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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1e133ab2 MS |
2 | /* |
3 | * Page table allocation functions | |
4 | * | |
5 | * Copyright IBM Corp. 2016 | |
6 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> | |
7 | */ | |
8 | ||
9 | #include <linux/mm.h> | |
10 | #include <linux/sysctl.h> | |
11 | #include <asm/mmu_context.h> | |
12 | #include <asm/pgalloc.h> | |
13 | #include <asm/gmap.h> | |
14 | #include <asm/tlb.h> | |
15 | #include <asm/tlbflush.h> | |
16 | ||
17 | #ifdef CONFIG_PGSTE | |
18 | ||
19 | static int page_table_allocate_pgste_min = 0; | |
20 | static int page_table_allocate_pgste_max = 1; | |
21 | int page_table_allocate_pgste = 0; | |
22 | EXPORT_SYMBOL(page_table_allocate_pgste); | |
23 | ||
24 | static struct ctl_table page_table_sysctl[] = { | |
25 | { | |
26 | .procname = "allocate_pgste", | |
27 | .data = &page_table_allocate_pgste, | |
28 | .maxlen = sizeof(int), | |
29 | .mode = S_IRUGO | S_IWUSR, | |
30 | .proc_handler = proc_dointvec, | |
31 | .extra1 = &page_table_allocate_pgste_min, | |
32 | .extra2 = &page_table_allocate_pgste_max, | |
33 | }, | |
34 | { } | |
35 | }; | |
36 | ||
37 | static struct ctl_table page_table_sysctl_dir[] = { | |
38 | { | |
39 | .procname = "vm", | |
40 | .maxlen = 0, | |
41 | .mode = 0555, | |
42 | .child = page_table_sysctl, | |
43 | }, | |
44 | { } | |
45 | }; | |
46 | ||
47 | static int __init page_table_register_sysctl(void) | |
48 | { | |
49 | return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM; | |
50 | } | |
51 | __initcall(page_table_register_sysctl); | |
52 | ||
53 | #endif /* CONFIG_PGSTE */ | |
54 | ||
55 | unsigned long *crst_table_alloc(struct mm_struct *mm) | |
56 | { | |
57 | struct page *page = alloc_pages(GFP_KERNEL, 2); | |
58 | ||
59 | if (!page) | |
60 | return NULL; | |
c9b5ad54 | 61 | arch_set_page_dat(page, 2); |
1e133ab2 MS |
62 | return (unsigned long *) page_to_phys(page); |
63 | } | |
64 | ||
65 | void crst_table_free(struct mm_struct *mm, unsigned long *table) | |
66 | { | |
67 | free_pages((unsigned long) table, 2); | |
68 | } | |
69 | ||
70 | static void __crst_table_upgrade(void *arg) | |
71 | { | |
72 | struct mm_struct *mm = arg; | |
73 | ||
0aaba41b | 74 | if (current->active_mm == mm) |
1e133ab2 | 75 | set_user_asce(mm); |
1e133ab2 MS |
76 | __tlb_flush_local(); |
77 | } | |
78 | ||
1aea9b3f | 79 | int crst_table_upgrade(struct mm_struct *mm, unsigned long end) |
1e133ab2 MS |
80 | { |
81 | unsigned long *table, *pgd; | |
1aea9b3f | 82 | int rc, notify; |
1e133ab2 | 83 | |
1aea9b3f | 84 | /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ |
2fc4876e | 85 | VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE); |
1aea9b3f MS |
86 | rc = 0; |
87 | notify = 0; | |
88 | while (mm->context.asce_limit < end) { | |
89 | table = crst_table_alloc(mm); | |
90 | if (!table) { | |
91 | rc = -ENOMEM; | |
92 | break; | |
93 | } | |
94 | spin_lock_bh(&mm->page_table_lock); | |
95 | pgd = (unsigned long *) mm->pgd; | |
f1c1174f | 96 | if (mm->context.asce_limit == _REGION2_SIZE) { |
1aea9b3f MS |
97 | crst_table_init(table, _REGION2_ENTRY_EMPTY); |
98 | p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd); | |
