1 /*
2 * Contiguous Memory Allocator
3 *
4 * Copyright (c) 2010-2011 by Samsung Electronics.
5 * Copyright IBM Corporation, 2013
6 * Copyright LG Electronics Inc., 2014
7 * Written by:
8 * Marek Szyprowski <m.szyprowski@samsung.com>
9 * Michal Nazarewicz <mina86@mina86.com>
10 * Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
11 * Joonsoo Kim <iamjoonsoo.kim@lge.com>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License as
15 * published by the Free Software Foundation; either version 2 of the
16 * License or (at your optional) any later version of the license.
17 */
18
19 #define pr_fmt(fmt) "cma: " fmt
20
21 #ifdef CONFIG_CMA_DEBUG
22 #ifndef DEBUG
23 # define DEBUG
24 #endif
25 #endif
26
27 #include <linux/memblock.h>
28 #include <linux/err.h>
29 #include <linux/mm.h>
30 #include <linux/mutex.h>
31 #include <linux/sizes.h>
32 #include <linux/slab.h>
33 #include <linux/log2.h>
34 #include <linux/cma.h>
35 #include <linux/highmem.h>
36 #include <linux/io.h>
37
38 struct cma {
39 unsigned long base_pfn;
40 unsigned long count;
41 unsigned long *bitmap;
42 unsigned int order_per_bit; /* Order of pages represented by one bit */
43 struct mutex lock;
44 };
45
46 static struct cma cma_areas[MAX_CMA_AREAS];
47 static unsigned cma_area_count;
48 static DEFINE_MUTEX(cma_mutex);
49
cma_get_base(const struct cma * cma)50 phys_addr_t cma_get_base(const struct cma *cma)
51 {
52 return PFN_PHYS(cma->base_pfn);
53 }
54
cma_get_size(const struct cma * cma)55 unsigned long cma_get_size(const struct cma *cma)
56 {
57 return cma->count << PAGE_SHIFT;
58 }
59
cma_bitmap_aligned_mask(const struct cma * cma,unsigned int align_order)60 static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
61 unsigned int align_order)
62 {
63 if (align_order <= cma->order_per_bit)
64 return 0;
65 return (1UL << (align_order - cma->order_per_bit)) - 1;
66 }
67
68 /*
69 * Find the offset of the base PFN from the specified align_order.
70 * The value returned is represented in order_per_bits.
71 */
cma_bitmap_aligned_offset(const struct cma * cma,unsigned int align_order)72 static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
73 unsigned int align_order)
74 {
75 return (cma->base_pfn & ((1UL << align_order) - 1))
76 >> cma->order_per_bit;
77 }
78
cma_bitmap_maxno(struct cma * cma)79 static unsigned long cma_bitmap_maxno(struct cma *cma)
80 {
81 return cma->count >> cma->order_per_bit;
82 }
83
cma_bitmap_pages_to_bits(const struct cma * cma,unsigned long pages)84 static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
85 unsigned long pages)
86 {
87 return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
88 }
89
cma_clear_bitmap(struct cma * cma,unsigned long pfn,unsigned int count)90 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
91 unsigned int count)
92 {
93 unsigned long bitmap_no, bitmap_count;
94
95 bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
96 bitmap_count = cma_bitmap_pages_to_bits(cma, count);
97
98 mutex_lock(&cma->lock);
99 bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
100 mutex_unlock(&cma->lock);
101 }
102
cma_activate_area(struct cma * cma)103 static int __init cma_activate_area(struct cma *cma)
104 {
105 int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
106 unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
107 unsigned i = cma->count >> pageblock_order;
108 struct zone *zone;
109
110 cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
111
112 if (!cma->bitmap)
113 return -ENOMEM;
114
115 WARN_ON_ONCE(!pfn_valid(pfn));
116 zone = page_zone(pfn_to_page(pfn));
117
118 do {
119 unsigned j;
120
121 base_pfn = pfn;
122 for (j = pageblock_nr_pages; j; --j, pfn++) {
123 WARN_ON_ONCE(!pfn_valid(pfn));
124 /*
125 * alloc_contig_range requires the pfn range
126 * specified to be in the same zone. Make this
127 * simple by forcing the entire CMA resv range
128 * to be in the same zone.
129 */
130 if (page_zone(pfn_to_page(pfn)) != zone)
131 goto err;
132 }
133 init_cma_reserved_pageblock(pfn_to_page(base_pfn));
134 } while (--i);
135
136 mutex_init(&cma->lock);
137 return 0;
138
139 err:
140 kfree(cma->bitmap);
141 cma->count = 0;
142 return -EINVAL;
143 }
144
cma_init_reserved_areas(void)145 static int __init cma_init_reserved_areas(void)
146 {
147 int i;
148
149 for (i = 0; i < cma_area_count; i++) {
150 int ret = cma_activate_area(&cma_areas[i]);
151
152 if (ret)
153 return ret;
154 }
155
156 return 0;
157 }
158 core_initcall(cma_init_reserved_areas);
159
160 /**
161 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
162 * @base: Base address of the reserved area
163 * @size: Size of the reserved area (in bytes),
164 * @order_per_bit: Order of pages represented by one bit on bitmap.
