xref: /OK3568_Linux_fs/kernel/arch/microblaze/mm/mmu_context.c (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun  * This file contains the routines for handling the MMU.
4*4882a593Smuzhiyun  *
5*4882a593Smuzhiyun  *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
6*4882a593Smuzhiyun  *
7*4882a593Smuzhiyun  *  Derived from arch/ppc/mm/4xx_mmu.c:
8*4882a593Smuzhiyun  *  -- paulus
9*4882a593Smuzhiyun  *
10*4882a593Smuzhiyun  *  Derived from arch/ppc/mm/init.c:
11*4882a593Smuzhiyun  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
12*4882a593Smuzhiyun  *
13*4882a593Smuzhiyun  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
14*4882a593Smuzhiyun  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
15*4882a593Smuzhiyun  *    Copyright (C) 1996 Paul Mackerras
16*4882a593Smuzhiyun  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
17*4882a593Smuzhiyun  *
18*4882a593Smuzhiyun  *  Derived from "arch/i386/mm/init.c"
19*4882a593Smuzhiyun  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
20*4882a593Smuzhiyun  */
21*4882a593Smuzhiyun 
22*4882a593Smuzhiyun #include <linux/mm.h>
23*4882a593Smuzhiyun #include <linux/init.h>
24*4882a593Smuzhiyun 
25*4882a593Smuzhiyun #include <asm/tlbflush.h>
26*4882a593Smuzhiyun #include <asm/mmu_context.h>
27*4882a593Smuzhiyun 
28*4882a593Smuzhiyun mm_context_t next_mmu_context;
29*4882a593Smuzhiyun unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
30*4882a593Smuzhiyun atomic_t nr_free_contexts;
31*4882a593Smuzhiyun struct mm_struct *context_mm[LAST_CONTEXT+1];
32*4882a593Smuzhiyun 
33*4882a593Smuzhiyun /*
34*4882a593Smuzhiyun  * Initialize the context management stuff.
35*4882a593Smuzhiyun  */
mmu_context_init(void)36*4882a593Smuzhiyun void __init mmu_context_init(void)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun 	/*
39*4882a593Smuzhiyun 	 * The use of context zero is reserved for the kernel.
40*4882a593Smuzhiyun 	 * This code assumes FIRST_CONTEXT < 32.
41*4882a593Smuzhiyun 	 */
42*4882a593Smuzhiyun 	context_map[0] = (1 << FIRST_CONTEXT) - 1;
43*4882a593Smuzhiyun 	next_mmu_context = FIRST_CONTEXT;
44*4882a593Smuzhiyun 	atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun 
47*4882a593Smuzhiyun /*
48*4882a593Smuzhiyun  * Steal a context from a task that has one at the moment.
49*4882a593Smuzhiyun  *
50*4882a593Smuzhiyun  * This isn't an LRU system, it just frees up each context in
51*4882a593Smuzhiyun  * turn (sort-of pseudo-random replacement :).  This would be the
52*4882a593Smuzhiyun  * place to implement an LRU scheme if anyone were motivated to do it.
53*4882a593Smuzhiyun  */
steal_context(void)54*4882a593Smuzhiyun void steal_context(void)
55*4882a593Smuzhiyun {
56*4882a593Smuzhiyun 	struct mm_struct *mm;
57*4882a593Smuzhiyun 
58*4882a593Smuzhiyun 	/* free up context `next_mmu_context' */
59*4882a593Smuzhiyun 	/* if we shouldn't free context 0, don't... */
60*4882a593Smuzhiyun 	if (next_mmu_context < FIRST_CONTEXT)
61*4882a593Smuzhiyun 		next_mmu_context = FIRST_CONTEXT;
62*4882a593Smuzhiyun 	mm = context_mm[next_mmu_context];
63*4882a593Smuzhiyun 	flush_tlb_mm(mm);
64*4882a593Smuzhiyun 	destroy_context(mm);
65*4882a593Smuzhiyun }
66