1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ALPHA_MMU_CONTEXT_H
3 #define __ALPHA_MMU_CONTEXT_H
4
5 /*
6 * get a new mmu context..
7 *
8 * Copyright (C) 1996, Linus Torvalds
9 */
10
11 #include <linux/mm_types.h>
12 #include <linux/sched.h>
13
14 #include <asm/machvec.h>
15 #include <asm/compiler.h>
16 #include <asm-generic/mm_hooks.h>
17
18 /*
19 * Force a context reload. This is needed when we change the page
20 * table pointer or when we update the ASN of the current process.
21 */
22
23 /* Don't get into trouble with dueling __EXTERN_INLINEs. */
24 #ifndef __EXTERN_INLINE
25 #include <asm/io.h>
26 #endif
27
28
29 static inline unsigned long
__reload_thread(struct pcb_struct * pcb)30 __reload_thread(struct pcb_struct *pcb)
31 {
32 register unsigned long a0 __asm__("$16");
33 register unsigned long v0 __asm__("$0");
34
35 a0 = virt_to_phys(pcb);
36 __asm__ __volatile__(
37 "call_pal %2 #__reload_thread"
38 : "=r"(v0), "=r"(a0)
39 : "i"(PAL_swpctx), "r"(a0)
40 : "$1", "$22", "$23", "$24", "$25");
41
42 return v0;
43 }
44
45
46 /*
47 * The maximum ASN's the processor supports. On the EV4 this is 63
48 * but the PAL-code doesn't actually use this information. On the
49 * EV5 this is 127, and EV6 has 255.
50 *
51 * On the EV4, the ASNs are more-or-less useless anyway, as they are
52 * only used as an icache tag, not for TB entries. On the EV5 and EV6,
53 * ASN's also validate the TB entries, and thus make a lot more sense.
54 *
55 * The EV4 ASN's don't even match the architecture manual, ugh. And
56 * I quote: "If a processor implements address space numbers (ASNs),
57 * and the old PTE has the Address Space Match (ASM) bit clear (ASNs
58 * in use) and the Valid bit set, then entries can also effectively be
59 * made coherent by assigning a new, unused ASN to the currently
60 * running process and not reusing the previous ASN before calling the
61 * appropriate PALcode routine to invalidate the translation buffer (TB)".
62 *
63 * In short, the EV4 has a "kind of" ASN capability, but it doesn't actually
64 * work correctly and can thus not be used (explaining the lack of PAL-code
65 * support).
66 */
67 #define EV4_MAX_ASN 63
68 #define EV5_MAX_ASN 127
69 #define EV6_MAX_ASN 255
70
71 #ifdef CONFIG_ALPHA_GENERIC
72 # define MAX_ASN (alpha_mv.max_asn)
73 #else
74 # ifdef CONFIG_ALPHA_EV4
75 # define MAX_ASN EV4_MAX_ASN
76 # elif defined(CONFIG_ALPHA_EV5)
77 # define MAX_ASN EV5_MAX_ASN
78 # else
79 # define MAX_ASN EV6_MAX_ASN
80 # endif
81 #endif
82
83 /*
84 * cpu_last_asn(processor):
85 * 63 0
86 * +-------------+----------------+--------------+
87 * | asn version | this processor | hardware asn |
88 * +-------------+----------------+--------------+
89 */
90
91 #include <asm/smp.h>
92 #ifdef CONFIG_SMP
93 #define cpu_last_asn(cpuid) (cpu_data[cpuid].last_asn)
94 #else
95 extern unsigned long last_asn;
96 #define cpu_last_asn(cpuid) last_asn
97 #endif /* CONFIG_SMP */
98
99 #define WIDTH_HARDWARE_ASN 8
100 #define ASN_FIRST_VERSION (1UL << WIDTH_HARDWARE_ASN)
101 #define HARDWARE_ASN_MASK ((1UL << WIDTH_HARDWARE_ASN) - 1)
102
103 /*
104 * NOTE! The way this is set up, the high bits of the "asn_cache" (and
105 * the "mm->context") are the ASN _version_ code. A version of 0 is
106 * always considered invalid, so to invalidate another process you only
107 * need to do "p->mm->context = 0".
108 *
109 * If we need more ASN's than the processor has, we invalidate the old
110 * user TLB's (tbiap()) and start a new ASN version. That will automatically
111 * force a new asn for any other processes the next time they want to
112 * run.