165 * @res_cma: Pointer to store the created cma region.
166 *
167 * This function creates custom contiguous area from already reserved memory.
168 */
cma_init_reserved_mem(phys_addr_t base,phys_addr_t size,unsigned int order_per_bit,struct cma ** res_cma)169 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
170 unsigned int order_per_bit,
171 struct cma **res_cma)
172 {
173 struct cma *cma;
174 phys_addr_t alignment;
175
176 /* Sanity checks */
177 if (cma_area_count == ARRAY_SIZE(cma_areas)) {
178 pr_err("Not enough slots for CMA reserved regions!\n");
179 return -ENOSPC;
180 }
181
182 if (!size || !memblock_is_region_reserved(base, size))
183 return -EINVAL;
184
185 /* ensure minimal alignment requied by mm core */
186 alignment = PAGE_SIZE <<
187 max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
188
189 /* alignment should be aligned with order_per_bit */
190 if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
191 return -EINVAL;
192
193 if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
194 return -EINVAL;
195
196 /*
197 * Each reserved area must be initialised later, when more kernel
198 * subsystems (like slab allocator) are available.
199 */
200 cma = &cma_areas[cma_area_count];
201 cma->base_pfn = PFN_DOWN(base);
202 cma->count = size >> PAGE_SHIFT;
203 cma->order_per_bit = order_per_bit;
204 *res_cma = cma;
205 cma_area_count++;
206 totalcma_pages += (size / PAGE_SIZE);
207
208 return 0;
209 }
210
211 /**
212 * cma_declare_contiguous() - reserve custom contiguous area
213 * @base: Base address of the reserved area optional, use 0 for any
214 * @size: Size of the reserved area (in bytes),
215 * @limit: End address of the reserved memory (optional, 0 for any).
216 * @alignment: Alignment for the CMA area, should be power of 2 or zero
217 * @order_per_bit: Order of pages represented by one bit on bitmap.
218 * @fixed: hint about where to place the reserved area
219 * @res_cma: Pointer to store the created cma region.
220 *
221 * This function reserves memory from early allocator. It should be
222 * called by arch specific code once the early allocator (memblock or bootmem)
223 * has been activated and all other subsystems have already allocated/reserved
224 * memory. This function allows to create custom reserved areas.
225 *
226 * If @fixed is true, reserve contiguous area at exactly @base. If false,
227 * reserve in range from @base to @limit.
228 */
cma_declare_contiguous(phys_addr_t base,phys_addr_t size,phys_addr_t limit,phys_addr_t alignment,unsigned int order_per_bit,bool fixed,struct cma ** res_cma)229 int __init cma_declare_contiguous(phys_addr_t base,
230 phys_addr_t size, phys_addr_t limit,
231 phys_addr_t alignment, unsigned int order_per_bit,
232 bool fixed, struct cma **res_cma)
233 {
234 phys_addr_t memblock_end = memblock_end_of_DRAM();
235 phys_addr_t highmem_start;
236 int ret = 0;
237
238 #ifdef CONFIG_X86
239 /*
240 * high_memory isn't direct mapped memory so retrieving its physical
241 * address isn't appropriate. But it would be useful to check the
242 * physical address of the highmem boundary so it's justfiable to get
243 * the physical address from it. On x86 there is a validation check for
244 * this case, so the following workaround is needed to avoid it.
245 */
246 highmem_start = __pa_nodebug(high_memory);
247 #else
248 highmem_start = __pa(high_memory);
249 #endif
250 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
251 __func__, &size, &base, &limit, &alignment);
252
253 if (cma_area_count == ARRAY_SIZE(cma_areas)) {
254 pr_err("Not enough slots for CMA reserved regions!\n");
255 return -ENOSPC;
256 }
257
258 if (!size)
259 return -EINVAL;
260
261 if (alignment && !is_power_of_2(alignment))
262 return -EINVAL;
263
264 /*
265 * Sanitise input arguments.
266 * Pages both ends in CMA area could be merged into adjacent unmovable
267 * migratetype page by page allocator's buddy algorithm. In the case,
268 * you couldn't get a contiguous memory, which is not what we want.
269 */
270 alignment = max(alignment, (phys_addr_t)PAGE_SIZE <<
271 max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
272 base = ALIGN(base, alignment);
273 size = ALIGN(size, alignment);
274 limit &= ~(alignment - 1);
275
276 if (!base)
277 fixed = false;
278
279 /* size should be aligned with order_per_bit */
280 if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
281 return -EINVAL;
282
283 /*
284 * If allocating at a fixed base the request region must not cross the
285 * low/high memory boundary.
