2 * Contiguous Memory Allocator
4 * Copyright (c) 2010-2011 by Samsung Electronics.
5 * Copyright IBM Corporation, 2013
6 * Copyright LG Electronics Inc., 2014
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>
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.
19 #define pr_fmt(fmt) "cma: " fmt
21 #ifdef CONFIG_CMA_DEBUG
27 #include <linux/memblock.h>
28 #include <linux/err.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>
40 struct cma cma_areas
[MAX_CMA_AREAS
];
41 unsigned cma_area_count
;
42 static DEFINE_MUTEX(cma_mutex
);
44 phys_addr_t
cma_get_base(struct cma
*cma
)
46 return PFN_PHYS(cma
->base_pfn
);
49 unsigned long cma_get_size(struct cma
*cma
)
51 return cma
->count
<< PAGE_SHIFT
;
54 static unsigned long cma_bitmap_aligned_mask(struct cma
*cma
, int align_order
)
56 if (align_order
<= cma
->order_per_bit
)
58 return (1UL << (align_order
- cma
->order_per_bit
)) - 1;
62 * Find a PFN aligned to the specified order and return an offset represented in
65 static unsigned long cma_bitmap_aligned_offset(struct cma
*cma
, int align_order
)
67 if (align_order
<= cma
->order_per_bit
)
70 return (ALIGN(cma
->base_pfn
, (1UL << align_order
))
71 - cma
->base_pfn
) >> cma
->order_per_bit
;
74 static unsigned long cma_bitmap_pages_to_bits(struct cma
*cma
,
77 return ALIGN(pages
, 1UL << cma
->order_per_bit
) >> cma
->order_per_bit
;
80 static void cma_clear_bitmap(struct cma
*cma
, unsigned long pfn
, int count
)
82 unsigned long bitmap_no
, bitmap_count
;
84 bitmap_no
= (pfn
- cma
->base_pfn
) >> cma
->order_per_bit
;
85 bitmap_count
= cma_bitmap_pages_to_bits(cma
, count
);
87 mutex_lock(&cma
->lock
);
88 bitmap_clear(cma
->bitmap
, bitmap_no
, bitmap_count
);
89 mutex_unlock(&cma
->lock
);
92 static int __init
cma_activate_area(struct cma
*cma
)
94 int bitmap_size
= BITS_TO_LONGS(cma_bitmap_maxno(cma
)) * sizeof(long);
95 unsigned long base_pfn
= cma
->base_pfn
, pfn
= base_pfn
;
96 unsigned i
= cma
->count
>> pageblock_order
;
99 cma
->bitmap
= kzalloc(bitmap_size
, GFP_KERNEL
);
104 WARN_ON_ONCE(!pfn_valid(pfn
));
105 zone
= page_zone(pfn_to_page(pfn
));
111 for (j
= pageblock_nr_pages
; j
; --j
, pfn
++) {
112 WARN_ON_ONCE(!pfn_valid(pfn
));
114 * alloc_contig_range requires the pfn range
115 * specified to be in the same zone. Make this
116 * simple by forcing the entire CMA resv range
117 * to be in the same zone.
119 if (page_zone(pfn_to_page(pfn
)) != zone
)
122 init_cma_reserved_pageblock(pfn_to_page(base_pfn
));
125 mutex_init(&cma
->lock
);
134 static int __init
cma_init_reserved_areas(void)
138 for (i
= 0; i
< cma_area_count
; i
++) {
139 int ret
= cma_activate_area(&cma_areas
[i
]);
147 core_initcall(cma_init_reserved_areas
);
150 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
151 * @base: Base address of the reserved area
152 * @size: Size of the reserved area (in bytes),
153 * @order_per_bit: Order of pages represented by one bit on bitmap.
154 * @res_cma: Pointer to store the created cma region.
156 * This function creates custom contiguous area from already reserved memory.