113 */
114
115 #ifndef __EXTERN_INLINE
116 #define __EXTERN_INLINE extern inline
117 #define __MMU_EXTERN_INLINE
118 #endif
119
120 extern inline unsigned long
__get_new_mm_context(struct mm_struct * mm,long cpu)121 __get_new_mm_context(struct mm_struct *mm, long cpu)
122 {
123 unsigned long asn = cpu_last_asn(cpu);
124 unsigned long next = asn + 1;
125
126 if ((asn & HARDWARE_ASN_MASK) >= MAX_ASN) {
127 tbiap();
128 imb();
129 next = (asn & ~HARDWARE_ASN_MASK) + ASN_FIRST_VERSION;
130 }
131 cpu_last_asn(cpu) = next;
132 return next;
133 }
134
135 __EXTERN_INLINE void
ev5_switch_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm,struct task_struct * next)136 ev5_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
137 struct task_struct *next)
138 {
139 /* Check if our ASN is of an older version, and thus invalid. */
140 unsigned long asn;
141 unsigned long mmc;
142 long cpu = smp_processor_id();
143
144 #ifdef CONFIG_SMP
145 cpu_data[cpu].asn_lock = 1;
146 barrier();
147 #endif
148 asn = cpu_last_asn(cpu);
149 mmc = next_mm->context[cpu];
150 if ((mmc ^ asn) & ~HARDWARE_ASN_MASK) {
151 mmc = __get_new_mm_context(next_mm, cpu);
152 next_mm->context[cpu] = mmc;
153 }
154 #ifdef CONFIG_SMP
155 else
156 cpu_data[cpu].need_new_asn = 1;
157 #endif
158
159 /* Always update the PCB ASN. Another thread may have allocated
160 a new mm->context (via flush_tlb_mm) without the ASN serial
161 number wrapping. We have no way to detect when this is needed. */
162 task_thread_info(next)->pcb.asn = mmc & HARDWARE_ASN_MASK;
163 }
164
165 __EXTERN_INLINE void
ev4_switch_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm,struct task_struct * next)166 ev4_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
167 struct task_struct *next)
168 {
169 /* As described, ASN's are broken for TLB usage. But we can
170 optimize for switching between threads -- if the mm is
171 unchanged from current we needn't flush. */
172 /* ??? May not be needed because EV4 PALcode recognizes that
173 ASN's are broken and does a tbiap itself on swpctx, under
174 the "Must set ASN or flush" rule. At least this is true
175 for a 1992 SRM, reports Joseph Martin (jmartin@hlo.dec.com).
176 I'm going to leave this here anyway, just to Be Sure. -- r~ */
177 if (prev_mm != next_mm)
178 tbiap();
179
180 /* Do continue to allocate ASNs, because we can still use them
181 to avoid flushing the icache. */
182 ev5_switch_mm(prev_mm, next_mm, next);
183 }
184
185 extern void __load_new_mm_context(struct mm_struct *);
186
187 #ifdef CONFIG_SMP
188 #define check_mmu_context() \
189 do { \
190 int cpu = smp_processor_id(); \
191 cpu_data[cpu].asn_lock = 0; \
192 barrier(); \
193 if (cpu_data[cpu].need_new_asn) { \
194 struct mm_struct * mm = current->active_mm; \
195 cpu_data[cpu].need_new_asn = 0; \
196 if (!mm->context[cpu]) \
197 __load_new_mm_context(mm); \
198 } \
199 } while(0)
200 #else
201 #define check_mmu_context() do { } while(0)
202 #endif
203
204 __EXTERN_INLINE void
ev5_activate_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm)205 ev5_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
206 {
207 __load_new_mm_context(next_mm);
208 }
209
210 __EXTERN_INLINE void
ev4_activate_mm(struct mm_struct * prev_mm,struct mm_struct * next_mm)211 ev4_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
212 {
213 __load_new_mm_context(next_mm);
214 tbiap();
215 }
216
217 #define deactivate_mm(tsk,mm) do { } while (0)
218
219 #ifdef CONFIG_ALPHA_GENERIC
220 # define switch_mm(a,b,c) alpha_mv.mv_switch_mm((a),(b),(c))
221 # define activate_mm(x,y) alpha_mv.mv_activate_mm((x),(y))
222 #else
223 # ifdef CONFIG_ALPHA_EV4
224 # define switch_mm(a,b,c) ev4_switch_mm((a),(b),(c))
225 # define activate_mm(x,y) ev4_activate_mm((x),(y))
226 # else
227 # define switch_mm(a,b,c) ev5_switch_mm((a),(b),(c))
228 # define activate_mm(x,y) ev5_activate_mm((x),(y))
229 # endif
230 #endif
231
232 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)233 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
234 {
235 int i;
236
237 for_each_online_cpu(i)
238 mm->context[i] = 0;
239 if (tsk != current)
240 task_thread_info(tsk)->pcb.ptbr
241 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
242 return 0;
243 }
244
245 extern inline void
destroy_context(struct mm_struct * mm)246 destroy_context(struct mm_struct *mm)
247 {
248 /* Nothing to do. */
249 }
250
251 static inline void
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)252 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
253 {
254 task_thread_info(tsk)->pcb.ptbr
255 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
256 }
257
258 #ifdef __MMU_EXTERN_INLINE
259 #undef __EXTERN_INLINE
260 #undef __MMU_EXTERN_INLINE
261 #endif
262
263 #endif /* __ALPHA_MMU_CONTEXT_H */
264
