projects/linux·blob v6.7 · refs

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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
34/*
35 * Allocate a block of memory to be used to back the virtual memory map
36 * or to back the page tables that are used to create the mapping.
37 * Uses the main allocators if they are available, else bootmem.
38 */
39
40static void * __ref __earlyonly_bootmem_alloc(int node,
41 unsigned long size,
42 unsigned long align,
43 unsigned long goal)
44{
45 return memblock_alloc_try_nid_raw(size, align, goal,
46 MEMBLOCK_ALLOC_ACCESSIBLE, node);
47}
48
49void * __meminit vmemmap_alloc_block(unsigned long size, int node)
50{
51 /* If the main allocator is up use that, fallback to bootmem. */
52 if (slab_is_available()) {
53 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
54 int order = get_order(size);
55 static bool warned;
56 struct page *page;
57
58 page = alloc_pages_node(node, gfp_mask, order);
59 if (page)
60 return page_address(page);
61
62 if (!warned) {
63 warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
64 "vmemmap alloc failure: order:%u", order);
65 warned = true;
66 }
67 return NULL;
68 } else
69 return __earlyonly_bootmem_alloc(node, size, size,
70 __pa(MAX_DMA_ADDRESS));
71}
72
73static void * __meminit altmap_alloc_block_buf(unsigned long size,
74 struct vmem_altmap *altmap);
75
76/* need to make sure size is all the same during early stage */
77void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
78 struct vmem_altmap *altmap)
79{
80 void *ptr;
81
82 if (altmap)
83 return altmap_alloc_block_buf(size, altmap);
84
85 ptr = sparse_buffer_alloc(size);
86 if (!ptr)
87 ptr = vmemmap_alloc_block(size, node);
88 return ptr;
89}
90
91static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
92{
93 return altmap->base_pfn + altmap->reserve + altmap->alloc
94 + altmap->align;
95}
96
97static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
98{
99 unsigned long allocated = altmap->alloc + altmap->align;
100
101 if (altmap->free > allocated)
102 return altmap->free - allocated;
103 return 0;
104}
105
106static void * __meminit altmap_alloc_block_buf(unsigned long size,
107 struct vmem_altmap *altmap)
108{
109 unsigned long pfn, nr_pfns, nr_align;
110
111 if (size & ~PAGE_MASK) {
112 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
113 __func__, size);
114 return NULL;
115 }
116
117 pfn = vmem_altmap_next_pfn(altmap);
118 nr_pfns = size >> PAGE_SHIFT;
119 nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
120 nr_align = ALIGN(pfn, nr_align) - pfn;
121 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
122 return NULL;
123
124 altmap->alloc += nr_pfns;
125 altmap->align += nr_align;
126 pfn += nr_align;
127
128 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
129 __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
130 return __va(__pfn_to_phys(pfn));
131}
132
133void __meminit vmemmap_verify(pte_t *pte, int node,
134 unsigned long start, unsigned long end)
135{
136 unsigned long pfn = pte_pfn(ptep_get(pte));
137 int actual_node = early_pfn_to_nid(pfn);
138
139 if (node_distance(actual_node, node) > LOCAL_DISTANCE)
140 pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
141 start, end - 1);
142}
143
144pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
145 struct vmem_altmap *altmap,
146 struct page *reuse)
147{
148 pte_t *pte = pte_offset_kernel(pmd, addr);
149 if (pte_none(ptep_get(pte))) {
150 pte_t entry;
151 void *p;
152
153 if (!reuse) {
154 p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
155 if (!p)
156 return NULL;
157 } else {
158 /*
159 * When a PTE/PMD entry is freed from the init_mm
160 * there's a free_pages() call to this page allocated
161 * above. Thus this get_page() is paired with the
162 * put_page_testzero() on the freeing path.
163 * This can only called by certain ZONE_DEVICE path,
164 * and through vmemmap_populate_compound_pages() when
165 * slab is available.
