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>
39 unsigned long base_pfn
;
41 unsigned long *bitmap
;
42 unsigned int order_per_bit
; /* Order of pages represented by one bit */
46 static struct cma cma_areas
[MAX_CMA_AREAS
];
47 static unsigned cma_area_count
;
48 static DEFINE_MUTEX(cma_mutex
);
50 phys_addr_t
cma_get_base(struct cma
*cma
)
52 return PFN_PHYS(cma
->base_pfn
);
55 unsigned long cma_get_size(struct cma
*cma
)
57 return cma
->count
<< PAGE_SHIFT
;
60 static unsigned long cma_bitmap_aligned_mask(struct cma
*cma
, int align_order
)
62 if (align_order
<= cma
->order_per_bit
)
64 return (1UL << (align_order
- cma
->order_per_bit
)) - 1;
68 * Find a PFN aligned to the specified order and return an offset represented in
71 static unsigned long cma_bitmap_aligned_offset(struct cma
*cma
, int align_order
)
73 if (align_order
<= cma
->order_per_bit
)
76 return (ALIGN(cma
->base_pfn
, (1UL << align_order
))
77 - cma
->base_pfn
) >> cma
->order_per_bit
;
80 static unsigned long cma_bitmap_maxno(struct cma
*cma
)
82 return cma
->count
>> cma
->order_per_bit
;
85 static unsigned long cma_bitmap_pages_to_bits(struct cma
*cma
,
88 return ALIGN(pages
, 1UL << cma
->order_per_bit
) >> cma
->order_per_bit
;
91 static void cma_clear_bitmap(struct cma
*cma
, unsigned long pfn
, int count
)
93 unsigned long bitmap_no
, bitmap_count
;
95 bitmap_no
= (pfn
- cma
->base_pfn
) >> cma
->order_per_bit
;
96 bitmap_count
= cma_bitmap_pages_to_bits(cma
, count
);
98 mutex_lock(&cma
->lock
);
99 bitmap_clear(cma
->bitmap
, bitmap_no
, bitmap_count
);
100 mutex_unlock(&cma
->lock
);
103 static int __init
cma_activate_area(struct cma
*cma
)
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
;
110 cma
->bitmap
= kzalloc(bitmap_size
, GFP_KERNEL
);
115 WARN_ON_ONCE(!pfn_valid(pfn
));
116 zone
= page_zone(pfn_to_page(pfn
));
122 for (j
= pageblock_nr_pages
; j
; --j
, pfn
++) {
123 WARN_ON_ONCE(!pfn_valid(pfn
));
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.
130 if (page_zone(pfn_to_page(pfn
)) != zone
)
133 init_cma_reserved_pageblock(pfn_to_page(base_pfn
));
136 mutex_init(&cma
->lock
);
145 static int __init
cma_init_reserved_areas(void)
149 for (i
= 0; i
< cma_area_count
; i
++) {
150 int ret
= cma_activate_area(&cma_areas
[i
]);
158 core_initcall(cma_init_reserved_areas
);
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.
167 * This function creates custom contiguous area from already reserved memory.
169 int __init
cma_init_reserved_mem(phys_addr_t base
, phys_addr_t size
,
170 int order_per_bit
, struct cma
**res_cma
)
173 phys_addr_t alignment
;
176 if (cma_area_count
== ARRAY_SIZE(cma_areas
)) {
177 pr_err("Not enough slots for CMA reserved regions!\n");
181 if (!size
|| !memblock_is_region_reserved(base
, size
))
184 /* ensure minimal alignment requied by mm core */
185 alignment
= PAGE_SIZE
<< max(MAX_ORDER
- 1, pageblock_order
);
187 /* alignment should be aligned with order_per_bit */
188 if (!IS_ALIGNED(alignment
>> PAGE_SHIFT
, 1 << order_per_bit
))
191 if (ALIGN(base
, alignment
) != base
|| ALIGN(size
, alignment
) != size
)
195 * Each reserved area must be initialised later, when more kernel
196 * subsystems (like slab allocator) are available.
