xref: /openbmc/linux/mm/sparse.c (revision 0b46b4ac)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * sparse memory mappings.
4  */
5 #include <linux/mm.h>
6 #include <linux/slab.h>
7 #include <linux/mmzone.h>
8 #include <linux/memblock.h>
9 #include <linux/compiler.h>
10 #include <linux/highmem.h>
11 #include <linux/export.h>
12 #include <linux/spinlock.h>
13 #include <linux/vmalloc.h>
14 #include <linux/swap.h>
15 #include <linux/swapops.h>
16 #include <linux/bootmem_info.h>
17 
18 #include "internal.h"
19 #include <asm/dma.h>
20 
21 /*
22  * Permanent SPARSEMEM data:
23  *
24  * 1) mem_section	- memory sections, mem_map's for valid memory
25  */
26 #ifdef CONFIG_SPARSEMEM_EXTREME
27 struct mem_section **mem_section;
28 #else
29 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
30 	____cacheline_internodealigned_in_smp;
31 #endif
32 EXPORT_SYMBOL(mem_section);
33 
34 #ifdef NODE_NOT_IN_PAGE_FLAGS
35 /*
36  * If we did not store the node number in the page then we have to
37  * do a lookup in the section_to_node_table in order to find which
38  * node the page belongs to.
39  */
40 #if MAX_NUMNODES <= 256
41 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
42 #else
43 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
44 #endif
45 
page_to_nid(const struct page * page)46 int page_to_nid(const struct page *page)
47 {
48 	return section_to_node_table[page_to_section(page)];
49 }
50 EXPORT_SYMBOL(page_to_nid);
51 
set_section_nid(unsigned long section_nr,int nid)52 static void set_section_nid(unsigned long section_nr, int nid)
53 {
54 	section_to_node_table[section_nr] = nid;
55 }
56 #else /* !NODE_NOT_IN_PAGE_FLAGS */
set_section_nid(unsigned long section_nr,int nid)57 static inline void set_section_nid(unsigned long section_nr, int nid)
58 {
59 }
60 #endif
61 
62 #ifdef CONFIG_SPARSEMEM_EXTREME
sparse_index_alloc(int nid)63 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
64 {
65 	struct mem_section *section = NULL;
66 	unsigned long array_size = SECTIONS_PER_ROOT *
67 				   sizeof(struct mem_section);
68 
69 	if (slab_is_available()) {
70 		section = kzalloc_node(array_size, GFP_KERNEL, nid);
71 	} else {
72 		section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
73 					      nid);
74 		if (!section)
75 			panic("%s: Failed to allocate %lu bytes nid=%d\n",
76 			      __func__, array_size, nid);
77 	}
78 
79 	return section;
80 }
81 
sparse_index_init(unsigned long section_nr,int nid)82 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
83 {
84 	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
85 	struct mem_section *section;
86 
87 	/*
88 	 * An existing section is possible in the sub-section hotplug
89 	 * case. First hot-add instantiates, follow-on hot-add reuses
90 	 * the existing section.
91 	 *
92 	 * The mem_hotplug_lock resolves the apparent race below.
93 	 */
94 	if (mem_section[root])
95 		return 0;
96 
97 	section = sparse_index_alloc(nid);
98 	if (!section)
99 		return -ENOMEM;
100 
101 	mem_section[root] = section;
102 
103 	return 0;
104 }
105 #else /* !SPARSEMEM_EXTREME */
sparse_index_init(unsigned long section_nr,int nid)106 static inline int sparse_index_init(unsigned long section_nr, int nid)
107 {
108 	return 0;
109 }
110 #endif
111 
112 /*
113  * During early boot, before section_mem_map is used for an actual
114  * mem_map, we use section_mem_map to store the section's NUMA
115  * node.  This keeps us from having to use another data structure.  The
116  * node information is cleared just before we store the real mem_map.
