Merge branch 'ebpf_maps'

Alexei Starovoitov says:

====================
implementation of eBPF maps

v1->v2:
renamed flags for MAP_UPDATE_ELEM command to be more concise,
clarified commit logs and improved comments in patches 1,3,7
per discussions with Daniel

Old v1 cover:

this set of patches adds implementation of HASH and ARRAY types of eBPF maps
which were described in manpage in commit b4fc1a46("Merge branch 'bpf-next'")

The difference vs previous version of these patches from August:
- added 'flags' attribute to BPF_MAP_UPDATE_ELEM
- in HASH type implementation removed per-map kmem_cache.
  I was doing kmem_cache_create() for every map to enable selective slub
  debugging to check for overflows and leaks. Now it's not needed, so just
  use normal kmalloc() for map elements.
- added ARRAY type which was mentioned in manpage, but wasn't public yet
- added map testsuite and removed temporary bits from test_stubs

Note, eBPF programs cannot be attached to events yet.
It will come in the next set.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/bpf.h

@@ -22,7 +22,7 @@ struct bpf_map_ops {
 
 	/* funcs callable from userspace and from eBPF programs */
 	void *(*map_lookup_elem)(struct bpf_map *map, void *key);
-	int (*map_update_elem)(struct bpf_map *map, void *key, void *value);
+	int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
 	int (*map_delete_elem)(struct bpf_map *map, void *key);
 };
 
@@ -133,4 +133,9 @@ struct bpf_prog *bpf_prog_get(u32 ufd);
 /* verify correctness of eBPF program */
 int bpf_check(struct bpf_prog *fp, union bpf_attr *attr);
 
+/* verifier prototypes for helper functions called from eBPF programs */
+extern struct bpf_func_proto bpf_map_lookup_elem_proto;
+extern struct bpf_func_proto bpf_map_update_elem_proto;
+extern struct bpf_func_proto bpf_map_delete_elem_proto;
+
 #endif /* _LINUX_BPF_H */

include/uapi/linux/bpf.h

@@ -82,7 +82,7 @@ enum bpf_cmd {
 
 	/* create or update key/value pair in a given map
 	 * err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)
-	 * Using attr->map_fd, attr->key, attr->value
+	 * Using attr->map_fd, attr->key, attr->value, attr->flags
 	 * returns zero or negative error
 	 */
 	BPF_MAP_UPDATE_ELEM,
@@ -111,12 +111,19 @@ enum bpf_cmd {
 
 enum bpf_map_type {
 	BPF_MAP_TYPE_UNSPEC,
+	BPF_MAP_TYPE_HASH,
+	BPF_MAP_TYPE_ARRAY,
 };
 
 enum bpf_prog_type {
 	BPF_PROG_TYPE_UNSPEC,
 };
 
+/* flags for BPF_MAP_UPDATE_ELEM command */
+#define BPF_ANY		0 /* create new element or update existing */
+#define BPF_NOEXIST	1 /* create new element if it didn't exist */
+#define BPF_EXIST	2 /* update existing element */
+
 union bpf_attr {
 	struct { /* anonymous struct used by BPF_MAP_CREATE command */
 		__u32	map_type;	/* one of enum bpf_map_type */
@@ -132,6 +139,7 @@ union bpf_attr {
 			__aligned_u64 value;
 			__aligned_u64 next_key;
 		};
+		__u64		flags;
 	};
 
 	struct { /* anonymous struct used by BPF_PROG_LOAD command */
@@ -150,6 +158,9 @@ union bpf_attr {
  */
 enum bpf_func_id {
 	BPF_FUNC_unspec,
+	BPF_FUNC_map_lookup_elem, /* void *map_lookup_elem(&map, &key) */
+	BPF_FUNC_map_update_elem, /* int map_update_elem(&map, &key, &value, flags) */
+	BPF_FUNC_map_delete_elem, /* int map_delete_elem(&map, &key) */
 	__BPF_FUNC_MAX_ID,
 };
 

