queue_stack_maps.c

// SPDX-License-Identifier: GPL-2.0
/*
 * queue_stack_maps.c: BPF queue and stack maps
 *
 * Copyright (c) 2018 Politecnico di Torino
 */
#include <linux/bpf.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/btf_ids.h>
#include "percpu_freelist.h"

#define QUEUE_STACK_CREATE_FLAG_MASK \
	(BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)

struct bpf_queue_stack {
	struct bpf_map map;
	raw_spinlock_t lock;
	u32 head, tail;
	u32 size; /* max_entries + 1 */

	char elements[] __aligned(8);
};

static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
{
	return container_of(map, struct bpf_queue_stack, map);
}

static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
{
	return qs->head == qs->tail;
}

static bool queue_stack_map_is_full(struct bpf_queue_stack *qs)
{
	u32 head = qs->head + 1;

	if (unlikely(head >= qs->size))
		head = 0;

	return head == qs->tail;
}

/* Called from syscall */
static int queue_stack_map_alloc_check(union bpf_attr *attr)
{
	/* check sanity of attributes */
	if (attr->max_entries == 0 || attr->key_size != 0 ||
	    attr->value_size == 0 ||
	    attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK ||
	    !bpf_map_flags_access_ok(attr->map_flags))
		return -EINVAL;

	if (attr->value_size > KMALLOC_MAX_SIZE)
		/* if value_size is bigger, the user space won't be able to
		 * access the elements.
		 */
		return -E2BIG;

	return 0;
}

static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr)
{
	int numa_node = bpf_map_attr_numa_node(attr);
	struct bpf_queue_stack *qs;
	u64 size, queue_size;

	size = (u64) attr->max_entries + 1;