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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/pgalloc.h>
14#include <asm/gmap.h>
15#include <asm/tlb.h>
16#include <asm/tlbflush.h>
17
18#ifdef CONFIG_PGSTE
19
20int page_table_allocate_pgste = 0;
21EXPORT_SYMBOL(page_table_allocate_pgste);
22
23static struct ctl_table page_table_sysctl[] = {
24 {
25 .procname = "allocate_pgste",
26 .data = &page_table_allocate_pgste,
27 .maxlen = sizeof(int),
28 .mode = S_IRUGO | S_IWUSR,
29 .proc_handler = proc_dointvec_minmax,
30 .extra1 = SYSCTL_ZERO,
31 .extra2 = SYSCTL_ONE,
32 },
33 { }
34};
35
36static struct ctl_table page_table_sysctl_dir[] = {
37 {
38 .procname = "vm",
39 .maxlen = 0,
40 .mode = 0555,
41 .child = page_table_sysctl,
42 },
43 { }
44};
45
46static int __init page_table_register_sysctl(void)
47{
48 return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
49}
50__initcall(page_table_register_sysctl);
51
52#endif /* CONFIG_PGSTE */
53
54unsigned long *crst_table_alloc(struct mm_struct *mm)
55{
56 struct page *page = alloc_pages(GFP_KERNEL, 2);
57
58 if (!page)
59 return NULL;
60 arch_set_page_dat(page, 2);
61 return (unsigned long *) page_to_phys(page);
62}
63
64void crst_table_free(struct mm_struct *mm, unsigned long *table)
65{
66 free_pages((unsigned long) table, 2);
67}
68
69static void __crst_table_upgrade(void *arg)
70{
71 struct mm_struct *mm = arg;
72
73 if (current->active_mm == mm)
74 set_user_asce(mm);
75 __tlb_flush_local();
76}
77
78int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
79{
80 unsigned long *table, *pgd;
81 int rc, notify;
82
83 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
84 VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
85 rc = 0;
86 notify = 0;
87 while (mm->context.asce_limit < end) {
88 table = crst_table_alloc(mm);
89 if (!table) {
90 rc = -ENOMEM;
91 break;
92 }
93 spin_lock_bh(&mm->page_table_lock);
94 pgd = (unsigned long *) mm->pgd;
95 if (mm->context.asce_limit == _REGION2_SIZE) {
96 crst_table_init(table, _REGION2_ENTRY_EMPTY);
97 p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd);
98 mm->pgd = (pgd_t *) table;
99 mm->context.asce_limit = _REGION1_SIZE;
100 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
101 _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
102 mm_inc_nr_puds(mm);
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;
117}
118
119void crst_table_downgrade(struct mm_struct *mm)
120{
121 pgd_t *pgd;
122
123 /* downgrade should only happen from 3 to 2 levels (compat only) */
124 VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
125
126 if (current->active_mm == mm) {
127 clear_user_asce();
128 __tlb_flush_mm(mm);
129 }
130
131 pgd = mm->pgd;
132 mm_dec_nr_pmds(mm);
133 mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
134 mm->context.asce_limit = _REGION3_SIZE;
135 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
136 _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
137 crst_table_free(mm, (unsigned long *) pgd);
138
139 if (current->active_mm == mm)
140 set_user_asce(mm);
141}
142
143static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
144{
145 unsigned int old, new;
146
147 do {
148 old = atomic_read(v);
149 new = old ^ bits;
150 } while (atomic_cmpxchg(v, old, new) != old);
151 return new;
152}
153
154#ifdef CONFIG_PGSTE
155
156struct page *page_table_alloc_pgste(struct mm_struct *mm)
157{
158 struct page *page;
159 u64 *table;
160
161 page = alloc_page(GFP_KERNEL);
162 if (page) {
163 table = (u64 *)page_to_phys(page);
164 memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
165 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
166 }
167 return page;
168}
169
170void page_table_free_pgste(struct page *page)
171{
172 __free_page(page);
173}
174
175#endif /* CONFIG_PGSTE */
176
177/*
178 * page table entry allocation/free routines.