117  */
sparse_encode_early_nid(int nid)118 static inline unsigned long sparse_encode_early_nid(int nid)
119 {
120 	return ((unsigned long)nid << SECTION_NID_SHIFT);
121 }
122 
sparse_early_nid(struct mem_section * section)123 static inline int sparse_early_nid(struct mem_section *section)
124 {
125 	return (section->section_mem_map >> SECTION_NID_SHIFT);
126 }
127 
128 /* Validate the physical addressing limitations of the model */
mminit_validate_memmodel_limits(unsigned long * start_pfn,unsigned long * end_pfn)129 static void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
130 						unsigned long *end_pfn)
131 {
132 	unsigned long max_sparsemem_pfn = (PHYSMEM_END + 1) >> PAGE_SHIFT;
133 
134 	/*
135 	 * Sanity checks - do not allow an architecture to pass
136 	 * in larger pfns than the maximum scope of sparsemem:
137 	 */
138 	if (*start_pfn > max_sparsemem_pfn) {
139 		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
140 			"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
141 			*start_pfn, *end_pfn, max_sparsemem_pfn);
142 		WARN_ON_ONCE(1);
143 		*start_pfn = max_sparsemem_pfn;
144 		*end_pfn = max_sparsemem_pfn;
145 	} else if (*end_pfn > max_sparsemem_pfn) {
146 		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
147 			"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
148 			*start_pfn, *end_pfn, max_sparsemem_pfn);
149 		WARN_ON_ONCE(1);
150 		*end_pfn = max_sparsemem_pfn;
151 	}
152 }
153 
154 /*
155  * There are a number of times that we loop over NR_MEM_SECTIONS,
156  * looking for section_present() on each.  But, when we have very
157  * large physical address spaces, NR_MEM_SECTIONS can also be
158  * very large which makes the loops quite long.
159  *
160  * Keeping track of this gives us an easy way to break out of
161  * those loops early.
162  */
163 unsigned long __highest_present_section_nr;
__section_mark_present(struct mem_section * ms,unsigned long section_nr)164 static void __section_mark_present(struct mem_section *ms,
165 		unsigned long section_nr)
166 {
167 	if (section_nr > __highest_present_section_nr)
168 		__highest_present_section_nr = section_nr;
169 
170 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
171 }
172 
173 #define for_each_present_section_nr(start, section_nr)		\
174 	for (section_nr = next_present_section_nr(start-1);	\
175 	     section_nr != -1;								\
176 	     section_nr = next_present_section_nr(section_nr))
177 
first_present_section_nr(void)178 static inline unsigned long first_present_section_nr(void)
179 {
180 	return next_present_section_nr(-1);
181 }
182 
183 #ifdef CONFIG_SPARSEMEM_VMEMMAP
subsection_mask_set(unsigned long * map,unsigned long pfn,unsigned long nr_pages)184 static void subsection_mask_set(unsigned long *map, unsigned long pfn,
185 		unsigned long nr_pages)
186 {
187 	int idx = subsection_map_index(pfn);
188 	int end = subsection_map_index(pfn + nr_pages - 1);
189 
190 	bitmap_set(map, idx, end - idx + 1);
191 }
192 
subsection_map_init(unsigned long pfn,unsigned long nr_pages)193 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
194 {
195 	int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
196 	unsigned long nr, start_sec = pfn_to_section_nr(pfn);
197 
198 	if (!nr_pages)
199 		return;
200 
201 	for (nr = start_sec; nr <= end_sec; nr++) {
202 		struct mem_section *ms;
203 		unsigned long pfns;
204 
205 		pfns = min(nr_pages, PAGES_PER_SECTION
206 				- (pfn & ~PAGE_SECTION_MASK));
207 		ms = __nr_to_section(nr);
208 		subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
209 
210 		pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
211 				pfns, subsection_map_index(pfn),
212 				subsection_map_index(pfn + pfns - 1));
213 
214 		pfn += pfns;
215 		nr_pages -= pfns;
216 	}
217 }
218 #else
subsection_map_init(unsigned long pfn,unsigned long nr_pages)219 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
220 {
221 }
222 #endif
223 
224 /* Record a memory area against a node. */
memory_present(int nid,unsigned long start,unsigned long end)225 static void __init memory_present(int nid, unsigned long start, unsigned long end)
226 {
227 	unsigned long pfn;
228 
229 #ifdef CONFIG_SPARSEMEM_EXTREME
230 	if (unlikely(!mem_section)) {
231 		unsigned long size, align;
232 
233 		size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
234 		align = 1 << (INTERNODE_CACHE_SHIFT);
235 		mem_section = memblock_alloc(size, align);
236 		if (!mem_section)
237 			panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
238 			      __func__, size, align);
239 	}
240 #endif
241 
242 	start &= PAGE_SECTION_MASK;
243 	mminit_validate_memmodel_limits(&start, &end);
244 	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
245 		unsigned long section = pfn_to_section_nr(pfn);
246 		struct mem_section *ms;
247 
248 		sparse_index_init(section, nid);
249 		set_section_nid(section, nid);
250 
251 		ms = __nr_to_section(section);
252 		if (!ms->section_mem_map) {
253 			ms->section_mem_map = sparse_encode_early_nid(nid) |
254 							SECTION_IS_ONLINE;
255 			__section_mark_present(ms, section);
256 		}
257 	}
258 }
259 
260 /*
261  * Mark all memblocks as present using memory_present().
