text: /*
   * 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>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License or (at your optional) any later version of the license.
   */
  
  #define pr_fmt(fmt) "cma: " fmt
  
  #ifdef CONFIG_CMA_DEBUG
  #ifndef DEBUG
  #  define DEBUG
  #endif
  #endif
  #define CREATE_TRACE_POINTS
  
  #include <linux/memblock.h>
  #include <linux/err.h>
  #include <linux/mm.h>
  #include <linux/mutex.h>
  #include <linux/sizes.h>
  #include <linux/slab.h>
  #include <linux/log2.h>
  #include <linux/cma.h>
  #include <linux/highmem.h>
  #include <linux/io.h>
  #include <trace/events/cma.h>
  
  #include "cma.h"
  
  struct cma cma_areas[MAX_CMA_AREAS];
  unsigned cma_area_count;
  static DEFINE_MUTEX(cma_mutex);
  
  phys_addr_t cma_get_base(const struct cma *cma)
  {
  	return PFN_PHYS(cma->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 ? cma->name : "(undefined)";
  }
  
  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,
  					       unsigned int align_order)
  {
  	return (cma->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, unsigned long pfn,
  			     unsigned int count)
  {
  	unsigned long bitmap_no, bitmap_count;
  
  	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
  	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
  
  	mutex_lock(&cma->lock);
  	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
  	mutex_unlock(&cma->lock);
  }
  
  static int __init cma_activate_area(struct cma *cma)
  {
  	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
  	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
  	unsigned i = cma->count >> pageblock_order;
  	struct zone *zone;
  
  	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  
  	if (!cma->bitmap)
  		return -ENOMEM;
  
  	WARN_ON_ONCE(!pfn_valid(pfn));
  	zone = page_zone(pfn_to_page(pfn));
  
  	do {
  		unsigned j;
  
  		base_pfn = pfn;
  		for (j = pageblock_nr_pages; j; --j, pfn++) {
  			WARN_ON_ONCE(!pfn_valid(pfn));
  			/*
  			 * alloc_contig_range requires the pfn range
  			 * specified to be in the same zone. Make this
  			 * simple by forcing the entire CMA resv range
  			 * to be in the same zone.
  			 */
  			if (page_zone(pfn_to_page(pfn)) != zone)
  				goto not_in_zone;
  		}
  		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
  	} while (--i);
  
  	mutex_init(&cma->lock);
  
  #ifdef CONFIG_CMA_DEBUGFS
  	INIT_HLIST_HEAD(&cma->mem_head);
  	spin_lock_init(&cma->mem_head_lock);
  #endif
  
  	return 0;
  
  not_in_zone:
  	pr_err("CMA area %s could not be activated\n", cma->name);
  	kfree(cma->bitmap);
  	cma->count = 0;
  	return -EINVAL;
  }
  
  static int __init cma_init_reserved_areas(void)
  {
  	int i;
  
  	for (i = 0; i < cma_area_count; i++) {
  		int ret = cma_activate_area(&cma_areas[i]);
  
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  core_initcall(cma_init_reserved_areas);
  
  /**
   * 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.
   * @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;
  	phys_addr_t alignment;
  
  	/* Sanity checks */
  	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
  		pr_err("Not enough slots for CMA reserved regions!\n");
  		return -ENOSPC;
  	}
  
  	if (!size || !memblock_is_region_reserved(base, size))
  		return -EINVAL;
  
  	/* ensure minimal alignment required by mm core */
  	alignment = PAGE_SIZE <<
  			max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
  
  	/* alignment should be aligned with order_per_bit */
  	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
  		return -EINVAL;
  
  	if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
  		return -EINVAL;
  
  	/*
  	 * Each reserved area must be initialised later, when more kernel
  	 * subsystems (like slab allocator) are available.
  	 */
  	cma = &cma_areas[cma_area_count];
  	if (name) {
  		cma->name = name;
  	} else {
  		cma->name = kasprintf(GFP_KERNEL, "cma%d\n", cma_area_count);
  		if (!cma->name)
  			return -ENOMEM;
  	}
  	cma->base_pfn = PFN_DOWN(base);
  	cma->count = size >> PAGE_SHIFT;
  	cma->order_per_bit = order_per_bit;
  	*res_cma = cma;
  	cma_area_count++;
  	totalcma_pages += (size / PAGE_SIZE);
  
  	return 0;
  }
  
  /**
   * cma_declare_contiguous() - 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
   * @res_cma: Pointer to store the created cma region.
   *
   * 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(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)
  {
  	phys_addr_t memblock_end = memblock_end_of_DRAM();
  	phys_addr_t highmem_start;
  	int ret = 0;
  
  	/*
  	 * We can't use __pa(high_memory) directly, since high_memory
  	 * isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
  	 * complain. Find the boundary by adding one to the last valid
  	 * address.
  	 */
  	highmem_start = __pa(high_memory - 1) + 1;
  	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;
  
  	/*
  	 * Sanitise input arguments.
  	 * Pages both ends in CMA area could be merged into adjacent unmovable
  	 * migratetype page by page allocator's buddy algorithm. In the case,
  	 * you couldn't get a contiguous memory, which is not what we want.
  	 */
  	alignment = max(alignment,  (phys_addr_t)PAGE_SIZE <<
  			  max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
  	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 allocating at a fixed base the request region must not cross the
  	 * low/high memory boundary.
  	 */
  	if (fixed && base < highmem_start && base + size > highmem_start) {
  		ret = -EINVAL;
  		pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
  			&base, &highmem_start);
  		goto err;
  	}
  
