xref: /openbmc/linux/mm/cma.c (revision 1d24eb2d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Contiguous Memory Allocator
4  *
5  * Copyright (c) 2010-2011 by Samsung Electronics.
6  * Copyright IBM Corporation, 2013
7  * Copyright LG Electronics Inc., 2014
8  * Written by:
9  *	Marek Szyprowski <m.szyprowski@samsung.com>
10  *	Michal Nazarewicz <mina86@mina86.com>
11  *	Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
12  *	Joonsoo Kim <iamjoonsoo.kim@lge.com>
13  */
14 
15 #define pr_fmt(fmt) "cma: " fmt
16 
17 #ifdef CONFIG_CMA_DEBUG
18 #ifndef DEBUG
19 #  define DEBUG
20 #endif
21 #endif
22 #define CREATE_TRACE_POINTS
23 
24 #include <linux/memblock.h>
25 #include <linux/err.h>
26 #include <linux/mm.h>
27 #include <linux/sizes.h>
28 #include <linux/slab.h>
29 #include <linux/log2.h>
30 #include <linux/cma.h>
31 #include <linux/highmem.h>
32 #include <linux/io.h>
33 #include <linux/kmemleak.h>
34 #include <trace/events/cma.h>
35 
36 #include "internal.h"
37 #include "cma.h"
38 
39 struct cma cma_areas[MAX_CMA_AREAS];
40 unsigned cma_area_count;
41 static DEFINE_MUTEX(cma_mutex);
42 
43 phys_addr_t cma_get_base(const struct cma *cma)
44 {
45 	return PFN_PHYS(cma->base_pfn);
46 }
47 
48 unsigned long cma_get_size(const struct cma *cma)
49 {
50 	return cma->count << PAGE_SHIFT;
51 }
52 
53 const char *cma_get_name(const struct cma *cma)
54 {
55 	return cma->name;
56 }
57 
58 static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
59 					     unsigned int align_order)
60 {
61 	if (align_order <= cma->order_per_bit)
62 		return 0;
63 	return (1UL << (align_order - cma->order_per_bit)) - 1;
64 }
65 
66 /*
67  * Find the offset of the base PFN from the specified align_order.
68  * The value returned is represented in order_per_bits.
69  */
70 static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
71 					       unsigned int align_order)
72 {
73 	return (cma->base_pfn & ((1UL << align_order) - 1))
74 		>> cma->order_per_bit;
75 }
76 
77 static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
78 					      unsigned long pages)
79 {
80 	return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
81 }
82 
83 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
84 			     unsigned long count)
85 {
86 	unsigned long bitmap_no, bitmap_count;
87 	unsigned long flags;
88 
89 	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
90 	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
91 
92 	spin_lock_irqsave(&cma->lock, flags);
93 	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
94 	spin_unlock_irqrestore(&cma->lock, flags);
95 }
96 
97 static void __init cma_activate_area(struct cma *cma)
98 {
99 	unsigned long base_pfn = cma->base_pfn, pfn;
100 	struct zone *zone;
101 
102 	cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
103 	if (!cma->bitmap)
104 		goto out_error;
105 
106 	/*
107 	 * alloc_contig_range() requires the pfn range specified to be in the
108 	 * same zone. Simplify by forcing the entire CMA resv range to be in the
109 	 * same zone.
