// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Contiguous Memory Allocator
 *
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Copyright IBM Corporation, 2013
 * Copyright LG Electronics Inc., 2014
 * Written by:
 *      Marek Szyprowski <m.szyprowski@samsung.com>
 *      Michal Nazarewicz <mina86@mina86.com>
 *      Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
 *      Joonsoo Kim <iamjoonsoo.kim@lge.com>
 */

#define pr_fmt(fmt) "cma: " fmt

#define CREATE_TRACE_POINTS

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/log2.h>
#include <linux/cma.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/kmemleak.h>
#include <trace/events/cma.h>

#include "internal.h"
#include "cma.h"

struct cma cma_areas[MAX_CMA_AREAS];
unsigned int cma_area_count;

phys_addr_t cma_get_base(const struct cma *cma)
{
        WARN_ON_ONCE(cma->nranges != 1);
        return PFN_PHYS(cma->ranges[0].base_pfn);
}

unsigned long cma_get_size(const struct cma *cma)
{
        return cma->count << PAGE_SHIFT;
}

const char *cma_get_name(const struct cma *cma)
{
        return cma->name;
}

static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
                                             unsigned int align_order)
{
        if (align_order <= cma->order_per_bit)
                return 0;
        return (1UL << (align_order - cma->order_per_bit)) - 1;
}

/*
 * Find the offset of the base PFN from the specified align_order.
 * The value returned is represented in order_per_bits.
 */
static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
                                               const struct cma_memrange *cmr,
                                               unsigned int align_order)
{
        return (cmr->base_pfn & ((1UL << align_order) - 1))
                >> cma->order_per_bit;
}

static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
                                              unsigned long pages)
{
        return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
}

static void cma_clear_bitmap(struct cma *cma, const struct cma_memrange *cmr,
                             unsigned long pfn, unsigned long count)
{
        unsigned long bitmap_no, bitmap_count;
        unsigned long flags;

        bitmap_no = (pfn - cmr->base_pfn) >> cma->order_per_bit;
        bitmap_count = cma_bitmap_pages_to_bits(cma, count);

        spin_lock_irqsave(&cma->lock, flags);
        bitmap_clear(cmr->bitmap, bitmap_no, bitmap_count);
        cma->available_count += count;
        spin_unlock_irqrestore(&cma->lock, flags);
}

/*
 * Check if a CMA area contains no ranges that intersect with
 * multiple zones. Store the result in the flags in case
 * this gets called more than once.
 */
bool cma_validate_zones(struct cma *cma)
{
        int r;
        unsigned long base_pfn;
        struct cma_memrange *cmr;
        bool valid_bit_set;

        /*
         * If already validated, return result of previous check.
         * Either the valid or invalid bit will be set if this
         * check has already been done. If neither is set, the
         * check has not been performed yet.
         */
        valid_bit_set = test_bit(CMA_ZONES_VALID, &cma->flags);
        if (valid_bit_set || test_bit(CMA_ZONES_INVALID, &cma->flags))
                return valid_bit_set;

        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                base_pfn = cmr->base_pfn;

                /*
                 * alloc_contig_range() requires the pfn range specified
                 * to be in the same zone. Simplify by forcing the entire
                 * CMA resv range to be in the same zone.
                 */
                WARN_ON_ONCE(!pfn_valid(base_pfn));
                if (pfn_range_intersects_zones(cma->nid, base_pfn, cmr->count)) {
                        set_bit(CMA_ZONES_INVALID, &cma->flags);
                        return false;
                }
        }

        set_bit(CMA_ZONES_VALID, &cma->flags);

        return true;
}

static void __init cma_activate_area(struct cma *cma)
{
        unsigned long pfn, end_pfn, early_pfn[CMA_MAX_RANGES];
        int allocrange, r;
        struct cma_memrange *cmr;
        unsigned long bitmap_count, count;

        for (allocrange = 0; allocrange < cma->nranges; allocrange++) {
                cmr = &cma->ranges[allocrange];
                early_pfn[allocrange] = cmr->early_pfn;
                cmr->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma, cmr),
                                            GFP_KERNEL);
                if (!cmr->bitmap)
                        goto cleanup;
        }

        if (!cma_validate_zones(cma))
                goto cleanup;

