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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
39void __init arm64_hugetlb_cma_reserve(void)
40{
41 int order;
42
43#ifdef CONFIG_ARM64_4K_PAGES
44 order = PUD_SHIFT - PAGE_SHIFT;
45#else
46 order = CONT_PMD_SHIFT - PAGE_SHIFT;
47#endif
48 /*
49 * HugeTLB CMA reservation is required for gigantic
50 * huge pages which could not be allocated via the
51 * page allocator. Just warn if there is any change
52 * breaking this assumption.
53 */
54 WARN_ON(order <= MAX_ORDER);
55 hugetlb_cma_reserve(order);
56}
57#endif /* CONFIG_CMA */
58
59#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
60bool arch_hugetlb_migration_supported(struct hstate *h)
61{
62 size_t pagesize = huge_page_size(h);
63
64 switch (pagesize) {
65#ifdef CONFIG_ARM64_4K_PAGES
66 case PUD_SIZE:
67#endif
68 case PMD_SIZE:
69 case CONT_PMD_SIZE:
70 case CONT_PTE_SIZE:
71 return true;
72 }
73 pr_warn("%s: unrecognized huge page size 0x%lx\n",
74 __func__, pagesize);
75 return false;
76}
77#endif
78
79int pmd_huge(pmd_t pmd)
80{
81 return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
82}
83
84int pud_huge(pud_t pud)
85{
86#ifndef __PAGETABLE_PMD_FOLDED
87 return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
88#else
89 return 0;
90#endif
91}
92
93/*
94 * Select all bits except the pfn
95 */
96static inline pgprot_t pte_pgprot(pte_t pte)
97{
98 unsigned long pfn = pte_pfn(pte);
99
100 return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
101}
102
103static int find_num_contig(struct mm_struct *mm, unsigned long addr,
104 pte_t *ptep, size_t *pgsize)
105{
106 pgd_t *pgdp = pgd_offset(mm, addr);
107 p4d_t *p4dp;
108 pud_t *pudp;
109 pmd_t *pmdp;
110
111 *pgsize = PAGE_SIZE;
112 p4dp = p4d_offset(pgdp, addr);
113 pudp = pud_offset(p4dp, addr);
114 pmdp = pmd_offset(pudp, addr);
115 if ((pte_t *)pmdp == ptep) {
116 *pgsize = PMD_SIZE;
117 return CONT_PMDS;
118 }
119 return CONT_PTES;
120}
121
122static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
123{
124 int contig_ptes = 0;
125
126 *pgsize = size;
127
128 switch (size) {
129#ifdef CONFIG_ARM64_4K_PAGES
130 case PUD_SIZE:
131#endif
132 case PMD_SIZE:
133 contig_ptes = 1;
134 break;
135 case CONT_PMD_SIZE:
136 *pgsize = PMD_SIZE;
137 contig_ptes = CONT_PMDS;
138 break;
139 case CONT_PTE_SIZE:
140 *pgsize = PAGE_SIZE;
141 contig_ptes = CONT_PTES;
142 break;
143 }
144
145 return contig_ptes;
146}
147
148/*
149 * Changing some bits of contiguous entries requires us to follow a
150 * Break-Before-Make approach, breaking the whole contiguous set
151 * before we can change any entries. See ARM DDI 0487A.k_iss10775,
152 * "Misprogramming of the Contiguous bit", page D4-1762.
153 *
154 * This helper performs the break step.
155 */
156static pte_t get_clear_flush(struct mm_struct *mm,
157 unsigned long addr,
158 pte_t *ptep,
159 unsigned long pgsize,
160 unsigned long ncontig)
161{
162 pte_t orig_pte = huge_ptep_get(ptep);
163 bool valid = pte_valid(orig_pte);
164 unsigned long i, saddr = addr;
165
166 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
167 pte_t pte = ptep_get_and_clear(mm, addr, ptep);
168
169 /*
170 * If HW_AFDBM is enabled, then the HW could turn on
171 * the dirty or accessed bit for any page in the set,
172 * so check them all.
173 */
174 if (pte_dirty(pte))
175 orig_pte = pte_mkdirty(orig_pte);
176
177 if (pte_young(pte))
178 orig_pte = pte_mkyoung(orig_pte);
179 }
180
181 if (valid) {
182 struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
183 flush_tlb_range(&vma, saddr, addr);
184 }
185 return orig_pte;
186}
187
188/*
189 * Changing some bits of contiguous entries requires us to follow a
190 * Break-Before-Make approach, breaking the whole contiguous set
191 * before we can change any entries. See ARM DDI 0487A.k_iss10775,
192 * "Misprogramming of the Contiguous bit", page D4-1762.
