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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/bootmem.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 #include <asm/dma.h>
31 #include <asm/pgalloc.h>
32 #include <asm/pgtable.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
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_virt_alloc_try_nid_raw(size, align, goal,
46 BOOTMEM_ALLOC_ACCESSIBLE, node);
47 }
48
49 static void *vmemmap_buf;
50 static void *vmemmap_buf_end;
51
52 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
53 {
54 /* If the main allocator is up use that, fallback to bootmem. */
55 if (slab_is_available()) {
56 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
57 int order = get_order(size);
58 static bool warned;
59 struct page *page;
60
61 page = alloc_pages_node(node, gfp_mask, order);
62 if (page)
63 return page_address(page);
64
65 if (!warned) {
66 warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
67 "vmemmap alloc failure: order:%u", order);
68 warned = true;
69 }
70 return NULL;
71 } else
72 return __earlyonly_bootmem_alloc(node, size, size,
73 __pa(MAX_DMA_ADDRESS));
74 }
75
76 /* need to make sure size is all the same during early stage */
77 static void * __meminit alloc_block_buf(unsigned long size, int node)
78 {
79 void *ptr;
80
81 if (!vmemmap_buf)
82 return vmemmap_alloc_block(size, node);
83
84 /* take the from buf */
85 ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
86 if (ptr + size > vmemmap_buf_end)
87 return vmemmap_alloc_block(size, node);
88
89 vmemmap_buf = ptr + size;
90
91 return ptr;
92 }
93
94 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
95 {
96 return altmap->base_pfn + altmap->reserve + altmap->alloc
97 + altmap->align;
98 }
99
100 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
101 {
102 unsigned long allocated = altmap->alloc + altmap->align;
103
104 if (altmap->free > allocated)
105 return altmap->free - allocated;
106 return 0;
107 }
108
109 /**
110 * vmem_altmap_alloc - allocate pages from the vmem_altmap reservation
111 * @altmap - reserved page pool for the allocation
112 * @nr_pfns - size (in pages) of the allocation
113 *
114 * Allocations are aligned to the size of the request
115 */
116 static unsigned long __meminit vmem_altmap_alloc(struct vmem_altmap *altmap,
117 unsigned long nr_pfns)
118 {
119 unsigned long pfn = vmem_altmap_next_pfn(altmap);
120 unsigned long nr_align;
121
122 nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
123 nr_align = ALIGN(pfn, nr_align) - pfn;
124
125 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
126 return ULONG_MAX;
127 altmap->alloc += nr_pfns;
128 altmap->align += nr_align;
129 return pfn + nr_align;
130 }
131
132 static void * __meminit altmap_alloc_block_buf(unsigned long size,
133 struct vmem_altmap *altmap)
134 {
135 unsigned long pfn, nr_pfns;
136 void *ptr;
137
138 if (size & ~PAGE_MASK) {
139 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
140 __func__, size);
141 return NULL;
142 }
143
144 nr_pfns = size >> PAGE_SHIFT;
145 pfn = vmem_altmap_alloc(altmap, nr_pfns);
146 if (pfn < ULONG_MAX)
147 ptr = __va(__pfn_to_phys(pfn));
148 else
149 ptr = NULL;
150 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
151 __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
152
153 return ptr;
154 }
155
156 /* need to make sure size is all the same during early stage */
157 void * __meminit __vmemmap_alloc_block_buf(unsigned long size, int node,
158 struct vmem_altmap *altmap)
159 {
160 if (altmap)
161 return altmap_alloc_block_buf(size, altmap);
162 return alloc_block_buf(size, node);
163 }
164
165 void __meminit vmemmap_verify(pte_t *pte, int node,
166 unsigned long start, unsigned long end)
167 {
168 unsigned long pfn = pte_pfn(*pte);
169 int actual_node = early_pfn_to_nid(pfn);
170
171 if (node_distance(actual_node, node) > LOCAL_DISTANCE)
172 pr_warn("[%lx-%lx] potential offnode page_structs\n",
173 start, end - 1);
174 }
175
