/* SPDX-License-Identifier: GPL-2.0 */

  #ifndef _MM_PERCPU_INTERNAL_H
  #define _MM_PERCPU_INTERNAL_H
  
  #include <linux/types.h>
  #include <linux/percpu.h>

  /*

   * There are two chunk types: root and memcg-aware.
   * Chunks of each type have separate slots list.
   *
   * Memcg-aware chunks have an attached vector of obj_cgroup pointers, which is
   * used to store memcg membership data of a percpu object.  Obj_cgroups are
   * ref-counted pointers to a memory cgroup with an ability to switch dynamically
   * to the parent memory cgroup.  This allows to reclaim a deleted memory cgroup
   * without reclaiming of all outstanding objects, which hold a reference at it.
   */
  enum pcpu_chunk_type {
  	PCPU_CHUNK_ROOT,
  #ifdef CONFIG_MEMCG_KMEM
  	PCPU_CHUNK_MEMCG,
  #endif
  	PCPU_NR_CHUNK_TYPES,
  	PCPU_FAIL_ALLOC = PCPU_NR_CHUNK_TYPES
  };
  
  /*

   * pcpu_block_md is the metadata block struct.
   * Each chunk's bitmap is split into a number of full blocks.
   * All units are in terms of bits.

   *
   * The scan hint is the largest known contiguous area before the contig hint.
   * It is not necessarily the actual largest contig hint though.  There is an
   * invariant that the scan_hint_start > contig_hint_start iff
   * scan_hint == contig_hint.  This is necessary because when scanning forward,
   * we don't know if a new contig hint would be better than the current one.

   */
  struct pcpu_block_md {

  	int			scan_hint;	/* scan hint for block */
  	int			scan_hint_start; /* block relative starting
  						    position of the scan hint */

  	int                     contig_hint;    /* contig hint for block */
  	int                     contig_hint_start; /* block relative starting
  						      position of the contig hint */
  	int                     left_free;      /* size of free space along
  						   the left side of the block */
  	int                     right_free;     /* size of free space along
  						   the right side of the block */
  	int                     first_free;     /* block position of first free */

  	int			nr_bits;	/* total bits responsible for */

  };

  struct pcpu_chunk {

  #ifdef CONFIG_PERCPU_STATS
  	int			nr_alloc;	/* # of allocations */
  	size_t			max_alloc_size; /* largest allocation size */
  #endif

  	struct list_head	list;		/* linked to pcpu_slot lists */

  	int			free_bytes;	/* free bytes in the chunk */

  	struct pcpu_block_md	chunk_md;

  	void			*base_addr;	/* base address of this chunk */

  	unsigned long		*alloc_map;	/* allocation map */
  	unsigned long		*bound_map;	/* boundary map */

  	struct pcpu_block_md	*md_blocks;	/* metadata blocks */

  
  	void			*data;		/* chunk data */

  	bool			immutable;	/* no [de]population allowed */

  	int			start_offset;	/* the overlap with the previous
  						   region to have a page aligned
  						   base_addr */

  	int			end_offset;	/* additional area required to
  						   have the region end page
  						   aligned */

  #ifdef CONFIG_MEMCG_KMEM
  	struct obj_cgroup	**obj_cgroups;	/* vector of object cgroups */
  #endif

  
  	int			nr_pages;	/* # of pages served by this chunk */

  	int			nr_populated;	/* # of populated pages */

  	int                     nr_empty_pop_pages; /* # of empty populated pages */

  	unsigned long		populated[];	/* populated bitmap */
  };
  
  extern spinlock_t pcpu_lock;

  extern struct list_head *pcpu_chunk_lists;

  extern int pcpu_nr_slots;

  extern int pcpu_nr_empty_pop_pages;

  
  extern struct pcpu_chunk *pcpu_first_chunk;
  extern struct pcpu_chunk *pcpu_reserved_chunk;

  /**

   * pcpu_chunk_nr_blocks - converts nr_pages to # of md_blocks
   * @chunk: chunk of interest
   *
   * This conversion is from the number of physical pages that the chunk
   * serves to the number of bitmap blocks used.
   */
  static inline int pcpu_chunk_nr_blocks(struct pcpu_chunk *chunk)
  {
  	return chunk->nr_pages * PAGE_SIZE / PCPU_BITMAP_BLOCK_SIZE;
  }
  
  /**

   * pcpu_nr_pages_to_map_bits - converts the pages to size of bitmap
   * @pages: number of physical pages
   *
   * This conversion is from physical pages to the number of bits
   * required in the bitmap.
   */
  static inline int pcpu_nr_pages_to_map_bits(int pages)
  {
  	return pages * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
  }
  
  /**
   * pcpu_chunk_map_bits - helper to convert nr_pages to size of bitmap
   * @chunk: chunk of interest
   *
   * This conversion is from the number of physical pages that the chunk
   * serves to the number of bits in the bitmap.
   */
  static inline int pcpu_chunk_map_bits(struct pcpu_chunk *chunk)
  {
  	return pcpu_nr_pages_to_map_bits(chunk->nr_pages);
  }

