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 
__earlyonly_bootmem_alloc(int node,unsigned long size,unsigned long align,unsigned long goal)40 static 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 
vmemmap_alloc_block(unsigned long size,int node)49 void * __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 
73 static 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 */
vmemmap_alloc_block_buf(unsigned long size,int node,struct vmem_altmap * altmap)77 void * __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 
vmem_altmap_next_pfn(struct vmem_altmap * altmap)91 static 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 
vmem_altmap_nr_free(struct vmem_altmap * altmap)97 static 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 
altmap_alloc_block_buf(unsigned long size,struct vmem_altmap * altmap)106 static 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 
vmemmap_verify(pte_t * pte,int node,unsigned long start,unsigned long end)133 void __meminit vmemmap_verify(pte_t *pte, int node,
134 				unsigned long start, unsigned long end)
135 {
136 	unsigned long pfn = pte_pfn(*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 
vmemmap_pte_populate(pmd_t * pmd,unsigned long addr,int node,struct vmem_altmap * altmap,struct page * reuse)144 pte_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(*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 
vmemmap_alloc_block_zero(unsigned long size,int node)176 static 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 
vmemmap_pmd_populate(pud_t * pud,unsigned long addr,int node)187 pmd_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 
vmemmap_pud_populate(p4d_t * p4d,unsigned long addr,int node)199 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
200 {
201 	pud_t *pud = pud_offset(p4d, addr);
202 	if (pud_none(*pud)) {
203 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
204 		if (!p)
205 			return NULL;
206 		pud_populate(&init_mm, pud, p);
207 	}
208 	return pud;
209 }
210 
vmemmap_p4d_populate(pgd_t * pgd,unsigned long addr,int node)211 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
212 {
213 	p4d_t *p4d = p4d_offset(pgd, addr);
214 	if (p4d_none(*p4d)) {
215 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
216 		if (!p)
217 			return NULL;
218 		p4d_populate(&init_mm, p4d, p);
219 	}
220 	return p4d;
221 }
222 
vmemmap_pgd_populate(unsigned long addr,int node)223 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
224 {
225 	pgd_t *pgd = pgd_offset_k(addr);
226 	if (pgd_none(*pgd)) {
227 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
228 		if (!p)
229 			return NULL;
230 		pgd_populate(&init_mm, pgd, p);
231 	}
232 	return pgd;
233 }
234 
vmemmap_populate_address(unsigned long addr,int node,struct vmem_altmap * altmap,struct page * reuse)235 static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
236 					      struct vmem_altmap *altmap,
237 					      struct page *reuse)
238 {
239 	pgd_t *pgd;
240 	p4d_t *p4d;
241 	pud_t *pud;
242 	pmd_t *pmd;
243 	pte_t *pte;
244 
245 	pgd = vmemmap_pgd_populate(addr, node);
246 	if (!pgd)
247 		return NULL;
248 	p4d = vmemmap_p4d_populate(pgd, addr, node);
249 	if (!p4d)
250 		return NULL;
251 	pud = vmemmap_pud_populate(p4d, addr, node);
252 	if (!pud)
253 		return NULL;
254 	pmd = vmemmap_pmd_populate(pud, addr, node);
255 	if (!pmd)
256 		return NULL;
257 	pte = vmemmap_pte_populate(pmd, addr, node, altmap, reuse);
258 	if (!pte)
259 		return NULL;
260 	vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
261 
262 	return pte;
263 }
264 
vmemmap_populate_range(unsigned long start,unsigned long end,int node,struct vmem_altmap * altmap,struct page * reuse)265 static int __meminit vmemmap_populate_range(unsigned long start,
266 					    unsigned long end, int node,
267 					    struct vmem_altmap *altmap,
268 					    struct page *reuse)
269 {
270 	unsigned long addr = start;
271 	pte_t *pte;
272 
273 	for (; addr < end; addr += PAGE_SIZE) {
274 		pte = vmemmap_populate_address(addr, node, altmap, reuse);
275 		if (!pte)
276 			return -ENOMEM;
277 	}
278 
279 	return 0;
280 }
281 
vmemmap_populate_basepages(unsigned long start,unsigned long end,int node,struct vmem_altmap * altmap)282 int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
283 					 int node, struct vmem_altmap *altmap)
284 {
285 	return vmemmap_populate_range(start, end, node, altmap, NULL);
286 }
287 
288 /*
289  * For compound pages bigger than section size (e.g. x86 1G compound
290  * pages with 2M subsection size) fill the rest of sections as tail
291  * pages.