110 	 */
111 	WARN_ON_ONCE(!pfn_valid(base_pfn));
112 	zone = page_zone(pfn_to_page(base_pfn));
113 	for (pfn = base_pfn + 1; pfn < base_pfn + cma->count; pfn++) {
114 		WARN_ON_ONCE(!pfn_valid(pfn));
115 		if (page_zone(pfn_to_page(pfn)) != zone)
116 			goto not_in_zone;
117 	}
118 
119 	for (pfn = base_pfn; pfn < base_pfn + cma->count;
120 	     pfn += pageblock_nr_pages)
121 		init_cma_reserved_pageblock(pfn_to_page(pfn));
122 
123 	spin_lock_init(&cma->lock);
124 
125 #ifdef CONFIG_CMA_DEBUGFS
126 	INIT_HLIST_HEAD(&cma->mem_head);
127 	spin_lock_init(&cma->mem_head_lock);
128 #endif
129 
130 	return;
131 
132 not_in_zone:
133 	bitmap_free(cma->bitmap);
134 out_error:
135 	/* Expose all pages to the buddy, they are useless for CMA. */
136 	if (!cma->reserve_pages_on_error) {
137 		for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
138 			free_reserved_page(pfn_to_page(pfn));
139 	}
140 	totalcma_pages -= cma->count;
141 	cma->count = 0;
142 	pr_err("CMA area %s could not be activated\n", cma->name);
143 	return;
144 }
145 
146 static int __init cma_init_reserved_areas(void)
147 {
148 	int i;
149 
150 	for (i = 0; i < cma_area_count; i++)
151 		cma_activate_area(&cma_areas[i]);
152 
153 	return 0;
154 }
155 core_initcall(cma_init_reserved_areas);
156 
157 void __init cma_reserve_pages_on_error(struct cma *cma)
158 {
159 	cma->reserve_pages_on_error = true;
160 }
161 
162 /**
163  * cma_init_reserved_mem() - create custom contiguous area from reserved memory
164  * @base: Base address of the reserved area
165  * @size: Size of the reserved area (in bytes),
166  * @order_per_bit: Order of pages represented by one bit on bitmap.
167  * @name: The name of the area. If this parameter is NULL, the name of
168  *        the area will be set to "cmaN", where N is a running counter of
169  *        used areas.
170  * @res_cma: Pointer to store the created cma region.
171  *
172  * This function creates custom contiguous area from already reserved memory.
173  */
174 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
175 				 unsigned int order_per_bit,
176 				 const char *name,
177 				 struct cma **res_cma)
178 {
179 	struct cma *cma;
180 
181 	/* Sanity checks */
182 	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
183 		pr_err("Not enough slots for CMA reserved regions!\n");
184 		return -ENOSPC;
185 	}
186 
187 	if (!size || !memblock_is_region_reserved(base, size))
188 		return -EINVAL;
189 
190 	/* alignment should be aligned with order_per_bit */
191 	if (!IS_ALIGNED(CMA_MIN_ALIGNMENT_PAGES, 1 << order_per_bit))
192 		return -EINVAL;
193 
194 	/* ensure minimal alignment required by mm core */
195 	if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
196 		return -EINVAL;
197 
198 	/*
199 	 * Each reserved area must be initialised later, when more kernel
200 	 * subsystems (like slab allocator) are available.
201 	 */
202 	cma = &cma_areas[cma_area_count];
203 
204 	if (name)
205 		snprintf(cma->name, CMA_MAX_NAME, name);
206 	else
207 		snprintf(cma->name, CMA_MAX_NAME,  "cma%d\n", cma_area_count);
208 
209 	cma->base_pfn = PFN_DOWN(base);
210 	cma->count = size >> PAGE_SHIFT;
211 	cma->order_per_bit = order_per_bit;
212 	*res_cma = cma;
213 	cma_area_count++;
214 	totalcma_pages += (size / PAGE_SIZE);
215 
216 	return 0;
217 }
218 
219 /**
220  * cma_declare_contiguous_nid() - reserve custom contiguous area
221  * @base: Base address of the reserved area optional, use 0 for any
222  * @size: Size of the reserved area (in bytes),
223  * @limit: End address of the reserved memory (optional, 0 for any).
224  * @alignment: Alignment for the CMA area, should be power of 2 or zero
225  * @order_per_bit: Order of pages represented by one bit on bitmap.
226  * @fixed: hint about where to place the reserved area
227  * @name: The name of the area. See function cma_init_reserved_mem()
228  * @res_cma: Pointer to store the created cma region.