158 int __init
cma_init_reserved_mem(phys_addr_t base
, phys_addr_t size
,
159 int order_per_bit
, struct cma
**res_cma
)
162 phys_addr_t alignment
;
165 if (cma_area_count
== ARRAY_SIZE(cma_areas
)) {
166 pr_err("Not enough slots for CMA reserved regions!\n");
170 if (!size
|| !memblock_is_region_reserved(base
, size
))
173 /* ensure minimal alignment requied by mm core */
174 alignment
= PAGE_SIZE
<< max(MAX_ORDER
- 1, pageblock_order
);
176 /* alignment should be aligned with order_per_bit */
177 if (!IS_ALIGNED(alignment
>> PAGE_SHIFT
, 1 << order_per_bit
))
180 if (ALIGN(base
, alignment
) != base
|| ALIGN(size
, alignment
) != size
)
184 * Each reserved area must be initialised later, when more kernel
185 * subsystems (like slab allocator) are available.
187 cma
= &cma_areas
[cma_area_count
];
188 cma
->base_pfn
= PFN_DOWN(base
);
189 cma
->count
= size
>> PAGE_SHIFT
;
190 cma
->order_per_bit
= order_per_bit
;
193 totalcma_pages
+= (size
/ PAGE_SIZE
);
199 * cma_declare_contiguous() - reserve custom contiguous area
200 * @base: Base address of the reserved area optional, use 0 for any
201 * @size: Size of the reserved area (in bytes),
202 * @limit: End address of the reserved memory (optional, 0 for any).
203 * @alignment: Alignment for the CMA area, should be power of 2 or zero
204 * @order_per_bit: Order of pages represented by one bit on bitmap.
205 * @fixed: hint about where to place the reserved area
206 * @res_cma: Pointer to store the created cma region.
208 * This function reserves memory from early allocator. It should be
209 * called by arch specific code once the early allocator (memblock or bootmem)
210 * has been activated and all other subsystems have already allocated/reserved
211 * memory. This function allows to create custom reserved areas.
213 * If @fixed is true, reserve contiguous area at exactly @base. If false,
214 * reserve in range from @base to @limit.
216 int __init
cma_declare_contiguous(phys_addr_t base
,
217 phys_addr_t size
, phys_addr_t limit
,
218 phys_addr_t alignment
, unsigned int order_per_bit
,
219 bool fixed
, struct cma
**res_cma
)
221 phys_addr_t memblock_end
= memblock_end_of_DRAM();
222 phys_addr_t highmem_start
;
227 * high_memory isn't direct mapped memory so retrieving its physical
228 * address isn't appropriate. But it would be useful to check the
229 * physical address of the highmem boundary so it's justfiable to get
230 * the physical address from it. On x86 there is a validation check for
231 * this case, so the following workaround is needed to avoid it.
233 highmem_start
= __pa_nodebug(high_memory
);
235 highmem_start
= __pa(high_memory
);
237 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
238 __func__
, &size
, &base
, &limit
, &alignment
);
240 if (cma_area_count
== ARRAY_SIZE(cma_areas
)) {
241 pr_err("Not enough slots for CMA reserved regions!\n");
248 if (alignment
&& !is_power_of_2(alignment
))
252 * Sanitise input arguments.
253 * Pages both ends in CMA area could be merged into adjacent unmovable
254 * migratetype page by page allocator's buddy algorithm. In the case,
255 * you couldn't get a contiguous memory, which is not what we want.
257 alignment
= max(alignment
,
258 (phys_addr_t
)PAGE_SIZE
<< max(MAX_ORDER
- 1, pageblock_order
));
259 base
= ALIGN(base
, alignment
);
260 size
= ALIGN(size
, alignment
);
261 limit
&= ~(alignment
- 1);
266 /* size should be aligned with order_per_bit */
267 if (!IS_ALIGNED(size
>> PAGE_SHIFT
, 1 << order_per_bit
))
271 * If allocating at a fixed base the request region must not cross the
272 * low/high memory boundary.
274 if (fixed
&& base
< highmem_start
&& base
+ size
> highmem_start
) {
276 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
277 &base
, &highmem_start
);
282 * If the limit is unspecified or above the memblock end, its effective
283 * value will be the memblock end. Set it explicitly to simplify further
286 if (limit
== 0 || limit
> memblock_end
)
287 limit
= memblock_end
;
291 if (memblock_is_region_reserved(base
, size
) ||
292 memblock_reserve(base
, size
) < 0) {
297 phys_addr_t addr
= 0;
300 * All pages in the reserved area must come from the same zone.
