1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * arch/arm64/mm/hugetlbpage.c
4 *
5 * Copyright (C) 2013 Linaro Ltd.
6 *
7 * Based on arch/x86/mm/hugetlbpage.c.
8 */
9
10 #include <linux/init.h>
11 #include <linux/fs.h>
12 #include <linux/mm.h>
13 #include <linux/hugetlb.h>
14 #include <linux/pagemap.h>
15 #include <linux/err.h>
16 #include <linux/sysctl.h>
17 #include <asm/mman.h>
18 #include <asm/tlb.h>
19 #include <asm/tlbflush.h>
20
21 /*
22 * HugeTLB Support Matrix
23 *
24 * ---------------------------------------------------
25 * | Page Size | CONT PTE | PMD | CONT PMD | PUD |
26 * ---------------------------------------------------
27 * | 4K | 64K | 2M | 32M | 1G |
28 * | 16K | 2M | 32M | 1G | |
29 * | 64K | 2M | 512M | 16G | |
30 * ---------------------------------------------------
31 */
32
33 /*
34 * Reserve CMA areas for the largest supported gigantic
35 * huge page when requested. Any other smaller gigantic
36 * huge pages could still be served from those areas.
37 */
38 #ifdef CONFIG_CMA
39 void __init arm64_hugetlb_cma_reserve(void)
40 {
41 int order;
42
43 if (pud_sect_supported())
44 order = PUD_SHIFT - PAGE_SHIFT;
45 else
46 order = CONT_PMD_SHIFT - PAGE_SHIFT;
47
48 hugetlb_cma_reserve(order);
49 }
50 #endif /* CONFIG_CMA */
51
52 static bool __hugetlb_valid_size(unsigned long size)
53 {
54 switch (size) {
55 #ifndef __PAGETABLE_PMD_FOLDED
56 case PUD_SIZE:
57 return pud_sect_supported();
58 #endif
59 case CONT_PMD_SIZE:
60 case PMD_SIZE:
61 case CONT_PTE_SIZE:
62 return true;
63 }
64
65 return false;
66 }
67
68 #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
69 bool arch_hugetlb_migration_supported(struct hstate *h)
70 {
71 size_t pagesize = huge_page_size(h);
72
73 if (!__hugetlb_valid_size(pagesize)) {
74 pr_warn("%s: unrecognized huge page size 0x%lx\n",
75 __func__, pagesize);
76 return false;
77 }
78 return true;
79 }
80 #endif
81
82 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
83 pte_t *ptep, size_t *pgsize)
84 {
85 pgd_t *pgdp = pgd_offset(mm, addr);
86 p4d_t *p4dp;
87 pud_t *pudp;
88 pmd_t *pmdp;
89
90 *pgsize = PAGE_SIZE;
91 p4dp = p4d_offset(pgdp, addr);
92 pudp = pud_offset(p4dp, addr);
93 pmdp = pmd_offset(pudp, addr);
94 if ((pte_t *)pmdp == ptep) {
95 *pgsize = PMD_SIZE;
96 return CONT_PMDS;
97 }
98 return CONT_PTES;
99 }
100
101 static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
102 {
103 int contig_ptes = 0;
104
105 *pgsize = size;
106
107 switch (size) {
108 #ifndef __PAGETABLE_PMD_FOLDED
109 case PUD_SIZE:
110 if (pud_sect_supported())
111 contig_ptes = 1;
112 break;
113 #endif
114 case PMD_SIZE:
115 contig_ptes = 1;
116 break;
117 case CONT_PMD_SIZE:
118 *pgsize = PMD_SIZE;
119 contig_ptes = CONT_PMDS;
120 break;
121 case CONT_PTE_SIZE:
122 *pgsize = PAGE_SIZE;
123 contig_ptes = CONT_PTES;
124 break;
125 }
126
127 return contig_ptes;
128 }
129
130 pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
131 {
132 int ncontig, i;
133 size_t pgsize;
134 pte_t orig_pte = __ptep_get(ptep);
135
136 if (!pte_present(orig_pte) || !pte_cont(orig_pte))
137 return orig_pte;
138
139 ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize);
140 for (i = 0; i < ncontig; i++, ptep++) {
141 pte_t pte = __ptep_get(ptep);
142
143 if (pte_dirty(pte))
144 orig_pte = pte_mkdirty(orig_pte);
145
146 if (pte_young(pte))
147 orig_pte = pte_mkyoung(orig_pte);
148 }
149 return orig_pte;
150 }
151
152 /*
153 * Changing some bits of contiguous entries requires us to follow a
154 * Break-Before-Make approach, breaking the whole contiguous set
155 * before we can change any entries. See ARM DDI 0487A.k_iss10775,
156 * "Misprogramming of the Contiguous bit", page D4-1762.