kernel/bpf/Makefile

 obj-y := core.o
-obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o
+obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o hashtab.o arraymap.o helpers.o
 ifdef CONFIG_TEST_BPF
 obj-$(CONFIG_BPF_SYSCALL) += test_stub.o
 endif

kernel/bpf/arraymap.c

+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bpf.h>
+#include <linux/err.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+struct bpf_array {
+	struct bpf_map map;
+	u32 elem_size;
+	char value[0] __aligned(8);
+};
+
+/* Called from syscall */
+static struct bpf_map *array_map_alloc(union bpf_attr *attr)
+{
+	struct bpf_array *array;
+	u32 elem_size;
+
+	/* check sanity of attributes */
+	if (attr->max_entries == 0 || attr->key_size != 4 ||
+	    attr->value_size == 0)
+		return ERR_PTR(-EINVAL);
+
+	elem_size = round_up(attr->value_size, 8);
+
+	/* allocate all map elements and zero-initialize them */
+	array = kzalloc(sizeof(*array) + attr->max_entries * elem_size,
+			GFP_USER | __GFP_NOWARN);
+	if (!array) {
+		array = vzalloc(array->map.max_entries * array->elem_size);
+		if (!array)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	/* copy mandatory map attributes */
+	array->map.key_size = attr->key_size;
+	array->map.value_size = attr->value_size;
+	array->map.max_entries = attr->max_entries;
+
+	array->elem_size = elem_size;
+
+	return &array->map;
+
+}
+
+/* Called from syscall or from eBPF program */
+static void *array_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	u32 index = *(u32 *)key;
+
+	if (index >= array->map.max_entries)
+		return NULL;
+
+	return array->value + array->elem_size * index;
+}
+
+/* Called from syscall */
+static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	u32 index = *(u32 *)key;
+	u32 *next = (u32 *)next_key;
+
+	if (index >= array->map.max_entries) {
+		*next = 0;
+		return 0;
+	}
+
+	if (index == array->map.max_entries - 1)
+		return -ENOENT;
+
+	*next = index + 1;
+	return 0;
+}
+
+/* Called from syscall or from eBPF program */
+static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
+				 u64 map_flags)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	u32 index = *(u32 *)key;
+
+	if (map_flags > BPF_EXIST)
+		/* unknown flags */
+		return -EINVAL;
+
+	if (index >= array->map.max_entries)
+		/* all elements were pre-allocated, cannot insert a new one */
+		return -E2BIG;
+
+	if (map_flags == BPF_NOEXIST)
+		/* all elemenets already exist */
+		return -EEXIST;
+
+	memcpy(array->value + array->elem_size * index, value, array->elem_size);
+	return 0;
+}
+
+/* Called from syscall or from eBPF program */
+static int array_map_delete_elem(struct bpf_map *map, void *key)
+{
+	return -EINVAL;
+}
+
+/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
+static void array_map_free(struct bpf_map *map)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+
+	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
+	 * so the programs (can be more than one that used this map) were
+	 * disconnected from events. Wait for outstanding programs to complete
+	 * and free the array
+	 */
+	synchronize_rcu();
+
+	kvfree(array);
+}
+
+static struct bpf_map_ops array_ops = {
+	.map_alloc = array_map_alloc,
+	.map_free = array_map_free,
+	.map_get_next_key = array_map_get_next_key,
+	.map_lookup_elem = array_map_lookup_elem,
+	.map_update_elem = array_map_update_elem,
+	.map_delete_elem = array_map_delete_elem,
+};
+
+static struct bpf_map_type_list tl = {
+	.ops = &array_ops,
+	.type = BPF_MAP_TYPE_ARRAY,
+};
+
+static int __init register_array_map(void)
+{
+	bpf_register_map_type(&tl);
+	return 0;
+}
+late_initcall(register_array_map);

