1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * mm/percpu-vm.c - vmalloc area based chunk allocation
4 *
5 * Copyright (C) 2010 SUSE Linux Products GmbH
6 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
7 *
8 * Chunks are mapped into vmalloc areas and populated page by page.
9 * This is the default chunk allocator.
10 */
11
12 static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
13 unsigned int cpu, int page_idx)
14 {
15 /* must not be used on pre-mapped chunk */
16 WARN_ON(chunk->immutable);
17
18 return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
19 }
20
21 /**
22 * pcpu_get_pages - get temp pages array
23 *
24 * Returns pointer to array of pointers to struct page which can be indexed
25 * with pcpu_page_idx(). Note that there is only one array and accesses
26 * should be serialized by pcpu_alloc_mutex.
27 *
28 * RETURNS:
29 * Pointer to temp pages array on success.
30 */
31 static struct page **pcpu_get_pages(void)
32 {
33 static struct page **pages;
34 size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
35
36 lockdep_assert_held(&pcpu_alloc_mutex);
37
38 if (!pages)
39 pages = pcpu_mem_zalloc(pages_size, GFP_KERNEL);
40 return pages;
41 }
42
43 /**
44 * pcpu_free_pages - free pages which were allocated for @chunk
45 * @chunk: chunk pages were allocated for
46 * @pages: array of pages to be freed, indexed by pcpu_page_idx()
47 * @page_start: page index of the first page to be freed
48 * @page_end: page index of the last page to be freed + 1
49 *
50 * Free pages [@page_start and @page_end) in @pages for all units.
51 * The pages were allocated for @chunk.
52 */
53 static void pcpu_free_pages(struct pcpu_chunk *chunk,
54 struct page **pages, int page_start, int page_end)
55 {
56 unsigned int cpu;
57 int i;
58
59 for_each_possible_cpu(cpu) {
60 for (i = page_start; i < page_end; i++) {
61 struct page *page = pages[pcpu_page_idx(cpu, i)];
62
63 if (page)
64 __free_page(page);
65 }
66 }
67 }
68
69 /**
70 * pcpu_alloc_pages - allocates pages for @chunk
71 * @chunk: target chunk
72 * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
73 * @page_start: page index of the first page to be allocated
74 * @page_end: page index of the last page to be allocated + 1
75 * @gfp: allocation flags passed to the underlying allocator
76 *
77 * Allocate pages [@page_start,@page_end) into @pages for all units.
78 * The allocation is for @chunk. Percpu core doesn't care about the
79 * content of @pages and will pass it verbatim to pcpu_map_pages().
80 */
81 static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
82 struct page **pages, int page_start, int page_end,
83 gfp_t gfp)
84 {
85 unsigned int cpu, tcpu;
86 int i;
87
88 gfp |= __GFP_HIGHMEM;
89
90 for_each_possible_cpu(cpu) {
91 for (i = page_start; i < page_end; i++) {
92 struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
93
94 *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
95 if (!*pagep)
96 goto err;
97 }
98 }
99 return 0;
100
101 err:
102 while (--i >= page_start)
103 __free_page(pages[pcpu_page_idx(cpu, i)]);
104
105 for_each_possible_cpu(tcpu) {
106 if (tcpu == cpu)
107 break;
108 for (i = page_start; i < page_end; i++)
109 __free_page(pages[pcpu_page_idx(tcpu, i)]);
110 }
111 return -ENOMEM;
112 }
113
114 /**
115 * pcpu_pre_unmap_flush - flush cache prior to unmapping
116 * @chunk: chunk the regions to be flushed belongs to
117 * @page_start: page index of the first page to be flushed
118 * @page_end: page index of the last page to be flushed + 1
119 *
120 * Pages in [@page_start,@page_end) of @chunk are about to be
121 * unmapped. Flush cache. As each flushing trial can be very
122 * expensive, issue flush on the whole region at once rather than
123 * doing it for each cpu. This could be an overkill but is more
124 * scalable.
125 */
126 static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
127 int page_start, int page_end)
128 {
129 flush_cache_vunmap(
130 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
131 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
132 }
133
134 static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
135 {
136 unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
137 }
138
139 /**
140 * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
141 * @chunk: chunk of interest
142 * @pages: pages array which can be used to pass information to free
143 * @page_start: page index of the first page to unmap
144 * @page_end: page index of the last page to unmap + 1
145 *
146 * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
147 * Corresponding elements in @pages were cleared by the caller and can
148 * be used to carry information to pcpu_free_pages() which will be
149 * called after all unmaps are finished. The caller should call
150 * proper pre/post flush functions.
151 */
152 static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
153 struct page **pages, int page_start, int page_end)
154 {
155 unsigned int cpu;
156 int i;
157
158 for_each_possible_cpu(cpu) {
159 for (i = page_start; i < page_end; i++) {
160 struct page *page;
161
162 page = pcpu_chunk_page(chunk, cpu, i);
163 WARN_ON(!page);
164 pages[pcpu_page_idx(cpu, i)] = page;
165 }
166 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
167 page_end - page_start);
168 }
169 }
170
171 /**
172 * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
173 * @chunk: pcpu_chunk the regions to be flushed belong to
174 * @page_start: page index of the first page to be flushed
175 * @page_end: page index of the last page to be flushed + 1
176 *
177 * Pages [@page_start,@page_end) of @chunk have been unmapped. Flush
178 * TLB for the regions. This can be skipped if the area is to be
179 * returned to vmalloc as vmalloc will handle TLB flushing lazily.