157 *
158 * This helper performs the break step.
159 */
160 static pte_t get_clear_contig(struct mm_struct *mm,
161 unsigned long addr,
162 pte_t *ptep,
163 unsigned long pgsize,
164 unsigned long ncontig)
165 {
166 pte_t orig_pte = __ptep_get(ptep);
167 unsigned long i;
168
169 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
170 pte_t pte = __ptep_get_and_clear(mm, addr, ptep);
171
172 /*
173 * If HW_AFDBM is enabled, then the HW could turn on
174 * the dirty or accessed bit for any page in the set,
175 * so check them all.
176 */
177 if (pte_dirty(pte))
178 orig_pte = pte_mkdirty(orig_pte);
179
180 if (pte_young(pte))
181 orig_pte = pte_mkyoung(orig_pte);
182 }
183 return orig_pte;
184 }
185
186 static pte_t get_clear_contig_flush(struct mm_struct *mm,
187 unsigned long addr,
188 pte_t *ptep,
189 unsigned long pgsize,
190 unsigned long ncontig)
191 {
192 pte_t orig_pte = get_clear_contig(mm, addr, ptep, pgsize, ncontig);
193 struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
194
195 flush_tlb_range(&vma, addr, addr + (pgsize * ncontig));
196 return orig_pte;
197 }
198
199 /*
200 * Changing some bits of contiguous entries requires us to follow a
201 * Break-Before-Make approach, breaking the whole contiguous set
202 * before we can change any entries. See ARM DDI 0487A.k_iss10775,
203 * "Misprogramming of the Contiguous bit", page D4-1762.
204 *
205 * This helper performs the break step for use cases where the
206 * original pte is not needed.
207 */
208 static void clear_flush(struct mm_struct *mm,
209 unsigned long addr,
210 pte_t *ptep,
211 unsigned long pgsize,
212 unsigned long ncontig)
213 {
214 struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
215 unsigned long i, saddr = addr;
216
217 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
218 __ptep_get_and_clear(mm, addr, ptep);
219
220 flush_tlb_range(&vma, saddr, addr);
221 }
222
223 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
224 pte_t *ptep, pte_t pte, unsigned long sz)
225 {
226 size_t pgsize;
227 int i;
228 int ncontig;
229 unsigned long pfn, dpfn;
230 pgprot_t hugeprot;
231
232 ncontig = num_contig_ptes(sz, &pgsize);
233
234 if (!pte_present(pte)) {
235 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize)
236 __set_ptes(mm, addr, ptep, pte, 1);
237 return;
238 }
239
240 if (!pte_cont(pte)) {
241 __set_ptes(mm, addr, ptep, pte, 1);
242 return;
243 }
244
245 pfn = pte_pfn(pte);
246 dpfn = pgsize >> PAGE_SHIFT;
247 hugeprot = pte_pgprot(pte);
248
249 clear_flush(mm, addr, ptep, pgsize, ncontig);
250
251 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
252 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
253 }
254
255 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
256 unsigned long addr, unsigned long sz)
257 {
258 pgd_t *pgdp;
259 p4d_t *p4dp;
260 pud_t *pudp;
261 pmd_t *pmdp;
262 pte_t *ptep = NULL;
263
264 pgdp = pgd_offset(mm, addr);
265 p4dp = p4d_alloc(mm, pgdp, addr);
266 if (!p4dp)
267 return NULL;
268
269 pudp = pud_alloc(mm, p4dp, addr);
270 if (!pudp)
271 return NULL;
272
273 if (sz == PUD_SIZE) {
274 ptep = (pte_t *)pudp;
275 } else if (sz == (CONT_PTE_SIZE)) {
276 pmdp = pmd_alloc(mm, pudp, addr);
277 if (!pmdp)
278 return NULL;
279
280 WARN_ON(addr & (sz - 1));