kernel/bpf/hashtab.c

+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bpf.h>
+#include <linux/jhash.h>
+#include <linux/filter.h>
+#include <linux/vmalloc.h>
+
+struct bpf_htab {
+	struct bpf_map map;
+	struct hlist_head *buckets;
+	spinlock_t lock;
+	u32 count;	/* number of elements in this hashtable */
+	u32 n_buckets;	/* number of hash buckets */
+	u32 elem_size;	/* size of each element in bytes */
+};
+
+/* each htab element is struct htab_elem + key + value */
+struct htab_elem {
+	struct hlist_node hash_node;
+	struct rcu_head rcu;
+	u32 hash;
+	char key[0] __aligned(8);
+};
+
+/* Called from syscall */
+static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
+{
+	struct bpf_htab *htab;
+	int err, i;
+
+	htab = kzalloc(sizeof(*htab), GFP_USER);
+	if (!htab)
+		return ERR_PTR(-ENOMEM);
+
+	/* mandatory map attributes */
+	htab->map.key_size = attr->key_size;
+	htab->map.value_size = attr->value_size;
+	htab->map.max_entries = attr->max_entries;
+
+	/* check sanity of attributes.
+	 * value_size == 0 may be allowed in the future to use map as a set
+	 */
+	err = -EINVAL;
+	if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
+	    htab->map.value_size == 0)
+		goto free_htab;
+
+	/* hash table size must be power of 2 */
+	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
+
+	err = -E2BIG;
+	if (htab->map.key_size > MAX_BPF_STACK)
+		/* eBPF programs initialize keys on stack, so they cannot be
+		 * larger than max stack size
+		 */
+		goto free_htab;
+
+	err = -ENOMEM;
+	htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct hlist_head),
+				      GFP_USER | __GFP_NOWARN);
+
+	if (!htab->buckets) {
+		htab->buckets = vmalloc(htab->n_buckets * sizeof(struct hlist_head));
+		if (!htab->buckets)
+			goto free_htab;
+	}
+
+	for (i = 0; i < htab->n_buckets; i++)
+		INIT_HLIST_HEAD(&htab->buckets[i]);
+
+	spin_lock_init(&htab->lock);
+	htab->count = 0;
+
+	htab->elem_size = sizeof(struct htab_elem) +
+			  round_up(htab->map.key_size, 8) +
+			  htab->map.value_size;
+	return &htab->map;
+
+free_htab:
+	kfree(htab);
+	return ERR_PTR(err);
+}
+
+static inline u32 htab_map_hash(const void *key, u32 key_len)
+{
+	return jhash(key, key_len, 0);
+}
+
+static inline struct hlist_head *select_bucket(struct bpf_htab *htab, u32 hash)
+{
+	return &htab->buckets[hash & (htab->n_buckets - 1)];
+}
+
+static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,
+					 void *key, u32 key_size)
+{
+	struct htab_elem *l;
+
+	hlist_for_each_entry_rcu(l, head, hash_node)
+		if (l->hash == hash && !memcmp(&l->key, key, key_size))
+			return l;
+
+	return NULL;
+}
+
+/* Called from syscall or from eBPF program */
+static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_head *head;
+	struct htab_elem *l;
+	u32 hash, key_size;
+
+	/* Must be called with rcu_read_lock. */
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size);
+
+	head = select_bucket(htab, hash);
+
+	l = lookup_elem_raw(head, hash, key, key_size);
+
+	if (l)
+		return l->key + round_up(map->key_size, 8);
+
+	return NULL;
+}
+
+/* Called from syscall */
+static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_head *head;
+	struct htab_elem *l, *next_l;
+	u32 hash, key_size;
+	int i;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size);
+
+	head = select_bucket(htab, hash);
+
+	/* lookup the key */
+	l = lookup_elem_raw(head, hash, key, key_size);
+
+	if (!l) {
+		i = 0;
+		goto find_first_elem;
+	}
+
+	/* key was found, get next key in the same bucket */
+	next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
+				  struct htab_elem, hash_node);
+
+	if (next_l) {
+		/* if next elem in this hash list is non-zero, just return it */
+		memcpy(next_key, next_l->key, key_size);
+		return 0;
+	}
+
+	/* no more elements in this hash list, go to the next bucket */
+	i = hash & (htab->n_buckets - 1);
+	i++;
+
+find_first_elem:
+	/* iterate over buckets */
+	for (; i < htab->n_buckets; i++) {
+		head = select_bucket(htab, i);
+
+		/* pick first element in the bucket */
+		next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
+					  struct htab_elem, hash_node);
