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

/*
 * SLUB : A Slab allocator without object queues.
 *
 * (C) 2007 SGI, Christoph Lameter
 */
#include <linux/kfence.h>
#include <linux/kobject.h>
#include <linux/reciprocal_div.h>
#include <linux/local_lock.h>

enum stat_item {
    ALLOC_FASTPATH,        /* Allocation from cpu slab */
    ALLOC_SLOWPATH,        /* Allocation by getting a new cpu slab */
    FREE_FASTPATH,        /* Free to cpu slab */
    FREE_SLOWPATH,        /* Freeing not to cpu slab */
    FREE_FROZEN,        /* Freeing to frozen slab */
    FREE_ADD_PARTIAL,    /* Freeing moves slab to partial list */
    FREE_REMOVE_PARTIAL,    /* Freeing removes last object */
    ALLOC_FROM_PARTIAL,    /* Cpu slab acquired from node partial list */
    ALLOC_SLAB,        /* Cpu slab acquired from page allocator */
    ALLOC_REFILL,        /* Refill cpu slab from slab freelist */
    ALLOC_NODE_MISMATCH,    /* Switching cpu slab */
    FREE_SLAB,        /* Slab freed to the page allocator */
    CPUSLAB_FLUSH,        /* Abandoning of the cpu slab */
    DEACTIVATE_FULL,    /* Cpu slab was full when deactivated */
    DEACTIVATE_EMPTY,    /* Cpu slab was empty when deactivated */
    DEACTIVATE_TO_HEAD,    /* Cpu slab was moved to the head of partials */
    DEACTIVATE_TO_TAIL,    /* Cpu slab was moved to the tail of partials */
    DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
    DEACTIVATE_BYPASS,    /* Implicit deactivation */
    ORDER_FALLBACK,        /* Number of times fallback was necessary */
    CMPXCHG_DOUBLE_CPU_FAIL,/* Failure of this_cpu_cmpxchg_double */
    CMPXCHG_DOUBLE_FAIL,    /* Number of times that cmpxchg double did not match */
    CPU_PARTIAL_ALLOC,    /* Used cpu partial on alloc */
    CPU_PARTIAL_FREE,    /* Refill cpu partial on free */
    CPU_PARTIAL_NODE,    /* Refill cpu partial from node partial */
    CPU_PARTIAL_DRAIN,    /* Drain cpu partial to node partial */
    NR_SLUB_STAT_ITEMS
};

#ifndef CONFIG_SLUB_TINY
/*
 * When changing the layout, make sure freelist and tid are still compatible
 * with this_cpu_cmpxchg_double() alignment requirements.
 */
struct kmem_cache_cpu {
    union {
        struct {
            void **freelist;    /* Pointer to next available object */
            unsigned long tid;    /* Globally unique transaction id */
        };
        freelist_aba_t freelist_tid;
    };
    struct slab *slab;    /* The slab from which we are allocating */
#ifdef CONFIG_SLUB_CPU_PARTIAL
    struct slab *partial;    /* Partially allocated frozen slabs */
#endif
    local_lock_t lock;    /* Protects the fields above */
#ifdef CONFIG_SLUB_STATS
    unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
};
#endif /* CONFIG_SLUB_TINY */

#ifdef CONFIG_SLUB_CPU_PARTIAL
#define slub_percpu_partial(c)        ((c)->partial)

#define slub_set_percpu_partial(c, p)        \
({                        \
    slub_percpu_partial(c) = (p)->next;    \
})

#define slub_percpu_partial_read_once(c)     READ_ONCE(slub_percpu_partial(c))
#else
#define slub_percpu_partial(c)            NULL

#define slub_set_percpu_partial(c, p)

#define slub_percpu_partial_read_once(c)    NULL
#endif // CONFIG_SLUB_CPU_PARTIAL

/*
 * Word size structure that can be atomically updated or read and that
 * contains both the order and the number of objects that a slab of the
 * given order would contain.
 */
struct kmem_cache_order_objects {
    unsigned int x;
};

/*
 * Slab cache management.
 */
struct kmem_cache {
#ifndef CONFIG_SLUB_TINY
    struct kmem_cache_cpu __percpu *cpu_slab;
#endif
    /* Used for retrieving partial slabs, etc. */
    slab_flags_t flags;
    unsigned long min_partial;
    unsigned int size;    /* The size of an object including metadata */
    unsigned int object_size;/* The size of an object without metadata */
    struct reciprocal_value reciprocal_size;
    unsigned int offset;    /* Free pointer offset */
#ifdef CONFIG_SLUB_CPU_PARTIAL
    /* Number of per cpu partial objects to keep around */
    unsigned int cpu_partial;
    /* Number of per cpu partial slabs to keep around */
    unsigned int cpu_partial_slabs;
#endif
    struct kmem_cache_order_objects oo;

    /* Allocation and freeing of slabs */
    struct kmem_cache_order_objects min;
    gfp_t allocflags;    /* gfp flags to use on each alloc */
    int refcount;        /* Refcount for slab cache destroy */
    void (*ctor)(void *);
    unsigned int inuse;        /* Offset to metadata */
    unsigned int align;        /* Alignment */
    unsigned int red_left_pad;    /* Left redzone padding size */
    const char *name;    /* Name (only for display!) */
    struct list_head list;    /* List of slab caches */
#ifdef CONFIG_SYSFS
    struct kobject kobj;    /* For sysfs */
#endif
#ifdef CONFIG_SLAB_FREELIST_HARDENED
    unsigned long random;
#endif

#ifdef CONFIG_NUMA
    /*
     * Defragmentation by allocating from a remote node.
     */
    unsigned int remote_node_defrag_ratio;
#endif

#ifdef CONFIG_SLAB_FREELIST_RANDOM
    unsigned int *random_seq;
#endif

#ifdef CONFIG_KASAN_GENERIC
    struct kasan_cache kasan_info;
#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];
};

#if defined(CONFIG_SYSFS) && !defined(CONFIG_SLUB_TINY)
#define SLAB_SUPPORTS_SYSFS
void sysfs_slab_unlink(struct kmem_cache *);
void sysfs_slab_release(struct kmem_cache *);
#else
static inline void sysfs_slab_unlink(struct kmem_cache *s)
{
}
static inline void sysfs_slab_release(struct kmem_cache *s)
{
}
#endif

void *fixup_red_left(struct kmem_cache *s, void *p);

static inline void *nearest_obj(struct kmem_cache *cache, const struct slab *slab,
                void *x) {
    void *object = x - (x - slab_address(slab)) % cache->size;
    void *last_object = slab_address(slab) +
        (slab->objects - 1) * cache->size;
    void *result = (unlikely(object > last_object)) ? last_object : object;

    result = fixup_red_left(cache, result);
    return result;
}

/* Determine object index from a given position */
static inline unsigned int __obj_to_index(const struct kmem_cache *cache,
                      void *addr, void *obj)
{
    return reciprocal_divide(kasan_reset_tag(obj) - addr,
                 cache->reciprocal_size);
}

static inline unsigned int obj_to_index(const struct kmem_cache *cache,
                    const struct slab *slab, void *obj)
{
    if (is_kfence_address(obj))
        return 0;
    return __obj_to_index(cache, slab_address(slab), obj);
}

static inline int objs_per_slab(const struct kmem_cache *cache,
                     const struct slab *slab)
{
    return slab->objects;
}
#endif /* _LINUX_SLUB_DEF_H */