[PATCH] ocfs2: zero_user_page conversion
[wrt350n-kernel.git] / arch / cris / mm / tlb.c
blobc4a98e2e529e04dd46b85ff768bdabad3df8d1a4
1 /*
2 * linux/arch/cris/mm/tlb.c
4 * Copyright (C) 2000, 2001 Axis Communications AB
5 *
6 * Authors: Bjorn Wesen (bjornw@axis.com)
8 */
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <asm/tlb.h>
14 #define D(x)
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
19 * of which mm's we have assigned which page_id's, so that we know when
20 * to invalidate TLB entries.
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.
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.
30 struct mm_struct *page_id_map[NUM_PAGEID];
31 static int map_replace_ptr = 1; /* which page_id_map entry to replace next */
33 /* the following functions are similar to those used in the PPC port */
35 static inline void
36 alloc_context(struct mm_struct *mm)
38 struct mm_struct *old_mm;
40 D(printk("tlb: alloc context %d (%p)\n", map_replace_ptr, mm));
42 /* did we replace an mm ? */
44 old_mm = page_id_map[map_replace_ptr];
46 if(old_mm) {
47 /* throw out any TLB entries belonging to the mm we replace
48 * in the map
50 flush_tlb_mm(old_mm);
52 old_mm->context.page_id = NO_CONTEXT;
55 /* insert it into the page_id_map */
57 mm->context.page_id = map_replace_ptr;
58 page_id_map[map_replace_ptr] = mm;
60 map_replace_ptr++;
62 if(map_replace_ptr == INVALID_PAGEID)
63 map_replace_ptr = 0; /* wrap around */
66 /*
67 * if needed, get a new MMU context for the mm. otherwise nothing is done.
70 void
71 get_mmu_context(struct mm_struct *mm)
73 if(mm->context.page_id == NO_CONTEXT)
74 alloc_context(mm);
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.
81 * the only thing we really need to do here is mark the used PID slot
82 * as empty.
85 void
86 destroy_context(struct mm_struct *mm)
88 if(mm->context.page_id != NO_CONTEXT) {
89 D(printk("destroy_context %d (%p)\n", mm->context.page_id, mm));
90 flush_tlb_mm(mm); /* TODO this might be redundant ? */
91 page_id_map[mm->context.page_id] = NULL;
95 /* called once during VM initialization, from init.c */
97 void __init
98 tlb_init(void)
100 int i;
102 /* clear the page_id map */
104 for (i = 1; i < ARRAY_SIZE(page_id_map); i++)
105 page_id_map[i] = NULL;
107 /* invalidate the entire TLB */
109 flush_tlb_all();
111 /* the init_mm has context 0 from the boot */
113 page_id_map[0] = &init_mm;