  #ifdef CONFIG_MEMCG_KMEM
  static inline enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
  {
  	if (chunk->obj_cgroups)
  		return PCPU_CHUNK_MEMCG;
  	return PCPU_CHUNK_ROOT;
  }
  
  static inline bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
  {
  	return chunk_type == PCPU_CHUNK_MEMCG;
  }
  
  #else
  static inline enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
  {
  	return PCPU_CHUNK_ROOT;
  }
  
  static inline bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
  {
  	return false;
  }
  #endif
  
  static inline struct list_head *pcpu_chunk_list(enum pcpu_chunk_type chunk_type)
  {
  	return &pcpu_chunk_lists[pcpu_nr_slots *
  				 pcpu_is_memcg_chunk(chunk_type)];
  }

  #ifdef CONFIG_PERCPU_STATS
  
  #include <linux/spinlock.h>
  
  struct percpu_stats {
  	u64 nr_alloc;		/* lifetime # of allocations */
  	u64 nr_dealloc;		/* lifetime # of deallocations */
  	u64 nr_cur_alloc;	/* current # of allocations */
  	u64 nr_max_alloc;	/* max # of live allocations */
  	u32 nr_chunks;		/* current # of live chunks */
  	u32 nr_max_chunks;	/* max # of live chunks */
  	size_t min_alloc_size;	/* min allocaiton size */
  	size_t max_alloc_size;	/* max allocation size */
  };
  
  extern struct percpu_stats pcpu_stats;
  extern struct pcpu_alloc_info pcpu_stats_ai;
  
  /*
   * For debug purposes. We don't care about the flexible array.
   */
  static inline void pcpu_stats_save_ai(const struct pcpu_alloc_info *ai)
  {
  	memcpy(&pcpu_stats_ai, ai, sizeof(struct pcpu_alloc_info));
  
  	/* initialize min_alloc_size to unit_size */
  	pcpu_stats.min_alloc_size = pcpu_stats_ai.unit_size;
  }
  
  /*
   * pcpu_stats_area_alloc - increment area allocation stats
   * @chunk: the location of the area being allocated
   * @size: size of area to allocate in bytes
   *
   * CONTEXT:
   * pcpu_lock.
   */
  static inline void pcpu_stats_area_alloc(struct pcpu_chunk *chunk, size_t size)
  {
  	lockdep_assert_held(&pcpu_lock);
  
  	pcpu_stats.nr_alloc++;
  	pcpu_stats.nr_cur_alloc++;
  	pcpu_stats.nr_max_alloc =
  		max(pcpu_stats.nr_max_alloc, pcpu_stats.nr_cur_alloc);
  	pcpu_stats.min_alloc_size =
  		min(pcpu_stats.min_alloc_size, size);
  	pcpu_stats.max_alloc_size =
  		max(pcpu_stats.max_alloc_size, size);
  
  	chunk->nr_alloc++;
  	chunk->max_alloc_size = max(chunk->max_alloc_size, size);
  }
  
  /*
   * pcpu_stats_area_dealloc - decrement allocation stats
   * @chunk: the location of the area being deallocated
   *
   * CONTEXT:
   * pcpu_lock.
   */
  static inline void pcpu_stats_area_dealloc(struct pcpu_chunk *chunk)
  {
  	lockdep_assert_held(&pcpu_lock);
  
  	pcpu_stats.nr_dealloc++;
  	pcpu_stats.nr_cur_alloc--;
  
  	chunk->nr_alloc--;
  }
  
  /*
   * pcpu_stats_chunk_alloc - increment chunk stats
   */
  static inline void pcpu_stats_chunk_alloc(void)
  {

  	unsigned long flags;
  	spin_lock_irqsave(&pcpu_lock, flags);

  
  	pcpu_stats.nr_chunks++;
  	pcpu_stats.nr_max_chunks =
  		max(pcpu_stats.nr_max_chunks, pcpu_stats.nr_chunks);

  	spin_unlock_irqrestore(&pcpu_lock, flags);

  }
  
  /*
   * pcpu_stats_chunk_dealloc - decrement chunk stats
   */
  static inline void pcpu_stats_chunk_dealloc(void)
  {

  	unsigned long flags;
  	spin_lock_irqsave(&pcpu_lock, flags);

  
  	pcpu_stats.nr_chunks--;

  	spin_unlock_irqrestore(&pcpu_lock, flags);

  }
  
  #else
  
  static inline void pcpu_stats_save_ai(const struct pcpu_alloc_info *ai)
  {
  }
  
  static inline void pcpu_stats_area_alloc(struct pcpu_chunk *chunk, size_t size)
  {
  }
  
  static inline void pcpu_stats_area_dealloc(struct pcpu_chunk *chunk)
  {
  }
  
  static inline void pcpu_stats_chunk_alloc(void)
  {
  }
  
  static inline void pcpu_stats_chunk_dealloc(void)
  {
  }
  
  #endif /* !CONFIG_PERCPU_STATS */

  #endif