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 <asm/system.h>
11 #include <asm/machvec.h>
12 #include <asm/compiler.h>
13 #include <asm-generic/mm_hooks.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
26 static inline unsigned long
__reload_thread(struct pcb_struct * pcb)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 #include <asm/smp.h>
89 #ifdef CONFIG_SMP
90 #define cpu_last_asn(cpuid) (cpu_data[cpuid].last_asn)
91 #else
92 extern 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
117 extern inline unsigned long
__get_new_mm_context(struct mm_struct * mm,long cpu)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
ev5_switch_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm,struct task_struct * next)133 ev5_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 task_thread_info(next)->pcb.asn = mmc & HARDWARE_ASN_MASK;
160 }
161
162 __EXTERN_INLINE void
ev4_switch_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm,struct task_struct * next)163 ev4_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
182 extern void __load_new_mm_context(struct mm_struct *);
183
184 #ifdef CONFIG_SMP
185 #define check_mmu_context() \
186 do { \
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
ev5_activate_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm)202 ev5_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
ev4_activate_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm)208 ev4_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
229 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)230 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
231 {
232 int i;
233
234 for_each_online_cpu(i)
235 mm->context[i] = 0;
236 if (tsk != current)
237 task_thread_info(tsk)->pcb.ptbr
238 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
239 return 0;
240 }
241
242 extern inline void
destroy_context(struct mm_struct * mm)243 destroy_context(struct mm_struct *mm)
244 {
245 /* Nothing to do. */
246 }
247
248 static inline void
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)249 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
250 {
251 task_thread_info(tsk)->pcb.ptbr
252 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
253 }
254
255 #ifdef __MMU_EXTERN_INLINE
256 #undef __EXTERN_INLINE
257 #undef __MMU_EXTERN_INLINE
258 #endif
259
260 #endif /* __ALPHA_MMU_CONTEXT_H */
261