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
 27struct mem_section **mem_section;
 28#else
 29struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
 30	____cacheline_internodealigned_in_smp;
 31#endif
 32EXPORT_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
 41static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
 42#else
 43static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
 44#endif
 45
 46int page_to_nid(const struct page *page)
 47{
 48	return section_to_node_table[page_to_section(page)];
 49}
 50EXPORT_SYMBOL(page_to_nid);
 51
 52static 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 */
 57static inline void set_section_nid(unsigned long section_nr, int nid)
 58{
 59}
 60#endif
 61
 62#ifdef CONFIG_SPARSEMEM_EXTREME
 63static 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
 82static 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 */
106static 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 */
118static inline unsigned long sparse_encode_early_nid(int nid)
119{
120	return ((unsigned long)nid << SECTION_NID_SHIFT);
121}
122
123static 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 */
129static void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
130						unsigned long *end_pfn)
131{
132	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-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 */
163unsigned long __highest_present_section_nr;
164static 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
178static inline unsigned long first_present_section_nr(void)
179{
180	return next_present_section_nr(-1);
181}
182
183#ifdef CONFIG_SPARSEMEM_VMEMMAP
184static 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
193void __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
219void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
220{
221}
222#endif
223
224/* Record a memory area against a node. */
225static 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 */
265static 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 */
279static 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 */
292struct 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
300static 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
310static unsigned long usemap_size(void)
311{
312	return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
313}
314
315size_t mem_section_usage_size(void)
316{
317	return sizeof(struct mem_section_usage) + usemap_size();
318}
319
320#ifdef CONFIG_MEMORY_HOTREMOVE
321static 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
 
331static struct mem_section_usage * __init
332sparse_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);
351again:
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
360static 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
403static struct mem_section_usage * __init
404sparse_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
410static 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
417static unsigned long __init section_map_size(void)
418{
419	return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
420}
421
422#else
423static unsigned long __init section_map_size(void)
424{
425	return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
426}
427
428struct 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
448static void *sparsemap_buf __meminitdata;
449static void *sparsemap_buf_end __meminitdata;
450
451static 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
457static 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
470static 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
479void * __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
497void __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 */
505static 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;
542failed:
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 */
558void __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 */
592void 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 */
610void 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
631static 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
638static 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}
646static 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
654static 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
675static 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
681static 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
703static 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
711static 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
717static 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
747static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
748{
749	return 0;
750}
751
752static bool is_subsection_map_empty(struct mem_section *ms)
753{
754	return true;
755}
756
757static 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 */
779static 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
828static 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 */
890int __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
925void 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 */