1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Virtual Memory Map support
4 *
5 * (C) 2007 sgi. Christoph Lameter.
6 *
7 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
8 * virt_to_page, page_address() to be implemented as a base offset
9 * calculation without memory access.
10 *
11 * However, virtual mappings need a page table and TLBs. Many Linux
12 * architectures already map their physical space using 1-1 mappings
13 * via TLBs. For those arches the virtual memory map is essentially
14 * for free if we use the same page size as the 1-1 mappings. In that
15 * case the overhead consists of a few additional pages that are
16 * allocated to create a view of memory for vmemmap.
17 *
18 * The architecture is expected to provide a vmemmap_populate() function
19 * to instantiate the mapping.
20 */
21#include <linux/mm.h>
22#include <linux/mmzone.h>
23#include <linux/memblock.h>
24#include <linux/memremap.h>
25#include <linux/highmem.h>
26#include <linux/slab.h>
27#include <linux/spinlock.h>
28#include <linux/vmalloc.h>
29#include <linux/sched.h>
30
31#include <asm/dma.h>
32#include <asm/pgalloc.h>
33#include <asm/tlbflush.h>
34
35#include "hugetlb_vmemmap.h"
36
37/*
38 * Flags for vmemmap_populate_range and friends.
39 */
40/* Get a ref on the head page struct page, for ZONE_DEVICE compound pages */
41#define VMEMMAP_POPULATE_PAGEREF 0x0001
42
43#include "internal.h"
44
45/*
46 * Allocate a block of memory to be used to back the virtual memory map
47 * or to back the page tables that are used to create the mapping.
48 * Uses the main allocators if they are available, else bootmem.
49 */
50
51static void * __ref __earlyonly_bootmem_alloc(int node,
52 unsigned long size,
53 unsigned long align,
54 unsigned long goal)
55{
56 return memmap_alloc(size, align, min_addr: goal, nid: node, exact_nid: false);
57}
58
59void * __meminit vmemmap_alloc_block(unsigned long size, int node)
60{
61 /* If the main allocator is up use that, fallback to bootmem. */
62 if (slab_is_available()) {
63 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
64 int order = get_order(size);
65 static bool warned;
66 struct page *page;
67
68 page = alloc_pages_node(node, gfp_mask, order);
69 if (page)
70 return page_address(page);
71
72 if (!warned) {
73 warn_alloc(gfp_mask: gfp_mask & ~__GFP_NOWARN, NULL,
74 fmt: "vmemmap alloc failure: order:%u", order);
75 warned = true;
76 }
77 return NULL;
78 } else
79 return __earlyonly_bootmem_alloc(node, size, align: size,
80 __pa(MAX_DMA_ADDRESS));
81}
82
83static void * __meminit altmap_alloc_block_buf(unsigned long size,
84 struct vmem_altmap *altmap);
85
86/* need to make sure size is all the same during early stage */
87void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
88 struct vmem_altmap *altmap)
89{
90 void *ptr;
91
92 if (altmap)
93 return altmap_alloc_block_buf(size, altmap);
94
95 ptr = sparse_buffer_alloc(size);
96 if (!ptr)
97 ptr = vmemmap_alloc_block(size, node);
98 return ptr;
99}
100
101static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
102{
103 return altmap->base_pfn + altmap->reserve + altmap->alloc
104 + altmap->align;
105}
106
107static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
108{
109 unsigned long allocated = altmap->alloc + altmap->align;
110
111 if (altmap->free > allocated)
112 return altmap->free - allocated;
113 return 0;
114}
115
116static void * __meminit altmap_alloc_block_buf(unsigned long size,
117 struct vmem_altmap *altmap)
118{
119 unsigned long pfn, nr_pfns, nr_align;
120
121 if (size & ~PAGE_MASK) {
122 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
123 __func__, size);
124 return NULL;
125 }
126
127 pfn = vmem_altmap_next_pfn(altmap);
128 nr_pfns = size >> PAGE_SHIFT;
129 nr_align = 1UL << find_first_bit(addr: &nr_pfns, BITS_PER_LONG);
130 nr_align = ALIGN(pfn, nr_align) - pfn;
131 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
132 return NULL;
133
134 altmap->alloc += nr_pfns;
135 altmap->align += nr_align;
136 pfn += nr_align;
137
138 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
139 __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
140 return __va(__pfn_to_phys(pfn));
141}
142
143void __meminit vmemmap_verify(pte_t *pte, int node,
144 unsigned long start, unsigned long end)
145{
146 unsigned long pfn = pte_pfn(pte: ptep_get(ptep: pte));
147 int actual_node = early_pfn_to_nid(pfn);
148
149 if (node_distance(actual_node, node) > LOCAL_DISTANCE)
150 pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
151 start, end - 1);
152}
153
154pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
155 struct vmem_altmap *altmap,
156 unsigned long ptpfn, unsigned long flags)
157{
158 pte_t *pte = pte_offset_kernel(pmd, address: addr);
159 if (pte_none(pte: ptep_get(ptep: pte))) {
160 pte_t entry;
161 void *p;
162
163 if (ptpfn == (unsigned long)-1) {
164 p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
165 if (!p)
166 return NULL;
167 ptpfn = PHYS_PFN(__pa(p));
168 } else {
169 /*
170 * When a PTE/PMD entry is freed from the init_mm
171 * there's a free_pages() call to this page allocated
172 * above. Thus this get_page() is paired with the
173 * put_page_testzero() on the freeing path.