        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                if (early_pfn[r] != cmr->base_pfn) {
                        count = early_pfn[r] - cmr->base_pfn;
                        bitmap_count = cma_bitmap_pages_to_bits(cma, count);
                        bitmap_set(cmr->bitmap, 0, bitmap_count);
                }

                for (pfn = early_pfn[r]; pfn < cmr->base_pfn + cmr->count;
                     pfn += pageblock_nr_pages)
                        init_cma_reserved_pageblock(pfn_to_page(pfn));
        }

        spin_lock_init(&cma->lock);

        mutex_init(&cma->alloc_mutex);

#ifdef CONFIG_CMA_DEBUGFS
        INIT_HLIST_HEAD(&cma->mem_head);
        spin_lock_init(&cma->mem_head_lock);
#endif
        set_bit(CMA_ACTIVATED, &cma->flags);

        return;

cleanup:
        for (r = 0; r < allocrange; r++)
                bitmap_free(cma->ranges[r].bitmap);

        /* Expose all pages to the buddy, they are useless for CMA. */
        if (!test_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags)) {
                for (r = 0; r < allocrange; r++) {
                        cmr = &cma->ranges[r];
                        end_pfn = cmr->base_pfn + cmr->count;
                        for (pfn = early_pfn[r]; pfn < end_pfn; pfn++)
                                free_reserved_page(pfn_to_page(pfn));
                }
        }
        totalcma_pages -= cma->count;
        cma->available_count = cma->count = 0;
        pr_err("CMA area %s could not be activated\n", cma->name);
}

static int __init cma_init_reserved_areas(void)
{
        int i;

        for (i = 0; i < cma_area_count; i++)
                cma_activate_area(&cma_areas[i]);

        return 0;
}
core_initcall(cma_init_reserved_areas);

void __init cma_reserve_pages_on_error(struct cma *cma)
{
        set_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags);
}

static int __init cma_new_area(const char *name, phys_addr_t size,
                               unsigned int order_per_bit,
                               struct cma **res_cma)
{
        struct cma *cma;

        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
                pr_err("Not enough slots for CMA reserved regions!\n");
                return -ENOSPC;
        }

        /*
         * Each reserved area must be initialised later, when more kernel
         * subsystems (like slab allocator) are available.
         */
        cma = &cma_areas[cma_area_count];
        cma_area_count++;

        if (name)
                strscpy(cma->name, name);
        else
                snprintf(cma->name, CMA_MAX_NAME,  "cma%d\n", cma_area_count);

        cma->available_count = cma->count = size >> PAGE_SHIFT;
        cma->order_per_bit = order_per_bit;
        *res_cma = cma;
        totalcma_pages += cma->count;

        return 0;
}

static void __init cma_drop_area(struct cma *cma)
{
        totalcma_pages -= cma->count;
        cma_area_count--;
}

/**
 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
 * @base: Base address of the reserved area
 * @size: Size of the reserved area (in bytes),
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @name: The name of the area. If this parameter is NULL, the name of
 *        the area will be set to "cmaN", where N is a running counter of
 *        used areas.
 * @res_cma: Pointer to store the created cma region.
 *
 * This function creates custom contiguous area from already reserved memory.
 */
int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
                                 unsigned int order_per_bit,
                                 const char *name,
                                 struct cma **res_cma)
{
        struct cma *cma;
        int ret;

        /* Sanity checks */
        if (!size || !memblock_is_region_reserved(base, size))
                return -EINVAL;

        /*
         * CMA uses CMA_MIN_ALIGNMENT_BYTES as alignment requirement which
         * needs pageblock_order to be initialized. Let's enforce it.
         */
        if (!pageblock_order) {
                pr_err("pageblock_order not yet initialized. Called during early boot?\n");
                return -EINVAL;
        }

        /* ensure minimal alignment required by mm core */
        if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
                return -EINVAL;

        ret = cma_new_area(name, size, order_per_bit, &cma);
        if (ret != 0)
                return ret;

        cma->ranges[0].base_pfn = PFN_DOWN(base);
        cma->ranges[0].early_pfn = PFN_DOWN(base);
        cma->ranges[0].count = cma->count;
        cma->nranges = 1;
        cma->nid = NUMA_NO_NODE;

