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-rw-r--r--include/asm-powerpc/mmu_context.h280
1 files changed, 0 insertions, 280 deletions
diff --git a/include/asm-powerpc/mmu_context.h b/include/asm-powerpc/mmu_context.h
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--- a/include/asm-powerpc/mmu_context.h
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1#ifndef __ASM_POWERPC_MMU_CONTEXT_H
2#define __ASM_POWERPC_MMU_CONTEXT_H
3#ifdef __KERNEL__
4
5#include <asm/mmu.h>
6#include <asm/cputable.h>
7#include <asm-generic/mm_hooks.h>
8
9#ifndef CONFIG_PPC64
10#include <asm/atomic.h>
11#include <linux/bitops.h>
12
13/*
14 * On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use a set of 16 VSIDs
15 * (virtual segment identifiers) for each context. Although the
16 * hardware supports 24-bit VSIDs, and thus >1 million contexts,
17 * we only use 32,768 of them. That is ample, since there can be
18 * at most around 30,000 tasks in the system anyway, and it means
19 * that we can use a bitmap to indicate which contexts are in use.
20 * Using a bitmap means that we entirely avoid all of the problems
21 * that we used to have when the context number overflowed,
22 * particularly on SMP systems.
23 * -- paulus.
24 */
25
26/*
27 * This function defines the mapping from contexts to VSIDs (virtual
28 * segment IDs). We use a skew on both the context and the high 4 bits
29 * of the 32-bit virtual address (the "effective segment ID") in order
30 * to spread out the entries in the MMU hash table. Note, if this
31 * function is changed then arch/ppc/mm/hashtable.S will have to be
32 * changed to correspond.
33 */
34#define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
35 & 0xffffff)
36
37/*
38 The MPC8xx has only 16 contexts. We rotate through them on each
39 task switch. A better way would be to keep track of tasks that
40 own contexts, and implement an LRU usage. That way very active
41 tasks don't always have to pay the TLB reload overhead. The
42 kernel pages are mapped shared, so the kernel can run on behalf
43 of any task that makes a kernel entry. Shared does not mean they
44 are not protected, just that the ASID comparison is not performed.
45 -- Dan
46
47 The IBM4xx has 256 contexts, so we can just rotate through these
48 as a way of "switching" contexts. If the TID of the TLB is zero,
49 the PID/TID comparison is disabled, so we can use a TID of zero
50 to represent all kernel pages as shared among all contexts.
51 -- Dan
52 */
53
54static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
55{
56}
57
58#ifdef CONFIG_8xx
59#define NO_CONTEXT 16
60#define LAST_CONTEXT 15
61#define FIRST_CONTEXT 0
62
63#elif defined(CONFIG_4xx)
64#define NO_CONTEXT 256
65#define LAST_CONTEXT 255
66#define FIRST_CONTEXT 1
67
68#elif defined(CONFIG_E200) || defined(CONFIG_E500)
69#define NO_CONTEXT 256
70#define LAST_CONTEXT 255
71#define FIRST_CONTEXT 1
72
73#else
74
75/* PPC 6xx, 7xx CPUs */
76#define NO_CONTEXT ((unsigned long) -1)
77#define LAST_CONTEXT 32767
78#define FIRST_CONTEXT 1
79#endif
80
81/*
82 * Set the current MMU context.
83 * On 32-bit PowerPCs (other than the 8xx embedded chips), this is done by
84 * loading up the segment registers for the user part of the address space.
85 *
86 * Since the PGD is immediately available, it is much faster to simply
87 * pass this along as a second parameter, which is required for 8xx and
88 * can be used for debugging on all processors (if you happen to have
89 * an Abatron).
90 */
91extern void set_context(unsigned long contextid, pgd_t *pgd);
92
93/*
94 * Bitmap of contexts in use.
95 * The size of this bitmap is LAST_CONTEXT + 1 bits.
96 */
97extern unsigned long context_map[];
98
99/*
100 * This caches the next context number that we expect to be free.
101 * Its use is an optimization only, we can't rely on this context
102 * number to be free, but it usually will be.
103 */
104extern unsigned long next_mmu_context;
105
106/*
107 * If we don't have sufficient contexts to give one to every task
108 * that could be in the system, we need to be able to steal contexts.
109 * These variables support that.
110 */
111#if LAST_CONTEXT < 30000
112#define FEW_CONTEXTS 1
113extern atomic_t nr_free_contexts;
114extern struct mm_struct *context_mm[LAST_CONTEXT+1];
115extern void steal_context(void);
116#endif
117
118/*
119 * Get a new mmu context for the address space described by `mm'.