198 cma
= &cma_areas
[cma_area_count
];
199 cma
->base_pfn
= PFN_DOWN(base
);
200 cma
->count
= size
>> PAGE_SHIFT
;
201 cma
->order_per_bit
= order_per_bit
;
204 totalcma_pages
+= (size
/ PAGE_SIZE
);
210 * cma_declare_contiguous() - reserve custom contiguous area
211 * @base: Base address of the reserved area optional, use 0 for any
212 * @size: Size of the reserved area (in bytes),
213 * @limit: End address of the reserved memory (optional, 0 for any).
214 * @alignment: Alignment for the CMA area, should be power of 2 or zero
215 * @order_per_bit: Order of pages represented by one bit on bitmap.
216 * @fixed: hint about where to place the reserved area
217 * @res_cma: Pointer to store the created cma region.
219 * This function reserves memory from early allocator. It should be
220 * called by arch specific code once the early allocator (memblock or bootmem)
221 * has been activated and all other subsystems have already allocated/reserved
222 * memory. This function allows to create custom reserved areas.
224 * If @fixed is true, reserve contiguous area at exactly @base. If false,
225 * reserve in range from @base to @limit.
227 int __init
cma_declare_contiguous(phys_addr_t base
,
228 phys_addr_t size
, phys_addr_t limit
,
229 phys_addr_t alignment
, unsigned int order_per_bit
,
230 bool fixed
, struct cma
**res_cma
)
232 phys_addr_t memblock_end
= memblock_end_of_DRAM();
233 phys_addr_t highmem_start
;
238 * high_memory isn't direct mapped memory so retrieving its physical
239 * address isn't appropriate. But it would be useful to check the
240 * physical address of the highmem boundary so it's justfiable to get
241 * the physical address from it. On x86 there is a validation check for
242 * this case, so the following workaround is needed to avoid it.
244 highmem_start
= __pa_nodebug(high_memory
);
246 highmem_start
= __pa(high_memory
);
248 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
249 __func__
, &size
, &base
, &limit
, &alignment
);
251 if (cma_area_count
== ARRAY_SIZE(cma_areas
)) {
252 pr_err("Not enough slots for CMA reserved regions!\n");
259 if (alignment
&& !is_power_of_2(alignment
))
263 * Sanitise input arguments.
264 * Pages both ends in CMA area could be merged into adjacent unmovable
265 * migratetype page by page allocator's buddy algorithm. In the case,
266 * you couldn't get a contiguous memory, which is not what we want.
268 alignment
= max(alignment
,
269 (phys_addr_t
)PAGE_SIZE
<< max(MAX_ORDER
- 1, pageblock_order
));
270 base
= ALIGN(base
, alignment
);
271 size
= ALIGN(size
, alignment
);
272 limit
&= ~(alignment
- 1);
277 /* size should be aligned with order_per_bit */
278 if (!IS_ALIGNED(size
>> PAGE_SHIFT
, 1 << order_per_bit
))
282 * If allocating at a fixed base the request region must not cross the
283 * low/high memory boundary.
285 if (fixed
&& base
< highmem_start
&& base
+ size
> highmem_start
) {
287 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
288 &base
, &highmem_start
);
293 * If the limit is unspecified or above the memblock end, its effective
294 * value will be the memblock end. Set it explicitly to simplify further
297 if (limit
== 0 || limit
> memblock_end
)
298 limit
= memblock_end
;
302 if (memblock_is_region_reserved(base
, size
) ||
303 memblock_reserve(base
, size
) < 0) {
308 phys_addr_t addr
= 0;
311 * All pages in the reserved area must come from the same zone.
312 * If the requested region crosses the low/high memory boundary,
313 * try allocating from high memory first and fall back to low
314 * memory in case of failure.