        *res_cma = cma;

        return 0;
}

/*
 * Structure used while walking physical memory ranges and finding out
 * which one(s) to use for a CMA area.
 */
struct cma_init_memrange {
        phys_addr_t base;
        phys_addr_t size;
        struct list_head list;
};

/*
 * Work array used during CMA initialization.
 */
static struct cma_init_memrange memranges[CMA_MAX_RANGES] __initdata;

static bool __init revsizecmp(struct cma_init_memrange *mlp,
                              struct cma_init_memrange *mrp)
{
        return mlp->size > mrp->size;
}

static bool __init basecmp(struct cma_init_memrange *mlp,
                           struct cma_init_memrange *mrp)
{
        return mlp->base < mrp->base;
}

/*
 * Helper function to create sorted lists.
 */
static void __init list_insert_sorted(
        struct list_head *ranges,
        struct cma_init_memrange *mrp,
        bool (*cmp)(struct cma_init_memrange *lh, struct cma_init_memrange *rh))
{
        struct list_head *mp;
        struct cma_init_memrange *mlp;

        if (list_empty(ranges))
                list_add(&mrp->list, ranges);
        else {
                list_for_each(mp, ranges) {
                        mlp = list_entry(mp, struct cma_init_memrange, list);
                        if (cmp(mlp, mrp))
                                break;
                }
                __list_add(&mrp->list, mlp->list.prev, &mlp->list);
        }
}

static int __init cma_fixed_reserve(phys_addr_t base, phys_addr_t size)
{
        if (IS_ENABLED(CONFIG_HIGHMEM)) {
                phys_addr_t highmem_start = __pa(high_memory - 1) + 1;

                /*
                 * If allocating at a fixed base the request region must not
                 * cross the low/high memory boundary.
                 */
                if (base < highmem_start && base + size > highmem_start) {
                        pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
                               &base, &highmem_start);
                        return -EINVAL;
                }
        }

        if (memblock_is_region_reserved(base, size) ||
            memblock_reserve(base, size) < 0) {
                return -EBUSY;
        }

        return 0;
}

static phys_addr_t __init cma_alloc_mem(phys_addr_t base, phys_addr_t size,
                        phys_addr_t align, phys_addr_t limit, int nid)
{
        phys_addr_t addr = 0;

        /*
         * If there is enough memory, try a bottom-up allocation first.
         * It will place the new cma area close to the start of the node
         * and guarantee that the compaction is moving pages out of the
         * cma area and not into it.
         * Avoid using first 4GB to not interfere with constrained zones
         * like DMA/DMA32.
         */
#ifdef CONFIG_PHYS_ADDR_T_64BIT
        if (!memblock_bottom_up() && limit >= SZ_4G + size) {
                memblock_set_bottom_up(true);
                addr = memblock_alloc_range_nid(size, align, SZ_4G, limit,
                                                nid, true);
                memblock_set_bottom_up(false);
        }
#endif

        /*
         * On systems with HIGHMEM try allocating from there before consuming
         * memory in lower zones.
         */
        if (!addr && IS_ENABLED(CONFIG_HIGHMEM)) {
                phys_addr_t highmem = __pa(high_memory - 1) + 1;

                /*
                 * All pages in the reserved area must come from the same zone.
                 * If the requested region crosses the low/high memory boundary,
                 * try allocating from high memory first and fall back to low
                 * memory in case of failure.
                 */
                if (base < highmem && limit > highmem) {
                        addr = memblock_alloc_range_nid(size, align, highmem,
                                                        limit, nid, true);
                        limit = highmem;
                }
        }

        if (!addr)
                addr = memblock_alloc_range_nid(size, align, base, limit, nid,
                                                true);

        return addr;
}

static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
                        phys_addr_t size, phys_addr_t limit,
                        phys_addr_t alignment, unsigned int order_per_bit,
                        bool fixed, const char *name, struct cma **res_cma,
                        int nid)
{
        phys_addr_t memblock_end = memblock_end_of_DRAM();
        phys_addr_t base = *basep;
        int ret;

        pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
                __func__, &size, &base, &limit, &alignment);

