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/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
#pragma once
#include <errno.h>
#include "bpf_arena_alloc.h"
#include "bpf_arena_list.h"
struct htab_bucket {
struct arena_list_head head;
};
typedef struct htab_bucket __arena htab_bucket_t;
struct htab {
htab_bucket_t *buckets;
int n_buckets;
};
typedef struct htab __arena htab_t;
static inline htab_bucket_t *__select_bucket(htab_t *htab, __u32 hash)
{
htab_bucket_t *b = htab->buckets;
cast_kern(b);
return &b[hash & (htab->n_buckets - 1)];
}
static inline arena_list_head_t *select_bucket(htab_t *htab, __u32 hash)
{
return &__select_bucket(htab, hash)->head;
}
struct hashtab_elem {
int hash;
int key;
int value;
struct arena_list_node hash_node;
};
typedef struct hashtab_elem __arena hashtab_elem_t;
static hashtab_elem_t *lookup_elem_raw(arena_list_head_t *head, __u32 hash, int key)
{
hashtab_elem_t *l;
list_for_each_entry(l, head, hash_node)
if (l->hash == hash && l->key == key)
return l;
return NULL;
}
static int htab_hash(int key)
{
return key;
}
__weak int htab_lookup_elem(htab_t *htab __arg_arena, int key)
{
hashtab_elem_t *l_old;
arena_list_head_t *head;
cast_kern(htab);
head = select_bucket(htab, key);
l_old = lookup_elem_raw(head, htab_hash(key), key);
if (l_old)
return l_old->value;
return 0;
}
__weak int htab_update_elem(htab_t *htab __arg_arena, int key, int value)
{
hashtab_elem_t *l_new = NULL, *l_old;
arena_list_head_t *head;
cast_kern(htab);
head = select_bucket(htab, key);
l_old = lookup_elem_raw(head, htab_hash(key), key);
l_new = bpf_alloc(sizeof(*l_new));
if (!l_new)
return -ENOMEM;
l_new->key = key;
l_new->hash = htab_hash(key);
l_new->value = value;
list_add_head(&l_new->hash_node, head);
if (l_old) {
list_del(&l_old->hash_node);
bpf_free(l_old);
}
return 0;
}
void htab_init(htab_t *htab)
{
void __arena *buckets = bpf_arena_alloc_pages(&arena, NULL, 2, NUMA_NO_NODE, 0);
cast_user(buckets);
htab->buckets = buckets;
htab->n_buckets = 2 * PAGE_SIZE / sizeof(struct htab_bucket);
}
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