1 // SPDX-License-Identifier: GPL-2.0
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/sysctl.h>
10 #include <linux/slab.h>
11 #include <linux/mm.h>
12 #include <asm/mmu_context.h>
13 #include <asm/page-states.h>
14 #include <asm/pgalloc.h>
15 #include <asm/gmap.h>
16 #include <asm/tlb.h>
17 #include <asm/tlbflush.h>
18
19 #ifdef CONFIG_PGSTE
20
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_minmax,
31 .extra1 = SYSCTL_ZERO,
32 .extra2 = SYSCTL_ONE,
33 },
34 };
35
36 static int __init page_table_register_sysctl(void)
37 {
38 return register_sysctl("vm", page_table_sysctl) ? 0 : -ENOMEM;
39 }
40 __initcall(page_table_register_sysctl);
41
42 #endif /* CONFIG_PGSTE */
43
44 unsigned long *crst_table_alloc(struct mm_struct *mm)
45 {
46 struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER);
47 unsigned long *table;
48
49 if (!ptdesc)
50 return NULL;
51 table = ptdesc_to_virt(ptdesc);
52 __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
53 return table;
54 }
55
56 void crst_table_free(struct mm_struct *mm, unsigned long *table)
57 {
58 if (!table)
59 return;
60 pagetable_free(virt_to_ptdesc(table));
61 }
62
63 static void __crst_table_upgrade(void *arg)
64 {
65 struct mm_struct *mm = arg;
66
67 /* change all active ASCEs to avoid the creation of new TLBs */
68 if (current->active_mm == mm) {
69 get_lowcore()->user_asce.val = mm->context.asce;
70 local_ctl_load(7, &get_lowcore()->user_asce);
71 }
72 __tlb_flush_local();
73 }
74
75 int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
76 {
77 unsigned long *pgd = NULL, *p4d = NULL, *__pgd;
78 unsigned long asce_limit = mm->context.asce_limit;
79
80 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
81 VM_BUG_ON(asce_limit < _REGION2_SIZE);
82
83 if (end <= asce_limit)
84 return 0;
85
86 if (asce_limit == _REGION2_SIZE) {
87 p4d = crst_table_alloc(mm);
88 if (unlikely(!p4d))
89 goto err_p4d;
90 crst_table_init(p4d, _REGION2_ENTRY_EMPTY);
91 }
92 if (end > _REGION1_SIZE) {
93 pgd = crst_table_alloc(mm);
94 if (unlikely(!pgd))
95 goto err_pgd;
96 crst_table_init(pgd, _REGION1_ENTRY_EMPTY);
97 }
98
99 spin_lock_bh(&mm->page_table_lock);
100
101 /*
102 * This routine gets called with mmap_lock lock held and there is
103 * no reason to optimize for the case of otherwise. However, if
104 * that would ever change, the below check will let us know.
