1 /*
2 * Switch a 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) 1996, 1997, 1998, 1999 by Ralf Baechle
9 * Copyright (C) 1999 Silicon Graphics, Inc.
10 */
11 #ifndef _ASM_MMU_CONTEXT_H
12 #define _ASM_MMU_CONTEXT_H
13
14 #include <linux/errno.h>
15 #include <linux/sched.h>
16 #include <linux/mm_types.h>
17 #include <linux/smp.h>
18 #include <linux/slab.h>
19
20 #include <asm/barrier.h>
21 #include <asm/cacheflush.h>
22 #include <asm/dsemul.h>
23 #include <asm/ginvt.h>
24 #include <asm/hazards.h>
25 #include <asm/tlbflush.h>
26 #include <asm-generic/mm_hooks.h>
27
28 #define htw_set_pwbase(pgd) \
29 do { \
30 if (cpu_has_htw) { \
31 write_c0_pwbase(pgd); \
32 back_to_back_c0_hazard(); \
33 } \
34 } while (0)
35
36 extern void tlbmiss_handler_setup_pgd(unsigned long);
37 extern char tlbmiss_handler_setup_pgd_end[];
38
39 /* Note: This is also implemented with uasm in arch/mips/kvm/entry.c */
40 #define TLBMISS_HANDLER_SETUP_PGD(pgd) \
41 do { \
42 tlbmiss_handler_setup_pgd((unsigned long)(pgd)); \
43 htw_set_pwbase((unsigned long)pgd); \
44 } while (0)
45
46 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
47
48 #define TLBMISS_HANDLER_RESTORE() \
49 write_c0_xcontext((unsigned long) smp_processor_id() << \
50 SMP_CPUID_REGSHIFT)
51
52 #define TLBMISS_HANDLER_SETUP() \
53 do { \
54 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir); \
55 TLBMISS_HANDLER_RESTORE(); \
56 } while (0)
57
58 #else /* !CONFIG_MIPS_PGD_C0_CONTEXT: using pgd_current*/
59
60 /*
61 * For the fast tlb miss handlers, we keep a per cpu array of pointers
62 * to the current pgd for each processor. Also, the proc. id is stuffed
63 * into the context register.
64 */
65 extern unsigned long pgd_current[];
66
67 #define TLBMISS_HANDLER_RESTORE() \
68 write_c0_context((unsigned long) smp_processor_id() << \
69 SMP_CPUID_REGSHIFT)
70
71 #define TLBMISS_HANDLER_SETUP() \
72 TLBMISS_HANDLER_RESTORE(); \
73 back_to_back_c0_hazard(); \
74 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
75 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT*/
76
77 /*
78 * The ginvt instruction will invalidate wired entries when its type field
79 * targets anything other than the entire TLB. That means that if we were to
80 * allow the kernel to create wired entries with the MMID of current->active_mm
81 * then those wired entries could be invalidated when we later use ginvt to
82 * invalidate TLB entries with that MMID.
83 *
84 * In order to prevent ginvt from trashing wired entries, we reserve one MMID
85 * for use by the kernel when creating wired entries. This MMID will never be
86 * assigned to a struct mm, and we'll never target it with a ginvt instruction.
87 */
88 #define MMID_KERNEL_WIRED 0
89
90 /*
91 * All unused by hardware upper bits will be considered
92 * as a software asid extension.