166 */
167 get_page(reuse);
168 p = page_to_virt(reuse);
169 }
170 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
171 set_pte_at(&init_mm, addr, pte, entry);
172 }
173 return pte;
174}
175
176static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
177{
178 void *p = vmemmap_alloc_block(size, node);
179
180 if (!p)
181 return NULL;
182 memset(p, 0, size);
183
184 return p;
185}
186
187pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
188{
189 pmd_t *pmd = pmd_offset(pud, addr);
190 if (pmd_none(*pmd)) {
191 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
192 if (!p)
193 return NULL;
194 pmd_populate_kernel(&init_mm, pmd, p);
195 }
196 return pmd;
197}
198
199void __weak __meminit pmd_init(void *addr)
200{
201}
202
203pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
204{
205 pud_t *pud = pud_offset(p4d, addr);
206 if (pud_none(*pud)) {
207 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
208 if (!p)
209 return NULL;
210 pmd_init(p);
211 pud_populate(&init_mm, pud, p);
212 }
213 return pud;
214}
215
216void __weak __meminit pud_init(void *addr)
217{
218}
219
220p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
221{
222 p4d_t *p4d = p4d_offset(pgd, addr);
223 if (p4d_none(*p4d)) {
224 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
225 if (!p)
226 return NULL;
227 pud_init(p);
228 p4d_populate(&init_mm, p4d, p);
229 }
230 return p4d;
231}
232
233pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
234{
235 pgd_t *pgd = pgd_offset_k(addr);
236 if (pgd_none(*pgd)) {
237 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
238 if (!p)
239 return NULL;
240 pgd_populate(&init_mm, pgd, p);
241 }
242 return pgd;
243}
244
245static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
246 struct vmem_altmap *altmap,
247 struct page *reuse)
248{
249 pgd_t *pgd;
250 p4d_t *p4d;
251 pud_t *pud;
252 pmd_t *pmd;
253 pte_t *pte;
254
255 pgd = vmemmap_pgd_populate(addr, node);
256 if (!pgd)
257 return NULL;
258 p4d = vmemmap_p4d_populate(pgd, addr, node);
259 if (!p4d)
260 return NULL;
261 pud = vmemmap_pud_populate(p4d, addr, node);
262 if (!pud)
263 return NULL;
264 pmd = vmemmap_pmd_populate(pud, addr, node);
265 if (!pmd)
266 return NULL;
267 pte = vmemmap_pte_populate(pmd, addr, node, altmap, reuse);
268 if (!pte)
269 return NULL;
270 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
271
272 return pte;
273}
274
275static int __meminit vmemmap_populate_range(unsigned long start,
276 unsigned long end, int node,
277 struct vmem_altmap *altmap,
278 struct page *reuse)
279{
280 unsigned long addr = start;
281 pte_t *pte;
282
283 for (; addr < end; addr += PAGE_SIZE) {
284 pte = vmemmap_populate_address(addr, node, altmap, reuse);
285 if (!pte)
286 return -ENOMEM;
287 }
288
289 return 0;
290}
291
292int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
293 int node, struct vmem_altmap *altmap)
294{
295 return vmemmap_populate_range(start, end, node, altmap, NULL);
296}
297
298void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
299 unsigned long addr, unsigned long next)
300{
301}
302
303int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
304 unsigned long addr, unsigned long next)
305{
306 return 0;
307}
308
309int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
310 int node, struct vmem_altmap *altmap)
311{
312 unsigned long addr;
313 unsigned long next;
314 pgd_t *pgd;
315 p4d_t *p4d;
316 pud_t *pud;
317 pmd_t *pmd;
318
319 for (addr = start; addr < end; addr = next) {
320 next = pmd_addr_end(addr, end);
321
322 pgd = vmemmap_pgd_populate(addr, node);
323 if (!pgd)
324 return -ENOMEM;
325
326 p4d = vmemmap_p4d_populate(pgd, addr, node);
327 if (!p4d)
328 return -ENOMEM;
329
330 pud = vmemmap_pud_populate(p4d, addr, node);
331 if (!pud)
332 return -ENOMEM;
333
334 pmd = pmd_offset(pud, addr);
335 if (pmd_none(READ_ONCE(*pmd))) {
336 void *p;
337
338 p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
339 if (p) {
340 vmemmap_set_pmd(pmd, p, node, addr, next);
341 continue;
342 } else if (altmap) {
343 /*
344 * No fallback: In any case we care about, the
345 * altmap should be reasonably sized and aligned
346 * such that vmemmap_alloc_block_buf() will always
347 * succeed. For consistency with the PTE case,
348 * return an error here as failure could indicate
349 * a configuration issue with the size of the altmap.