174 * This can only called by certain ZONE_DEVICE path,
175 * and through vmemmap_populate_compound_pages() when
176 * slab is available.
177 */
178 if (flags & VMEMMAP_POPULATE_PAGEREF)
179 get_page(pfn_to_page(ptpfn));
180 }
181 entry = pfn_pte(page_nr: ptpfn, PAGE_KERNEL);
182 set_pte_at(&init_mm, addr, pte, entry);
183 }
184 return pte;
185}
186
187static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
188{
189 void *p = vmemmap_alloc_block(size, node);
190
191 if (!p)
192 return NULL;
193 memset(p, 0, size);
194
195 return p;
196}
197
198pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
199{
200 pmd_t *pmd = pmd_offset(pud, address: addr);
201 if (pmd_none(pmd: *pmd)) {
202 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
203 if (!p)
204 return NULL;
205 kernel_pte_init(addr: p);
206 pmd_populate_kernel(mm: &init_mm, pmd, pte: p);
207 }
208 return pmd;
209}
210
211pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
212{
213 pud_t *pud = pud_offset(p4d, address: addr);
214 if (pud_none(pud: *pud)) {
215 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
216 if (!p)
217 return NULL;
218 pmd_init(addr: p);
219 pud_populate(mm: &init_mm, pud, pmd: p);
220 }
221 return pud;
222}
223
224p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
225{
226 p4d_t *p4d = p4d_offset(pgd, address: addr);
227 if (p4d_none(p4d: *p4d)) {
228 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
229 if (!p)
230 return NULL;
231 pud_init(addr: p);
232 p4d_populate(mm: &init_mm, p4d, pud: p);
233 }
234 return p4d;
235}
236
237pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
238{
239 pgd_t *pgd = pgd_offset_k(addr);
240 if (pgd_none(pgd: *pgd)) {
241 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
242 if (!p)
243 return NULL;
244 pgd_populate(mm: &init_mm, pgd, p4d: p);
245 }
246 return pgd;
247}
248
249static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
250 struct vmem_altmap *altmap,
251 unsigned long ptpfn,
252 unsigned long flags)
253{
254 pgd_t *pgd;
255 p4d_t *p4d;
256 pud_t *pud;
257 pmd_t *pmd;
258 pte_t *pte;
259
260 pgd = vmemmap_pgd_populate(addr, node);
261 if (!pgd)
262 return NULL;
263 p4d = vmemmap_p4d_populate(pgd, addr, node);
264 if (!p4d)
265 return NULL;
266 pud = vmemmap_pud_populate(p4d, addr, node);
267 if (!pud)
268 return NULL;
269 pmd = vmemmap_pmd_populate(pud, addr, node);
270 if (!pmd)
271 return NULL;
272 pte = vmemmap_pte_populate(pmd, addr, node, altmap, ptpfn, flags);
273 if (!pte)
274 return NULL;
275 vmemmap_verify(pte, node, start: addr, end: addr + PAGE_SIZE);
276
277 return pte;
278}
279
280static int __meminit vmemmap_populate_range(unsigned long start,
281 unsigned long end, int node,
282 struct vmem_altmap *altmap,
283 unsigned long ptpfn,
284 unsigned long flags)
285{
286 unsigned long addr = start;
287 pte_t *pte;
288
289 for (; addr < end; addr += PAGE_SIZE) {
290 pte = vmemmap_populate_address(addr, node, altmap,
291 ptpfn, flags);
292 if (!pte)
293 return -ENOMEM;
294 }
295
296 return 0;
297}
298
299int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
300 int node, struct vmem_altmap *altmap)
301{
302 return vmemmap_populate_range(start, end, node, altmap, ptpfn: -1, flags: 0);
303}
304
305/*
306 * Undo populate_hvo, and replace it with a normal base page mapping.
307 * Used in memory init in case a HVO mapping needs to be undone.
308 *
309 * This can happen when it is discovered that a memblock allocated
310 * hugetlb page spans multiple zones, which can only be verified
311 * after zones have been initialized.