262  * This is a convenience function that is useful to mark all of the systems
263  * memory as present during initialization.
264  */
memblocks_present(void)265 static void __init memblocks_present(void)
266 {
267 	unsigned long start, end;
268 	int i, nid;
269 
270 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
271 		memory_present(nid, start, end);
272 }
273 
274 /*
275  * Subtle, we encode the real pfn into the mem_map such that
276  * the identity pfn - section_mem_map will return the actual
277  * physical page frame number.
278  */
sparse_encode_mem_map(struct page * mem_map,unsigned long pnum)279 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
280 {
281 	unsigned long coded_mem_map =
282 		(unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
283 	BUILD_BUG_ON(SECTION_MAP_LAST_BIT > PFN_SECTION_SHIFT);
284 	BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
285 	return coded_mem_map;
286 }
287 
288 #ifdef CONFIG_MEMORY_HOTPLUG
289 /*
290  * Decode mem_map from the coded memmap
291  */
sparse_decode_mem_map(unsigned long coded_mem_map,unsigned long pnum)292 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
293 {
294 	/* mask off the extra low bits of information */
295 	coded_mem_map &= SECTION_MAP_MASK;
296 	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
297 }
298 #endif /* CONFIG_MEMORY_HOTPLUG */
299 
sparse_init_one_section(struct mem_section * ms,unsigned long pnum,struct page * mem_map,struct mem_section_usage * usage,unsigned long flags)300 static void __meminit sparse_init_one_section(struct mem_section *ms,
301 		unsigned long pnum, struct page *mem_map,
302 		struct mem_section_usage *usage, unsigned long flags)
303 {
304 	ms->section_mem_map &= ~SECTION_MAP_MASK;
305 	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
306 		| SECTION_HAS_MEM_MAP | flags;
307 	ms->usage = usage;
308 }
309 
usemap_size(void)310 static unsigned long usemap_size(void)
311 {
312 	return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
313 }
314 
mem_section_usage_size(void)315 size_t mem_section_usage_size(void)
316 {
317 	return sizeof(struct mem_section_usage) + usemap_size();
318 }
319 
320 #ifdef CONFIG_MEMORY_HOTREMOVE
pgdat_to_phys(struct pglist_data * pgdat)321 static inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat)
322 {
323 #ifndef CONFIG_NUMA
324 	VM_BUG_ON(pgdat != &contig_page_data);
325 	return __pa_symbol(&contig_page_data);
326 #else
327 	return __pa(pgdat);
328 #endif
329 }
330 
331 static struct mem_section_usage * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data * pgdat,unsigned long size)332 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
333 					 unsigned long size)
334 {
335 	struct mem_section_usage *usage;
336 	unsigned long goal, limit;
337 	int nid;
338 	/*
339 	 * A page may contain usemaps for other sections preventing the
340 	 * page being freed and making a section unremovable while
341 	 * other sections referencing the usemap remain active. Similarly,
342 	 * a pgdat can prevent a section being removed. If section A
343 	 * contains a pgdat and section B contains the usemap, both
344 	 * sections become inter-dependent. This allocates usemaps
345 	 * from the same section as the pgdat where possible to avoid
346 	 * this problem.
