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(v: &nr_free_contexts, i: 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 | } |
66 | |