/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SLAB_DEF_H
#define    _LINUX_SLAB_DEF_H

#include <linux/kfence.h>
#include <linux/reciprocal_div.h>

/*
 * Definitions unique to the original Linux SLAB allocator.
 */

struct kmem_cache {
    struct array_cache __percpu *cpu_cache;

/* 1) Cache tunables. Protected by slab_mutex */
    unsigned int batchcount;
    unsigned int limit;
    unsigned int shared;

    unsigned int size;
    struct reciprocal_value reciprocal_buffer_size;
/* 2) touched by every alloc & free from the backend */

    slab_flags_t flags;        /* constant flags */
    unsigned int num;        /* # of objs per slab */

/* 3) cache_grow/shrink */
    /* order of pgs per slab (2^n) */
    unsigned int gfporder;

    /* force GFP flags, e.g. GFP_DMA */
    gfp_t allocflags;

    size_t colour;            /* cache colouring range */
    unsigned int colour_off;    /* colour offset */
    unsigned int freelist_size;

    /* constructor func */
    void (*ctor)(void *obj);

/* 4) cache creation/removal */
    const char *name;
    struct list_head list;
    int refcount;
    int object_size;
    int align;

/* 5) statistics */
#ifdef CONFIG_DEBUG_SLAB
    unsigned long num_active;
    unsigned long num_allocations;
    unsigned long high_mark;
    unsigned long grown;
    unsigned long reaped;
    unsigned long errors;
    unsigned long max_freeable;
    unsigned long node_allocs;
    unsigned long node_frees;
    unsigned long node_overflow;
    atomic_t allochit;
    atomic_t allocmiss;
    atomic_t freehit;
    atomic_t freemiss;

    /*
     * If debugging is enabled, then the allocator can add additional
     * fields and/or padding to every object. 'size' contains the total
     * object size including these internal fields, while 'obj_offset'
     * and 'object_size' contain the offset to the user object and its
     * size.
     */
    int obj_offset;
#endif /* CONFIG_DEBUG_SLAB */

#ifdef CONFIG_KASAN_GENERIC
    struct kasan_cache kasan_info;
#endif

#ifdef CONFIG_SLAB_FREELIST_RANDOM
    unsigned int *random_seq;
#endif

#ifdef CONFIG_HARDENED_USERCOPY
    unsigned int useroffset;    /* Usercopy region offset */
    unsigned int usersize;        /* Usercopy region size */
#endif

    struct kmem_cache_node *node[MAX_NUMNODES];
};

static inline void *nearest_obj(struct kmem_cache *cache, const struct slab *slab,
                void *x)
{
    void *object = x - (x - slab->s_mem) % cache->size;
    void *last_object = slab->s_mem + (cache->num - 1) * cache->size;

    if (unlikely(object > last_object))
        return last_object;
    else
        return object;
}

/*
 * We want to avoid an expensive divide : (offset / cache->size)
 *   Using the fact that size is a constant for a particular cache,
 *   we can replace (offset / cache->size) by
 *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
 */
static inline unsigned int obj_to_index(const struct kmem_cache *cache,
                    const struct slab *slab, void *obj)
{
    u32 offset = (obj - slab->s_mem);
    return reciprocal_divide(offset, cache->reciprocal_buffer_size);
}

static inline int objs_per_slab(const struct kmem_cache *cache,
                     const struct slab *slab)
{
    if (is_kfence_address(slab_address(slab)))
        return 1;
    return cache->num;
}

#endif    /* _LINUX_SLAB_DEF_H */