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 
52 static inline void set_rasid_register (unsigned long val)
53 {
54 	__asm__ __volatile__ (" wsr %0, rasid\n\t"
55 			      " isync\n" : : "a" (val));
56 }
57 
58 static inline unsigned long get_rasid_register (void)
59 {
60 	unsigned long tmp;
61 	__asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
62 	return tmp;
63 }
64 
65 static inline void
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
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
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
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 
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  */
128 static inline void destroy_context(struct mm_struct *mm)
129 {
130 	invalidate_page_directory();
131 }
132 
133 
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