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 #ifndef CONFIG_MMU
17 #include <asm/nommu_context.h>
18 #else
19
20 #include <linux/stringify.h>
21 #include <linux/sched.h>
22
23 #include <variant/core.h>
24
25 #include <asm/pgtable.h>
26 #include <asm/cacheflush.h>
27 #include <asm/tlbflush.h>
28 #include <asm-generic/mm_hooks.h>
29
30 #if (XCHAL_HAVE_TLBS != 1)
31 # error "Linux must have an MMU!"
32 #endif
33
34 extern unsigned long asid_cache;
35
36 /*
37 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
38 * any user or kernel context.
39 *
40 * 0 invalid
41 * 1 kernel
42 * 2 reserved
43 * 3 reserved
44 * 4...255 available
45 */
46
47 #define NO_CONTEXT 0
48 #define ASID_USER_FIRST 4
49 #define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1)
50 #define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8))
51
set_rasid_register(unsigned long val)52 static inline void set_rasid_register (unsigned long val)
53 {
54 __asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t"
55 " isync\n" : : "a" (val));
56 }
57
get_rasid_register(void)58 static inline unsigned long get_rasid_register (void)
59 {
60 unsigned long tmp;
61 __asm__ __volatile__ (" rsr %0,"__stringify(RASID)"\n\t" : "=a" (tmp));
62 return tmp;
63 }
64
65 static inline void
__get_new_mmu_context(struct mm_struct * mm)66 __get_new_mmu_context(struct mm_struct *mm)
67 {
68 extern void flush_tlb_all(void);
69 if (! (++asid_cache & ASID_MASK) ) {
70 flush_tlb_all(); /* start new asid cycle */
71 asid_cache += ASID_USER_FIRST;
72 }
73 mm->context = asid_cache;
74 }
75
76 static inline void
__load_mmu_context(struct mm_struct * mm)77 __load_mmu_context(struct mm_struct *mm)
78 {
79 set_rasid_register(ASID_INSERT(mm->context));
80 invalidate_page_directory();
81 }
82
83 /*
84 * Initialize the context related info for a new mm_struct
85 * instance.
86 */
87
88 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)89 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
90 {
91 mm->context = NO_CONTEXT;
92 return 0;
93 }
94
95 /*
96 * After we have set current->mm to a new value, this activates
97 * the context for the new mm so we see the new mappings.
98 */
99 static inline void
activate_mm(struct mm_struct * prev,struct mm_struct * next)100 activate_mm(struct mm_struct *prev, struct mm_struct *next)
101 {
102 /* Unconditionally get a new ASID. */
103
104 __get_new_mmu_context(next);
105 __load_mmu_context(next);
106 }
107
108
switch_mm(struct mm_struct * prev,struct mm_struct * next,struct task_struct * tsk)109 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
110 struct task_struct *tsk)
111 {
112 unsigned long asid = asid_cache;
113
114 /* Check if our ASID is of an older version and thus invalid */
115
116 if (next->context == NO_CONTEXT || ((next->context^asid) & ~ASID_MASK))
117 __get_new_mmu_context(next);
118
119 __load_mmu_context(next);
120 }
121
122 #define deactivate_mm(tsk, mm) do { } while(0)
123
124 /*
125 * Destroy context related info for an mm_struct that is about
126 * to be put to rest.
127 */
destroy_context(struct mm_struct * mm)128 static inline void destroy_context(struct mm_struct *mm)
129 {
130 invalidate_page_directory();
131 }
132
133
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)134 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
135 {
136 /* Nothing to do. */
137
138 }
139
140 #endif /* CONFIG_MMU */
141 #endif /* _XTENSA_MMU_CONTEXT_H */
142