347 	 */
348 	goal = pgdat_to_phys(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
349 	limit = goal + (1UL << PA_SECTION_SHIFT);
350 	nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
351 again:
352 	usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
353 	if (!usage && limit) {
354 		limit = 0;
355 		goto again;
356 	}
357 	return usage;
358 }
359 
check_usemap_section_nr(int nid,struct mem_section_usage * usage)360 static void __init check_usemap_section_nr(int nid,
361 		struct mem_section_usage *usage)
362 {
363 	unsigned long usemap_snr, pgdat_snr;
364 	static unsigned long old_usemap_snr;
365 	static unsigned long old_pgdat_snr;
366 	struct pglist_data *pgdat = NODE_DATA(nid);
367 	int usemap_nid;
368 
369 	/* First call */
370 	if (!old_usemap_snr) {
371 		old_usemap_snr = NR_MEM_SECTIONS;
372 		old_pgdat_snr = NR_MEM_SECTIONS;
373 	}
374 
375 	usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
376 	pgdat_snr = pfn_to_section_nr(pgdat_to_phys(pgdat) >> PAGE_SHIFT);
377 	if (usemap_snr == pgdat_snr)
378 		return;
379 
380 	if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
381 		/* skip redundant message */
382 		return;
383 
384 	old_usemap_snr = usemap_snr;
385 	old_pgdat_snr = pgdat_snr;
386 
387 	usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
388 	if (usemap_nid != nid) {
389 		pr_info("node %d must be removed before remove section %ld\n",
390 			nid, usemap_snr);
391 		return;
392 	}
393 	/*
394 	 * There is a circular dependency.
395 	 * Some platforms allow un-removable section because they will just
396 	 * gather other removable sections for dynamic partitioning.
397 	 * Just notify un-removable section's number here.
398 	 */
399 	pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
400 		usemap_snr, pgdat_snr, nid);
401 }
402 #else
403 static struct mem_section_usage * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data * pgdat,unsigned long size)404 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
405 					 unsigned long size)
406 {
407 	return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
408 }
409 
check_usemap_section_nr(int nid,struct mem_section_usage * usage)410 static void __init check_usemap_section_nr(int nid,
411 		struct mem_section_usage *usage)
412 {
413 }
414 #endif /* CONFIG_MEMORY_HOTREMOVE */
415 
416 #ifdef CONFIG_SPARSEMEM_VMEMMAP
section_map_size(void)417 static unsigned long __init section_map_size(void)
418 {
419 	return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
420 }
421 
422 #else
section_map_size(void)423 static unsigned long __init section_map_size(void)
424 {
425 	return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
426 }
427 
__populate_section_memmap(unsigned long pfn,unsigned long nr_pages,int nid,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)428 struct page __init *__populate_section_memmap(unsigned long pfn,
429 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
430 		struct dev_pagemap *pgmap)
431 {
432 	unsigned long size = section_map_size();
433 	struct page *map = sparse_buffer_alloc(size);
434 	phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
435 
436 	if (map)
437 		return map;
438 
439 	map = memmap_alloc(size, size, addr, nid, false);
440 	if (!map)
441 		panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
442 		      __func__, size, PAGE_SIZE, nid, &addr);
443 
444 	return map;
445 }
446 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
447 
448 static void *sparsemap_buf __meminitdata;
449 static void *sparsemap_buf_end __meminitdata;
450 
