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Linux kernel mirror (for testing)
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kernel
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linux
1/*
2 * include/asm-xtensa/mmu_context.h
3 *
4 * Switch an MMU context.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2001 - 2005 Tensilica Inc.
11 */
12
13#ifndef _XTENSA_MMU_CONTEXT_H
14#define _XTENSA_MMU_CONTEXT_H
15
16#include <linux/stringify.h>
17
18#include <asm/pgtable.h>
19#include <asm/cacheflush.h>
20#include <asm/tlbflush.h>
21#include <asm-generic/mm_hooks.h>
22
23#define XCHAL_MMU_ASID_BITS 8
24
25#if (XCHAL_HAVE_TLBS != 1)
26# error "Linux must have an MMU!"
27#endif
28
29extern unsigned long asid_cache;
30
31/*
32 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
33 * any user or kernel context.
34 *
35 * 0 invalid
36 * 1 kernel
37 * 2 reserved
38 * 3 reserved
39 * 4...255 available
40 */
41
42#define NO_CONTEXT 0
43#define ASID_USER_FIRST 4
44#define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1)
45#define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8))
46
47static inline void set_rasid_register (unsigned long val)
48{
49 __asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t"
50 " isync\n" : : "a" (val));
51}
52
53static inline unsigned long get_rasid_register (void)
54{
55 unsigned long tmp;
56 __asm__ __volatile__ (" rsr %0,"__stringify(RASID)"\n\t" : "=a" (tmp));
57 return tmp;
58}
59
60static inline void
61__get_new_mmu_context(struct mm_struct *mm)
62{
63 extern void flush_tlb_all(void);
64 if (! (++asid_cache & ASID_MASK) ) {
65 flush_tlb_all(); /* start new asid cycle */
66 asid_cache += ASID_USER_FIRST;
67 }
68 mm->context = asid_cache;
69}
70
71static inline void
72__load_mmu_context(struct mm_struct *mm)
73{
74 set_rasid_register(ASID_INSERT(mm->context));
75 invalidate_page_directory();
76}
77
78/*
79 * Initialize the context related info for a new mm_struct
80 * instance.
81 */
82
83static inline int
84init_new_context(struct task_struct *tsk, struct mm_struct *mm)
85{
86 mm->context = NO_CONTEXT;
87 return 0;
88}
89
90/*
91 * After we have set current->mm to a new value, this activates
92 * the context for the new mm so we see the new mappings.
93 */
94static inline void
95activate_mm(struct mm_struct *prev, struct mm_struct *next)
96{
97 /* Unconditionally get a new ASID. */
98
99 __get_new_mmu_context(next);
100 __load_mmu_context(next);
101}
102
103
104static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
105 struct task_struct *tsk)
106{
107 unsigned long asid = asid_cache;
108
109 /* Check if our ASID is of an older version and thus invalid */
110
111 if (next->context == NO_CONTEXT || ((next->context^asid) & ~ASID_MASK))
112 __get_new_mmu_context(next);
113
114 __load_mmu_context(next);
115}
116
117#define deactivate_mm(tsk, mm) do { } while(0)
118
119/*
120 * Destroy context related info for an mm_struct that is about
121 * to be put to rest.
122 */
123static inline void destroy_context(struct mm_struct *mm)
124{
125 invalidate_page_directory();
126}
127
128
129static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
130{
131 /* Nothing to do. */
132
133}
134
135#endif /* _XTENSA_MMU_CONTEXT_H */