        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
                pr_err("Not enough slots for CMA reserved regions!\n");
                return -ENOSPC;
        }

        if (!size)
                return -EINVAL;

        if (alignment && !is_power_of_2(alignment))
                return -EINVAL;

        if (!IS_ENABLED(CONFIG_NUMA))
                nid = NUMA_NO_NODE;

        /* Sanitise input arguments. */
        alignment = max_t(phys_addr_t, alignment, CMA_MIN_ALIGNMENT_BYTES);
        if (fixed && base & (alignment - 1)) {
                pr_err("Region at %pa must be aligned to %pa bytes\n",
                        &base, &alignment);
                return -EINVAL;
        }
        base = ALIGN(base, alignment);
        size = ALIGN(size, alignment);
        limit &= ~(alignment - 1);

        if (!base)
                fixed = false;

        /* size should be aligned with order_per_bit */
        if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
                return -EINVAL;


        /*
         * If the limit is unspecified or above the memblock end, its effective
         * value will be the memblock end. Set it explicitly to simplify further
         * checks.
         */
        if (limit == 0 || limit > memblock_end)
                limit = memblock_end;

        if (base + size > limit) {
                pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
                        &size, &base, &limit);
                return -EINVAL;
        }

        /* Reserve memory */
        if (fixed) {
                ret = cma_fixed_reserve(base, size);
                if (ret)
                        return ret;
        } else {
                base = cma_alloc_mem(base, size, alignment, limit, nid);
                if (!base)
                        return -ENOMEM;

                /*
                 * kmemleak scans/reads tracked objects for pointers to other
                 * objects but this address isn't mapped and accessible
                 */
                kmemleak_ignore_phys(base);
        }

        ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
        if (ret) {
                memblock_phys_free(base, size);
                return ret;
        }

        (*res_cma)->nid = nid;
        *basep = base;

        return 0;
}

/*
 * Create CMA areas with a total size of @total_size. A normal allocation
 * for one area is tried first. If that fails, the biggest memblock
 * ranges above 4G are selected, and allocated bottom up.
 *
 * The complexity here is not great, but this function will only be
 * called during boot, and the lists operated on have fewer than
 * CMA_MAX_RANGES elements (default value: 8).
 */
int __init cma_declare_contiguous_multi(phys_addr_t total_size,
                        phys_addr_t align, unsigned int order_per_bit,
                        const char *name, struct cma **res_cma, int nid)
{
        phys_addr_t start = 0, end;
        phys_addr_t size, sizesum, sizeleft;
        struct cma_init_memrange *mrp, *mlp, *failed;
        struct cma_memrange *cmrp;
        LIST_HEAD(ranges);
        LIST_HEAD(final_ranges);
        struct list_head *mp, *next;
        int ret, nr = 1;
        u64 i;
        struct cma *cma;

        /*
         * First, try it the normal way, producing just one range.
         */
        ret = __cma_declare_contiguous_nid(&start, total_size, 0, align,
                        order_per_bit, false, name, res_cma, nid);
        if (ret != -ENOMEM)
                goto out;

        /*
         * Couldn't find one range that fits our needs, so try multiple
         * ranges.
         *
         * No need to do the alignment checks here, the call to
         * cma_declare_contiguous_nid above would have caught
         * any issues. With the checks, we know that:
         *
         * - @align is a power of 2
         * - @align is >= pageblock alignment
         * - @size is aligned to @align and to @order_per_bit
         *
         * So, as long as we create ranges that have a base
         * aligned to @align, and a size that is aligned to
         * both @align and @order_to_bit, things will work out.
         */
        nr = 0;
        sizesum = 0;
        failed = NULL;

        ret = cma_new_area(name, total_size, order_per_bit, &cma);
        if (ret != 0)
                goto out;

        align = max_t(phys_addr_t, align, CMA_MIN_ALIGNMENT_BYTES);
        /*
         * Create a list of ranges above 4G, largest range first.
         */
        for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
                if (upper_32_bits(start) == 0)
                        continue;

                start = ALIGN(start, align);
                if (start >= end)
                        continue;

                end = ALIGN_DOWN(end, align);
                if (end <= start)
                        continue;

                size = end - start;
                size = ALIGN_DOWN(size, (PAGE_SIZE << order_per_bit));
                if (!size)
                        continue;
                sizesum += size;

                pr_debug("consider %016llx - %016llx\n", (u64)start, (u64)end);