193 *
194 * This helper performs the break step for use cases where the
195 * original pte is not needed.
196 */
197static void clear_flush(struct mm_struct *mm,
198 unsigned long addr,
199 pte_t *ptep,
200 unsigned long pgsize,
201 unsigned long ncontig)
202{
203 struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
204 unsigned long i, saddr = addr;
205
206 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
207 pte_clear(mm, addr, ptep);
208
209 flush_tlb_range(&vma, saddr, addr);
210}
211
212void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
213 pte_t *ptep, pte_t pte)
214{
215 size_t pgsize;
216 int i;
217 int ncontig;
218 unsigned long pfn, dpfn;
219 pgprot_t hugeprot;
220
221 /*
222 * Code needs to be expanded to handle huge swap and migration
223 * entries. Needed for HUGETLB and MEMORY_FAILURE.
224 */
225 WARN_ON(!pte_present(pte));
226
227 if (!pte_cont(pte)) {
228 set_pte_at(mm, addr, ptep, pte);
229 return;
230 }
231
232 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
233 pfn = pte_pfn(pte);
234 dpfn = pgsize >> PAGE_SHIFT;
235 hugeprot = pte_pgprot(pte);
236
237 clear_flush(mm, addr, ptep, pgsize, ncontig);
238
239 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
240 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
241}
242
243void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
244 pte_t *ptep, pte_t pte, unsigned long sz)
245{
246 int i, ncontig;
247 size_t pgsize;
248
249 ncontig = num_contig_ptes(sz, &pgsize);
250
251 for (i = 0; i < ncontig; i++, ptep++)
252 set_pte(ptep, pte);
253}
254
255pte_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_offset(pgdp, addr);
266 pudp = pud_alloc(mm, p4dp, addr);
267 if (!pudp)
268 return NULL;
269
270 if (sz == PUD_SIZE) {
271 ptep = (pte_t *)pudp;
272 } else if (sz == (CONT_PTE_SIZE)) {
273 pmdp = pmd_alloc(mm, pudp, addr);
274 if (!pmdp)
275 return NULL;
276
277 WARN_ON(addr & (sz - 1));
278 /*
279 * Note that if this code were ever ported to the
280 * 32-bit arm platform then it will cause trouble in
281 * the case where CONFIG_HIGHPTE is set, since there
282 * will be no pte_unmap() to correspond with this
283 * pte_alloc_map().
284 */
285 ptep = pte_alloc_map(mm, pmdp, addr);
286 } else if (sz == PMD_SIZE) {
287 if (want_pmd_share(vma, addr) && pud_none(READ_ONCE(*pudp)))
288 ptep = huge_pmd_share(mm, vma, addr, pudp);
289 else
290 ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
291 } else if (sz == (CONT_PMD_SIZE)) {
292 pmdp = pmd_alloc(mm, pudp, addr);
293 WARN_ON(addr & (sz - 1));
294 return (pte_t *)pmdp;
295 }
296
297 return ptep;
298}
299
300pte_t *huge_pte_offset(struct mm_struct *mm,
301 unsigned long addr, unsigned long sz)
302{
303 pgd_t *pgdp;
304 p4d_t *p4dp;
305 pud_t *pudp, pud;
306 pmd_t *pmdp, pmd;
307
308 pgdp = pgd_offset(mm, addr);
309 if (!pgd_present(READ_ONCE(*pgdp)))
310 return NULL;
311
312 p4dp = p4d_offset(pgdp, addr);
313 if (!p4d_present(READ_ONCE(*p4dp)))
314 return NULL;
315
316 pudp = pud_offset(p4dp, addr);
317 pud = READ_ONCE(*pudp);
318 if (sz != PUD_SIZE && pud_none(pud))
319 return NULL;
320 /* hugepage or swap? */
321 if (pud_huge(pud) || !pud_present(pud))
322 return (pte_t *)pudp;
323 /* table; check the next level */
324
325 if (sz == CONT_PMD_SIZE)
326 addr &= CONT_PMD_MASK;
327
328 pmdp = pmd_offset(pudp, addr);
329 pmd = READ_ONCE(*pmdp);
330 if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
331 pmd_none(pmd))
332 return NULL;
333 if (pmd_huge(pmd) || !pmd_present(pmd))
334 return (pte_t *)pmdp;
335
336 if (sz == CONT_PTE_SIZE)
337 return pte_offset_kernel(pmdp, (addr & CONT_PTE_MASK));
338
339 return NULL;
340}
341
342pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
343{
344 size_t pagesize = 1UL << shift;
345
346 if (pagesize == CONT_PTE_SIZE) {
347 entry = pte_mkcont(entry);
348 } else if (pagesize == CONT_PMD_SIZE) {
349 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
350 } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
351 pr_warn("%s: unrecognized huge page size 0x%lx\n",
352 __func__, pagesize);
353 }
354 return entry;
355}
356
357void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
358 pte_t *ptep, unsigned long sz)
359{
360 int i, ncontig;
361 size_t pgsize;
362
363 ncontig = num_contig_ptes(sz, &pgsize);
364
365 for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
366 pte_clear(mm, addr, ptep);
367}
368
369pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
370 unsigned long addr, pte_t *ptep)
371{
372 int ncontig;
373 size_t pgsize;
374 pte_t orig_pte = huge_ptep_get(ptep);
375
376 if (!pte_cont(orig_pte))
377 return ptep_get_and_clear(mm, addr, ptep);
378
379 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
380
381 return get_clear_flush(mm, addr, ptep, pgsize, ncontig);
382}
383
384/*
385 * huge_ptep_set_access_flags will update access flags (dirty, accesssed)
386 * and write permission.