229  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
230  *
231  * This function reserves memory from early allocator. It should be
232  * called by arch specific code once the early allocator (memblock or bootmem)
233  * has been activated and all other subsystems have already allocated/reserved
234  * memory. This function allows to create custom reserved areas.
235  *
236  * If @fixed is true, reserve contiguous area at exactly @base.  If false,
237  * reserve in range from @base to @limit.
238  */
239 int __init cma_declare_contiguous_nid(phys_addr_t base,
240 			phys_addr_t size, phys_addr_t limit,
241 			phys_addr_t alignment, unsigned int order_per_bit,
242 			bool fixed, const char *name, struct cma **res_cma,
243 			int nid)
244 {
245 	phys_addr_t memblock_end = memblock_end_of_DRAM();
246 	phys_addr_t highmem_start;
247 	int ret = 0;
248 
249 	/*
250 	 * We can't use __pa(high_memory) directly, since high_memory
251 	 * isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
252 	 * complain. Find the boundary by adding one to the last valid
253 	 * address.
254 	 */
255 	highmem_start = __pa(high_memory - 1) + 1;
256 	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
257 		__func__, &size, &base, &limit, &alignment);
258 
259 	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
260 		pr_err("Not enough slots for CMA reserved regions!\n");
261 		return -ENOSPC;
262 	}
263 
264 	if (!size)
265 		return -EINVAL;
266 
267 	if (alignment && !is_power_of_2(alignment))
268 		return -EINVAL;
269 
270 	/* Sanitise input arguments. */
271 	alignment = max_t(phys_addr_t, alignment, CMA_MIN_ALIGNMENT_BYTES);
272 	if (fixed && base & (alignment - 1)) {
273 		ret = -EINVAL;
274 		pr_err("Region at %pa must be aligned to %pa bytes\n",
275 			&base, &alignment);
276 		goto err;
277 	}
278 	base = ALIGN(base, alignment);
279 	size = ALIGN(size, alignment);
280 	limit &= ~(alignment - 1);
281 
282 	if (!base)
283 		fixed = false;
284 
285 	/* size should be aligned with order_per_bit */
286 	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
287 		return -EINVAL;
288 
289 	/*
290 	 * If allocating at a fixed base the request region must not cross the
291 	 * low/high memory boundary.
292 	 */
293 	if (fixed && base < highmem_start && base + size > highmem_start) {
294 		ret = -EINVAL;
295 		pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
296 			&base, &highmem_start);
297 		goto err;
298 	}
299 
300 	/*
301 	 * If the limit is unspecified or above the memblock end, its effective
302 	 * value will be the memblock end. Set it explicitly to simplify further
303 	 * checks.
304 	 */
305 	if (limit == 0 || limit > memblock_end)
306 		limit = memblock_end;
307 
308 	if (base + size > limit) {
309 		ret = -EINVAL;
310 		pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
311 			&size, &base, &limit);
312 		goto err;
313 	}
314 
315 	/* Reserve memory */
316 	if (fixed) {
317 		if (memblock_is_region_reserved(base, size) ||
318 		    memblock_reserve(base, size) < 0) {
319 			ret = -EBUSY;
320 			goto err;
321 		}
322 	} else {
323 		phys_addr_t addr = 0;
324 
325 		/*
326 		 * If there is enough memory, try a bottom-up allocation first.
327 		 * It will place the new cma area close to the start of the node
328 		 * and guarantee that the compaction is moving pages out of the
329 		 * cma area and not into it.
330 		 * Avoid using first 4GB to not interfere with constrained zones
331 		 * like DMA/DMA32.
332 		 */
333 #ifdef CONFIG_PHYS_ADDR_T_64BIT
334 		if (!memblock_bottom_up() && memblock_end >= SZ_4G + size) {
335 			memblock_set_bottom_up(true);
336 			addr = memblock_alloc_range_nid(size, alignment, SZ_4G,
337 							limit, nid, true);
338 			memblock_set_bottom_up(false);
339 		}
340 #endif
341 
342 		/*
343 		 * All pages in the reserved area must come from the same zone.