+		if (next_l) {
+			/* if it's not empty, just return it */
+			memcpy(next_key, next_l->key, key_size);
+			return 0;
+		}
+	}
+
+	/* itereated over all buckets and all elements */
+	return -ENOENT;
+}
+
+/* Called from syscall or from eBPF program */
+static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
+				u64 map_flags)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct htab_elem *l_new, *l_old;
+	struct hlist_head *head;
+	unsigned long flags;
+	u32 key_size;
+	int ret;
+
+	if (map_flags > BPF_EXIST)
+		/* unknown flags */
+		return -EINVAL;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	/* allocate new element outside of lock */
+	l_new = kmalloc(htab->elem_size, GFP_ATOMIC);
+	if (!l_new)
+		return -ENOMEM;
+
+	key_size = map->key_size;
+
+	memcpy(l_new->key, key, key_size);
+	memcpy(l_new->key + round_up(key_size, 8), value, map->value_size);
+
+	l_new->hash = htab_map_hash(l_new->key, key_size);
+
+	/* bpf_map_update_elem() can be called in_irq() */
+	spin_lock_irqsave(&htab->lock, flags);
+
+	head = select_bucket(htab, l_new->hash);
+
+	l_old = lookup_elem_raw(head, l_new->hash, key, key_size);
+
+	if (!l_old && unlikely(htab->count >= map->max_entries)) {
+		/* if elem with this 'key' doesn't exist and we've reached
+		 * max_entries limit, fail insertion of new elem
+		 */
+		ret = -E2BIG;
+		goto err;
+	}
+
+	if (l_old && map_flags == BPF_NOEXIST) {
+		/* elem already exists */
+		ret = -EEXIST;
+		goto err;
+	}
+
+	if (!l_old && map_flags == BPF_EXIST) {
+		/* elem doesn't exist, cannot update it */
+		ret = -ENOENT;
+		goto err;
+	}
+
+	/* add new element to the head of the list, so that concurrent
+	 * search will find it before old elem
+	 */
+	hlist_add_head_rcu(&l_new->hash_node, head);
+	if (l_old) {
+		hlist_del_rcu(&l_old->hash_node);
+		kfree_rcu(l_old, rcu);
+	} else {
+		htab->count++;
+	}
+	spin_unlock_irqrestore(&htab->lock, flags);
+
+	return 0;
+err:
+	spin_unlock_irqrestore(&htab->lock, flags);
+	kfree(l_new);
+	return ret;
+}
+
+/* Called from syscall or from eBPF program */
+static int htab_map_delete_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_head *head;
+	struct htab_elem *l;
+	unsigned long flags;
+	u32 hash, key_size;
+	int ret = -ENOENT;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size);
+
+	spin_lock_irqsave(&htab->lock, flags);
+
+	head = select_bucket(htab, hash);
+
+	l = lookup_elem_raw(head, hash, key, key_size);
+
+	if (l) {
+		hlist_del_rcu(&l->hash_node);
+		htab->count--;
+		kfree_rcu(l, rcu);
+		ret = 0;
+	}
+
+	spin_unlock_irqrestore(&htab->lock, flags);
+	return ret;
+}
+
+static void delete_all_elements(struct bpf_htab *htab)
+{
+	int i;
+
+	for (i = 0; i < htab->n_buckets; i++) {
+		struct hlist_head *head = select_bucket(htab, i);
+		struct hlist_node *n;
+		struct htab_elem *l;
+
+		hlist_for_each_entry_safe(l, n, head, hash_node) {
+			hlist_del_rcu(&l->hash_node);
+			htab->count--;
+			kfree(l);
+		}
+	}
+}
+
+/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
+static void htab_map_free(struct bpf_map *map)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+
+	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
+	 * so the programs (can be more than one that used this map) were
+	 * disconnected from events. Wait for outstanding critical sections in
+	 * these programs to complete
+	 */
+	synchronize_rcu();
+
+	/* some of kfree_rcu() callbacks for elements of this map may not have
+	 * executed. It's ok. Proceed to free residual elements and map itself
+	 */
+	delete_all_elements(htab);
+	kvfree(htab->buckets);
+	kfree(htab);
+}
+
+static struct bpf_map_ops htab_ops = {
+	.map_alloc = htab_map_alloc,
+	.map_free = htab_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_lookup_elem = htab_map_lookup_elem,
+	.map_update_elem = htab_map_update_elem,
+	.map_delete_elem = htab_map_delete_elem,
+};
+
+static struct bpf_map_type_list tl = {
+	.ops = &htab_ops,
+	.type = BPF_MAP_TYPE_HASH,
+};
+
+static int __init register_htab_map(void)
+{
+	bpf_register_map_type(&tl);
+	return 0;
+}
+late_initcall(register_htab_map);

