arch/microblaze/mm/mmu_context.c

   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
  28 mm_context_t next_mmu_context;
  29 unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
  30 atomic_t nr_free_contexts;
  31 struct mm_struct *context_mm[LAST_CONTEXT+1];
  32
  33 /*
  34  * Initialize the context management stuff.
  35  */
  36 void __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  */
  54 void 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 }