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}
474