kernel/bpf/helpers.c

+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bpf.h>
+#include <linux/rcupdate.h>
+
+/* If kernel subsystem is allowing eBPF programs to call this function,
+ * inside its own verifier_ops->get_func_proto() callback it should return
+ * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
+ *
+ * Different map implementations will rely on rcu in map methods
+ * lookup/update/delete, therefore eBPF programs must run under rcu lock
+ * if program is allowed to access maps, so check rcu_read_lock_held in
+ * all three functions.
+ */
+static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+	/* verifier checked that R1 contains a valid pointer to bpf_map
+	 * and R2 points to a program stack and map->key_size bytes were
+	 * initialized
+	 */
+	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+	void *key = (void *) (unsigned long) r2;
+	void *value;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	value = map->ops->map_lookup_elem(map, key);
+
+	/* lookup() returns either pointer to element value or NULL
+	 * which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
+	 */
+	return (unsigned long) value;
+}
+
+struct bpf_func_proto bpf_map_lookup_elem_proto = {
+	.func = bpf_map_lookup_elem,
+	.gpl_only = false,
+	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+	.arg1_type = ARG_CONST_MAP_PTR,
+	.arg2_type = ARG_PTR_TO_MAP_KEY,
+};
+
+static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+	void *key = (void *) (unsigned long) r2;
+	void *value = (void *) (unsigned long) r3;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	return map->ops->map_update_elem(map, key, value, r4);
+}
+
+struct bpf_func_proto bpf_map_update_elem_proto = {
+	.func = bpf_map_update_elem,
+	.gpl_only = false,
+	.ret_type = RET_INTEGER,
+	.arg1_type = ARG_CONST_MAP_PTR,
+	.arg2_type = ARG_PTR_TO_MAP_KEY,
+	.arg3_type = ARG_PTR_TO_MAP_VALUE,
+	.arg4_type = ARG_ANYTHING,
+};
+
+static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+	void *key = (void *) (unsigned long) r2;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	return map->ops->map_delete_elem(map, key);
+}
+
+struct bpf_func_proto bpf_map_delete_elem_proto = {
+	.func = bpf_map_delete_elem,
+	.gpl_only = false,
+	.ret_type = RET_INTEGER,
+	.arg1_type = ARG_CONST_MAP_PTR,
+	.arg2_type = ARG_PTR_TO_MAP_KEY,
+};

kernel/bpf/syscall.c

@@ -169,7 +169,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	if (copy_from_user(key, ukey, map->key_size) != 0)
 		goto free_key;
 
-	err = -ESRCH;
+	err = -ENOENT;
 	rcu_read_lock();
 	value = map->ops->map_lookup_elem(map, key);
 	if (!value)
@@ -190,7 +190,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	return err;
 }
 