sparse_buffer_free(unsigned long size)451 static inline void __meminit sparse_buffer_free(unsigned long size)
452 {
453 	WARN_ON(!sparsemap_buf || size == 0);
454 	memblock_free(sparsemap_buf, size);
455 }
456 
sparse_buffer_init(unsigned long size,int nid)457 static void __init sparse_buffer_init(unsigned long size, int nid)
458 {
459 	phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
460 	WARN_ON(sparsemap_buf);	/* forgot to call sparse_buffer_fini()? */
461 	/*
462 	 * Pre-allocated buffer is mainly used by __populate_section_memmap
463 	 * and we want it to be properly aligned to the section size - this is
464 	 * especially the case for VMEMMAP which maps memmap to PMDs
465 	 */
466 	sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
467 	sparsemap_buf_end = sparsemap_buf + size;
468 }
469 
sparse_buffer_fini(void)470 static void __init sparse_buffer_fini(void)
471 {
472 	unsigned long size = sparsemap_buf_end - sparsemap_buf;
473 
474 	if (sparsemap_buf && size > 0)
475 		sparse_buffer_free(size);
476 	sparsemap_buf = NULL;
477 }
478 
sparse_buffer_alloc(unsigned long size)479 void * __meminit sparse_buffer_alloc(unsigned long size)
480 {
481 	void *ptr = NULL;
482 
483 	if (sparsemap_buf) {
484 		ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
485 		if (ptr + size > sparsemap_buf_end)
486 			ptr = NULL;
487 		else {
488 			/* Free redundant aligned space */
489 			if ((unsigned long)(ptr - sparsemap_buf) > 0)
490 				sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
491 			sparsemap_buf = ptr + size;
492 		}
493 	}
494 	return ptr;
495 }
496 
vmemmap_populate_print_last(void)497 void __weak __meminit vmemmap_populate_print_last(void)
498 {
499 }
500 
501 /*
502  * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
503  * And number of present sections in this node is map_count.
504  */
sparse_init_nid(int nid,unsigned long pnum_begin,unsigned long pnum_end,unsigned long map_count)505 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
506 				   unsigned long pnum_end,
507 				   unsigned long map_count)
508 {
509 	struct mem_section_usage *usage;
510 	unsigned long pnum;
511 	struct page *map;
512 
513 	usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
514 			mem_section_usage_size() * map_count);
515 	if (!usage) {
516 		pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
517 		goto failed;
518 	}
519 	sparse_buffer_init(map_count * section_map_size(), nid);
520 	for_each_present_section_nr(pnum_begin, pnum) {
521 		unsigned long pfn = section_nr_to_pfn(pnum);
522 
523 		if (pnum >= pnum_end)
524 			break;
525 
526 		map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
527 				nid, NULL, NULL);
528 		if (!map) {
529 			pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
530 			       __func__, nid);
531 			pnum_begin = pnum;
532 			sparse_buffer_fini();
533 			goto failed;
534 		}
535 		check_usemap_section_nr(nid, usage);
536 		sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
537 				SECTION_IS_EARLY);
538 		usage = (void *) usage + mem_section_usage_size();
539 	}
540 	sparse_buffer_fini();
541 	return;
542 failed:
543 	/* We failed to allocate, mark all the following pnums as not present */
544 	for_each_present_section_nr(pnum_begin, pnum) {
545 		struct mem_section *ms;
546 
547 		if (pnum >= pnum_end)
548 			break;
549 		ms = __nr_to_section(pnum);
550 		ms->section_mem_map = 0;
551 	}
552 }
553 
554 /*
555  * Allocate the accumulated non-linear sections, allocate a mem_map
556  * for each and record the physical to section mapping.