                /*
                 * If we don't yet have used the maximum number of
                 * areas, grab a new one.
                 *
                 * If we can't use anymore, see if this range is not
                 * smaller than the smallest one already recorded. If
                 * not, re-use the smallest element.
                 */
                if (nr < CMA_MAX_RANGES)
                        mrp = &memranges[nr++];
                else {
                        mrp = list_last_entry(&ranges,
                                              struct cma_init_memrange, list);
                        if (size < mrp->size)
                                continue;
                        list_del(&mrp->list);
                        sizesum -= mrp->size;
                        pr_debug("deleted %016llx - %016llx from the list\n",
                                (u64)mrp->base, (u64)mrp->base + size);
                }
                mrp->base = start;
                mrp->size = size;

                /*
                 * Now do a sorted insert.
                 */
                list_insert_sorted(&ranges, mrp, revsizecmp);
                pr_debug("added %016llx - %016llx to the list\n",
                    (u64)mrp->base, (u64)mrp->base + size);
                pr_debug("total size now %llu\n", (u64)sizesum);
        }

        /*
         * There is not enough room in the CMA_MAX_RANGES largest
         * ranges, so bail out.
         */
        if (sizesum < total_size) {
                cma_drop_area(cma);
                ret = -ENOMEM;
                goto out;
        }

        /*
         * Found ranges that provide enough combined space.
         * Now, sorted them by address, smallest first, because we
         * want to mimic a bottom-up memblock allocation.
         */
        sizesum = 0;
        list_for_each_safe(mp, next, &ranges) {
                mlp = list_entry(mp, struct cma_init_memrange, list);
                list_del(mp);
                list_insert_sorted(&final_ranges, mlp, basecmp);
                sizesum += mlp->size;
                if (sizesum >= total_size)
                        break;
        }

        /*
         * Walk the final list, and add a CMA range for
         * each range, possibly not using the last one fully.
         */
        nr = 0;
        sizeleft = total_size;
        list_for_each(mp, &final_ranges) {
                mlp = list_entry(mp, struct cma_init_memrange, list);
                size = min(sizeleft, mlp->size);
                if (memblock_reserve(mlp->base, size)) {
                        /*
                         * Unexpected error. Could go on to
                         * the next one, but just abort to
                         * be safe.
                         */
                        failed = mlp;
                        break;
                }

                pr_debug("created region %d: %016llx - %016llx\n",
                    nr, (u64)mlp->base, (u64)mlp->base + size);
                cmrp = &cma->ranges[nr++];
                cmrp->base_pfn = PHYS_PFN(mlp->base);
                cmrp->early_pfn = cmrp->base_pfn;
                cmrp->count = size >> PAGE_SHIFT;

                sizeleft -= size;
                if (sizeleft == 0)
                        break;
        }

        if (failed) {
                list_for_each(mp, &final_ranges) {
                        mlp = list_entry(mp, struct cma_init_memrange, list);
                        if (mlp == failed)
                                break;
                        memblock_phys_free(mlp->base, mlp->size);
                }
                cma_drop_area(cma);
                ret = -ENOMEM;
                goto out;
        }

        cma->nranges = nr;
        cma->nid = nid;
        *res_cma = cma;

out:
        if (ret != 0)
                pr_err("Failed to reserve %lu MiB\n",
                        (unsigned long)total_size / SZ_1M);
        else
                pr_info("Reserved %lu MiB in %d range%s\n",
                        (unsigned long)total_size / SZ_1M, nr, str_plural(nr));
        return ret;
}

