Commit 395cacb5 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Daniel Borkmann
Browse files

netdevsim: bpf: support fake map offload 



Add to netdevsim ability to pretend it's offloading BPF maps.
We only allow allocation of tiny 2 entry maps, to keep things
simple.  Mutex lock may seem heavy for the operations we
perform, but we want to make sure callbacks can sleep.

Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 064a07cb

drivers/net/netdevsim/bpf.c

+246 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/bpf_verifier.h>

#include <linux/debugfs.h>

#include <linux/kernel.h>

#include <linux/mutex.h>

#include <linux/rtnetlink.h>

#include <net/pkt_cls.h>
@@ -31,6 +32,19 @@ struct nsim_bpf_bound_prog { 
	struct list_head l;

};



#define NSIM_BPF_MAX_KEYS		2



struct nsim_bpf_bound_map {

	struct netdevsim *ns;

	struct bpf_offloaded_map *map;

	struct mutex mutex;

	struct nsim_map_entry {

		void *key;

		void *value;

	} entry[NSIM_BPF_MAX_KEYS];

	struct list_head l;

};



static int nsim_debugfs_bpf_string_read(struct seq_file *file, void *data)

{

	const char **str = file->private;
@@ -284,6 +298,224 @@ nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf) 
	return 0;

}



static bool

nsim_map_key_match(struct bpf_map *map, struct nsim_map_entry *e, void *key)

{

	return e->key && !memcmp(key, e->key, map->key_size);

}



static int nsim_map_key_find(struct bpf_offloaded_map *offmap, void *key)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	unsigned int i;



	for (i = 0; i < ARRAY_SIZE(nmap->entry); i++)

		if (nsim_map_key_match(&offmap->map, &nmap->entry[i], key))

			return i;



	return -ENOENT;

}



static int

nsim_map_alloc_elem(struct bpf_offloaded_map *offmap, unsigned int idx)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;



	nmap->entry[idx].key = kmalloc(offmap->map.key_size, GFP_USER);

	if (!nmap->entry[idx].key)

		return -ENOMEM;

	nmap->entry[idx].value = kmalloc(offmap->map.value_size, GFP_USER);

	if (!nmap->entry[idx].value) {

		kfree(nmap->entry[idx].key);

		nmap->entry[idx].key = NULL;

		return -ENOMEM;

	}



	return 0;

}



static int

nsim_map_get_next_key(struct bpf_offloaded_map *offmap,

		      void *key, void *next_key)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	int idx = -ENOENT;



	mutex_lock(&nmap->mutex);



	if (key)

		idx = nsim_map_key_find(offmap, key);

	if (idx == -ENOENT)

		idx = 0;

	else

		idx++;



	for (; idx < ARRAY_SIZE(nmap->entry); idx++) {

		if (nmap->entry[idx].key) {

			memcpy(next_key, nmap->entry[idx].key,

			       offmap->map.key_size);

			break;

		}

	}



	mutex_unlock(&nmap->mutex);



	if (idx == ARRAY_SIZE(nmap->entry))

		return -ENOENT;

	return 0;

}



static int

nsim_map_lookup_elem(struct bpf_offloaded_map *offmap, void *key, void *value)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	int idx;



	mutex_lock(&nmap->mutex);



	idx = nsim_map_key_find(offmap, key);

	if (idx >= 0)

		memcpy(value, nmap->entry[idx].value, offmap->map.value_size);



	mutex_unlock(&nmap->mutex);



	return idx < 0 ? idx : 0;

}



static int

nsim_map_update_elem(struct bpf_offloaded_map *offmap,

		     void *key, void *value, u64 flags)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	int idx, err = 0;



	mutex_lock(&nmap->mutex);



	idx = nsim_map_key_find(offmap, key);

	if (idx < 0 && flags == BPF_EXIST) {

		err = idx;

		goto exit_unlock;

	}

	if (idx >= 0 && flags == BPF_NOEXIST) {

		err = -EEXIST;

		goto exit_unlock;

	}



	if (idx < 0) {

		for (idx = 0; idx < ARRAY_SIZE(nmap->entry); idx++)

			if (!nmap->entry[idx].key)

				break;

		if (idx == ARRAY_SIZE(nmap->entry)) {

			err = -E2BIG;

			goto exit_unlock;

		}



		err = nsim_map_alloc_elem(offmap, idx);

		if (err)

			goto exit_unlock;

	}



	memcpy(nmap->entry[idx].key, key, offmap->map.key_size);

	memcpy(nmap->entry[idx].value, value, offmap->map.value_size);

exit_unlock:

	mutex_unlock(&nmap->mutex);



	return err;

