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linux
1#ifndef __ALPHA_MMU_CONTEXT_H
2#define __ALPHA_MMU_CONTEXT_H
3
4/*
5 * get a new mmu context..
6 *
7 * Copyright (C) 1996, Linus Torvalds
8 */
9
10#include <linux/config.h>
11#include <asm/system.h>
12#include <asm/machvec.h>
13#include <asm/compiler.h>
14
15/*
16 * Force a context reload. This is needed when we change the page
17 * table pointer or when we update the ASN of the current process.
18 */
19
20/* Don't get into trouble with dueling __EXTERN_INLINEs. */
21#ifndef __EXTERN_INLINE
22#include <asm/io.h>
23#endif
24
25
26extern inline unsigned long
27__reload_thread(struct pcb_struct *pcb)
28{
29 register unsigned long a0 __asm__("$16");
30 register unsigned long v0 __asm__("$0");
31
32 a0 = virt_to_phys(pcb);
33 __asm__ __volatile__(
34 "call_pal %2 #__reload_thread"
35 : "=r"(v0), "=r"(a0)
36 : "i"(PAL_swpctx), "r"(a0)
37 : "$1", "$22", "$23", "$24", "$25");
38
39 return v0;
40}
41
42
43/*
44 * The maximum ASN's the processor supports. On the EV4 this is 63
45 * but the PAL-code doesn't actually use this information. On the
46 * EV5 this is 127, and EV6 has 255.
47 *
48 * On the EV4, the ASNs are more-or-less useless anyway, as they are
49 * only used as an icache tag, not for TB entries. On the EV5 and EV6,
50 * ASN's also validate the TB entries, and thus make a lot more sense.
51 *
52 * The EV4 ASN's don't even match the architecture manual, ugh. And
53 * I quote: "If a processor implements address space numbers (ASNs),
54 * and the old PTE has the Address Space Match (ASM) bit clear (ASNs
55 * in use) and the Valid bit set, then entries can also effectively be
56 * made coherent by assigning a new, unused ASN to the currently
57 * running process and not reusing the previous ASN before calling the
58 * appropriate PALcode routine to invalidate the translation buffer (TB)".
59 *
60 * In short, the EV4 has a "kind of" ASN capability, but it doesn't actually
61 * work correctly and can thus not be used (explaining the lack of PAL-code
62 * support).
63 */
64#define EV4_MAX_ASN 63
65#define EV5_MAX_ASN 127
66#define EV6_MAX_ASN 255
67
68#ifdef CONFIG_ALPHA_GENERIC
69# define MAX_ASN (alpha_mv.max_asn)
70#else
71# ifdef CONFIG_ALPHA_EV4
72# define MAX_ASN EV4_MAX_ASN
73# elif defined(CONFIG_ALPHA_EV5)
74# define MAX_ASN EV5_MAX_ASN
75# else
76# define MAX_ASN EV6_MAX_ASN
77# endif
78#endif
79
80/*
81 * cpu_last_asn(processor):
82 * 63 0
83 * +-------------+----------------+--------------+
84 * | asn version | this processor | hardware asn |
85 * +-------------+----------------+--------------+
86 */
87
88#ifdef CONFIG_SMP
89#include <asm/smp.h>
90#define cpu_last_asn(cpuid) (cpu_data[cpuid].last_asn)
91#else
92extern unsigned long last_asn;
93#define cpu_last_asn(cpuid) last_asn
94#endif /* CONFIG_SMP */
95
96#define WIDTH_HARDWARE_ASN 8
97#define ASN_FIRST_VERSION (1UL << WIDTH_HARDWARE_ASN)
98#define HARDWARE_ASN_MASK ((1UL << WIDTH_HARDWARE_ASN) - 1)
99
100/*
101 * NOTE! The way this is set up, the high bits of the "asn_cache" (and
102 * the "mm->context") are the ASN _version_ code. A version of 0 is
103 * always considered invalid, so to invalidate another process you only
104 * need to do "p->mm->context = 0".
105 *
106 * If we need more ASN's than the processor has, we invalidate the old
107 * user TLB's (tbiap()) and start a new ASN version. That will automatically
108 * force a new asn for any other processes the next time they want to
109 * run.
