h>

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#include <asm/mmu_context.h>

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mm_context_t next_mmu_context;

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unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];

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atomic_t nr_free_contexts;

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struct mm_struct *context_mm[LAST_CONTEXT+1];

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/*

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 * Initialize the context management stuff.

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 */

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void __init mmu_context_init(void)

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{

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	/*

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	 * The use of context zero is reserved for the kernel.

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	 * This code assumes FIRST_CONTEXT < 32.

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	 */

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	context_map[0] = (1 << FIRST_CONTEXT) - 1;

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	next_mmu_context = FIRST_CONTEXT;

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	atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);

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}

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/*

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 * Steal a context from a task that has one at the moment.

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 *

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 * This isn't an LRU system, it just frees up each context in

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 * turn (sort-of pseudo-random replacement :).  This would be the

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 * place to implement an LRU scheme if anyone were motivated to do it.

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 */

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void steal_context(void)

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{

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	struct mm_struct *mm;

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	/* free up context `next_mmu_context' */

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	/* if we shouldn't free context 0, don't... */

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	if (next_mmu_context < FIRST_CONTEXT)

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		next_mmu_context = FIRST_CONTEXT;

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	mm = context_mm[next_mmu_context];

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	flush_tlb_mm(mm);

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	destroy_context(mm);

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}

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