387 *
388 * For a contiguous huge pte range we need to check whether or not write
389 * permission has to change only on the first pte in the set. Then for
390 * all the contiguous ptes we need to check whether or not there is a
391 * discrepancy between dirty or young.
392 */
393static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
394{
395 int i;
396
397 if (pte_write(pte) != pte_write(huge_ptep_get(ptep)))
398 return 1;
399
400 for (i = 0; i < ncontig; i++) {
401 pte_t orig_pte = huge_ptep_get(ptep + i);
402
403 if (pte_dirty(pte) != pte_dirty(orig_pte))
404 return 1;
405
406 if (pte_young(pte) != pte_young(orig_pte))
407 return 1;
408 }
409
410 return 0;
411}
412
413int huge_ptep_set_access_flags(struct vm_area_struct *vma,
414 unsigned long addr, pte_t *ptep,
415 pte_t pte, int dirty)
416{
417 int ncontig, i;
418 size_t pgsize = 0;
419 unsigned long pfn = pte_pfn(pte), dpfn;
420 pgprot_t hugeprot;
421 pte_t orig_pte;
422
423 if (!pte_cont(pte))
424 return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
425
426 ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
427 dpfn = pgsize >> PAGE_SHIFT;
428
429 if (!__cont_access_flags_changed(ptep, pte, ncontig))
430 return 0;
431
432 orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
433
434 /* Make sure we don't lose the dirty or young state */
435 if (pte_dirty(orig_pte))
436 pte = pte_mkdirty(pte);
437
438 if (pte_young(orig_pte))
439 pte = pte_mkyoung(pte);
440
441 hugeprot = pte_pgprot(pte);
442 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
443 set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));
444
445 return 1;
446}
447
448void huge_ptep_set_wrprotect(struct mm_struct *mm,
449 unsigned long addr, pte_t *ptep)
450{
451 unsigned long pfn, dpfn;
452 pgprot_t hugeprot;
453 int ncontig, i;
454 size_t pgsize;
455 pte_t pte;
456
457 if (!pte_cont(READ_ONCE(*ptep))) {
458 ptep_set_wrprotect(mm, addr, ptep);
459 return;
460 }
461
462 ncontig = find_num_contig(mm, addr, ptep, &pgsize);
463 dpfn = pgsize >> PAGE_SHIFT;
464
465 pte = get_clear_flush(mm, addr, ptep, pgsize, ncontig);
466 pte = pte_wrprotect(pte);
467
468 hugeprot = pte_pgprot(pte);
469 pfn = pte_pfn(pte);
470
471 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
472 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
473}
474
475void huge_ptep_clear_flush(struct vm_area_struct *vma,
476 unsigned long addr, pte_t *ptep)
477{
478 size_t pgsize;
479 int ncontig;
480
481 if (!pte_cont(READ_ONCE(*ptep))) {
482 ptep_clear_flush(vma, addr, ptep);
483 return;
484 }
485
486 ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
487 clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
488}
489
490static int __init hugetlbpage_init(void)
491{
492#ifdef CONFIG_ARM64_4K_PAGES
493 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
494#endif
495 hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
496 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
497 hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
498
499 return 0;
500}
501arch_initcall(hugetlbpage_init);
502
503bool __init arch_hugetlb_valid_size(unsigned long size)
504{
505 switch (size) {
506#ifdef CONFIG_ARM64_4K_PAGES
507 case PUD_SIZE:
508#endif
509 case CONT_PMD_SIZE:
510 case PMD_SIZE:
511 case CONT_PTE_SIZE:
512 return true;
513 }
514
515 return false;
516}