344 		 * If the requested region crosses the low/high memory boundary,
345 		 * try allocating from high memory first and fall back to low
346 		 * memory in case of failure.
347 		 */
348 		if (!addr && base < highmem_start && limit > highmem_start) {
349 			addr = memblock_alloc_range_nid(size, alignment,
350 					highmem_start, limit, nid, true);
351 			limit = highmem_start;
352 		}
353 
354 		if (!addr) {
355 			addr = memblock_alloc_range_nid(size, alignment, base,
356 					limit, nid, true);
357 			if (!addr) {
358 				ret = -ENOMEM;
359 				goto err;
360 			}
361 		}
362 
363 		/*
364 		 * kmemleak scans/reads tracked objects for pointers to other
365 		 * objects but this address isn't mapped and accessible
366 		 */
367 		kmemleak_ignore_phys(addr);
368 		base = addr;
369 	}
370 
371 	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
372 	if (ret)
373 		goto free_mem;
374 
375 	pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
376 		&base);
377 	return 0;
378 
379 free_mem:
380 	memblock_phys_free(base, size);
381 err:
382 	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
383 	return ret;
384 }
385 
386 #ifdef CONFIG_CMA_DEBUG
387 static void cma_debug_show_areas(struct cma *cma)
388 {
389 	unsigned long next_zero_bit, next_set_bit, nr_zero;
390 	unsigned long start = 0;
391 	unsigned long nr_part, nr_total = 0;
392 	unsigned long nbits = cma_bitmap_maxno(cma);
393 
394 	spin_lock_irq(&cma->lock);
395 	pr_info("number of available pages: ");
396 	for (;;) {
397 		next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start);
398 		if (next_zero_bit >= nbits)
399 			break;
400 		next_set_bit = find_next_bit(cma->bitmap, nbits, next_zero_bit);
401 		nr_zero = next_set_bit - next_zero_bit;
402 		nr_part = nr_zero << cma->order_per_bit;
403 		pr_cont("%s%lu@%lu", nr_total ? "+" : "", nr_part,
404 			next_zero_bit);
405 		nr_total += nr_part;
406 		start = next_zero_bit + nr_zero;
407 	}
408 	pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count);
409 	spin_unlock_irq(&cma->lock);
410 }
411 #else
412 static inline void cma_debug_show_areas(struct cma *cma) { }
413 #endif
414 
415 /**
416  * cma_alloc() - allocate pages from contiguous area
417  * @cma:   Contiguous memory region for which the allocation is performed.
418  * @count: Requested number of pages.
419  * @align: Requested alignment of pages (in PAGE_SIZE order).
420  * @no_warn: Avoid printing message about failed allocation
421  *
422  * This function allocates part of contiguous memory on specific
423  * contiguous memory area.
424  */
425 struct page *cma_alloc(struct cma *cma, unsigned long count,
426 		       unsigned int align, bool no_warn)
427 {
428 	unsigned long mask, offset;
429 	unsigned long pfn = -1;
430 	unsigned long start = 0;
431 	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
432 	unsigned long i;
433 	struct page *page = NULL;
434 	int ret = -ENOMEM;
435 
436 	if (!cma || !cma->count || !cma->bitmap)
437 		goto out;
438 
439 	pr_debug("%s(cma %p, count %lu, align %d)\n", __func__, (void *)cma,
440 		 count, align);
441 
442 	if (!count)
443 		goto out;
444 
445 	trace_cma_alloc_start(cma->name, count, align);
446 
447 	mask = cma_bitmap_aligned_mask(cma, align);
448 	offset = cma_bitmap_aligned_offset(cma, align);
449 	bitmap_maxno = cma_bitmap_maxno(cma);
450 	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
451 
452 	if (bitmap_count > bitmap_maxno)
453 		goto out;
454 
455 	for (;;) {
456 		spin_lock_irq(&cma->lock);
457 		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
458 				bitmap_maxno, start, bitmap_count, mask,
459 				offset);
460 		if (bitmap_no >= bitmap_maxno) {
461 			spin_unlock_irq(&cma->lock);
462 			break;
463 		}
464 		bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
465 		/*
466 		 * It's safe to drop the lock here. We've marked this region for
467 		 * our exclusive use. If the migration fails we will take the
468 		 * lock again and unmark it.