  	/*
  	 * 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;
  
  	/* Reserve memory */
  	if (fixed) {
  		if (memblock_is_region_reserved(base, size) ||
  		    memblock_reserve(base, size) < 0) {
  			ret = -EBUSY;
  			goto err;
  		}
  	} else {
  		phys_addr_t addr = 0;
  
  		/*
  		 * 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_start && limit > highmem_start) {
  			addr = memblock_alloc_range(size, alignment,
  						    highmem_start, limit,
  						    MEMBLOCK_NONE);
  			limit = highmem_start;
  		}
  
  		if (!addr) {
  			addr = memblock_alloc_range(size, alignment, base,
  						    limit,
  						    MEMBLOCK_NONE);
  			if (!addr) {
  				ret = -ENOMEM;
  				goto err;
  			}
  		}
  
  		/*
  		 * kmemleak scans/reads tracked objects for pointers to other
  		 * objects but this address isn't mapped and accessible
  		 */
  		kmemleak_ignore_phys(addr);
  		base = addr;
  	}
  
  	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
  	if (ret)
  		goto err;
  
  	pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
  		&base);
  	return 0;
  
  err:
  	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
  	return ret;
  }
  
  #ifdef CONFIG_CMA_DEBUG
  static void cma_debug_show_areas(struct cma *cma)
  {
  	unsigned long next_zero_bit, next_set_bit;
  	unsigned long start = 0;
  	unsigned int nr_zero, nr_total = 0;
  
  	mutex_lock(&cma->lock);
  	pr_info("number of available pages: ");
  	for (;;) {
  		next_zero_bit = find_next_zero_bit(cma->bitmap, cma->count, start);
  		if (next_zero_bit >= cma->count)
  			break;
  		next_set_bit = find_next_bit(cma->bitmap, cma->count, next_zero_bit);
  		nr_zero = next_set_bit - next_zero_bit;
  		pr_cont("%s%u@%lu", nr_total ? "+" : "", nr_zero, next_zero_bit);
  		nr_total += nr_zero;
  		start = next_zero_bit + nr_zero;
  	}
  	pr_cont("=> %u free of %lu total pages\n", nr_total, cma->count);
  	mutex_unlock(&cma->lock);
  }
  #else
  static inline void cma_debug_show_areas(struct cma *cma) { }
  #endif
  
  /**
   * 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).
   *
   * This function allocates part of contiguous memory on specific
   * contiguous memory area.
   */
  struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
  		       gfp_t gfp_mask)
  {
  	unsigned long mask, offset;
  	unsigned long pfn = -1;
  	unsigned long start = 0;
  	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
  	struct page *page = NULL;
  	int ret = -ENOMEM;
  
  	if (!cma || !cma->count)
  		return NULL;
  
  	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
  		 count, align);
  
  	if (!count)
  		return NULL;
  
  	mask = cma_bitmap_aligned_mask(cma, align);
  	offset = cma_bitmap_aligned_offset(cma, align);
  	bitmap_maxno = cma_bitmap_maxno(cma);
  	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
  
  	if (bitmap_count > bitmap_maxno)
  		return NULL;
  
  	for (;;) {
  		mutex_lock(&cma->lock);
  		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
  				bitmap_maxno, start, bitmap_count, mask,
  				offset);
  		if (bitmap_no >= bitmap_maxno) {
  			mutex_unlock(&cma->lock);
  			break;
  		}
  		bitmap_set(cma->bitmap, bitmap_no, bitmap_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.
  		 */
  		mutex_unlock(&cma->lock);
  
  		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
  		mutex_lock(&cma_mutex);
  		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
  					 gfp_mask);
  		mutex_unlock(&cma_mutex);
  		if (ret == 0) {
  			page = pfn_to_page(pfn);
  			break;
  		}
  
  		cma_clear_bitmap(cma, pfn, count);
  		if (ret != -EBUSY)
  			break;
  
  		pr_debug("%s(): memory range at %p is busy, retrying\n",
  			 __func__, pfn_to_page(pfn));
  		/* try again with a bit different memory target */
  		start = bitmap_no + mask + 1;
  	}
  
  	trace_cma_alloc(pfn, page, count, align);
  
  	if (ret && !(gfp_mask & __GFP_NOWARN)) {
  		pr_err("%s: alloc failed, req-size: %zu pages, ret: %d\n",
  			__func__, count, ret);
  		cma_debug_show_areas(cma);
  	}
  
  	pr_debug("%s(): returned %p\n", __func__, page);
  	return page;
  }
  
  /**
   * 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 alloc_cma().
   * 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 int count)
  {
  	unsigned long pfn;
  
  	if (!cma || !pages)
  		return false;
  
  	pr_debug("%s(page %p)\n", __func__, (void *)pages);
  
  	pfn = page_to_pfn(pages);
  
  	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
  		return false;
  
  	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
  
  	free_contig_range(pfn, count);
  	cma_clear_bitmap(cma, pfn, count);
  	trace_cma_release(pfn, 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;
  }
  