99 | mm->pgd = (pgd_t *) table; | |
f1c1174f | 100 | mm->context.asce_limit = _REGION1_SIZE; |
1aea9b3f MS |
101 | mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | |
102 | _ASCE_USER_BITS | _ASCE_TYPE_REGION2; | |
103 | } else { | |
104 | crst_table_init(table, _REGION1_ENTRY_EMPTY); | |
105 | pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd); | |
106 | mm->pgd = (pgd_t *) table; | |
107 | mm->context.asce_limit = -PAGE_SIZE; | |
108 | mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | | |
109 | _ASCE_USER_BITS | _ASCE_TYPE_REGION1; | |
110 | } | |
111 | notify = 1; | |
112 | spin_unlock_bh(&mm->page_table_lock); | |
113 | } | |
114 | if (notify) | |
115 | on_each_cpu(__crst_table_upgrade, mm, 0); | |
116 | return rc; | |
1e133ab2 MS |
117 | } |
118 | ||
723cacbd | 119 | void crst_table_downgrade(struct mm_struct *mm) |
1e133ab2 MS |
120 | { |
121 | pgd_t *pgd; | |
122 | ||
723cacbd | 123 | /* downgrade should only happen from 3 to 2 levels (compat only) */ |
2fc4876e | 124 | VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE); |
723cacbd | 125 | |
1e133ab2 MS |
126 | if (current->active_mm == mm) { |
127 | clear_user_asce(); | |
128 | __tlb_flush_mm(mm); | |
129 | } | |
723cacbd GS |
130 | |
131 | pgd = mm->pgd; | |
132 | mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN); | |
f1c1174f | 133 | mm->context.asce_limit = _REGION3_SIZE; |
723cacbd GS |
134 | mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | |
135 | _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT; | |
723cacbd GS |
136 | crst_table_free(mm, (unsigned long *) pgd); |
137 | ||
1e133ab2 MS |
138 | if (current->active_mm == mm) |
139 | set_user_asce(mm); | |
140 | } | |
141 | ||
142 | static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) | |
143 | { | |
144 | unsigned int old, new; | |
145 | ||
146 | do { | |
147 | old = atomic_read(v); | |
148 | new = old ^ bits; | |
149 | } while (atomic_cmpxchg(v, old, new) != old); | |
150 | return new; | |
151 | } | |
152 | ||
4be130a0 MS |
153 | #ifdef CONFIG_PGSTE |
154 | ||
155 | struct page *page_table_alloc_pgste(struct mm_struct *mm) | |
156 | { | |
157 | struct page *page; | |
41879ff6 | 158 | u64 *table; |
4be130a0 | 159 | |
faee35a5 | 160 | page = alloc_page(GFP_KERNEL); |
4be130a0 | 161 | if (page) { |
41879ff6 HC |
162 | table = (u64 *)page_to_phys(page); |
163 | memset64(table, _PAGE_INVALID, PTRS_PER_PTE); | |
164 | memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); | |
4be130a0 MS |
165 | } |
166 | return page; | |
167 | } | |
168 | ||
169 | void page_table_free_pgste(struct page *page) | |
170 | { | |
171 | __free_page(page); | |
172 | } | |
173 | ||
174 | #endif /* CONFIG_PGSTE */ | |
175 | ||
1e133ab2 MS |
176 | /* |
177 | * page table entry allocation/free routines. | |
178 | */ | |
179 | unsigned long *page_table_alloc(struct mm_struct *mm) | |
180 | { | |
181 | unsigned long *table; | |
182 | struct page *page; | |
183 | unsigned int mask, bit; | |
184 | ||
185 | /* Try to get a fragment of a 4K page as a 2K page table */ | |
186 | if (!mm_alloc_pgste(mm)) { | |
187 | table = NULL; | |
f28a4b4d | 188 | spin_lock_bh(&mm->context.lock); |
1e133ab2 MS |
189 | if (!list_empty(&mm->context.pgtable_list)) { |