312 *
313 * We know that:
314 * 1) The first @headsize / PAGE_SIZE vmemmap pages were individually
315 * allocated through memblock, and mapped.
316 *
317 * 2) The rest of the vmemmap pages are mirrors of the last head page.
318 */
319int __meminit vmemmap_undo_hvo(unsigned long addr, unsigned long end,
320 int node, unsigned long headsize)
321{
322 unsigned long maddr, pfn;
323 pte_t *pte;
324 int headpages;
325
326 /*
327 * Should only be called early in boot, so nothing will
328 * be accessing these page structures.
329 */
330 WARN_ON(!early_boot_irqs_disabled);
331
332 headpages = headsize >> PAGE_SHIFT;
333
334 /*
335 * Clear mirrored mappings for tail page structs.
336 */
337 for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
338 pte = virt_to_kpte(vaddr: maddr);
339 pte_clear(mm: &init_mm, addr: maddr, ptep: pte);
340 }
341
342 /*
343 * Clear and free mappings for head page and first tail page
344 * structs.
345 */
346 for (maddr = addr; headpages-- > 0; maddr += PAGE_SIZE) {
347 pte = virt_to_kpte(vaddr: maddr);
348 pfn = pte_pfn(pte: ptep_get(ptep: pte));
349 pte_clear(mm: &init_mm, addr: maddr, ptep: pte);
350 memblock_phys_free(PFN_PHYS(pfn), PAGE_SIZE);
351 }
352
353 flush_tlb_kernel_range(start: addr, end);
354
355 return vmemmap_populate(start: addr, end, node, NULL);
356}
357
358/*
359 * Write protect the mirrored tail page structs for HVO. This will be
360 * called from the hugetlb code when gathering and initializing the
361 * memblock allocated gigantic pages. The write protect can't be
362 * done earlier, since it can't be guaranteed that the reserved
363 * page structures will not be written to during initialization,
364 * even if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled.
365 *
366 * The PTEs are known to exist, and nothing else should be touching
367 * these pages. The caller is responsible for any TLB flushing.
368 */
369void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end,
370 int node, unsigned long headsize)
371{
372 unsigned long maddr;
373 pte_t *pte;
374
375 for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
376 pte = virt_to_kpte(vaddr: maddr);
377 ptep_set_wrprotect(mm: &init_mm, addr: maddr, ptep: pte);
378 }
379}
380
381/*
382 * Populate vmemmap pages HVO-style. The first page contains the head
383 * page and needed tail pages, the other ones are mirrors of the first
384 * page.
385 */
386int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
387 int node, unsigned long headsize)
388{
389 pte_t *pte;
390 unsigned long maddr;
391
392 for (maddr = addr; maddr < addr + headsize; maddr += PAGE_SIZE) {
393 pte = vmemmap_populate_address(addr: maddr, node, NULL, ptpfn: -1, flags: 0);
394 if (!pte)
395 return -ENOMEM;
396 }
397
398 /*
399 * Reuse the last page struct page mapped above for the rest.
400 */
401 return vmemmap_populate_range(start: maddr, end, node, NULL,
402 ptpfn: pte_pfn(pte: ptep_get(ptep: pte)), flags: 0);
403}
404
405void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
406 unsigned long addr, unsigned long next)
407{
408}
409
410int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
411 unsigned long addr, unsigned long next)
412{
413 return 0;
414}
415
416int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
417 int node, struct vmem_altmap *altmap)
418{
419 unsigned long addr;
420 unsigned long next;
421 pgd_t *pgd;
422 p4d_t *p4d;
423 pud_t *pud;
424 pmd_t *pmd;
425
426 for (addr = start; addr < end; addr = next) {
427 next = pmd_addr_end(addr, end);
428
429 pgd = vmemmap_pgd_populate(addr, node);
430 if (!pgd)
431 return -ENOMEM;
432
433 p4d = vmemmap_p4d_populate(pgd, addr, node);
434 if (!p4d)
435 return -ENOMEM;
436
437 pud = vmemmap_pud_populate(p4d, addr, node);
438 if (!pud)
439 return -ENOMEM;
440
441 pmd = pmd_offset(pud, address: addr);
442 if (pmd_none(READ_ONCE(*pmd))) {
443 void *p;
444
445 p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
446 if (p) {
447 vmemmap_set_pmd(pmd, p, node, addr, next);
448 continue;
449 } else if (altmap) {
450 /*
451 * No fallback: In any case we care about, the
452 * altmap should be reasonably sized and aligned
453 * such that vmemmap_alloc_block_buf() will always
454 * succeed. For consistency with the PTE case,
455 * return an error here as failure could indicate
456 * a configuration issue with the size of the altmap.
