// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Facebook
 */
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>

#include "map_in_map.h"

struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
{
        struct bpf_map *inner_map, *inner_map_meta;
        u32 inner_map_meta_size;
        CLASS(fd, f)(inner_map_ufd);

        inner_map = __bpf_map_get(f);
        if (IS_ERR(inner_map))
                return inner_map;

        /* Does not support >1 level map-in-map */
        if (inner_map->inner_map_meta)
                return ERR_PTR(-EINVAL);

        if (!inner_map->ops->map_meta_equal)
                return ERR_PTR(-ENOTSUPP);

        inner_map_meta_size = sizeof(*inner_map_meta);
        /* In some cases verifier needs to access beyond just base map. */
        if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops)
                inner_map_meta_size = sizeof(struct bpf_array);

        inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
        if (!inner_map_meta)
                return ERR_PTR(-ENOMEM);

        inner_map_meta->map_type = inner_map->map_type;
        inner_map_meta->key_size = inner_map->key_size;
        inner_map_meta->value_size = inner_map->value_size;
        inner_map_meta->map_flags = inner_map->map_flags;
        inner_map_meta->max_entries = inner_map->max_entries;

        inner_map_meta->record = btf_record_dup(inner_map->record);
        if (IS_ERR(inner_map_meta->record)) {
                /* btf_record_dup returns NULL or valid pointer in case of
                 * invalid/empty/valid, but ERR_PTR in case of errors. During
                 * equality NULL or IS_ERR is equivalent.
                 */
                struct bpf_map *ret = ERR_CAST(inner_map_meta->record);
                kfree(inner_map_meta);
                return ret;
        }
        /* Note: We must use the same BTF, as we also used btf_record_dup above
         * which relies on BTF being same for both maps, as some members like
         * record->fields.list_head have pointers like value_rec pointing into
         * inner_map->btf.
         */
        if (inner_map->btf) {
                btf_get(inner_map->btf);
                inner_map_meta->btf = inner_map->btf;
        }

        /* Misc members not needed in bpf_map_meta_equal() check. */
        inner_map_meta->ops = inner_map->ops;
        if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops) {
                struct bpf_array *inner_array_meta =
                        container_of(inner_map_meta, struct bpf_array, map);
                struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map);

                inner_array_meta->index_mask = inner_array->index_mask;
                inner_array_meta->elem_size = inner_array->elem_size;
                inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
        }
        return inner_map_meta;
}

void bpf_map_meta_free(struct bpf_map *map_meta)
{
        bpf_map_free_record(map_meta);
        btf_put(map_meta->btf);
        kfree(map_meta);
}

bool bpf_map_meta_equal(const struct bpf_map *meta0,
                        const struct bpf_map *meta1)
{
        /* No need to compare ops because it is covered by map_type */
        return meta0->map_type == meta1->map_type &&
                meta0->key_size == meta1->key_size &&
                meta0->value_size == meta1->value_size &&
                meta0->map_flags == meta1->map_flags &&
                btf_record_equal(meta0->record, meta1->record);
}

void *bpf_map_fd_get_ptr(struct bpf_map *map,
                         struct file *map_file /* not used */,
                         int ufd)
{
        struct bpf_map *inner_map, *inner_map_meta;
        CLASS(fd, f)(ufd);

        inner_map = __bpf_map_get(f);
        if (IS_ERR(inner_map))
                return inner_map;

        inner_map_meta = map->inner_map_meta;
        if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
                bpf_map_inc(inner_map);
        else
                inner_map = ERR_PTR(-EINVAL);

        return inner_map;
}

void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
{
        struct bpf_map *inner_map = ptr;

        /* Defer the freeing of inner map according to the sleepable attribute
         * of bpf program which owns the outer map, so unnecessary waiting for
         * RCU tasks trace grace period can be avoided.
         */
        if (need_defer) {
                if (atomic64_read(&map->sleepable_refcnt))
                        WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true);
                else
                        WRITE_ONCE(inner_map->free_after_rcu_gp, true);
        }
        bpf_map_put(inner_map);
}

u32 bpf_map_fd_sys_lookup_elem(void *ptr)
{
        return ((struct bpf_map *)ptr)->id;
}