-#define BPF_MAP_UPDATE_ELEM_LAST_FIELD value
+#define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags
 
 static int map_update_elem(union bpf_attr *attr)
 {
@@ -231,7 +231,7 @@ static int map_update_elem(union bpf_attr *attr)
 	 * therefore all map accessors rely on this fact, so do the same here
 	 */
 	rcu_read_lock();
-	err = map->ops->map_update_elem(map, key, value);
+	err = map->ops->map_update_elem(map, key, value, attr->flags);
 	rcu_read_unlock();
 
 free_value:

kernel/bpf/test_stub.c

@@ -18,26 +18,18 @@ struct bpf_context {
 	u64 arg2;
 };
 
-static u64 test_func(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
-{
-	return 0;
-}
-
-static struct bpf_func_proto test_funcs[] = {
-	[BPF_FUNC_unspec] = {
-		.func = test_func,
-		.gpl_only = true,
-		.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
-		.arg1_type = ARG_CONST_MAP_PTR,
-		.arg2_type = ARG_PTR_TO_MAP_KEY,
-	},
-};
-
 static const struct bpf_func_proto *test_func_proto(enum bpf_func_id func_id)
 {
-	if (func_id < 0 || func_id >= ARRAY_SIZE(test_funcs))
+	switch (func_id) {
+	case BPF_FUNC_map_lookup_elem:
+		return &bpf_map_lookup_elem_proto;
+	case BPF_FUNC_map_update_elem:
+		return &bpf_map_update_elem_proto;
+	case BPF_FUNC_map_delete_elem:
+		return &bpf_map_delete_elem_proto;
+	default:
 		return NULL;
-	return &test_funcs[func_id];
+	}
 }
 
 static const struct bpf_context_access {
@@ -78,38 +70,8 @@ static struct bpf_prog_type_list tl_prog = {
 	.type = BPF_PROG_TYPE_UNSPEC,
 };
 
-static struct bpf_map *test_map_alloc(union bpf_attr *attr)
-{
-	struct bpf_map *map;
-
-	map = kzalloc(sizeof(*map), GFP_USER);
-	if (!map)
-		return ERR_PTR(-ENOMEM);
-
-	map->key_size = attr->key_size;
-	map->value_size = attr->value_size;
-	map->max_entries = attr->max_entries;
-	return map;
-}
-
-static void test_map_free(struct bpf_map *map)
-{
-	kfree(map);
-}
-
-static struct bpf_map_ops test_map_ops = {
-	.map_alloc = test_map_alloc,
-	.map_free = test_map_free,
-};
-
-static struct bpf_map_type_list tl_map = {
-	.ops = &test_map_ops,
-	.type = BPF_MAP_TYPE_UNSPEC,
-};
-
 static int __init register_test_ops(void)
 {
-	bpf_register_map_type(&tl_map);
 	bpf_register_prog_type(&tl_prog);
 	return 0;
 }

samples/bpf/Makefile

@@ -2,9 +2,10 @@
 obj- := dummy.o
 
 # List of programs to build
-hostprogs-y := test_verifier
+hostprogs-y := test_verifier test_maps
 
 test_verifier-objs := test_verifier.o libbpf.o
+test_maps-objs := test_maps.o libbpf.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)

samples/bpf/libbpf.c

@@ -27,12 +27,13 @@ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
 	return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
 }
 
-int bpf_update_elem(int fd, void *key, void *value)
+int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
 {
 	union bpf_attr attr = {
 		.map_fd = fd,
 		.key = ptr_to_u64(key),
 		.value = ptr_to_u64(value),
+		.flags = flags,
 	};
 
 	return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));

samples/bpf/libbpf.h

@@ -6,7 +6,7 @@ struct bpf_insn;
 
 int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
 		   int max_entries);
-int bpf_update_elem(int fd, void *key, void *value);
+int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags);
 int bpf_lookup_elem(int fd, void *key, void *value);
 int bpf_delete_elem(int fd, void *key);
 int bpf_get_next_key(int fd, void *key, void *next_key);