557  */
sparse_init(void)558 void __init sparse_init(void)
559 {
560 	unsigned long pnum_end, pnum_begin, map_count = 1;
561 	int nid_begin;
562 
563 	memblocks_present();
564 
565 	pnum_begin = first_present_section_nr();
566 	nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
567 
568 	/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
569 	set_pageblock_order();
570 
571 	for_each_present_section_nr(pnum_begin + 1, pnum_end) {
572 		int nid = sparse_early_nid(__nr_to_section(pnum_end));
573 
574 		if (nid == nid_begin) {
575 			map_count++;
576 			continue;
577 		}
578 		/* Init node with sections in range [pnum_begin, pnum_end) */
579 		sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
580 		nid_begin = nid;
581 		pnum_begin = pnum_end;
582 		map_count = 1;
583 	}
584 	/* cover the last node */
585 	sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
586 	vmemmap_populate_print_last();
587 }
588 
589 #ifdef CONFIG_MEMORY_HOTPLUG
590 
591 /* Mark all memory sections within the pfn range as online */
online_mem_sections(unsigned long start_pfn,unsigned long end_pfn)592 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
593 {
594 	unsigned long pfn;
595 
596 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
597 		unsigned long section_nr = pfn_to_section_nr(pfn);
598 		struct mem_section *ms;
599 
600 		/* onlining code should never touch invalid ranges */
601 		if (WARN_ON(!valid_section_nr(section_nr)))
602 			continue;
603 
604 		ms = __nr_to_section(section_nr);
605 		ms->section_mem_map |= SECTION_IS_ONLINE;
606 	}
607 }
608 
609 /* Mark all memory sections within the pfn range as offline */
offline_mem_sections(unsigned long start_pfn,unsigned long end_pfn)610 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
611 {
612 	unsigned long pfn;
613 
614 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
615 		unsigned long section_nr = pfn_to_section_nr(pfn);
616 		struct mem_section *ms;
617 
618 		/*
619 		 * TODO this needs some double checking. Offlining code makes
620 		 * sure to check pfn_valid but those checks might be just bogus
621 		 */
622 		if (WARN_ON(!valid_section_nr(section_nr)))
623 			continue;
624 
625 		ms = __nr_to_section(section_nr);
626 		ms->section_mem_map &= ~SECTION_IS_ONLINE;
627 	}
628 }
629 
630 #ifdef CONFIG_SPARSEMEM_VMEMMAP
populate_section_memmap(unsigned long pfn,unsigned long nr_pages,int nid,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)631 static struct page * __meminit populate_section_memmap(unsigned long pfn,
632 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
633 		struct dev_pagemap *pgmap)
634 {
635 	return __populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
636 }
637 
depopulate_section_memmap(unsigned long pfn,unsigned long nr_pages,struct vmem_altmap * altmap)638 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
639 		struct vmem_altmap *altmap)
640 {
641 	unsigned long start = (unsigned long) pfn_to_page(pfn);
642 	unsigned long end = start + nr_pages * sizeof(struct page);
643 
644 	vmemmap_free(start, end, altmap);
645 }
free_map_bootmem(struct page * memmap)646 static void free_map_bootmem(struct page *memmap)
647 {
648 	unsigned long start = (unsigned long)memmap;
649 	unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
650 
651 	vmemmap_free(start, end, NULL);
652 }
653 
clear_subsection_map(unsigned long pfn,unsigned long nr_pages)654 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
655 {
656 	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
657 	DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
658 	struct mem_section *ms = __pfn_to_section(pfn);
659 	unsigned long *subsection_map = ms->usage
660 		? &ms->usage->subsection_map[0] : NULL;
661 
662 	subsection_mask_set(map, pfn, nr_pages);
663 	if (subsection_map)
664 		bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
665 
666 	if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
667 				"section already deactivated (%#lx + %ld)\n",
668 				pfn, nr_pages))
669 		return -EINVAL;
670 
671 	bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
672 	return 0;
673 }
674 
is_subsection_map_empty(struct mem_section * ms)675 static bool is_subsection_map_empty(struct mem_section *ms)
676 {
677 	return bitmap_empty(&ms->usage->subsection_map[0],
678 			    SUBSECTIONS_PER_SECTION);
679 }
680 
fill_subsection_map(unsigned long pfn,unsigned long nr_pages)681 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
682 {
683 	struct mem_section *ms = __pfn_to_section(pfn);
684 	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
685 	unsigned long *subsection_map;
686 	int rc = 0;
687 
688 	subsection_mask_set(map, pfn, nr_pages);
689 
690 	subsection_map = &ms->usage->subsection_map[0];
691 
692 	if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
693 		rc = -EINVAL;
694 	else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
695 		rc = -EEXIST;
696 	else
697 		bitmap_or(subsection_map, map, subsection_map,
698 				SUBSECTIONS_PER_SECTION);
699 
700 	return rc;
701 }
702 #else
populate_section_memmap(unsigned long pfn,unsigned long nr_pages,int nid,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)703 static struct page * __meminit populate_section_memmap(unsigned long pfn,
704 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
705 		struct dev_pagemap *pgmap)
706 {
707 	return kvmalloc_node(array_size(sizeof(struct page),
708 					PAGES_PER_SECTION), GFP_KERNEL, nid);
709 }
710 
depopulate_section_memmap(unsigned long pfn,unsigned long nr_pages,struct vmem_altmap * altmap)711 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
712 		struct vmem_altmap *altmap)
713 {
714 	kvfree(pfn_to_page(pfn));
715 }
716 
free_map_bootmem(struct page * memmap)717 static void free_map_bootmem(struct page *memmap)
718 {
719 	unsigned long maps_section_nr, removing_section_nr, i;
720 	unsigned long magic, nr_pages;
721 	struct page *page = virt_to_page(memmap);
722 
723 	nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
724 		>> PAGE_SHIFT;
725 
726 	for (i = 0; i < nr_pages; i++, page++) {
727 		magic = page->index;
728 
729 		BUG_ON(magic == NODE_INFO);
730 
731 		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
732 		removing_section_nr = page_private(page);
733 
734 		/*
735 		 * When this function is called, the removing section is
736 		 * logical offlined state. This means all pages are isolated
737 		 * from page allocator. If removing section's memmap is placed
738 		 * on the same section, it must not be freed.