292  *
293  * Note that memremap_pages() resets @nr_range value and will increment
294  * it after each range successful onlining. Thus the value or @nr_range
295  * at section memmap populate corresponds to the in-progress range
296  * being onlined here.
297  */
reuse_compound_section(unsigned long start_pfn,struct dev_pagemap * pgmap)298 static bool __meminit reuse_compound_section(unsigned long start_pfn,
299 					     struct dev_pagemap *pgmap)
300 {
301 	unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
302 	unsigned long offset = start_pfn -
303 		PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
304 
305 	return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
306 }
307 
compound_section_tail_page(unsigned long addr)308 static pte_t * __meminit compound_section_tail_page(unsigned long addr)
309 {
310 	pte_t *pte;
311 
312 	addr -= PAGE_SIZE;
313 
314 	/*
315 	 * Assuming sections are populated sequentially, the previous section's
316 	 * page data can be reused.
317 	 */
318 	pte = pte_offset_kernel(pmd_off_k(addr), addr);
319 	if (!pte)
320 		return NULL;
321 
322 	return pte;
323 }
324 
vmemmap_populate_compound_pages(unsigned long start_pfn,unsigned long start,unsigned long end,int node,struct dev_pagemap * pgmap)325 static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
326 						     unsigned long start,
327 						     unsigned long end, int node,
328 						     struct dev_pagemap *pgmap)
329 {
330 	unsigned long size, addr;
331 	pte_t *pte;
332 	int rc;
333 
334 	if (reuse_compound_section(start_pfn, pgmap)) {
335 		pte = compound_section_tail_page(start);
336 		if (!pte)
337 			return -ENOMEM;
338 
339 		/*
340 		 * Reuse the page that was populated in the prior iteration
341 		 * with just tail struct pages.
342 		 */
343 		return vmemmap_populate_range(start, end, node, NULL,
344 					      pte_page(*pte));
345 	}
346 
347 	size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
348 	for (addr = start; addr < end; addr += size) {
349 		unsigned long next, last = addr + size;
350 
351 		/* Populate the head page vmemmap page */
352 		pte = vmemmap_populate_address(addr, node, NULL, NULL);
353 		if (!pte)
354 			return -ENOMEM;
355 
356 		/* Populate the tail pages vmemmap page */
357 		next = addr + PAGE_SIZE;
358 		pte = vmemmap_populate_address(next, node, NULL, NULL);
359 		if (!pte)
360 			return -ENOMEM;
361 
362 		/*
363 		 * Reuse the previous page for the rest of tail pages
364 		 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
365 		 */
366 		next += PAGE_SIZE;
367 		rc = vmemmap_populate_range(next, last, node, NULL,
368 					    pte_page(*pte));
369 		if (rc)
370 			return -ENOMEM;
371 	}
372 
373 	return 0;
374 }
375 
__populate_section_memmap(unsigned long pfn,unsigned long nr_pages,int nid,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)376 struct page * __meminit __populate_section_memmap(unsigned long pfn,
377 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
378 		struct dev_pagemap *pgmap)
379 {
380 	unsigned long start = (unsigned long) pfn_to_page(pfn);
381 	unsigned long end = start + nr_pages * sizeof(struct page);
382 	int r;
383 
384 	if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
385 		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
386 		return NULL;
387 
388 	if (is_power_of_2(sizeof(struct page)) &&
389 	    pgmap && pgmap_vmemmap_nr(pgmap) > 1 && !altmap)
390 		r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
391 	else
392 		r = vmemmap_populate(start, end, nid, altmap);
393 
394 	if (r < 0)
395 		return NULL;
396 
397 	return pfn_to_page(pfn);
398 }
399