/**
 * cma_declare_contiguous_nid() - reserve custom contiguous area
 * @base: Base address of the reserved area optional, use 0 for any
 * @size: Size of the reserved area (in bytes),
 * @limit: End address of the reserved memory (optional, 0 for any).
 * @alignment: Alignment for the CMA area, should be power of 2 or zero
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @fixed: hint about where to place the reserved area
 * @name: The name of the area. See function cma_init_reserved_mem()
 * @res_cma: Pointer to store the created cma region.
 * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
 *
 * This function reserves memory from early allocator. It should be
 * called by arch specific code once the early allocator (memblock or bootmem)
 * has been activated and all other subsystems have already allocated/reserved
 * memory. This function allows to create custom reserved areas.
 *
 * If @fixed is true, reserve contiguous area at exactly @base.  If false,
 * reserve in range from @base to @limit.
 */
int __init cma_declare_contiguous_nid(phys_addr_t base,
                        phys_addr_t size, phys_addr_t limit,
                        phys_addr_t alignment, unsigned int order_per_bit,
                        bool fixed, const char *name, struct cma **res_cma,
                        int nid)
{
        int ret;

        ret = __cma_declare_contiguous_nid(&base, size, limit, alignment,
                        order_per_bit, fixed, name, res_cma, nid);
        if (ret != 0)
                pr_err("Failed to reserve %ld MiB\n",
                                (unsigned long)size / SZ_1M);
        else
                pr_info("Reserved %ld MiB at %pa\n",
                                (unsigned long)size / SZ_1M, &base);

        return ret;
}

static void cma_debug_show_areas(struct cma *cma)
{
        unsigned long start, end;
        unsigned long nr_part;
        unsigned long nbits;
        int r;
        struct cma_memrange *cmr;

        spin_lock_irq(&cma->lock);
        pr_info("number of available pages: ");
        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];

                nbits = cma_bitmap_maxno(cma, cmr);

                pr_info("range %d: ", r);
                for_each_clear_bitrange(start, end, cmr->bitmap, nbits) {
                        nr_part = (end - start) << cma->order_per_bit;
                        pr_cont("%s%lu@%lu", start ? "+" : "", nr_part, start);
                }
                pr_info("\n");
        }
        pr_cont("=> %lu free of %lu total pages\n", cma->available_count,
                        cma->count);
        spin_unlock_irq(&cma->lock);
}

static int cma_range_alloc(struct cma *cma, struct cma_memrange *cmr,
                                unsigned long count, unsigned int align,
                                struct page **pagep, gfp_t gfp)
{
        unsigned long bitmap_maxno, bitmap_no, bitmap_count;
        unsigned long start, pfn, mask, offset;
        int ret = -EBUSY;
        struct page *page = NULL;

        mask = cma_bitmap_aligned_mask(cma, align);
        offset = cma_bitmap_aligned_offset(cma, cmr, align);
        bitmap_maxno = cma_bitmap_maxno(cma, cmr);
        bitmap_count = cma_bitmap_pages_to_bits(cma, count);

        if (bitmap_count > bitmap_maxno)
                goto out;

        for (start = 0; ; start = bitmap_no + mask + 1) {
                spin_lock_irq(&cma->lock);
                /*
                 * If the request is larger than the available number
                 * of pages, stop right away.
                 */
                if (count > cma->available_count) {
                        spin_unlock_irq(&cma->lock);
                        break;
                }
                bitmap_no = bitmap_find_next_zero_area_off(cmr->bitmap,
                                bitmap_maxno, start, bitmap_count, mask,
                                offset);
                if (bitmap_no >= bitmap_maxno) {
                        spin_unlock_irq(&cma->lock);
                        break;
                }

                pfn = cmr->base_pfn + (bitmap_no << cma->order_per_bit);
                page = pfn_to_page(pfn);

                /*
                 * Do not hand out page ranges that are not contiguous, so
                 * callers can just iterate the pages without having to worry
                 * about these corner cases.
                 */
                if (!page_range_contiguous(page, count)) {
                        spin_unlock_irq(&cma->lock);
                        pr_warn_ratelimited("%s: %s: skipping incompatible area [0x%lx-0x%lx]",
                                            __func__, cma->name, pfn, pfn + count - 1);
                        continue;
                }

                bitmap_set(cmr->bitmap, bitmap_no, bitmap_count);
                cma->available_count -= count;
                /*
                 * It's safe to drop the lock here. We've marked this region for
                 * our exclusive use. If the migration fails we will take the
                 * lock again and unmark it.
                 */
                spin_unlock_irq(&cma->lock);