179 */
180unsigned long *page_table_alloc(struct mm_struct *mm)
181{
182 unsigned long *table;
183 struct page *page;
184 unsigned int mask, bit;
185
186 /* Try to get a fragment of a 4K page as a 2K page table */
187 if (!mm_alloc_pgste(mm)) {
188 table = NULL;
189 spin_lock_bh(&mm->context.lock);
190 if (!list_empty(&mm->context.pgtable_list)) {
191 page = list_first_entry(&mm->context.pgtable_list,
192 struct page, lru);
193 mask = atomic_read(&page->_refcount) >> 24;
194 mask = (mask | (mask >> 4)) & 3;
195 if (mask != 3) {
196 table = (unsigned long *) page_to_phys(page);
197 bit = mask & 1; /* =1 -> second 2K */
198 if (bit)
199 table += PTRS_PER_PTE;
200 atomic_xor_bits(&page->_refcount,
201 1U << (bit + 24));
202 list_del(&page->lru);
203 }
204 }
205 spin_unlock_bh(&mm->context.lock);
206 if (table)
207 return table;
208 }
209 /* Allocate a fresh page */
210 page = alloc_page(GFP_KERNEL);
211 if (!page)
212 return NULL;
213 if (!pgtable_pte_page_ctor(page)) {
214 __free_page(page);
215 return NULL;
216 }
217 arch_set_page_dat(page, 0);
218 /* Initialize page table */
219 table = (unsigned long *) page_to_phys(page);
220 if (mm_alloc_pgste(mm)) {
221 /* Return 4K page table with PGSTEs */
222 atomic_xor_bits(&page->_refcount, 3 << 24);
223 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
224 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
225 } else {
226 /* Return the first 2K fragment of the page */
227 atomic_xor_bits(&page->_refcount, 1 << 24);
228 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE);
229 spin_lock_bh(&mm->context.lock);
230 list_add(&page->lru, &mm->context.pgtable_list);
231 spin_unlock_bh(&mm->context.lock);
232 }
233 return table;
234}
235
236void page_table_free(struct mm_struct *mm, unsigned long *table)
237{
238 struct page *page;
239 unsigned int bit, mask;
240
241 page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
242 if (!mm_alloc_pgste(mm)) {
243 /* Free 2K page table fragment of a 4K page */
244 bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
245 spin_lock_bh(&mm->context.lock);
246 mask = atomic_xor_bits(&page->_refcount, 1U << (bit + 24));
247 mask >>= 24;
248 if (mask & 3)
249 list_add(&page->lru, &mm->context.pgtable_list);
250 else
251 list_del(&page->lru);
252 spin_unlock_bh(&mm->context.lock);
253 if (mask != 0)
254 return;
255 } else {
256 atomic_xor_bits(&page->_refcount, 3U << 24);
257 }
258
259 pgtable_pte_page_dtor(page);
260 __free_page(page);
261}
262
263void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
264 unsigned long vmaddr)
265{
266 struct mm_struct *mm;
267 struct page *page;
268 unsigned int bit, mask;
269
270 mm = tlb->mm;
271 page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
272 if (mm_alloc_pgste(mm)) {
273 gmap_unlink(mm, table, vmaddr);
274 table = (unsigned long *) (__pa(table) | 3);
275 tlb_remove_table(tlb, table);
276 return;
277 }
278 bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
279 spin_lock_bh(&mm->context.lock);
280 mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24));
281 mask >>= 24;
282 if (mask & 3)
283 list_add_tail(&page->lru, &mm->context.pgtable_list);
284 else
285 list_del(&page->lru);
286 spin_unlock_bh(&mm->context.lock);
287 table = (unsigned long *) (__pa(table) | (1U << bit));
288 tlb_remove_table(tlb, table);
289}
290
291void __tlb_remove_table(void *_table)
292{
293 unsigned int mask = (unsigned long) _table & 3;
294 void *table = (void *)((unsigned long) _table ^ mask);
295 struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
296
297 switch (mask) {
298 case 0: /* pmd, pud, or p4d */
299 free_pages((unsigned long) table, 2);
300 break;
301 case 1: /* lower 2K of a 4K page table */
302 case 2: /* higher 2K of a 4K page table */
303 mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24));
304 mask >>= 24;
305 if (mask != 0)
306 break;
307 /* fallthrough */
308 case 3: /* 4K page table with pgstes */
309 if (mask & 3)
310 atomic_xor_bits(&page->_refcount, 3 << 24);
311 pgtable_pte_page_dtor(page);
312 __free_page(page);
313 break;
314 }
315}
316
317/*
318 * Base infrastructure required to generate basic asces, region, segment,
319 * and page tables that do not make use of enhanced features like EDAT1.
