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