1 /*
2 * Switch an MMU context.
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2013 Tensilica Inc.
9 */
10
11 #ifndef _XTENSA_MMU_CONTEXT_H
12 #define _XTENSA_MMU_CONTEXT_H
13
14 #ifndef CONFIG_MMU
15 #include <asm/nommu_context.h>
16 #else
17
18 #include <linux/stringify.h>
19 #include <linux/sched.h>
20
21 #include <asm/vectors.h>
22
23 #include <asm/pgtable.h>
24 #include <asm/cacheflush.h>
25 #include <asm/tlbflush.h>
26 #include <asm-generic/mm_hooks.h>
27 #include <asm-generic/percpu.h>
28
29 #if (XCHAL_HAVE_TLBS != 1)
30 # error "Linux must have an MMU!"
31 #endif
32
33 DECLARE_PER_CPU(unsigned long, asid_cache);
34 #define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu)
35
36 /*
37 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
38 * any user or kernel context. We use the reserved values in the
39 * ASID_INSERT macro below.
40 *
41 * 0 invalid
42 * 1 kernel
43 * 2 reserved
44 * 3 reserved
45 * 4...255 available
46 */
47
48 #define NO_CONTEXT 0
49 #define ASID_USER_FIRST 4
50 #define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1)
51 #define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8))
52
53 void init_mmu(void);
54
set_rasid_register(unsigned long val)55 static inline void set_rasid_register (unsigned long val)
56 {
57 __asm__ __volatile__ (" wsr %0, rasid\n\t"
58 " isync\n" : : "a" (val));
59 }
60
get_rasid_register(void)61 static inline unsigned long get_rasid_register (void)
62 {
63 unsigned long tmp;
64 __asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
65 return tmp;
66 }
67
get_new_mmu_context(struct mm_struct * mm,unsigned int cpu)68 static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
69 {
70 unsigned long asid = cpu_asid_cache(cpu);
71 if ((++asid & ASID_MASK) == 0) {
72 /*
73 * Start new asid cycle; continue counting with next
74 * incarnation bits; skipping over 0, 1, 2, 3.
75 */
76 local_flush_tlb_all();
77 asid += ASID_USER_FIRST;
78 }
79 cpu_asid_cache(cpu) = asid;
80 mm->context.asid[cpu] = asid;
81 mm->context.cpu = cpu;
82 }
83
get_mmu_context(struct mm_struct * mm,unsigned int cpu)84 static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
85 {
86 /*
87 * Check if our ASID is of an older version and thus invalid.
88 */
89
90 if (mm) {
91 unsigned long asid = mm->context.asid[cpu];
92
93 if (asid == NO_CONTEXT ||
94 ((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
95 get_new_mmu_context(mm, cpu);
96 }
97 }
98
activate_context(struct mm_struct * mm,unsigned int cpu)99 static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
100 {
101 get_mmu_context(mm, cpu);
102 set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
103 invalidate_page_directory();
104 }
105
106 /*
107 * Initialize the context related info for a new mm_struct
108 * instance. Valid cpu values are 0..(NR_CPUS-1), so initializing
109 * to -1 says the process has never run on any core.
110 */
111
init_new_context(struct task_struct * tsk,struct mm_struct * mm)112 static inline int init_new_context(struct task_struct *tsk,
113 struct mm_struct *mm)
114 {
115 int cpu;
116 for_each_possible_cpu(cpu) {
117 mm->context.asid[cpu] = NO_CONTEXT;
118 }
119 mm->context.cpu = -1;
120 return 0;
121 }
122
switch_mm(struct mm_struct * prev,struct mm_struct * next,struct task_struct * tsk)123 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
124 struct task_struct *tsk)
125 {
126 unsigned int cpu = smp_processor_id();
127 int migrated = next->context.cpu != cpu;
128 /* Flush the icache if we migrated to a new core. */
129 if (migrated) {
130 __invalidate_icache_all();
131 next->context.cpu = cpu;
132 }
133 if (migrated || prev != next)
134 activate_context(next, cpu);
135 }
136
137 #define activate_mm(prev, next) switch_mm((prev), (next), NULL)
138 #define deactivate_mm(tsk, mm) do { } while (0)
139
140 /*
141 * Destroy context related info for an mm_struct that is about
142 * to be put to rest.
143 */
destroy_context(struct mm_struct * mm)144 static inline void destroy_context(struct mm_struct *mm)
145 {
146 invalidate_page_directory();
147 }
148
149
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)150 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
151 {
152 /* Nothing to do. */
153
154 }
155
156 #endif /* CONFIG_MMU */
157 #endif /* _XTENSA_MMU_CONTEXT_H */
158