281 ptep = pte_alloc_huge(mm, pmdp, addr);
282 } else if (sz == PMD_SIZE) {
283 if (want_pmd_share(vma, addr) && pud_none(READ_ONCE(*pudp)))
284 ptep = huge_pmd_share(mm, vma, addr, pudp);
285 else
286 ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
287 } else if (sz == (CONT_PMD_SIZE)) {
288 pmdp = pmd_alloc(mm, pudp, addr);
289 WARN_ON(addr & (sz - 1));
290 return (pte_t *)pmdp;
291 }
292
293 return ptep;
294 }
295
296 pte_t *huge_pte_offset(struct mm_struct *mm,
297 unsigned long addr, unsigned long sz)
298 {
299 pgd_t *pgdp;
300 p4d_t *p4dp;
301 pud_t *pudp, pud;
302 pmd_t *pmdp, pmd;
303
304 pgdp = pgd_offset(mm, addr);
305 if (!pgd_present(READ_ONCE(*pgdp)))
306 return NULL;
307
308 p4dp = p4d_offset(pgdp, addr);
309 if (!p4d_present(READ_ONCE(*p4dp)))
310 return NULL;
311
312 pudp = pud_offset(p4dp, addr);
313 pud = READ_ONCE(*pudp);
314 if (sz != PUD_SIZE && pud_none(pud))
315 return NULL;
316 /* hugepage or swap? */
317 if (pud_leaf(pud) || !pud_present(pud))
318 return (pte_t *)pudp;
319 /* table; check the next level */
320
321 if (sz == CONT_PMD_SIZE)
322 addr &= CONT_PMD_MASK;
323
324 pmdp = pmd_offset(pudp, addr);
325 pmd = READ_ONCE(*pmdp);
326 if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
327 pmd_none(pmd))
328 return NULL;
329 if (pmd_leaf(pmd) || !pmd_present(pmd))
330 return (pte_t *)pmdp;
331
332 if (sz == CONT_PTE_SIZE)
333 return pte_offset_huge(pmdp, (addr & CONT_PTE_MASK));
334
335 return NULL;
336 }
337
338 unsigned long hugetlb_mask_last_page(struct hstate *h)
339 {
340 unsigned long hp_size = huge_page_size(h);
341
342 switch (hp_size) {
343 #ifndef __PAGETABLE_PMD_FOLDED
344 case PUD_SIZE:
345 return PGDIR_SIZE - PUD_SIZE;
346 #endif
347 case CONT_PMD_SIZE:
348 return PUD_SIZE - CONT_PMD_SIZE;
349 case PMD_SIZE:
350 return PUD_SIZE - PMD_SIZE;
351 case CONT_PTE_SIZE:
352 return PMD_SIZE - CONT_PTE_SIZE;
353 default:
354 break;
355 }
356
357 return 0UL;
358 }
359
360 pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
361 {
362 size_t pagesize = 1UL << shift;
363
364 entry = pte_mkhuge(entry);
365 if (pagesize == CONT_PTE_SIZE) {
366 entry = pte_mkcont(entry);
367 } else if (pagesize == CONT_PMD_SIZE) {
368 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
369 } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
370 pr_warn("%s: unrecognized huge page size 0x%lx\n",
371 __func__, pagesize);
372 }
373 return entry;
374 }
375
376 void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
377 pte_t *ptep, unsigned long sz)
378 {
379 int i, ncontig;
380 size_t pgsize;
381
382 ncontig = num_contig_ptes(sz, &pgsize);
383
384 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
385 __pte_clear(mm, addr, ptep);
386 }
387
388 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
389 unsigned long addr, pte_t *ptep)
390 {
391 int ncontig;
392 size_t pgsize;
393 pte_t orig_pte = __ptep_get(ptep);
394
395 if (!pte_cont(orig_pte))
396 return __ptep_get_and_clear(mm, addr, ptep);
397
398 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
399
400 return get_clear_contig(mm, addr, ptep, pgsize, ncontig);
401 }
402
403 /*
404 * huge_ptep_set_access_flags will update access flags (dirty, accesssed)
405 * and write permission.