                mutex_lock(&cma->alloc_mutex);
                ret = alloc_contig_frozen_range(pfn, pfn + count, ACR_FLAGS_CMA, gfp);
                mutex_unlock(&cma->alloc_mutex);
                if (!ret)
                        break;

                cma_clear_bitmap(cma, cmr, pfn, count);
                if (ret != -EBUSY)
                        break;

                pr_debug("%s(): memory range at pfn 0x%lx %p is busy, retrying\n",
                         __func__, pfn, page);

                trace_cma_alloc_busy_retry(cma->name, pfn, page, count, align);
        }
out:
        if (!ret)
                *pagep = page;
        return ret;
}

static struct page *__cma_alloc_frozen(struct cma *cma,
                unsigned long count, unsigned int align, gfp_t gfp)
{
        struct page *page = NULL;
        int ret = -ENOMEM, r;
        unsigned long i;
        const char *name = cma ? cma->name : NULL;

        if (!cma || !cma->count)
                return page;

        pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
                (void *)cma, cma->name, count, align);

        if (!count)
                return page;

        trace_cma_alloc_start(name, count, cma->available_count, cma->count, align);

        for (r = 0; r < cma->nranges; r++) {
                page = NULL;

                ret = cma_range_alloc(cma, &cma->ranges[r], count, align,
                                       &page, gfp);
                if (ret != -EBUSY || page)
                        break;
        }

        /*
         * CMA can allocate multiple page blocks, which results in different
         * blocks being marked with different tags. Reset the tags to ignore
         * those page blocks.
         */
        if (page) {
                for (i = 0; i < count; i++)
                        page_kasan_tag_reset(page + i);
        }

        if (ret && !(gfp & __GFP_NOWARN)) {
                pr_err_ratelimited("%s: %s: alloc failed, req-size: %lu pages, ret: %d\n",
                                   __func__, cma->name, count, ret);
                cma_debug_show_areas(cma);
        }

        pr_debug("%s(): returned %p\n", __func__, page);
        trace_cma_alloc_finish(name, page ? page_to_pfn(page) : 0,
                               page, count, align, ret);
        if (page) {
                count_vm_event(CMA_ALLOC_SUCCESS);
                cma_sysfs_account_success_pages(cma, count);
        } else {
                count_vm_event(CMA_ALLOC_FAIL);
                cma_sysfs_account_fail_pages(cma, count);
        }

        return page;
}

struct page *cma_alloc_frozen(struct cma *cma, unsigned long count,
                unsigned int align, bool no_warn)
{
        gfp_t gfp = GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0);

        return __cma_alloc_frozen(cma, count, align, gfp);
}

struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order)
{
        gfp_t gfp = GFP_KERNEL | __GFP_COMP | __GFP_NOWARN;

        return __cma_alloc_frozen(cma, 1 << order, order, gfp);
}

/**
 * cma_alloc() - allocate pages from contiguous area
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @count: Requested number of pages.
 * @align: Requested alignment of pages (in PAGE_SIZE order).
 * @no_warn: Avoid printing message about failed allocation
 *
 * This function allocates part of contiguous memory on specific
 * contiguous memory area.
 */
struct page *cma_alloc(struct cma *cma, unsigned long count,
                       unsigned int align, bool no_warn)
{
        struct page *page;

        page = cma_alloc_frozen(cma, count, align, no_warn);
        if (page)
                set_pages_refcounted(page, count);

        return page;
}

static struct cma_memrange *find_cma_memrange(struct cma *cma,
                const struct page *pages, unsigned long count)
{
        struct cma_memrange *cmr = NULL;
        unsigned long pfn, end_pfn;
        int r;

        pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);

        if (!cma || !pages || count > cma->count)
                return NULL;

        pfn = page_to_pfn(pages);

        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                end_pfn = cmr->base_pfn + cmr->count;
                if (pfn >= cmr->base_pfn && pfn < end_pfn) {
                        if (pfn + count <= end_pfn)
                                break;