190 | page = list_first_entry(&mm->context.pgtable_list, | |
191 | struct page, lru); | |
192 | mask = atomic_read(&page->_mapcount); | |
193 | mask = (mask | (mask >> 4)) & 3; | |
194 | if (mask != 3) { | |
195 | table = (unsigned long *) page_to_phys(page); | |
196 | bit = mask & 1; /* =1 -> second 2K */ | |
197 | if (bit) | |
198 | table += PTRS_PER_PTE; | |
199 | atomic_xor_bits(&page->_mapcount, 1U << bit); | |
200 | list_del(&page->lru); | |
201 | } | |
202 | } | |
f28a4b4d | 203 | spin_unlock_bh(&mm->context.lock); |
1e133ab2 MS |
204 | if (table) |
205 | return table; | |
206 | } | |
207 | /* Allocate a fresh page */ | |
10d58bf2 | 208 | page = alloc_page(GFP_KERNEL); |
1e133ab2 MS |
209 | if (!page) |
210 | return NULL; | |
211 | if (!pgtable_page_ctor(page)) { | |
212 | __free_page(page); | |
213 | return NULL; | |
214 | } | |
c9b5ad54 | 215 | arch_set_page_dat(page, 0); |
1e133ab2 MS |
216 | /* Initialize page table */ |
217 | table = (unsigned long *) page_to_phys(page); | |
218 | if (mm_alloc_pgste(mm)) { | |
219 | /* Return 4K page table with PGSTEs */ | |
220 | atomic_set(&page->_mapcount, 3); | |
41879ff6 HC |
221 | memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); |
222 | memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); | |
1e133ab2 MS |
223 | } else { |
224 | /* Return the first 2K fragment of the page */ | |
225 | atomic_set(&page->_mapcount, 1); | |
41879ff6 | 226 | memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); |
f28a4b4d | 227 | spin_lock_bh(&mm->context.lock); |
1e133ab2 | 228 | list_add(&page->lru, &mm->context.pgtable_list); |
f28a4b4d | 229 | spin_unlock_bh(&mm->context.lock); |
1e133ab2 MS |
230 | } |
231 | return table; | |
232 | } | |
233 | ||
234 | void page_table_free(struct mm_struct *mm, unsigned long *table) | |
235 | { | |
236 | struct page *page; | |
237 | unsigned int bit, mask; | |
238 | ||
239 | page = pfn_to_page(__pa(table) >> PAGE_SHIFT); | |
240 | if (!mm_alloc_pgste(mm)) { | |
241 | /* Free 2K page table fragment of a 4K page */ | |
242 | bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); | |
f28a4b4d | 243 | spin_lock_bh(&mm->context.lock); |
1e133ab2 MS |
244 | mask = atomic_xor_bits(&page->_mapcount, 1U << bit); |
245 | if (mask & 3) | |
246 | list_add(&page->lru, &mm->context.pgtable_list); | |
247 | else | |
248 | list_del(&page->lru); | |
f28a4b4d | 249 | spin_unlock_bh(&mm->context.lock); |
1e133ab2 MS |
250 | if (mask != 0) |
251 | return; | |
252 | } | |
253 | ||
254 | pgtable_page_dtor(page); | |
255 | atomic_set(&page->_mapcount, -1); | |
256 | __free_page(page); | |
257 | } | |
258 | ||
259 | void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, | |
260 | unsigned long vmaddr) | |
261 | { | |
262 | struct mm_struct *mm; | |
263 | struct page *page; | |
264 | unsigned int bit, mask; | |
265 | ||
266 | mm = tlb->mm; | |
267 | page = pfn_to_page(__pa(table) >> PAGE_SHIFT); | |
268 | if (mm_alloc_pgste(mm)) { | |
269 | gmap_unlink(mm, table, vmaddr); | |
270 | table = (unsigned long *) (__pa(table) | 3); | |
271 | tlb_remove_table(tlb, table); | |
272 | return; | |
273 | } | |
274 | bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); | |
f28a4b4d | 275 | spin_lock_bh(&mm->context.lock); |