93 */
94 static inline u64 asid_version_mask(unsigned int cpu)
95 {
96 unsigned long asid_mask = cpu_asid_mask(&cpu_data[cpu]);
97
98 return ~(u64)(asid_mask | (asid_mask - 1));
99 }
100
101 static inline u64 asid_first_version(unsigned int cpu)
102 {
103 return ~asid_version_mask(cpu) + 1;
104 }
105
106 static inline u64 cpu_context(unsigned int cpu, const struct mm_struct *mm)
107 {
108 if (cpu_has_mmid)
109 return atomic64_read(&mm->context.mmid);
110
111 return mm->context.asid[cpu];
112 }
113
114 static inline void set_cpu_context(unsigned int cpu,
115 struct mm_struct *mm, u64 ctx)
116 {
117 if (cpu_has_mmid)
118 atomic64_set(&mm->context.mmid, ctx);
119 else
120 mm->context.asid[cpu] = ctx;
121 }
122
123 #define asid_cache(cpu) (cpu_data[cpu].asid_cache)
124 #define cpu_asid(cpu, mm) \
125 (cpu_context((cpu), (mm)) & cpu_asid_mask(&cpu_data[cpu]))
126
127 extern void get_new_mmu_context(struct mm_struct *mm);
128 extern void check_mmu_context(struct mm_struct *mm);
129 extern void check_switch_mmu_context(struct mm_struct *mm);
130
131 /*
132 * Initialize the context related info for a new mm_struct
133 * instance.
134 */
135 #define init_new_context init_new_context
136 static inline int
137 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
138 {
139 int i;
140
141 if (cpu_has_mmid) {
142 set_cpu_context(0, mm, 0);
143 } else {
144 for_each_possible_cpu(i)
145 set_cpu_context(i, mm, 0);
146 }
147
148 mm->context.bd_emupage_allocmap = NULL;
149 spin_lock_init(&mm->context.bd_emupage_lock);
150 init_waitqueue_head(&mm->context.bd_emupage_queue);
151
152 return 0;
153 }
154
155 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
156 struct task_struct *tsk)
157 {
158 unsigned int cpu = smp_processor_id();
159 unsigned long flags;
160 local_irq_save(flags);
161
162 htw_stop();
163 check_switch_mmu_context(next);
164
165 /*
166 * Mark current->active_mm as not "active" anymore.
167 * We don't want to mislead possible IPI tlb flush routines.
168 */
169 cpumask_clear_cpu(cpu, mm_cpumask(prev));
170 cpumask_set_cpu(cpu, mm_cpumask(next));
171 htw_start();
172
173 local_irq_restore(flags);
174 }
175
176 /*
177 * Destroy context related info for an mm_struct that is about
178 * to be put to rest.
179 */
180 #define destroy_context destroy_context
181 static inline void destroy_context(struct mm_struct *mm)
182 {
183 dsemul_mm_cleanup(mm);
184 }
185
186 static inline void
187 drop_mmu_context(struct mm_struct *mm)
188 {
189 unsigned long flags;
190 unsigned int cpu;
191 u32 old_mmid;
192 u64 ctx;
193
194 local_irq_save(flags);
195
196 cpu = smp_processor_id();
197 ctx = cpu_context(cpu, mm);
198
199 if (!ctx) {
200 /* no-op */
201 } else if (cpu_has_mmid) {
202 /*
203 * Globally invalidating TLB entries associated with the MMID
204 * is pretty cheap using the GINVT instruction, so we'll do
205 * that rather than incur the overhead of allocating a new
206 * MMID. The latter would be especially difficult since MMIDs
207 * are global & other CPUs may be actively using ctx.
208 */
209 htw_stop();
210 old_mmid = read_c0_memorymapid();
211 write_c0_memorymapid(ctx & cpu_asid_mask(&cpu_data[cpu]));
212 mtc0_tlbw_hazard();
213 ginvt_mmid();
214 sync_ginv();
215 write_c0_memorymapid(old_mmid);
216 instruction_hazard();
217 htw_start();
218 } else if (cpumask_test_cpu(cpu, mm_cpumask(mm))) {
219 /*
220 * mm is currently active, so we can't really drop it.
221 * Instead we bump the ASID.
222 */
223 htw_stop();
224 get_new_mmu_context(mm);
225 write_c0_entryhi(cpu_asid(cpu, mm));
226 htw_start();
227 } else {
228 /* will get a new context next time */
229 set_cpu_context(cpu, mm, 0);
230 }
231
232 local_irq_restore(flags);
233 }
234
235 #include <asm-generic/mmu_context.h>
236
237 #endif /* _ASM_MMU_CONTEXT_H */
238
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.