/* 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