1e133ab2 MS |
276 | mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit); |
277 | if (mask & 3) | |
278 | list_add_tail(&page->lru, &mm->context.pgtable_list); | |
279 | else | |
280 | list_del(&page->lru); | |
f28a4b4d | 281 | spin_unlock_bh(&mm->context.lock); |
1e133ab2 MS |
282 | table = (unsigned long *) (__pa(table) | (1U << bit)); |
283 | tlb_remove_table(tlb, table); | |
284 | } | |
285 | ||
286 | static void __tlb_remove_table(void *_table) | |
287 | { | |
288 | unsigned int mask = (unsigned long) _table & 3; | |
289 | void *table = (void *)((unsigned long) _table ^ mask); | |
290 | struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT); | |
291 | ||
292 | switch (mask) { | |
1aea9b3f | 293 | case 0: /* pmd, pud, or p4d */ |
1e133ab2 MS |
294 | free_pages((unsigned long) table, 2); |
295 | break; | |
296 | case 1: /* lower 2K of a 4K page table */ | |
297 | case 2: /* higher 2K of a 4K page table */ | |
298 | if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0) | |
299 | break; | |
300 | /* fallthrough */ | |
301 | case 3: /* 4K page table with pgstes */ | |
302 | pgtable_page_dtor(page); | |
303 | atomic_set(&page->_mapcount, -1); | |
304 | __free_page(page); | |
305 | break; | |
306 | } | |
307 | } | |
308 | ||
309 | static void tlb_remove_table_smp_sync(void *arg) | |
310 | { | |
311 | /* Simply deliver the interrupt */ | |
312 | } | |
313 | ||
314 | static void tlb_remove_table_one(void *table) | |
315 | { | |
316 | /* | |
317 | * This isn't an RCU grace period and hence the page-tables cannot be | |
318 | * assumed to be actually RCU-freed. | |
319 | * | |
320 | * It is however sufficient for software page-table walkers that rely | |
321 | * on IRQ disabling. See the comment near struct mmu_table_batch. | |
322 | */ | |
323 | smp_call_function(tlb_remove_table_smp_sync, NULL, 1); | |
324 | __tlb_remove_table(table); | |
325 | } | |
326 | ||
327 | static void tlb_remove_table_rcu(struct rcu_head *head) | |
328 | { | |
329 | struct mmu_table_batch *batch; | |
330 | int i; | |
331 | ||
332 | batch = container_of(head, struct mmu_table_batch, rcu); | |
333 | ||
334 | for (i = 0; i < batch->nr; i++) | |
335 | __tlb_remove_table(batch->tables[i]); | |
336 | ||
337 | free_page((unsigned long)batch); | |
338 | } | |
339 | ||
340 | void tlb_table_flush(struct mmu_gather *tlb) | |
341 | { | |
342 | struct mmu_table_batch **batch = &tlb->batch; | |
343 | ||
344 | if (*batch) { | |
345 | call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); | |
346 | *batch = NULL; | |
347 | } | |
348 | } | |
349 | ||
350 | void tlb_remove_table(struct mmu_gather *tlb, void *table) | |
351 | { | |
352 | struct mmu_table_batch **batch = &tlb->batch; | |
353 | ||
354 | tlb->mm->context.flush_mm = 1; | |
355 | if (*batch == NULL) { | |
356 | *batch = (struct mmu_table_batch *) | |
357 | __get_free_page(GFP_NOWAIT | __GFP_NOWARN); | |
358 | if (*batch == NULL) { | |
359 | __tlb_flush_mm_lazy(tlb->mm); | |
360 | tlb_remove_table_one(table); | |
361 | return; | |
362 | } | |
363 | (*batch)->nr = 0; | |
364 | } | |
365 | (*batch)->tables[(*batch)->nr++] = table; | |
366 | if ((*batch)->nr == MAX_TABLE_BATCH) | |
367 | tlb_flush_mmu(tlb); | |
368 | } |