}



static int nsim_map_delete_elem(struct bpf_offloaded_map *offmap, void *key)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	int idx;



	if (offmap->map.map_type == BPF_MAP_TYPE_ARRAY)

		return -EINVAL;



	mutex_lock(&nmap->mutex);



	idx = nsim_map_key_find(offmap, key);

	if (idx >= 0) {

		kfree(nmap->entry[idx].key);

		kfree(nmap->entry[idx].value);

		memset(&nmap->entry[idx], 0, sizeof(nmap->entry[idx]));

	}



	mutex_unlock(&nmap->mutex);



	return idx < 0 ? idx : 0;

}



static const struct bpf_map_dev_ops nsim_bpf_map_ops = {

	.map_get_next_key	= nsim_map_get_next_key,

	.map_lookup_elem	= nsim_map_lookup_elem,

	.map_update_elem	= nsim_map_update_elem,

	.map_delete_elem	= nsim_map_delete_elem,

};



static int

nsim_bpf_map_alloc(struct netdevsim *ns, struct bpf_offloaded_map *offmap)

{

	struct nsim_bpf_bound_map *nmap;

	unsigned int i;

	int err;



	if (WARN_ON(offmap->map.map_type != BPF_MAP_TYPE_ARRAY &&

		    offmap->map.map_type != BPF_MAP_TYPE_HASH))

		return -EINVAL;

	if (offmap->map.max_entries > NSIM_BPF_MAX_KEYS)

		return -ENOMEM;

	if (offmap->map.map_flags)

		return -EINVAL;



	nmap = kzalloc(sizeof(*nmap), GFP_USER);

	if (!nmap)

		return -ENOMEM;



	offmap->dev_priv = nmap;

	nmap->ns = ns;

	nmap->map = offmap;

	mutex_init(&nmap->mutex);



	if (offmap->map.map_type == BPF_MAP_TYPE_ARRAY) {

		for (i = 0; i < ARRAY_SIZE(nmap->entry); i++) {

			u32 *key;



			err = nsim_map_alloc_elem(offmap, i);

			if (err)

				goto err_free;

			key = nmap->entry[i].key;

			*key = i;

		}

	}



	offmap->dev_ops = &nsim_bpf_map_ops;

	list_add_tail(&nmap->l, &ns->bpf_bound_maps);



	return 0;



err_free:

	while (--i) {

		kfree(nmap->entry[i].key);

		kfree(nmap->entry[i].value);

	}

	kfree(nmap);

	return err;

}



static void nsim_bpf_map_free(struct bpf_offloaded_map *offmap)

{

	struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

	unsigned int i;



	for (i = 0; i < ARRAY_SIZE(nmap->entry); i++) {

		kfree(nmap->entry[i].key);

		kfree(nmap->entry[i].value);

	}

	list_del_init(&nmap->l);

	mutex_destroy(&nmap->mutex);

	kfree(nmap);

}



int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf)

{

	struct netdevsim *ns = netdev_priv(dev);
@@ -328,6 +560,14 @@ int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf) 
			return err;



		return nsim_xdp_set_prog(ns, bpf);

	case BPF_OFFLOAD_MAP_ALLOC:

		if (!ns->bpf_map_accept)

			return -EOPNOTSUPP;



		return nsim_bpf_map_alloc(ns, bpf->offmap);

	case BPF_OFFLOAD_MAP_FREE:

		nsim_bpf_map_free(bpf->offmap);

		return 0;

	default:

		return -EINVAL;

	}
@@ -336,6 +576,7 @@ int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf) 
int nsim_bpf_init(struct netdevsim *ns)

{

	INIT_LIST_HEAD(&ns->bpf_bound_progs);

	INIT_LIST_HEAD(&ns->bpf_bound_maps);



	debugfs_create_u32("bpf_offloaded_id", 0400, ns->ddir,

			   &ns->bpf_offloaded_id);
@@ -362,12 +603,17 @@ int nsim_bpf_init(struct netdevsim *ns) 
	debugfs_create_bool("bpf_xdpoffload_accept", 0600, ns->ddir,

			    &ns->bpf_xdpoffload_accept);



	ns->bpf_map_accept = true;

	debugfs_create_bool("bpf_map_accept", 0600, ns->ddir,

			    &ns->bpf_map_accept);



	return 0;

}



void nsim_bpf_uninit(struct netdevsim *ns)

{

	WARN_ON(!list_empty(&ns->bpf_bound_progs));

	WARN_ON(!list_empty(&ns->bpf_bound_maps));

	WARN_ON(ns->xdp_prog);

	WARN_ON(ns->bpf_offloaded);

}

drivers/net/netdevsim/netdevsim.h

+3 −0
Original line number Diff line number Diff line
@@ -61,6 +61,9 @@ struct netdevsim { 
	bool bpf_tc_non_bound_accept;

	bool bpf_xdpdrv_accept;

	bool bpf_xdpoffload_accept;



	bool bpf_map_accept;

	struct list_head bpf_bound_maps;

};



extern struct dentry *nsim_ddir;

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