cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mmu_context.c (1825B)

      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}