LXR linux/arch/microblaze/mm/mmu

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * This file contains the routines for handling the MMU.
   4 *
   5 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
   6 *
   7 *  Derived from arch/ppc/mm/4xx_mmu.c:
   8 *  -- paulus
   9 *
  10 *  Derived from arch/ppc/mm/init.c:
  11 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  12 *
  13 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  14 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  15 *    Copyright (C) 1996 Paul Mackerras
  16 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
  17 *
  18 *  Derived from "arch/i386/mm/init.c"
  19 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  20 */
  21
  22#include <linux/mm.h>
  23#include <linux/init.h>
  24
  25#include <asm/tlbflush.h>
  26#include <asm/mmu_context.h>
  27
  28mm_context_t next_mmu_context;
  29unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
  30atomic_t nr_free_contexts;
  31struct mm_struct *context_mm[LAST_CONTEXT+1];
  32
  33/*
  34 * Initialize the context management stuff.
  35 */
  36void __init mmu_context_init(void)
  37{
  38        /*
  39         * The use of context zero is reserved for the kernel.
  40         * This code assumes FIRST_CONTEXT < 32.
  41         */
  42        context_map[0] = (1 << FIRST_CONTEXT) - 1;
  43        next_mmu_context = FIRST_CONTEXT;
  44        atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
  45}
  46
  47/*
  48 * Steal a context from a task that has one at the moment.
  49 *
  50 * This isn't an LRU system, it just frees up each context in
  51 * turn (sort-of pseudo-random replacement :).  This would be the
  52 * place to implement an LRU scheme if anyone were motivated to do it.
  53 */
  54void steal_context(void)
  55{
  56        struct mm_struct *mm;
  57
  58        /* free up context `next_mmu_context' */
  59        /* if we shouldn't free context 0, don't... */
  60        if (next_mmu_context < FIRST_CONTEXT)
  61                next_mmu_context = FIRST_CONTEXT;
  62        mm = context_mm[next_mmu_context];
  63        flush_tlb_mm(mm);
  64        destroy_context(mm);
  65}
  66