301 * If the requested region crosses the low/high memory boundary,
302 * try allocating from high memory first and fall back to low
303 * memory in case of failure.
305 if (base
< highmem_start
&& limit
> highmem_start
) {
306 addr
= memblock_alloc_range(size
, alignment
,
307 highmem_start
, limit
);
308 limit
= highmem_start
;
312 addr
= memblock_alloc_range(size
, alignment
, base
,
321 * kmemleak scans/reads tracked objects for pointers to other
322 * objects but this address isn't mapped and accessible
324 kmemleak_ignore(phys_to_virt(addr
));
328 ret
= cma_init_reserved_mem(base
, size
, order_per_bit
, res_cma
);
332 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size
/ SZ_1M
,
337 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size
/ SZ_1M
);
342 * cma_alloc() - allocate pages from contiguous area
343 * @cma: Contiguous memory region for which the allocation is performed.
344 * @count: Requested number of pages.
345 * @align: Requested alignment of pages (in PAGE_SIZE order).
347 * This function allocates part of contiguous memory on specific
348 * contiguous memory area.
350 struct page
*cma_alloc(struct cma
*cma
, int count
, unsigned int align
)
352 unsigned long mask
, offset
, pfn
, start
= 0;
353 unsigned long bitmap_maxno
, bitmap_no
, bitmap_count
;
354 struct page
*page
= NULL
;
357 if (!cma
|| !cma
->count
)
360 pr_debug("%s(cma %p, count %d, align %d)\n", __func__
, (void *)cma
,
366 mask
= cma_bitmap_aligned_mask(cma
, align
);
367 offset
= cma_bitmap_aligned_offset(cma
, align
);
368 bitmap_maxno
= cma_bitmap_maxno(cma
);
369 bitmap_count
= cma_bitmap_pages_to_bits(cma
, count
);
372 mutex_lock(&cma
->lock
);
373 bitmap_no
= bitmap_find_next_zero_area_off(cma
->bitmap
,
374 bitmap_maxno
, start
, bitmap_count
, mask
,
376 if (bitmap_no
>= bitmap_maxno
) {
377 mutex_unlock(&cma
->lock
);
380 bitmap_set(cma
->bitmap
, bitmap_no
, bitmap_count
);
382 * It's safe to drop the lock here. We've marked this region for
383 * our exclusive use. If the migration fails we will take the
384 * lock again and unmark it.
386 mutex_unlock(&cma
->lock
);
388 pfn
= cma
->base_pfn
+ (bitmap_no
<< cma
->order_per_bit
);
389 mutex_lock(&cma_mutex
);
390 ret
= alloc_contig_range(pfn
, pfn
+ count
, MIGRATE_CMA
);
391 mutex_unlock(&cma_mutex
);
393 page
= pfn_to_page(pfn
);
397 cma_clear_bitmap(cma
, pfn
, count
);
401 pr_debug("%s(): memory range at %p is busy, retrying\n",
402 __func__
, pfn_to_page(pfn
));
403 /* try again with a bit different memory target */
404 start
= bitmap_no
+ mask
+ 1;
407 pr_debug("%s(): returned %p\n", __func__
, page
);
412 * cma_release() - release allocated pages
413 * @cma: Contiguous memory region for which the allocation is performed.
414 * @pages: Allocated pages.
415 * @count: Number of allocated pages.
417 * This function releases memory allocated by alloc_cma().
418 * It returns false when provided pages do not belong to contiguous area and
421 bool cma_release(struct cma
*cma
, struct page
*pages
, int count
)
428 pr_debug("%s(page %p)\n", __func__
, (void *)pages
);
430 pfn
= page_to_pfn(pages
);
432 if (pfn
< cma
->base_pfn
|| pfn
>= cma
->base_pfn
+ cma
->count
)
435 VM_BUG_ON(pfn
+ count
> cma
->base_pfn
+ cma
->count
);
437 free_contig_range(pfn
, count
);
438 cma_clear_bitmap(cma
, pfn
, count
);