739 		 * If it is freed, page allocator may allocate it which will
740 		 * be removed physically soon.
741 		 */
742 		if (maps_section_nr != removing_section_nr)
743 			put_page_bootmem(page);
744 	}
745 }
746 
clear_subsection_map(unsigned long pfn,unsigned long nr_pages)747 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
748 {
749 	return 0;
750 }
751 
is_subsection_map_empty(struct mem_section * ms)752 static bool is_subsection_map_empty(struct mem_section *ms)
753 {
754 	return true;
755 }
756 
fill_subsection_map(unsigned long pfn,unsigned long nr_pages)757 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
758 {
759 	return 0;
760 }
761 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
762 
763 /*
764  * To deactivate a memory region, there are 3 cases to handle across
765  * two configurations (SPARSEMEM_VMEMMAP={y,n}):
766  *
767  * 1. deactivation of a partial hot-added section (only possible in
768  *    the SPARSEMEM_VMEMMAP=y case).
769  *      a) section was present at memory init.
770  *      b) section was hot-added post memory init.
771  * 2. deactivation of a complete hot-added section.
772  * 3. deactivation of a complete section from memory init.
773  *
774  * For 1, when subsection_map does not empty we will not be freeing the
775  * usage map, but still need to free the vmemmap range.
776  *
777  * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
778  */
section_deactivate(unsigned long pfn,unsigned long nr_pages,struct vmem_altmap * altmap)779 static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
780 		struct vmem_altmap *altmap)
781 {
782 	struct mem_section *ms = __pfn_to_section(pfn);
783 	bool section_is_early = early_section(ms);
784 	struct page *memmap = NULL;
785 	bool empty;
786 
787 	if (clear_subsection_map(pfn, nr_pages))
788 		return;
789 
790 	empty = is_subsection_map_empty(ms);
791 	if (empty) {
792 		unsigned long section_nr = pfn_to_section_nr(pfn);
793 
794 		/*
795 		 * Mark the section invalid so that valid_section()
796 		 * return false. This prevents code from dereferencing
797 		 * ms->usage array.
798 		 */
799 		ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
800 
801 		/*
802 		 * When removing an early section, the usage map is kept (as the
803 		 * usage maps of other sections fall into the same page). It
804 		 * will be re-used when re-adding the section - which is then no
805 		 * longer an early section. If the usage map is PageReserved, it
806 		 * was allocated during boot.
807 		 */
808 		if (!PageReserved(virt_to_page(ms->usage))) {
809 			kfree_rcu(ms->usage, rcu);
810 			WRITE_ONCE(ms->usage, NULL);
811 		}
812 		memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
813 	}
814 
815 	/*
816 	 * The memmap of early sections is always fully populated. See
817 	 * section_activate() and pfn_valid() .