320 */
321
322static struct kmem_cache *base_pgt_cache;
323
324static unsigned long base_pgt_alloc(void)
325{
326 u64 *table;
327
328 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL);
329 if (table)
330 memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
331 return (unsigned long) table;
332}
333
334static void base_pgt_free(unsigned long table)
335{
336 kmem_cache_free(base_pgt_cache, (void *) table);
337}
338
339static unsigned long base_crst_alloc(unsigned long val)
340{
341 unsigned long table;
342
343 table = __get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
344 if (table)
345 crst_table_init((unsigned long *)table, val);
346 return table;
347}
348
349static void base_crst_free(unsigned long table)
350{
351 free_pages(table, CRST_ALLOC_ORDER);
352}
353
354#define BASE_ADDR_END_FUNC(NAME, SIZE) \
355static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \
356 unsigned long end) \
357{ \
358 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \
359 \
360 return (next - 1) < (end - 1) ? next : end; \
361}
362
363BASE_ADDR_END_FUNC(page, _PAGE_SIZE)
364BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE)
365BASE_ADDR_END_FUNC(region3, _REGION3_SIZE)
366BASE_ADDR_END_FUNC(region2, _REGION2_SIZE)
367BASE_ADDR_END_FUNC(region1, _REGION1_SIZE)
368
369static inline unsigned long base_lra(unsigned long address)
370{
371 unsigned long real;
372
373 asm volatile(
374 " lra %0,0(%1)\n"
375 : "=d" (real) : "a" (address) : "cc");
376 return real;
377}
378
379static int base_page_walk(unsigned long origin, unsigned long addr,
380 unsigned long end, int alloc)
381{
382 unsigned long *pte, next;
383
384 if (!alloc)
385 return 0;
386 pte = (unsigned long *) origin;
387 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT;
388 do {
389 next = base_page_addr_end(addr, end);
390 *pte = base_lra(addr);
391 } while (pte++, addr = next, addr < end);
392 return 0;
393}
394
395static int base_segment_walk(unsigned long origin, unsigned long addr,
396 unsigned long end, int alloc)
397{
398 unsigned long *ste, next, table;
399 int rc;
400
401 ste = (unsigned long *) origin;
402 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
403 do {
404 next = base_segment_addr_end(addr, end);
405 if (*ste & _SEGMENT_ENTRY_INVALID) {
406 if (!alloc)
407 continue;
408 table = base_pgt_alloc();
409 if (!table)
410 return -ENOMEM;
411 *ste = table | _SEGMENT_ENTRY;
412 }
413 table = *ste & _SEGMENT_ENTRY_ORIGIN;
414 rc = base_page_walk(table, addr, next, alloc);
415 if (rc)
416 return rc;
417 if (!alloc)
418 base_pgt_free(table);
419 cond_resched();
420 } while (ste++, addr = next, addr < end);
421 return 0;
422}
423
424static int base_region3_walk(unsigned long origin, unsigned long addr,
425 unsigned long end, int alloc)
426{
427 unsigned long *rtte, next, table;
428 int rc;
429
430 rtte = (unsigned long *) origin;
431 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT;
432 do {
433 next = base_region3_addr_end(addr, end);
434 if (*rtte & _REGION_ENTRY_INVALID) {
435 if (!alloc)
436 continue;
437 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
438 if (!table)
439 return -ENOMEM;
440 *rtte = table | _REGION3_ENTRY;
441 }
442 table = *rtte & _REGION_ENTRY_ORIGIN;
443 rc = base_segment_walk(table, addr, next, alloc);
444 if (rc)
445 return rc;
446 if (!alloc)
447 base_crst_free(table);
448 } while (rtte++, addr = next, addr < end);
449 return 0;
450}
451
452static int base_region2_walk(unsigned long origin, unsigned long addr,
453 unsigned long end, int alloc)
454{
455 unsigned long *rste, next, table;
456 int rc;
457
458 rste = (unsigned long *) origin;
459 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT;
460 do {
461 next = base_region2_addr_end(addr, end);
462 if (*rste & _REGION_ENTRY_INVALID) {
463 if (!alloc)
464 continue;
465 table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
466 if (!table)
467 return -ENOMEM;
468 *rste = table | _REGION2_ENTRY;
469 }
470 table = *rste & _REGION_ENTRY_ORIGIN;
471 rc = base_region3_walk(table, addr, next, alloc);
472 if (rc)
473 return rc;
474 if (!alloc)
475 base_crst_free(table);
476 } while (rste++, addr = next, addr < end);
477 return 0;
478}
479
480static int base_region1_walk(unsigned long origin, unsigned long addr,
481 unsigned long end, int alloc)
482{
483 unsigned long *rfte, next, table;
484 int rc;
485
486 rfte = (unsigned long *) origin;
487 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT;
488 do {
489 next = base_region1_addr_end(addr, end);
490 if (*rfte & _REGION_ENTRY_INVALID) {
491 if (!alloc)
492 continue;
493 table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
494 if (!table)
495 return -ENOMEM;
496 *rfte = table | _REGION1_ENTRY;
497 }
498 table = *rfte & _REGION_ENTRY_ORIGIN;
499 rc = base_region2_walk(table, addr, next, alloc);
500 if (rc)
501 return rc;
502 if (!alloc)
503 base_crst_free(table);
504 } while (rfte++, addr = next, addr < end);
505 return 0;
506}
507
508/**
509 * base_asce_free - free asce and tables returned from base_asce_alloc()
510 * @asce: asce to be freed
511 *
512 * Frees all region, segment, and page tables that were allocated with a
513 * corresponding base_asce_alloc() call.
