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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 | |
33 | mm_context_t next_mmu_context; |
34 | unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; |
35 | atomic_t nr_free_contexts; |
36 | struct mm_struct *context_mm[LAST_CONTEXT+1]; |
37 | |
38 | /* |
39 | * Initialize the context management stuff. |
40 | */ |
41 | void __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 | */ |
59 | void 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 | } |
71 |
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