818 	 */
819 	if (!section_is_early)
820 		depopulate_section_memmap(pfn, nr_pages, altmap);
821 	else if (memmap)
822 		free_map_bootmem(memmap);
823 
824 	if (empty)
825 		ms->section_mem_map = (unsigned long)NULL;
826 }
827 
section_activate(int nid,unsigned long pfn,unsigned long nr_pages,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)828 static struct page * __meminit section_activate(int nid, unsigned long pfn,
829 		unsigned long nr_pages, struct vmem_altmap *altmap,
830 		struct dev_pagemap *pgmap)
831 {
832 	struct mem_section *ms = __pfn_to_section(pfn);
833 	struct mem_section_usage *usage = NULL;
834 	struct page *memmap;
835 	int rc;
836 
837 	if (!ms->usage) {
838 		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
839 		if (!usage)
840 			return ERR_PTR(-ENOMEM);
841 		ms->usage = usage;
842 	}
843 
844 	rc = fill_subsection_map(pfn, nr_pages);
845 	if (rc) {
846 		if (usage)
847 			ms->usage = NULL;
848 		kfree(usage);
849 		return ERR_PTR(rc);
850 	}
851 
852 	/*
853 	 * The early init code does not consider partially populated
854 	 * initial sections, it simply assumes that memory will never be
855 	 * referenced.  If we hot-add memory into such a section then we
856 	 * do not need to populate the memmap and can simply reuse what
857 	 * is already there.
858 	 */
859 	if (nr_pages < PAGES_PER_SECTION && early_section(ms))
860 		return pfn_to_page(pfn);
861 
862 	memmap = populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
863 	if (!memmap) {
864 		section_deactivate(pfn, nr_pages, altmap);
865 		return ERR_PTR(-ENOMEM);
866 	}
867 
868 	return memmap;
869 }
870 
871 /**
872  * sparse_add_section - add a memory section, or populate an existing one
873  * @nid: The node to add section on
874  * @start_pfn: start pfn of the memory range
875  * @nr_pages: number of pfns to add in the section
876  * @altmap: alternate pfns to allocate the memmap backing store
877  * @pgmap: alternate compound page geometry for devmap mappings
878  *
879  * This is only intended for hotplug.
880  *
881  * Note that only VMEMMAP supports sub-section aligned hotplug,
882  * the proper alignment and size are gated by check_pfn_span().
883  *
884  *
885  * Return:
886  * * 0		- On success.
887  * * -EEXIST	- Section has been present.
888  * * -ENOMEM	- Out of memory.
889  */
sparse_add_section(int nid,unsigned long start_pfn,unsigned long nr_pages,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)890 int __meminit sparse_add_section(int nid, unsigned long start_pfn,
891 		unsigned long nr_pages, struct vmem_altmap *altmap,
892 		struct dev_pagemap *pgmap)
893 {
894 	unsigned long section_nr = pfn_to_section_nr(start_pfn);
895 	struct mem_section *ms;
896 	struct page *memmap;
897 	int ret;
898 
899 	ret = sparse_index_init(section_nr, nid);
900 	if (ret < 0)
901 		return ret;
902 
903 	memmap = section_activate(nid, start_pfn, nr_pages, altmap, pgmap);
904 	if (IS_ERR(memmap))
905 		return PTR_ERR(memmap);
906 
907 	/*
908 	 * Poison uninitialized struct pages in order to catch invalid flags
909 	 * combinations.
910 	 */
911 	page_init_poison(memmap, sizeof(struct page) * nr_pages);
912 
913 	ms = __nr_to_section(section_nr);
914 	set_section_nid(section_nr, nid);
915 	__section_mark_present(ms, section_nr);
916 
917 	/* Align memmap to section boundary in the subsection case */
918 	if (section_nr_to_pfn(section_nr) != start_pfn)
919 		memmap = pfn_to_page(section_nr_to_pfn(section_nr));
920 	sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
921 
922 	return 0;
923 }
924 
sparse_remove_section(unsigned long pfn,unsigned long nr_pages,struct vmem_altmap * altmap)925 void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
926 			   struct vmem_altmap *altmap)
927 {
928 	struct mem_section *ms = __pfn_to_section(pfn);
929 
930 	if (WARN_ON_ONCE(!valid_section(ms)))
931 		return;
932 
933 	section_deactivate(pfn, nr_pages, altmap);
934 }
935 #endif /* CONFIG_MEMORY_HOTPLUG */
936