514 */
515void base_asce_free(unsigned long asce)
516{
517 unsigned long table = asce & _ASCE_ORIGIN;
518
519 if (!asce)
520 return;
521 switch (asce & _ASCE_TYPE_MASK) {
522 case _ASCE_TYPE_SEGMENT:
523 base_segment_walk(table, 0, _REGION3_SIZE, 0);
524 break;
525 case _ASCE_TYPE_REGION3:
526 base_region3_walk(table, 0, _REGION2_SIZE, 0);
527 break;
528 case _ASCE_TYPE_REGION2:
529 base_region2_walk(table, 0, _REGION1_SIZE, 0);
530 break;
531 case _ASCE_TYPE_REGION1:
532 base_region1_walk(table, 0, -_PAGE_SIZE, 0);
533 break;
534 }
535 base_crst_free(table);
536}
537
538static int base_pgt_cache_init(void)
539{
540 static DEFINE_MUTEX(base_pgt_cache_mutex);
541 unsigned long sz = _PAGE_TABLE_SIZE;
542
543 if (base_pgt_cache)
544 return 0;
545 mutex_lock(&base_pgt_cache_mutex);
546 if (!base_pgt_cache)
547 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL);
548 mutex_unlock(&base_pgt_cache_mutex);
549 return base_pgt_cache ? 0 : -ENOMEM;
550}
551
552/**
553 * base_asce_alloc - create kernel mapping without enhanced DAT features
554 * @addr: virtual start address of kernel mapping
555 * @num_pages: number of consecutive pages
556 *
557 * Generate an asce, including all required region, segment and page tables,
558 * that can be used to access the virtual kernel mapping. The difference is
559 * that the returned asce does not make use of any enhanced DAT features like
560 * e.g. large pages. This is required for some I/O functions that pass an
561 * asce, like e.g. some service call requests.
562 *
563 * Note: the returned asce may NEVER be attached to any cpu. It may only be
564 * used for I/O requests. tlb entries that might result because the
565 * asce was attached to a cpu won't be cleared.
566 */
567unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages)
568{
569 unsigned long asce, table, end;
570 int rc;
571
572 if (base_pgt_cache_init())
573 return 0;
574 end = addr + num_pages * PAGE_SIZE;
575 if (end <= _REGION3_SIZE) {
576 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
577 if (!table)
578 return 0;
579 rc = base_segment_walk(table, addr, end, 1);
580 asce = table | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH;
581 } else if (end <= _REGION2_SIZE) {
582 table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
583 if (!table)
584 return 0;
585 rc = base_region3_walk(table, addr, end, 1);
586 asce = table | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
587 } else if (end <= _REGION1_SIZE) {
588 table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
589 if (!table)
590 return 0;
591 rc = base_region2_walk(table, addr, end, 1);
592 asce = table | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
593 } else {
594 table = base_crst_alloc(_REGION1_ENTRY_EMPTY);
595 if (!table)
596 return 0;
597 rc = base_region1_walk(table, addr, end, 1);
598 asce = table | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH;
599 }
600 if (rc) {
601 base_asce_free(asce);
602 asce = 0;
603 }
604 return asce;
605}