406 *
407 * For a contiguous huge pte range we need to check whether or not write
408 * permission has to change only on the first pte in the set. Then for
409 * all the contiguous ptes we need to check whether or not there is a
410 * discrepancy between dirty or young.
411 */
412 static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
413 {
414 int i;
415
416 if (pte_write(pte) != pte_write(__ptep_get(ptep)))
417 return 1;
418
419 for (i = 0; i < ncontig; i++) {
420 pte_t orig_pte = __ptep_get(ptep + i);
421
422 if (pte_dirty(pte) != pte_dirty(orig_pte))
423 return 1;
424
425 if (pte_young(pte) != pte_young(orig_pte))
426 return 1;
427 }
428
429 return 0;
430 }
431
432 int huge_ptep_set_access_flags(struct vm_area_struct *vma,
433 unsigned long addr, pte_t *ptep,
434 pte_t pte, int dirty)
435 {
436 int ncontig, i;
437 size_t pgsize = 0;
438 unsigned long pfn = pte_pfn(pte), dpfn;
439 struct mm_struct *mm = vma->vm_mm;
440 pgprot_t hugeprot;
441 pte_t orig_pte;
442
443 if (!pte_cont(pte))
444 return __ptep_set_access_flags(vma, addr, ptep, pte, dirty);
445
446 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
447 dpfn = pgsize >> PAGE_SHIFT;
448
449 if (!__cont_access_flags_changed(ptep, pte, ncontig))
450 return 0;
451
452 orig_pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
453
454 /* Make sure we don't lose the dirty or young state */
455 if (pte_dirty(orig_pte))
456 pte = pte_mkdirty(pte);
457
458 if (pte_young(orig_pte))
459 pte = pte_mkyoung(pte);
460
461 hugeprot = pte_pgprot(pte);
462 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
463 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
464
465 return 1;
466 }
467
468 void huge_ptep_set_wrprotect(struct mm_struct *mm,
469 unsigned long addr, pte_t *ptep)
470 {
471 unsigned long pfn, dpfn;
472 pgprot_t hugeprot;
473 int ncontig, i;
474 size_t pgsize;
475 pte_t pte;
476
477 if (!pte_cont(__ptep_get(ptep))) {
478 __ptep_set_wrprotect(mm, addr, ptep);
479 return;
480 }
481
482 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
483 dpfn = pgsize >> PAGE_SHIFT;
484
485 pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
486 pte = pte_wrprotect(pte);
487
488 hugeprot = pte_pgprot(pte);
489 pfn = pte_pfn(pte);
490
491 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
492 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
493 }
494
495 pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
496 unsigned long addr, pte_t *ptep)
497 {
498 struct mm_struct *mm = vma->vm_mm;
499 size_t pgsize;
500 int ncontig;
501
502 if (!pte_cont(__ptep_get(ptep)))
503 return ptep_clear_flush(vma, addr, ptep);
504
505 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
506 return get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
507 }
508
509 static int __init hugetlbpage_init(void)
510 {
511 if (pud_sect_supported())
512 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
513
514 hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
515 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
516 hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
517
518 return 0;
519 }
520 arch_initcall(hugetlbpage_init);
521
522 bool __init arch_hugetlb_valid_size(unsigned long size)
523 {
524 return __hugetlb_valid_size(size);
525 }
526
527 pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
528 {
529 if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) {
530 /*
531 * Break-before-make (BBM) is required for all user space mappings
532 * when the permission changes from executable to non-executable
533 * in cases where cpu is affected with errata #2645198.
534 */
535 if (pte_user_exec(__ptep_get(ptep)))
536 return huge_ptep_clear_flush(vma, addr, ptep);
537 }
538 return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
539 }
540
541 void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
542 pte_t old_pte, pte_t pte)
543 {
544 unsigned long psize = huge_page_size(hstate_vma(vma));
545
546 set_huge_pte_at(vma->vm_mm, addr, ptep, pte, psize);
547 }
548
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