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Linux kernel mirror (for testing)
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linux
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
33DECLARE_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#ifdef CONFIG_MMU
54void init_mmu(void);
55#else
56static inline void init_mmu(void) { }
57#endif
58
59static inline void set_rasid_register (unsigned long val)
60{
61 __asm__ __volatile__ (" wsr %0, rasid\n\t"
62 " isync\n" : : "a" (val));
63}
64
65static inline unsigned long get_rasid_register (void)
66{
67 unsigned long tmp;
68 __asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
69 return tmp;
70}
71
72static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
73{
74 unsigned long asid = cpu_asid_cache(cpu);
75 if ((++asid & ASID_MASK) == 0) {
76 /*
77 * Start new asid cycle; continue counting with next
78 * incarnation bits; skipping over 0, 1, 2, 3.
79 */
80 local_flush_tlb_all();
81 asid += ASID_USER_FIRST;
82 }
83 cpu_asid_cache(cpu) = asid;
84 mm->context.asid[cpu] = asid;
85 mm->context.cpu = cpu;
86}
87
88static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
89{
90 /*
91 * Check if our ASID is of an older version and thus invalid.
92 */
93
94 if (mm) {
95 unsigned long asid = mm->context.asid[cpu];
96
97 if (asid == NO_CONTEXT ||
98 ((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
99 get_new_mmu_context(mm, cpu);
100 }
101}
102
103static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
104{
105 get_mmu_context(mm, cpu);
106 set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
107 invalidate_page_directory();
108}
109
110/*
111 * Initialize the context related info for a new mm_struct
112 * instance. Valid cpu values are 0..(NR_CPUS-1), so initializing
113 * to -1 says the process has never run on any core.
114 */
115
116static inline int init_new_context(struct task_struct *tsk,
117 struct mm_struct *mm)
118{
119 int cpu;
120 for_each_possible_cpu(cpu) {
121 mm->context.asid[cpu] = NO_CONTEXT;
122 }
123 mm->context.cpu = -1;
124 return 0;
125}
126
127static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
128 struct task_struct *tsk)
129{
130 unsigned int cpu = smp_processor_id();
131 int migrated = next->context.cpu != cpu;
132 /* Flush the icache if we migrated to a new core. */
133 if (migrated) {
134 __invalidate_icache_all();
135 next->context.cpu = cpu;
136 }
137 if (migrated || prev != next)
138 activate_context(next, cpu);
139}
140
141#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
142#define deactivate_mm(tsk, mm) do { } while (0)
143
144/*
145 * Destroy context related info for an mm_struct that is about
146 * to be put to rest.
147 */
148static inline void destroy_context(struct mm_struct *mm)
149{
150 invalidate_page_directory();
151}
152
153
154static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
155{
156 /* Nothing to do. */
157
158}
159
160#endif /* CONFIG_MMU */
161#endif /* _XTENSA_MMU_CONTEXT_H */