286 */
287 if (fixed && base < highmem_start && base + size > highmem_start) {
288 ret = -EINVAL;
289 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
290 &base, &highmem_start);
291 goto err;
292 }
293
294 /*
295 * If the limit is unspecified or above the memblock end, its effective
296 * value will be the memblock end. Set it explicitly to simplify further
297 * checks.
298 */
299 if (limit == 0 || limit > memblock_end)
300 limit = memblock_end;
301
302 /* Reserve memory */
303 if (fixed) {
304 if (memblock_is_region_reserved(base, size) ||
305 memblock_reserve(base, size) < 0) {
306 ret = -EBUSY;
307 goto err;
308 }
309 } else {
310 phys_addr_t addr = 0;
311
312 /*
313 * All pages in the reserved area must come from the same zone.
314 * If the requested region crosses the low/high memory boundary,
315 * try allocating from high memory first and fall back to low
316 * memory in case of failure.
317 */
318 if (base < highmem_start && limit > highmem_start) {
319 addr = memblock_alloc_range(size, alignment,
320 highmem_start, limit);
321 limit = highmem_start;
322 }
323
324 if (!addr) {
325 addr = memblock_alloc_range(size, alignment, base,
326 limit);
327 if (!addr) {
328 ret = -ENOMEM;
329 goto err;
330 }
331 }
332
333 /*
334 * kmemleak scans/reads tracked objects for pointers to other
335 * objects but this address isn't mapped and accessible
336 */
337 kmemleak_ignore(phys_to_virt(addr));
338 base = addr;
339 }
340
341 ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
342 if (ret)
343 goto err;
344
345 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
346 &base);
347 return 0;
348
349 err:
350 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
351 return ret;
352 }
353
354 /**
355 * cma_alloc() - allocate pages from contiguous area
356 * @cma: Contiguous memory region for which the allocation is performed.
357 * @count: Requested number of pages.
358 * @align: Requested alignment of pages (in PAGE_SIZE order).
359 *
360 * This function allocates part of contiguous memory on specific
361 * contiguous memory area.
362 */
cma_alloc(struct cma * cma,size_t count,unsigned int align)363 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align)
364 {
365 unsigned long mask, offset, pfn, start = 0;
366 unsigned long bitmap_maxno, bitmap_no, bitmap_count;
367 struct page *page = NULL;
368 int ret;
369
370 if (!cma || !cma->count)
371 return NULL;
372
373 pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
374 count, align);
375
376 if (!count)
377 return NULL;
378
379 mask = cma_bitmap_aligned_mask(cma, align);
380 offset = cma_bitmap_aligned_offset(cma, align);
381 bitmap_maxno = cma_bitmap_maxno(cma);
382 bitmap_count = cma_bitmap_pages_to_bits(cma, count);
383
384 for (;;) {
385 mutex_lock(&cma->lock);
386 bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
387 bitmap_maxno, start, bitmap_count, mask,
388 offset);
389 if (bitmap_no >= bitmap_maxno) {
390 mutex_unlock(&cma->lock);
391 break;
392 }
393 bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
394 /*
395 * It's safe to drop the lock here. We've marked this region for
396 * our exclusive use. If the migration fails we will take the
397 * lock again and unmark it.
398 */
399 mutex_unlock(&cma->lock);
400
401 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
402 mutex_lock(&cma_mutex);
403 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
404 mutex_unlock(&cma_mutex);
405 if (ret == 0) {
406 page = pfn_to_page(pfn);
407 break;
408 }
409
410 cma_clear_bitmap(cma, pfn, count);
411 if (ret != -EBUSY)
412 break;
413
414 pr_debug("%s(): memory range at %p is busy, retrying\n",
415 __func__, pfn_to_page(pfn));
416 /* try again with a bit different memory target */
417 start = bitmap_no + mask + 1;
418 }
419
420 pr_debug("%s(): returned %p\n", __func__, page);
421 return page;
422 }
423
424 /**
425 * cma_release() - release allocated pages
426 * @cma: Contiguous memory region for which the allocation is performed.
427 * @pages: Allocated pages.
428 * @count: Number of allocated pages.
429 *
430 * This function releases memory allocated by alloc_cma().
431 * It returns false when provided pages do not belong to contiguous area and
432 * true otherwise.
433 */
cma_release(struct cma * cma,const struct page * pages,unsigned int count)434 bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
435 {
436 unsigned long pfn;
437
438 if (!cma || !pages)
439 return false;
440
441 pr_debug("%s(page %p)\n", __func__, (void *)pages);
442
443 pfn = page_to_pfn(pages);
444
445 if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
446 return false;
447
448 VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
449
450 free_contig_range(pfn, count);
451 cma_clear_bitmap(cma, pfn, count);
452
453 return true;
454 }
455