| Michal Simek | fc34d1e | 2009-05-26 16:30:14 +0200 | [diff] [blame^] | 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 | } |