86 строки
2.7 KiB
C
86 строки
2.7 KiB
C
/*
|
|
* This file contains the routines for handling the MMU on those
|
|
* PowerPC implementations where the MMU substantially follows the
|
|
* architecture specification. This includes the 6xx, 7xx, 7xxx,
|
|
* 8260, and 83xx implementations but excludes the 8xx and 4xx.
|
|
* -- paulus
|
|
*
|
|
* Derived from arch/ppc/mm/init.c:
|
|
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
|
|
*
|
|
* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
|
|
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
|
|
* Copyright (C) 1996 Paul Mackerras
|
|
* Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
|
|
*
|
|
* Derived from "arch/i386/mm/init.c"
|
|
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/init.h>
|
|
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
unsigned long next_mmu_context;
|
|
unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
|
|
#ifdef FEW_CONTEXTS
|
|
atomic_t nr_free_contexts;
|
|
struct mm_struct *context_mm[LAST_CONTEXT+1];
|
|
void steal_context(void);
|
|
#endif /* FEW_CONTEXTS */
|
|
|
|
/*
|
|
* Initialize the context management stuff.
|
|
*/
|
|
void __init
|
|
mmu_context_init(void)
|
|
{
|
|
/*
|
|
* Some processors have too few contexts to reserve one for
|
|
* init_mm, and require using context 0 for a normal task.
|
|
* Other processors reserve the use of context zero for the kernel.
|
|
* This code assumes FIRST_CONTEXT < 32.
|
|
*/
|
|
context_map[0] = (1 << FIRST_CONTEXT) - 1;
|
|
next_mmu_context = FIRST_CONTEXT;
|
|
#ifdef FEW_CONTEXTS
|
|
atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
|
|
#endif /* FEW_CONTEXTS */
|
|
}
|
|
|
|
#ifdef FEW_CONTEXTS
|
|
/*
|
|
* Steal a context from a task that has one at the moment.
|
|
* This is only used on 8xx and 4xx and we presently assume that
|
|
* they don't do SMP. If they do then this will have to check
|
|
* whether the MM we steal is in use.
|
|
* We also assume that this is only used on systems that don't
|
|
* use an MMU hash table - this is true for 8xx and 4xx.
|
|
* This isn't an LRU system, it just frees up each context in
|
|
* turn (sort-of pseudo-random replacement :). This would be the
|
|
* place to implement an LRU scheme if anyone was motivated to do it.
|
|
* -- paulus
|
|
*/
|
|
void
|
|
steal_context(void)
|
|
{
|
|
struct mm_struct *mm;
|
|
|
|
/* free up context `next_mmu_context' */
|
|
/* if we shouldn't free context 0, don't... */
|
|
if (next_mmu_context < FIRST_CONTEXT)
|
|
next_mmu_context = FIRST_CONTEXT;
|
|
mm = context_mm[next_mmu_context];
|
|
flush_tlb_mm(mm);
|
|
destroy_context(mm);
|
|
}
|
|
#endif /* FEW_CONTEXTS */
|