blob: b7f8de576777f83ab8f9c7f2e75c125b2d88822b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/cris/mm/tlb.c
3 *
4 * Copyright (C) 2000, 2001 Axis Communications AB
5 *
6 * Authors: Bjorn Wesen (bjornw@axis.com)
7 *
8 */
9
10#include <linux/init.h>
Ahmed S. Darwish84471572007-02-10 01:43:51 -080011#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <asm/tlb.h>
13
14#define D(x)
15
16/* The TLB can host up to 64 different mm contexts at the same time.
17 * The running context is R_MMU_CONTEXT, and each TLB entry contains a
18 * page_id that has to match to give a hit. In page_id_map, we keep track
Simon Arlott49b4ff32007-10-20 01:08:50 +020019 * of which mm we have assigned to which page_id, so that we know when
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 * to invalidate TLB entries.
21 *
22 * The last page_id is never running - it is used as an invalid page_id
23 * so we can make TLB entries that will never match.
24 *
25 * Notice that we need to make the flushes atomic, otherwise an interrupt
26 * handler that uses vmalloced memory might cause a TLB load in the middle
27 * of a flush causing.
28 */
29
30struct mm_struct *page_id_map[NUM_PAGEID];
31static int map_replace_ptr = 1; /* which page_id_map entry to replace next */
32
Linus Torvalds1da177e2005-04-16 15:20:36 -070033/* the following functions are similar to those used in the PPC port */
34
35static inline void
36alloc_context(struct mm_struct *mm)
37{
38 struct mm_struct *old_mm;
39
40 D(printk("tlb: alloc context %d (%p)\n", map_replace_ptr, mm));
41
42 /* did we replace an mm ? */
43
44 old_mm = page_id_map[map_replace_ptr];
45
46 if(old_mm) {
47 /* throw out any TLB entries belonging to the mm we replace
48 * in the map
49 */
50 flush_tlb_mm(old_mm);
51
Mikael Starvik4f18cfb2005-07-27 11:44:39 -070052 old_mm->context.page_id = NO_CONTEXT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 }
54
55 /* insert it into the page_id_map */
56
Mikael Starvik4f18cfb2005-07-27 11:44:39 -070057 mm->context.page_id = map_replace_ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 page_id_map[map_replace_ptr] = mm;
59
60 map_replace_ptr++;
61
62 if(map_replace_ptr == INVALID_PAGEID)
63 map_replace_ptr = 0; /* wrap around */
64}
65
66/*
67 * if needed, get a new MMU context for the mm. otherwise nothing is done.
68 */
69
70void
71get_mmu_context(struct mm_struct *mm)
72{
Mikael Starvik4f18cfb2005-07-27 11:44:39 -070073 if(mm->context.page_id == NO_CONTEXT)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 alloc_context(mm);
75}
76
77/* called by __exit_mm to destroy the used MMU context if any before
78 * destroying the mm itself. this is only called when the last user of the mm
79 * drops it.
80 *
81 * the only thing we really need to do here is mark the used PID slot
82 * as empty.
83 */
84
85void
86destroy_context(struct mm_struct *mm)
87{
Mikael Starvik4f18cfb2005-07-27 11:44:39 -070088 if(mm->context.page_id != NO_CONTEXT) {
89 D(printk("destroy_context %d (%p)\n", mm->context.page_id, mm));
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 flush_tlb_mm(mm); /* TODO this might be redundant ? */
Mikael Starvik4f18cfb2005-07-27 11:44:39 -070091 page_id_map[mm->context.page_id] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 }
93}
94
95/* called once during VM initialization, from init.c */
96
97void __init
98tlb_init(void)
99{
100 int i;
101
102 /* clear the page_id map */
103
Ahmed S. Darwish84471572007-02-10 01:43:51 -0800104 for (i = 1; i < ARRAY_SIZE(page_id_map); i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 page_id_map[i] = NULL;
106
107 /* invalidate the entire TLB */
108
109 flush_tlb_all();
110
111 /* the init_mm has context 0 from the boot */
112
113 page_id_map[0] = &init_mm;
114}