457 */
458 return -ENOMEM;
459 }
460 } else if (vmemmap_check_pmd(pmd, node, addr, next))
461 continue;
462 if (vmemmap_populate_basepages(start: addr, end: next, node, altmap))
463 return -ENOMEM;
464 }
465 return 0;
466}
467
468#ifndef vmemmap_populate_compound_pages
469/*
470 * For compound pages bigger than section size (e.g. x86 1G compound
471 * pages with 2M subsection size) fill the rest of sections as tail
472 * pages.
473 *
474 * Note that memremap_pages() resets @nr_range value and will increment
475 * it after each range successful onlining. Thus the value or @nr_range
476 * at section memmap populate corresponds to the in-progress range
477 * being onlined here.
478 */
479static bool __meminit reuse_compound_section(unsigned long start_pfn,
480 struct dev_pagemap *pgmap)
481{
482 unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
483 unsigned long offset = start_pfn -
484 PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
485
486 return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
487}
488
489static pte_t * __meminit compound_section_tail_page(unsigned long addr)
490{
491 pte_t *pte;
492
493 addr -= PAGE_SIZE;
494
495 /*
496 * Assuming sections are populated sequentially, the previous section's
497 * page data can be reused.
498 */
499 pte = pte_offset_kernel(pmd: pmd_off_k(va: addr), address: addr);
500 if (!pte)
501 return NULL;
502
503 return pte;
504}
505
506static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
507 unsigned long start,
508 unsigned long end, int node,
509 struct dev_pagemap *pgmap)
510{
511 unsigned long size, addr;
512 pte_t *pte;
513 int rc;
514
515 if (reuse_compound_section(start_pfn, pgmap)) {
516 pte = compound_section_tail_page(addr: start);
517 if (!pte)
518 return -ENOMEM;
519
520 /*
521 * Reuse the page that was populated in the prior iteration
522 * with just tail struct pages.
523 */
524 return vmemmap_populate_range(start, end, node, NULL,
525 ptpfn: pte_pfn(pte: ptep_get(ptep: pte)),
526 VMEMMAP_POPULATE_PAGEREF);
527 }
528
529 size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
530 for (addr = start; addr < end; addr += size) {
531 unsigned long next, last = addr + size;
532
533 /* Populate the head page vmemmap page */
534 pte = vmemmap_populate_address(addr, node, NULL, ptpfn: -1, flags: 0);
535 if (!pte)
536 return -ENOMEM;
537
538 /* Populate the tail pages vmemmap page */
539 next = addr + PAGE_SIZE;
540 pte = vmemmap_populate_address(addr: next, node, NULL, ptpfn: -1, flags: 0);
541 if (!pte)
542 return -ENOMEM;
543
544 /*
545 * Reuse the previous page for the rest of tail pages
546 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
547 */
548 next += PAGE_SIZE;
549 rc = vmemmap_populate_range(start: next, end: last, node, NULL,
550 ptpfn: pte_pfn(pte: ptep_get(ptep: pte)),
551 VMEMMAP_POPULATE_PAGEREF);
552 if (rc)
553 return -ENOMEM;
554 }
555
556 return 0;
557}
558
559#endif
560
561struct page * __meminit __populate_section_memmap(unsigned long pfn,
562 unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
563 struct dev_pagemap *pgmap)
564{
565 unsigned long start = (unsigned long) pfn_to_page(pfn);
566 unsigned long end = start + nr_pages * sizeof(struct page);
567 int r;
568
569 if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
570 !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
571 return NULL;
572
573 if (vmemmap_can_optimize(altmap, pgmap))
574 r = vmemmap_populate_compound_pages(start_pfn: pfn, start, end, node: nid, pgmap);
575 else
576 r = vmemmap_populate(start, end, node: nid, altmap);
577
578 if (r < 0)
579 return NULL;
580
581 if (system_state == SYSTEM_BOOTING)
582 memmap_boot_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE));
583 else
584 memmap_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE));
585
586 return pfn_to_page(pfn);
587}
588
589#ifdef CONFIG_SPARSEMEM_VMEMMAP_PREINIT
590/*
591 * This is called just before initializing sections for a NUMA node.
592 * Any special initialization that needs to be done before the
593 * generic initialization can be done from here. Sections that
594 * are initialized in hooks called from here will be skipped by
595 * the generic initialization.
596 */
597void __init sparse_vmemmap_init_nid_early(int nid)
598{
599 hugetlb_vmemmap_init_early(nid);
600}
601
602/*
603 * This is called just before the initialization of page structures
604 * through memmap_init. Zones are now initialized, so any work that
605 * needs to be done that needs zone information can be done from
606 * here.
607 */
608void __init sparse_vmemmap_init_nid_late(int nid)
609{
610 hugetlb_vmemmap_init_late(nid);
611}
612#endif
613

source code of linux/mm/sparse-vmemmap.c