                        VM_WARN_ON_ONCE(1);
                }
        }

        if (r == cma->nranges) {
                pr_debug("%s(page %p, count %lu, no cma range matches the page range)\n",
                         __func__, (void *)pages, count);
                return NULL;
        }

        return cmr;
}

static void __cma_release_frozen(struct cma *cma, struct cma_memrange *cmr,
                const struct page *pages, unsigned long count)
{
        unsigned long pfn = page_to_pfn(pages);

        pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);

        free_contig_frozen_range(pfn, count);
        cma_clear_bitmap(cma, cmr, pfn, count);
        cma_sysfs_account_release_pages(cma, count);
        trace_cma_release(cma->name, pfn, pages, count);
}

/**
 * cma_release() - release allocated pages
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @pages: Allocated pages.
 * @count: Number of allocated pages.
 *
 * This function releases memory allocated by cma_alloc().
 * It returns false when provided pages do not belong to contiguous area and
 * true otherwise.
 */
bool cma_release(struct cma *cma, const struct page *pages,
                 unsigned long count)
{
        struct cma_memrange *cmr;
        unsigned long ret = 0;
        unsigned long i, pfn;

        cmr = find_cma_memrange(cma, pages, count);
        if (!cmr)
                return false;

        pfn = page_to_pfn(pages);
        for (i = 0; i < count; i++, pfn++)
                ret += !put_page_testzero(pfn_to_page(pfn));

        WARN(ret, "%lu pages are still in use!\n", ret);

        __cma_release_frozen(cma, cmr, pages, count);

        return true;
}

bool cma_release_frozen(struct cma *cma, const struct page *pages,
                unsigned long count)
{
        struct cma_memrange *cmr;

        cmr = find_cma_memrange(cma, pages, count);
        if (!cmr)
                return false;

        __cma_release_frozen(cma, cmr, pages, count);

        return true;
}

int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
{
        int i;

        for (i = 0; i < cma_area_count; i++) {
                int ret = it(&cma_areas[i], data);

                if (ret)
                        return ret;
        }

        return 0;
}

bool cma_intersects(struct cma *cma, unsigned long start, unsigned long end)
{
        int r;
        struct cma_memrange *cmr;
        unsigned long rstart, rend;

        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];

                rstart = PFN_PHYS(cmr->base_pfn);
                rend = PFN_PHYS(cmr->base_pfn + cmr->count);
                if (end < rstart)
                        continue;
                if (start >= rend)
                        continue;
                return true;
        }

        return false;
}

/*
 * Very basic function to reserve memory from a CMA area that has not
 * yet been activated. This is expected to be called early, when the
 * system is single-threaded, so there is no locking. The alignment
 * checking is restrictive - only pageblock-aligned areas
 * (CMA_MIN_ALIGNMENT_BYTES) may be reserved through this function.
 * This keeps things simple, and is enough for the current use case.
 *
 * The CMA bitmaps have not yet been allocated, so just start
 * reserving from the bottom up, using a PFN to keep track
 * of what has been reserved. Unreserving is not possible.
 *
 * The caller is responsible for initializing the page structures
 * in the area properly, since this just points to memblock-allocated
 * memory. The caller should subsequently use init_cma_pageblock to
 * set the migrate type and CMA stats  the pageblocks that were reserved.
 *
 * If the CMA area fails to activate later, memory obtained through
 * this interface is not handed to the page allocator, this is
 * the responsibility of the caller (e.g. like normal memblock-allocated
 * memory).
 */
void __init *cma_reserve_early(struct cma *cma, unsigned long size)
{
        int r;
        struct cma_memrange *cmr;
        unsigned long available;
        void *ret = NULL;

        if (!cma || !cma->count)
                return NULL;
        /*
         * Can only be called early in init.
         */
        if (test_bit(CMA_ACTIVATED, &cma->flags))
                return NULL;

        if (!IS_ALIGNED(size, CMA_MIN_ALIGNMENT_BYTES))
                return NULL;

        if (!IS_ALIGNED(size, (PAGE_SIZE << cma->order_per_bit)))
                return NULL;

        size >>= PAGE_SHIFT;

        if (size > cma->available_count)
                return NULL;

        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                available = cmr->count - (cmr->early_pfn - cmr->base_pfn);
                if (size <= available) {
                        ret = phys_to_virt(PFN_PHYS(cmr->early_pfn));
                        cmr->early_pfn += size;
                        cma->available_count -= size;
                        return ret;
                }
        }

        return ret;
}