350 */
351 return -ENOMEM;
352 }
353 } else if (vmemmap_check_pmd(pmd, node, addr, next))
354 continue;
355 if (vmemmap_populate_basepages(addr, next, node, altmap))
356 return -ENOMEM;
357 }
358 return 0;
359}
360
361#ifndef vmemmap_populate_compound_pages
362/*
363 * For compound pages bigger than section size (e.g. x86 1G compound
364 * pages with 2M subsection size) fill the rest of sections as tail
365 * pages.
366 *
367 * Note that memremap_pages() resets @nr_range value and will increment
368 * it after each range successful onlining. Thus the value or @nr_range
369 * at section memmap populate corresponds to the in-progress range
370 * being onlined here.
371 */
372static bool __meminit reuse_compound_section(unsigned long start_pfn,
373 struct dev_pagemap *pgmap)
374{
375 unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
376 unsigned long offset = start_pfn -
377 PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
378
379 return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
380}
381
382static pte_t * __meminit compound_section_tail_page(unsigned long addr)
383{
384 pte_t *pte;
385
386 addr -= PAGE_SIZE;
387
388 /*
389 * Assuming sections are populated sequentially, the previous section's
390 * page data can be reused.
391 */
392 pte = pte_offset_kernel(pmd_off_k(addr), addr);
393 if (!pte)
394 return NULL;
395
396 return pte;
397}
398
399static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
400 unsigned long start,
401 unsigned long end, int node,
402 struct dev_pagemap *pgmap)
403{
404 unsigned long size, addr;
405 pte_t *pte;
406 int rc;
407
408 if (reuse_compound_section(start_pfn, pgmap)) {
409 pte = compound_section_tail_page(start);
410 if (!pte)
411 return -ENOMEM;
412
413 /*
414 * Reuse the page that was populated in the prior iteration
415 * with just tail struct pages.
416 */
417 return vmemmap_populate_range(start, end, node, NULL,
418 pte_page(ptep_get(pte)));
419 }
420
421 size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
422 for (addr = start; addr < end; addr += size) {
423 unsigned long next, last = addr + size;
424
425 /* Populate the head page vmemmap page */
426 pte = vmemmap_populate_address(addr, node, NULL, NULL);
427 if (!pte)
428 return -ENOMEM;
429
430 /* Populate the tail pages vmemmap page */
431 next = addr + PAGE_SIZE;
432 pte = vmemmap_populate_address(next, node, NULL, NULL);
433 if (!pte)
434 return -ENOMEM;
435
436 /*
437 * Reuse the previous page for the rest of tail pages
438 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
439 */
440 next += PAGE_SIZE;
441 rc = vmemmap_populate_range(next, last, node, NULL,
442 pte_page(ptep_get(pte)));
443 if (rc)
444 return -ENOMEM;
445 }
446
447 return 0;
448}
449
450#endif
451
452struct page * __meminit __populate_section_memmap(unsigned long pfn,
453 unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
454 struct dev_pagemap *pgmap)
455{
456 unsigned long start = (unsigned long) pfn_to_page(pfn);
457 unsigned long end = start + nr_pages * sizeof(struct page);
458 int r;
459
460 if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
461 !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
462 return NULL;
463
464 if (vmemmap_can_optimize(altmap, pgmap))
465 r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
466 else
467 r = vmemmap_populate(start, end, nid, altmap);
468
469 if (r < 0)
470 return NULL;
471
472 return pfn_to_page(pfn);
473}