469 		 */
470 		spin_unlock_irq(&cma->lock);
471 
472 		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
473 		mutex_lock(&cma_mutex);
474 		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
475 				     GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0));
476 		mutex_unlock(&cma_mutex);
477 		if (ret == 0) {
478 			page = pfn_to_page(pfn);
479 			break;
480 		}
481 
482 		cma_clear_bitmap(cma, pfn, count);
483 		if (ret != -EBUSY)
484 			break;
485 
486 		pr_debug("%s(): memory range at pfn 0x%lx %p is busy, retrying\n",
487 			 __func__, pfn, pfn_to_page(pfn));
488 
489 		trace_cma_alloc_busy_retry(cma->name, pfn, pfn_to_page(pfn),
490 					   count, align);
491 		/* try again with a bit different memory target */
492 		start = bitmap_no + mask + 1;
493 	}
494 
495 	trace_cma_alloc_finish(cma->name, pfn, page, count, align, ret);
496 
497 	/*
498 	 * CMA can allocate multiple page blocks, which results in different
499 	 * blocks being marked with different tags. Reset the tags to ignore
500 	 * those page blocks.
501 	 */
502 	if (page) {
503 		for (i = 0; i < count; i++)
504 			page_kasan_tag_reset(page + i);
505 	}
506 
507 	if (ret && !no_warn) {
508 		pr_err_ratelimited("%s: %s: alloc failed, req-size: %lu pages, ret: %d\n",
509 				   __func__, cma->name, count, ret);
510 		cma_debug_show_areas(cma);
511 	}
512 
513 	pr_debug("%s(): returned %p\n", __func__, page);
514 out:
515 	if (page) {
516 		count_vm_event(CMA_ALLOC_SUCCESS);
517 		cma_sysfs_account_success_pages(cma, count);
518 	} else {
519 		count_vm_event(CMA_ALLOC_FAIL);
520 		if (cma)
521 			cma_sysfs_account_fail_pages(cma, count);
522 	}
523 
524 	return page;
525 }
526 
527 bool cma_pages_valid(struct cma *cma, const struct page *pages,
528 		     unsigned long count)
529 {
530 	unsigned long pfn;
531 
532 	if (!cma || !pages)
533 		return false;
534 
535 	pfn = page_to_pfn(pages);
536 
537 	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) {
538 		pr_debug("%s(page %p, count %lu)\n", __func__,
539 						(void *)pages, count);
540 		return false;
541 	}
542 
543 	return true;
544 }
545 
546 /**
547  * cma_release() - release allocated pages
548  * @cma:   Contiguous memory region for which the allocation is performed.
549  * @pages: Allocated pages.
550  * @count: Number of allocated pages.
551  *
552  * This function releases memory allocated by cma_alloc().
553  * It returns false when provided pages do not belong to contiguous area and
554  * true otherwise.
555  */
556 bool cma_release(struct cma *cma, const struct page *pages,
557 		 unsigned long count)
558 {
559 	unsigned long pfn;
560 
561 	if (!cma_pages_valid(cma, pages, count))
562 		return false;
563 
564 	pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);
565 
566 	pfn = page_to_pfn(pages);
567 
568 	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
569 
570 	free_contig_range(pfn, count);
571 	cma_clear_bitmap(cma, pfn, count);
572 	trace_cma_release(cma->name, pfn, pages, count);
573 
574 	return true;
575 }
576 
577 int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
578 {
579 	int i;
580 
581 	for (i = 0; i < cma_area_count; i++) {
582 		int ret = it(&cma_areas[i], data);
583 
584 		if (ret)
585 			return ret;
586 	}
587 
588 	return 0;
589 }
590