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/Ethereal-msm8939-beta9/arch/microblaze/mm/mmu_context.c

https://bitbucket.org/MilosStamenkovic95/etherealos
C | 70 lines | 23 code | 6 blank | 41 comment | 1 complexity | d20901feb1400213e30370ec898c34d0 MD5 | raw file
 1/*
 2 * This file contains the routines for handling the MMU.
 3 *
 4 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
 5 *
 6 *  Derived from arch/ppc/mm/4xx_mmu.c:
 7 *  -- paulus
 8 *
 9 *  Derived from arch/ppc/mm/init.c:
10 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
11 *
12 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
13 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
14 *    Copyright (C) 1996 Paul Mackerras
15 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
16 *
17 *  Derived from "arch/i386/mm/init.c"
18 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
19 *
20 *  This program is free software; you can redistribute it and/or
21 *  modify it under the terms of the GNU General Public License
22 *  as published by the Free Software Foundation; either version
23 *  2 of the License, or (at your option) any later version.
24 *
25 */
26
27#include <linux/mm.h>
28#include <linux/init.h>
29
30#include <asm/tlbflush.h>
31#include <asm/mmu_context.h>
32
33mm_context_t next_mmu_context;
34unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
35atomic_t nr_free_contexts;
36struct mm_struct *context_mm[LAST_CONTEXT+1];
37
38/*
39 * Initialize the context management stuff.
40 */
41void __init mmu_context_init(void)
42{
43	/*
44	 * The use of context zero is reserved for the kernel.
45	 * This code assumes FIRST_CONTEXT < 32.
46	 */
47	context_map[0] = (1 << FIRST_CONTEXT) - 1;
48	next_mmu_context = FIRST_CONTEXT;
49	atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
50}
51
52/*
53 * Steal a context from a task that has one at the moment.
54 *
55 * This isn't an LRU system, it just frees up each context in
56 * turn (sort-of pseudo-random replacement :).  This would be the
57 * place to implement an LRU scheme if anyone were motivated to do it.
58 */
59void steal_context(void)
60{
61	struct mm_struct *mm;
62
63	/* free up context `next_mmu_context' */
64	/* if we shouldn't free context 0, don't... */
65	if (next_mmu_context < FIRST_CONTEXT)
66		next_mmu_context = FIRST_CONTEXT;
67	mm = context_mm[next_mmu_context];
68	flush_tlb_mm(mm);
69	destroy_context(mm);
70}