176 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
177 {
178 pte_t *pte = pte_offset_kernel(pmd, addr);
179 if (pte_none(*pte)) {
180 pte_t entry;
181 void *p = alloc_block_buf(PAGE_SIZE, node);
182 if (!p)
183 return NULL;
184 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
185 set_pte_at(&init_mm, addr, pte, entry);
186 }
187 return pte;
188 }
189
190 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
191 {
192 void *p = vmemmap_alloc_block(size, node);
193
194 if (!p)
195 return NULL;
196 memset(p, 0, size);
197
198 return p;
199 }
200
201 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
202 {
203 pmd_t *pmd = pmd_offset(pud, addr);
204 if (pmd_none(*pmd)) {
205 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
206 if (!p)
207 return NULL;
208 pmd_populate_kernel(&init_mm, pmd, p);
209 }
210 return pmd;
211 }
212
213 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
214 {
215 pud_t *pud = pud_offset(p4d, addr);
216 if (pud_none(*pud)) {
217 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
218 if (!p)
219 return NULL;
220 pud_populate(&init_mm, pud, p);
221 }
222 return pud;
223 }
224
225 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
226 {
227 p4d_t *p4d = p4d_offset(pgd, addr);
228 if (p4d_none(*p4d)) {
229 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
230 if (!p)
231 return NULL;
232 p4d_populate(&init_mm, p4d, p);
233 }
234 return p4d;
235 }
236
237 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
238 {
239 pgd_t *pgd = pgd_offset_k(addr);
240 if (pgd_none(*pgd)) {
241 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
242 if (!p)
243 return NULL;
244 pgd_populate(&init_mm, pgd, p);
245 }
246 return pgd;
247 }
248
249 int __meminit vmemmap_populate_basepages(unsigned long start,
250 unsigned long end, int node)
251 {
252 unsigned long addr = start;
253 pgd_t *pgd;
254 p4d_t *p4d;
255 pud_t *pud;
256 pmd_t *pmd;
257 pte_t *pte;
258
259 for (; addr < end; addr += PAGE_SIZE) {
260 pgd = vmemmap_pgd_populate(addr, node);
261 if (!pgd)
262 return -ENOMEM;
263 p4d = vmemmap_p4d_populate(pgd, addr, node);
264 if (!p4d)
265 return -ENOMEM;
266 pud = vmemmap_pud_populate(p4d, addr, node);
267 if (!pud)
268 return -ENOMEM;
269 pmd = vmemmap_pmd_populate(pud, addr, node);
270 if (!pmd)
271 return -ENOMEM;
272 pte = vmemmap_pte_populate(pmd, addr, node);
273 if (!pte)
274 return -ENOMEM;
275 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
276 }
277
278 return 0;
279 }
280
281 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
282 {
283 unsigned long start;
284 unsigned long end;
285 struct page *map;
286
287 map = pfn_to_page(pnum * PAGES_PER_SECTION);
288 start = (unsigned long)map;
289 end = (unsigned long)(map + PAGES_PER_SECTION);
290
291 if (vmemmap_populate(start, end, nid))
292 return NULL;
293
294 return map;
295 }
296
297 void __init sparse_mem_maps_populate_node(struct page **map_map,
298 unsigned long pnum_begin,
299 unsigned long pnum_end,
300 unsigned long map_count, int nodeid)
301 {
302 unsigned long pnum;
303 unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
304 void *vmemmap_buf_start;
305
306 size = ALIGN(size, PMD_SIZE);
307 vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
308 PMD_SIZE, __pa(MAX_DMA_ADDRESS));
309
310 if (vmemmap_buf_start) {
311 vmemmap_buf = vmemmap_buf_start;
312 vmemmap_buf_end = vmemmap_buf_start + size * map_count;
313 }
314
315 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
316 struct mem_section *ms;
317
318 if (!present_section_nr(pnum))
319 continue;
320
321 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
322 if (map_map[pnum])
323 continue;
324 ms = __nr_to_section(pnum);
325 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
326 __func__);
327 ms->section_mem_map = 0;
328 }
329
330 if (vmemmap_buf_start) {
331 /* need to free left buf */
332 memblock_free_early(__pa(vmemmap_buf),
333 vmemmap_buf_end - vmemmap_buf);
334 vmemmap_buf = NULL;
335 vmemmap_buf_end = NULL;
336 }
337 }