180 *
181 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
182 * for the whole region.
183 */
184 static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
185 int page_start, int page_end)
186 {
187 flush_tlb_kernel_range(
188 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
189 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
190 }
191
192 static int __pcpu_map_pages(unsigned long addr, struct page **pages,
193 int nr_pages)
194 {
195 return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
196 PAGE_KERNEL, pages);
197 }
198
199 /**
200 * pcpu_map_pages - map pages into a pcpu_chunk
201 * @chunk: chunk of interest
202 * @pages: pages array containing pages to be mapped
203 * @page_start: page index of the first page to map
204 * @page_end: page index of the last page to map + 1
205 *
206 * For each cpu, map pages [@page_start,@page_end) into @chunk. The
207 * caller is responsible for calling pcpu_post_map_flush() after all
208 * mappings are complete.
209 *
210 * This function is responsible for setting up whatever is necessary for
211 * reverse lookup (addr -> chunk).
212 */
213 static int pcpu_map_pages(struct pcpu_chunk *chunk,
214 struct page **pages, int page_start, int page_end)
215 {
216 unsigned int cpu, tcpu;
217 int i, err;
218
219 for_each_possible_cpu(cpu) {
220 err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
221 &pages[pcpu_page_idx(cpu, page_start)],
222 page_end - page_start);
223 if (err < 0)
224 goto err;
225
226 for (i = page_start; i < page_end; i++)
227 pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
228 chunk);
229 }
230 return 0;
231 err:
232 for_each_possible_cpu(tcpu) {
233 if (tcpu == cpu)
234 break;
235 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
236 page_end - page_start);
237 }
238 pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
239 return err;
240 }
241
242 /**
243 * pcpu_post_map_flush - flush cache after mapping
244 * @chunk: pcpu_chunk the regions to be flushed belong to
245 * @page_start: page index of the first page to be flushed
246 * @page_end: page index of the last page to be flushed + 1
247 *
248 * Pages [@page_start,@page_end) of @chunk have been mapped. Flush
249 * cache.
250 *
251 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
252 * for the whole region.
253 */
254 static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
255 int page_start, int page_end)
256 {
257 flush_cache_vmap(
258 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
259 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
260 }
261
262 /**
263 * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
264 * @chunk: chunk of interest
265 * @page_start: the start page
266 * @page_end: the end page
267 * @gfp: allocation flags passed to the underlying memory allocator
268 *
269 * For each cpu, populate and map pages [@page_start,@page_end) into
270 * @chunk.
271 *
272 * CONTEXT:
273 * pcpu_alloc_mutex, does GFP_KERNEL allocation.
274 */
275 static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
276 int page_start, int page_end, gfp_t gfp)
277 {
278 struct page **pages;
279
280 pages = pcpu_get_pages();
281 if (!pages)
282 return -ENOMEM;
283
284 if (pcpu_alloc_pages(chunk, pages, page_start, page_end, gfp))
285 return -ENOMEM;
286
287 if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
288 pcpu_free_pages(chunk, pages, page_start, page_end);
289 return -ENOMEM;
290 }
291 pcpu_post_map_flush(chunk, page_start, page_end);
292
293 return 0;
294 }
295
296 /**
297 * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
298 * @chunk: chunk to depopulate
299 * @page_start: the start page
300 * @page_end: the end page
301 *
302 * For each cpu, depopulate and unmap pages [@page_start,@page_end)
303 * from @chunk.
304 *
305 * CONTEXT:
306 * pcpu_alloc_mutex.
307 */
308 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
309 int page_start, int page_end)
310 {
311 struct page **pages;
312
313 /*
314 * If control reaches here, there must have been at least one
315 * successful population attempt so the temp pages array must
316 * be available now.
317 */
318 pages = pcpu_get_pages();
319 BUG_ON(!pages);
320
321 /* unmap and free */
322 pcpu_pre_unmap_flush(chunk, page_start, page_end);
323
324 pcpu_unmap_pages(chunk, pages, page_start, page_end);
325
326 /* no need to flush tlb, vmalloc will handle it lazily */
327
328 pcpu_free_pages(chunk, pages, page_start, page_end);
329 }
330
331 static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
332 {
333 struct pcpu_chunk *chunk;
334 struct vm_struct **vms;
335
336 chunk = pcpu_alloc_chunk(gfp);
337 if (!chunk)
338 return NULL;
339
340 vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
341 pcpu_nr_groups, pcpu_atom_size);
342 if (!vms) {
343 pcpu_free_chunk(chunk);
344 return NULL;
345 }
346
347 chunk->data = vms;
348 chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
349
350 pcpu_stats_chunk_alloc();
351 trace_percpu_create_chunk(chunk->base_addr);
352
353 return chunk;
354 }
355
356 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
357 {
358 if (!chunk)
359 return;
360
361 pcpu_stats_chunk_dealloc();
362 trace_percpu_destroy_chunk(chunk->base_addr);
363
364 if (chunk->data)
365 pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
366 pcpu_free_chunk(chunk);
367 }
368
369 static struct page *pcpu_addr_to_page(void *addr)
370 {
371 return vmalloc_to_page(addr);
372 }
373
374 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
375 {
376 /* no extra restriction */
377 return 0;
378 }