// SPDX-License-Identifier: GPL-2.0-or-later
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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 (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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* Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
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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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#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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