110 */
111
112#ifndef __EXTERN_INLINE
113#define __EXTERN_INLINE extern inline
114#define __MMU_EXTERN_INLINE
115#endif
116
117static inline unsigned long
118__get_new_mm_context(struct mm_struct *mm, long cpu)
119{
120 unsigned long asn = cpu_last_asn(cpu);
121 unsigned long next = asn + 1;
122
123 if ((asn & HARDWARE_ASN_MASK) >= MAX_ASN) {
124 tbiap();
125 imb();
126 next = (asn & ~HARDWARE_ASN_MASK) + ASN_FIRST_VERSION;
127 }
128 cpu_last_asn(cpu) = next;
129 return next;
130}
131
132__EXTERN_INLINE void
133ev5_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
134 struct task_struct *next)
135{
136 /* Check if our ASN is of an older version, and thus invalid. */
137 unsigned long asn;
138 unsigned long mmc;
139 long cpu = smp_processor_id();
140
141#ifdef CONFIG_SMP
142 cpu_data[cpu].asn_lock = 1;
143 barrier();
144#endif
145 asn = cpu_last_asn(cpu);
146 mmc = next_mm->context[cpu];
147 if ((mmc ^ asn) & ~HARDWARE_ASN_MASK) {
148 mmc = __get_new_mm_context(next_mm, cpu);
149 next_mm->context[cpu] = mmc;
150 }
151#ifdef CONFIG_SMP
152 else
153 cpu_data[cpu].need_new_asn = 1;
154#endif
155
156 /* Always update the PCB ASN. Another thread may have allocated
157 a new mm->context (via flush_tlb_mm) without the ASN serial
158 number wrapping. We have no way to detect when this is needed. */
159 next->thread_info->pcb.asn = mmc & HARDWARE_ASN_MASK;
160}
161
162__EXTERN_INLINE void
163ev4_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
164 struct task_struct *next)
165{
166 /* As described, ASN's are broken for TLB usage. But we can
167 optimize for switching between threads -- if the mm is
168 unchanged from current we needn't flush. */
169 /* ??? May not be needed because EV4 PALcode recognizes that
170 ASN's are broken and does a tbiap itself on swpctx, under
171 the "Must set ASN or flush" rule. At least this is true
172 for a 1992 SRM, reports Joseph Martin (jmartin@hlo.dec.com).
173 I'm going to leave this here anyway, just to Be Sure. -- r~ */
174 if (prev_mm != next_mm)
175 tbiap();
176
177 /* Do continue to allocate ASNs, because we can still use them
178 to avoid flushing the icache. */
179 ev5_switch_mm(prev_mm, next_mm, next);
180}
181
182extern void __load_new_mm_context(struct mm_struct *);
183
184#ifdef CONFIG_SMP
185#define check_mmu_context() \
186do { \
187 int cpu = smp_processor_id(); \
188 cpu_data[cpu].asn_lock = 0; \
189 barrier(); \
190 if (cpu_data[cpu].need_new_asn) { \
191 struct mm_struct * mm = current->active_mm; \
192 cpu_data[cpu].need_new_asn = 0; \
193 if (!mm->context[cpu]) \
194 __load_new_mm_context(mm); \
195 } \
196} while(0)
197#else
198#define check_mmu_context() do { } while(0)
199#endif
200
201__EXTERN_INLINE void
202ev5_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
203{
204 __load_new_mm_context(next_mm);
205}
206
207__EXTERN_INLINE void
208ev4_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
209{
210 __load_new_mm_context(next_mm);
211 tbiap();
212}
213
214#define deactivate_mm(tsk,mm) do { } while (0)
215
216#ifdef CONFIG_ALPHA_GENERIC
217# define switch_mm(a,b,c) alpha_mv.mv_switch_mm((a),(b),(c))
218# define activate_mm(x,y) alpha_mv.mv_activate_mm((x),(y))
219#else
220# ifdef CONFIG_ALPHA_EV4
221# define switch_mm(a,b,c) ev4_switch_mm((a),(b),(c))
222# define activate_mm(x,y) ev4_activate_mm((x),(y))
223# else
224# define switch_mm(a,b,c) ev5_switch_mm((a),(b),(c))
225# define activate_mm(x,y) ev5_activate_mm((x),(y))
226# endif
227#endif
228
229extern inline int
230init_new_context(struct task_struct *tsk, struct mm_struct *mm)
231{
232 int i;
233
234 for (i = 0; i < NR_CPUS; i++)
235 if (cpu_online(i))
236 mm->context[i] = 0;
237 if (tsk != current)
238 tsk->thread_info->pcb.ptbr
239 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
240 return 0;
241}
242
243extern inline void
244destroy_context(struct mm_struct *mm)
245{
246 /* Nothing to do. */
247}
248
249static inline void
250enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
251{
252 tsk->thread_info->pcb.ptbr
253 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
254}
255
256#ifdef __MMU_EXTERN_INLINE
257#undef __EXTERN_INLINE
258#undef __MMU_EXTERN_INLINE
259#endif
260
261#endif /* __ALPHA_MMU_CONTEXT_H */