316 if (base
< highmem_start
&& limit
> highmem_start
) {
317 addr
= memblock_alloc_range(size
, alignment
,
318 highmem_start
, limit
);
319 limit
= highmem_start
;
323 addr
= memblock_alloc_range(size
, alignment
, base
,
332 * kmemleak scans/reads tracked objects for pointers to other
333 * objects but this address isn't mapped and accessible
335 kmemleak_ignore(phys_to_virt(addr
));
339 ret
= cma_init_reserved_mem(base
, size
, order_per_bit
, res_cma
);
343 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size
/ SZ_1M
,
348 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size
/ SZ_1M
);
353 * cma_alloc() - allocate pages from contiguous area
354 * @cma: Contiguous memory region for which the allocation is performed.
355 * @count: Requested number of pages.
356 * @align: Requested alignment of pages (in PAGE_SIZE order).
358 * This function allocates part of contiguous memory on specific
359 * contiguous memory area.
361 struct page
*cma_alloc(struct cma
*cma
, int count
, unsigned int align
)
363 unsigned long mask
, offset
, pfn
, start
= 0;
364 unsigned long bitmap_maxno
, bitmap_no
, bitmap_count
;
365 struct page
*page
= NULL
;
368 if (!cma
|| !cma
->count
)
371 pr_debug("%s(cma %p, count %d, align %d)\n", __func__
, (void *)cma
,
377 mask
= cma_bitmap_aligned_mask(cma
, align
);
378 offset
= cma_bitmap_aligned_offset(cma
, align
);
379 bitmap_maxno
= cma_bitmap_maxno(cma
);
380 bitmap_count
= cma_bitmap_pages_to_bits(cma
, count
);
383 mutex_lock(&cma
->lock
);
384 bitmap_no
= bitmap_find_next_zero_area_off(cma
->bitmap
,
385 bitmap_maxno
, start
, bitmap_count
, mask
,
387 if (bitmap_no
>= bitmap_maxno
) {
388 mutex_unlock(&cma
->lock
);
391 bitmap_set(cma
->bitmap
, bitmap_no
, bitmap_count
);
393 * It's safe to drop the lock here. We've marked this region for
394 * our exclusive use. If the migration fails we will take the
395 * lock again and unmark it.
397 mutex_unlock(&cma
->lock
);
399 pfn
= cma
->base_pfn
+ (bitmap_no
<< cma
->order_per_bit
);
400 mutex_lock(&cma_mutex
);
401 ret
= alloc_contig_range(pfn
, pfn
+ count
, MIGRATE_CMA
);
402 mutex_unlock(&cma_mutex
);
404 page
= pfn_to_page(pfn
);
408 cma_clear_bitmap(cma
, pfn
, count
);
412 pr_debug("%s(): memory range at %p is busy, retrying\n",
413 __func__
, pfn_to_page(pfn
));
414 /* try again with a bit different memory target */
415 start
= bitmap_no
+ mask
+ 1;
418 pr_debug("%s(): returned %p\n", __func__
, page
);
423 * cma_release() - release allocated pages
424 * @cma: Contiguous memory region for which the allocation is performed.
425 * @pages: Allocated pages.
426 * @count: Number of allocated pages.
428 * This function releases memory allocated by alloc_cma().
429 * It returns false when provided pages do not belong to contiguous area and
432 bool cma_release(struct cma
*cma
, struct page
*pages
, int count
)
439 pr_debug("%s(page %p)\n", __func__
, (void *)pages
);
441 pfn
= page_to_pfn(pages
);
443 if (pfn
< cma
->base_pfn
|| pfn
>= cma
->base_pfn
+ cma
->count
)
446 VM_BUG_ON(pfn
+ count
> cma
->base_pfn
+ cma
->count
);
448 free_contig_range(pfn
, count
);
449 cma_clear_bitmap(cma
, pfn
, count
);