105 */
106 VM_BUG_ON(asce_limit != mm->context.asce_limit);
107
108 if (p4d) {
109 __pgd = (unsigned long *) mm->pgd;
110 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd);
111 mm->pgd = (pgd_t *) p4d;
112 mm->context.asce_limit = _REGION1_SIZE;
113 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
114 _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
115 mm_inc_nr_puds(mm);
116 }
117 if (pgd) {
118 __pgd = (unsigned long *) mm->pgd;
119 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd);
120 mm->pgd = (pgd_t *) pgd;
121 mm->context.asce_limit = TASK_SIZE_MAX;
122 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
123 _ASCE_USER_BITS | _ASCE_TYPE_REGION1;
124 }
125
126 spin_unlock_bh(&mm->page_table_lock);
127
128 on_each_cpu(__crst_table_upgrade, mm, 0);
129
130 return 0;
131
132 err_pgd:
133 crst_table_free(mm, p4d);
134 err_p4d:
135 return -ENOMEM;
136 }
137
138 #ifdef CONFIG_PGSTE
139
140 struct ptdesc *page_table_alloc_pgste(struct mm_struct *mm)
141 {
142 struct ptdesc *ptdesc;
143 u64 *table;
144
145 ptdesc = pagetable_alloc(GFP_KERNEL, 0);
146 if (ptdesc) {
147 table = (u64 *)ptdesc_to_virt(ptdesc);
148 __arch_set_page_dat(table, 1);
149 memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
150 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
151 }
152 return ptdesc;
153 }
154
155 void page_table_free_pgste(struct ptdesc *ptdesc)
156 {
157 pagetable_free(ptdesc);
158 }
159
160 #endif /* CONFIG_PGSTE */
161
162 unsigned long *page_table_alloc(struct mm_struct *mm)
163 {
164 struct ptdesc *ptdesc;
165 unsigned long *table;
166
167 ptdesc = pagetable_alloc(GFP_KERNEL, 0);
168 if (!ptdesc)
169 return NULL;
170 if (!pagetable_pte_ctor(ptdesc)) {
171 pagetable_free(ptdesc);
172 return NULL;
173 }
174 table = ptdesc_to_virt(ptdesc);
175 __arch_set_page_dat(table, 1);
176 /* pt_list is used by gmap only */
177 INIT_LIST_HEAD(&ptdesc->pt_list);
178 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
179 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
180 return table;
181 }
182
183 static void pagetable_pte_dtor_free(struct ptdesc *ptdesc)
184 {
185 pagetable_pte_dtor(ptdesc);
186 pagetable_free(ptdesc);
187 }
188
189 void page_table_free(struct mm_struct *mm, unsigned long *table)
190 {
191 struct ptdesc *ptdesc = virt_to_ptdesc(table);
192
193 pagetable_pte_dtor_free(ptdesc);
194 }
195
196 void __tlb_remove_table(void *table)
197 {
198 struct ptdesc *ptdesc = virt_to_ptdesc(table);
199 struct page *page = ptdesc_page(ptdesc);
200
201 if (compound_order(page) == CRST_ALLOC_ORDER) {
202 /* pmd, pud, or p4d */
203 pagetable_free(ptdesc);
204 return;
205 }
206 pagetable_pte_dtor_free(ptdesc);
207 }
208
209 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
210 static void pte_free_now(struct rcu_head *head)
211 {
212 struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head);
213
214 pagetable_pte_dtor_free(ptdesc);
215 }
216
217 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
218 {
219 struct ptdesc *ptdesc = virt_to_ptdesc(pgtable);
220
221 call_rcu(&ptdesc->pt_rcu_head, pte_free_now);
222 /*
223 * THPs are not allowed for KVM guests. Warn if pgste ever reaches here.
224 * Turn to the generic pte_free_defer() version once gmap is removed.
225 */
226 WARN_ON_ONCE(mm_has_pgste(mm));
227 }
228 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
229
230 /*
231 * Base infrastructure required to generate basic asces, region, segment,
232 * and page tables that do not make use of enhanced features like EDAT1.