120 */
121static inline void get_mmu_context(struct mm_struct *mm)
122{
123 unsigned long ctx;
124
125 if (mm->context.id != NO_CONTEXT)
126 return;
127#ifdef FEW_CONTEXTS
128 while (atomic_dec_if_positive(&nr_free_contexts) < 0)
129 steal_context();
130#endif
131 ctx = next_mmu_context;
132 while (test_and_set_bit(ctx, context_map)) {
133 ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
134 if (ctx > LAST_CONTEXT)
135 ctx = 0;
136 }
137 next_mmu_context = (ctx + 1) & LAST_CONTEXT;
138 mm->context.id = ctx;
139#ifdef FEW_CONTEXTS
140 context_mm[ctx] = mm;
141#endif
142}
143
144/*
145 * Set up the context for a new address space.
146 */
147static inline int init_new_context(struct task_struct *t, struct mm_struct *mm)
148{
149 mm->context.id = NO_CONTEXT;
150 mm->context.vdso_base = 0;
151 return 0;
152}
153
154/*
155 * We're finished using the context for an address space.
156 */
157static inline void destroy_context(struct mm_struct *mm)
158{
159 preempt_disable();
160 if (mm->context.id != NO_CONTEXT) {
161 clear_bit(mm->context.id, context_map);
162 mm->context.id = NO_CONTEXT;
163#ifdef FEW_CONTEXTS
164 atomic_inc(&nr_free_contexts);
165#endif
166 }
167 preempt_enable();
168}
169
170static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
171 struct task_struct *tsk)
172{
173#ifdef CONFIG_ALTIVEC
174 if (cpu_has_feature(CPU_FTR_ALTIVEC))
175 asm volatile ("dssall;\n"
176#ifndef CONFIG_POWER4
177 "sync;\n" /* G4 needs a sync here, G5 apparently not */
178#endif
179 : : );
180#endif /* CONFIG_ALTIVEC */
181
182 tsk->thread.pgdir = next->pgd;
183
184 /* No need to flush userspace segments if the mm doesnt change */
185 if (prev == next)
186 return;
187
188 /* Setup new userspace context */
189 get_mmu_context(next);
190 set_context(next->context.id, next->pgd);
191}
192
193#define deactivate_mm(tsk,mm) do { } while (0)
194
195/*
196 * After we have set current->mm to a new value, this activates
197 * the context for the new mm so we see the new mappings.
198 */
199#define activate_mm(active_mm, mm) switch_mm(active_mm, mm, current)
200
201extern void mmu_context_init(void);
202
203
204#else
205
206#include <linux/kernel.h>
207#include <linux/mm.h>
208#include <linux/sched.h>
209
210/*
211 * Copyright (C) 2001 PPC 64 Team, IBM Corp
212 *
213 * This program is free software; you can redistribute it and/or
214 * modify it under the terms of the GNU General Public License
215 * as published by the Free Software Foundation; either version
216 * 2 of the License, or (at your option) any later version.
217 */
218
219static inline void enter_lazy_tlb(struct mm_struct *mm,
220 struct task_struct *tsk)
221{
222}
223
224/*
225 * The proto-VSID space has 2^35 - 1 segments available for user mappings.
226 * Each segment contains 2^28 bytes. Each context maps 2^44 bytes,
227 * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
228 */
229#define NO_CONTEXT 0
230#define MAX_CONTEXT ((1UL << 19) - 1)
231
232extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
233extern void destroy_context(struct mm_struct *mm);
234
235extern void switch_stab(struct task_struct *tsk, struct mm_struct *mm);
236extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm);
237
238/*
239 * switch_mm is the entry point called from the architecture independent
240 * code in kernel/sched.c
241 */
242static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
243 struct task_struct *tsk)
244{
245 if (!cpu_isset(smp_processor_id(), next->cpu_vm_mask))
246 cpu_set(smp_processor_id(), next->cpu_vm_mask);
247
248 /* No need to flush userspace segments if the mm doesnt change */
249 if (prev == next)
250 return;
251
252#ifdef CONFIG_ALTIVEC
253 if (cpu_has_feature(CPU_FTR_ALTIVEC))
254 asm volatile ("dssall");
255#endif /* CONFIG_ALTIVEC */
256
257 if (cpu_has_feature(CPU_FTR_SLB))
258 switch_slb(tsk, next);
259 else
260 switch_stab(tsk, next);
261}
262
263#define deactivate_mm(tsk,mm) do { } while (0)
264
265/*
266 * After we have set current->mm to a new value, this activates
267 * the context for the new mm so we see the new mappings.
268 */
269static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
270{
271 unsigned long flags;
272
273 local_irq_save(flags);
274 switch_mm(prev, next, current);
275 local_irq_restore(flags);
276}
277
278#endif /* CONFIG_PPC64 */
279#endif /* __KERNEL__ */
280#endif /* __ASM_POWERPC_MMU_CONTEXT_H */
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-21 16:59:52 -0500