233 */
234
235 static struct kmem_cache *base_pgt_cache;
236
237 static unsigned long *base_pgt_alloc(void)
238 {
239 unsigned long *table;
240
241 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL);
242 if (table)
243 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
244 return table;
245 }
246
247 static void base_pgt_free(unsigned long *table)
248 {
249 kmem_cache_free(base_pgt_cache, table);
250 }
251
252 static unsigned long *base_crst_alloc(unsigned long val)
253 {
254 unsigned long *table;
255 struct ptdesc *ptdesc;
256
257 ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER);
258 if (!ptdesc)
259 return NULL;
260 table = ptdesc_address(ptdesc);
261 crst_table_init(table, val);
262 return table;
263 }
264
265 static void base_crst_free(unsigned long *table)
266 {
267 if (!table)
268 return;
269 pagetable_free(virt_to_ptdesc(table));
270 }
271
272 #define BASE_ADDR_END_FUNC(NAME, SIZE) \
273 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \
274 unsigned long end) \
275 { \
276 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \
277 \
278 return (next - 1) < (end - 1) ? next : end; \
279 }
280
281 BASE_ADDR_END_FUNC(page, _PAGE_SIZE)
282 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE)
283 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE)
284 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE)
285 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE)
286
287 static inline unsigned long base_lra(unsigned long address)
288 {
289 unsigned long real;
290
291 asm volatile(
292 " lra %0,0(%1)\n"
293 : "=d" (real) : "a" (address) : "cc");
294 return real;
295 }
296
297 static int base_page_walk(unsigned long *origin, unsigned long addr,
298 unsigned long end, int alloc)
299 {
300 unsigned long *pte, next;
301
302 if (!alloc)
303 return 0;
304 pte = origin;
305 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT;
306 do {
307 next = base_page_addr_end(addr, end);
308 *pte = base_lra(addr);
309 } while (pte++, addr = next, addr < end);
310 return 0;
311 }
312
313 static int base_segment_walk(unsigned long *origin, unsigned long addr,
314 unsigned long end, int alloc)
315 {
316 unsigned long *ste, next, *table;
317 int rc;
318
319 ste = origin;
320 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
321 do {
322 next = base_segment_addr_end(addr, end);
323 if (*ste & _SEGMENT_ENTRY_INVALID) {
324 if (!alloc)
325 continue;
326 table = base_pgt_alloc();
327 if (!table)
328 return -ENOMEM;
329 *ste = __pa(table) | _SEGMENT_ENTRY;
330 }
331 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN);
332 rc = base_page_walk(table, addr, next, alloc);
333 if (rc)
334 return rc;
335 if (!alloc)
336 base_pgt_free(table);
337 cond_resched();
338 } while (ste++, addr = next, addr < end);
339 return 0;
340 }
341
342 static int base_region3_walk(unsigned long *origin, unsigned long addr,
343 unsigned long end, int alloc)
344 {
345 unsigned long *rtte, next, *table;
346 int rc;
347
348 rtte = origin;
349 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT;
350 do {
351 next = base_region3_addr_end(addr, end);
352 if (*rtte & _REGION_ENTRY_INVALID) {
353 if (!alloc)
354 continue;
355 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
356 if (!table)
357 return -ENOMEM;
358 *rtte = __pa(table) | _REGION3_ENTRY;
359 }
360 table = __va(*rtte & _REGION_ENTRY_ORIGIN);
361 rc = base_segment_walk(table, addr, next, alloc);
362 if (rc)
363 return rc;
364 if (!alloc)
365 base_crst_free(table);
366 } while (rtte++, addr = next, addr < end);
367 return 0;
368 }
369
370 static int base_region2_walk(unsigned long *origin, unsigned long addr,
371 unsigned long end, int alloc)
372 {
373 unsigned long *rste, next, *table;
374 int rc;
375
376 rste = origin;
377 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT;
378 do {
379 next = base_region2_addr_end(addr, end);
380 if (*rste & _REGION_ENTRY_INVALID) {
381 if (!alloc)
382 continue;
383 table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
384 if (!table)
385 return -ENOMEM;
386 *rste = __pa(table) | _REGION2_ENTRY;
387 }
388 table = __va(*rste & _REGION_ENTRY_ORIGIN);
389 rc = base_region3_walk(table, addr, next, alloc);
390 if (rc)
391 return rc;
392 if (!alloc)
393 base_crst_free(table);
394 } while (rste++, addr = next, addr < end);
395 return 0;
396 }
397
398 static int base_region1_walk(unsigned long *origin, unsigned long addr,
399 unsigned long end, int alloc)
400 {
401 unsigned long *rfte, next, *table;
402 int rc;
403
404 rfte = origin;
405 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT;
406 do {
407 next = base_region1_addr_end(addr, end);
408 if (*rfte & _REGION_ENTRY_INVALID) {
409 if (!alloc)
410 continue;
411 table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
412 if (!table)
413 return -ENOMEM;
414 *rfte = __pa(table) | _REGION1_ENTRY;
415 }
416 table = __va(*rfte & _REGION_ENTRY_ORIGIN);
417 rc = base_region2_walk(table, addr, next, alloc);
418 if (rc)
419 return rc;
420 if (!alloc)
421 base_crst_free(table);
422 } while (rfte++, addr = next, addr < end);
423 return 0;
424 }
425
426 /**
427 * base_asce_free - free asce and tables returned from base_asce_alloc()
428 * @asce: asce to be freed
429 *
430 * Frees all region, segment, and page tables that were allocated with a
431 * corresponding base_asce_alloc() call.
432 */
433 void base_asce_free(unsigned long asce)
434 {
435 unsigned long *table = __va(asce & _ASCE_ORIGIN);
436
437 if (!asce)
438 return;
439 switch (asce & _ASCE_TYPE_MASK) {
440 case _ASCE_TYPE_SEGMENT:
441 base_segment_walk(table, 0, _REGION3_SIZE, 0);
442 break;
443 case _ASCE_TYPE_REGION3:
444 base_region3_walk(table, 0, _REGION2_SIZE, 0);
445 break;
446 case _ASCE_TYPE_REGION2:
447 base_region2_walk(table, 0, _REGION1_SIZE, 0);
448 break;
449 case _ASCE_TYPE_REGION1:
450 base_region1_walk(table, 0, TASK_SIZE_MAX, 0);
451 break;
452 }
453 base_crst_free(table);
454 }
455
456 static int base_pgt_cache_init(void)
457 {
458 static DEFINE_MUTEX(base_pgt_cache_mutex);
459 unsigned long sz = _PAGE_TABLE_SIZE;
460
461 if (base_pgt_cache)
462 return 0;
463 mutex_lock(&base_pgt_cache_mutex);
464 if (!base_pgt_cache)
465 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL);
466 mutex_unlock(&base_pgt_cache_mutex);
467 return base_pgt_cache ? 0 : -ENOMEM;
468 }
469
470 /**
471 * base_asce_alloc - create kernel mapping without enhanced DAT features
472 * @addr: virtual start address of kernel mapping
473 * @num_pages: number of consecutive pages
474 *
475 * Generate an asce, including all required region, segment and page tables,
476 * that can be used to access the virtual kernel mapping. The difference is
477 * that the returned asce does not make use of any enhanced DAT features like
478 * e.g. large pages. This is required for some I/O functions that pass an
479 * asce, like e.g. some service call requests.
480 *
481 * Note: the returned asce may NEVER be attached to any cpu. It may only be
482 * used for I/O requests. tlb entries that might result because the
483 * asce was attached to a cpu won't be cleared.
484 */
485 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages)
486 {
487 unsigned long asce, *table, end;
488 int rc;
489
490 if (base_pgt_cache_init())
491 return 0;
492 end = addr + num_pages * PAGE_SIZE;
493 if (end <= _REGION3_SIZE) {
494 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
495 if (!table)
496 return 0;
497 rc = base_segment_walk(table, addr, end, 1);
498 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH;
499 } else if (end <= _REGION2_SIZE) {
500 table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
501 if (!table)
502 return 0;
503 rc = base_region3_walk(table, addr, end, 1);
504 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
505 } else if (end <= _REGION1_SIZE) {
506 table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
507 if (!table)
508 return 0;
509 rc = base_region2_walk(table, addr, end, 1);
510 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
511 } else {
512 table = base_crst_alloc(_REGION1_ENTRY_EMPTY);
513 if (!table)
514 return 0;
515 rc = base_region1_walk(table, addr, end, 1);
516 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH;
517 }
518 if (rc) {
519 base_asce_free(asce);
520 asce = 0;
521 }
522 return asce;
523 }
524
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