samples/bpf/test_maps.c

+/*
+ * Testsuite for eBPF maps
+ *
+ * Copyright (c) 2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <linux/bpf.h>
+#include <errno.h>
+#include <string.h>
+#include <assert.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include "libbpf.h"
+
+/* sanity tests for map API */
+static void test_hashmap_sanity(int i, void *data)
+{
+	long long key, next_key, value;
+	int map_fd;
+
+	map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value), 2);
+	if (map_fd < 0) {
+		printf("failed to create hashmap '%s'\n", strerror(errno));
+		exit(1);
+	}
+
+	key = 1;
+	value = 1234;
+	/* insert key=1 element */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_ANY) == 0);
+
+	value = 0;
+	/* BPF_NOEXIST means: add new element if it doesn't exist */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == -1 &&
+	       /* key=1 already exists */
+	       errno == EEXIST);
+
+	assert(bpf_update_elem(map_fd, &key, &value, -1) == -1 && errno == EINVAL);
+
+	/* check that key=1 can be found */
+	assert(bpf_lookup_elem(map_fd, &key, &value) == 0 && value == 1234);
+
+	key = 2;
+	/* check that key=2 is not found */
+	assert(bpf_lookup_elem(map_fd, &key, &value) == -1 && errno == ENOENT);
+
+	/* BPF_EXIST means: update existing element */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_EXIST) == -1 &&
+	       /* key=2 is not there */
+	       errno == ENOENT);
+
+	/* insert key=2 element */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == 0);
+
+	/* key=1 and key=2 were inserted, check that key=0 cannot be inserted
+	 * due to max_entries limit
+	 */
+	key = 0;
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == -1 &&
+	       errno == E2BIG);
+
+	/* check that key = 0 doesn't exist */
+	assert(bpf_delete_elem(map_fd, &key) == -1 && errno == ENOENT);
+
+	/* iterate over two elements */
+	assert(bpf_get_next_key(map_fd, &key, &next_key) == 0 &&
+	       next_key == 2);
+	assert(bpf_get_next_key(map_fd, &next_key, &next_key) == 0 &&
+	       next_key == 1);
+	assert(bpf_get_next_key(map_fd, &next_key, &next_key) == -1 &&
+	       errno == ENOENT);
+
+	/* delete both elements */
+	key = 1;
+	assert(bpf_delete_elem(map_fd, &key) == 0);
+	key = 2;
+	assert(bpf_delete_elem(map_fd, &key) == 0);
+	assert(bpf_delete_elem(map_fd, &key) == -1 && errno == ENOENT);
+
+	key = 0;
+	/* check that map is empty */
+	assert(bpf_get_next_key(map_fd, &key, &next_key) == -1 &&
+	       errno == ENOENT);
+	close(map_fd);
+}
+
+static void test_arraymap_sanity(int i, void *data)
+{
+	int key, next_key, map_fd;
+	long long value;
+
+	map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value), 2);
+	if (map_fd < 0) {
+		printf("failed to create arraymap '%s'\n", strerror(errno));
+		exit(1);
+	}
+
+	key = 1;
+	value = 1234;
+	/* insert key=1 element */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_ANY) == 0);
+
+	value = 0;
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == -1 &&
+	       errno == EEXIST);
+
+	/* check that key=1 can be found */
+	assert(bpf_lookup_elem(map_fd, &key, &value) == 0 && value == 1234);
+
+	key = 0;
+	/* check that key=0 is also found and zero initialized */
+	assert(bpf_lookup_elem(map_fd, &key, &value) == 0 && value == 0);
+
+
+	/* key=0 and key=1 were inserted, check that key=2 cannot be inserted
+	 * due to max_entries limit
+	 */
+	key = 2;
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_EXIST) == -1 &&
+	       errno == E2BIG);
+
+	/* check that key = 2 doesn't exist */
+	assert(bpf_lookup_elem(map_fd, &key, &value) == -1 && errno == ENOENT);
+
+	/* iterate over two elements */
+	assert(bpf_get_next_key(map_fd, &key, &next_key) == 0 &&
+	       next_key == 0);
+	assert(bpf_get_next_key(map_fd, &next_key, &next_key) == 0 &&
+	       next_key == 1);
+	assert(bpf_get_next_key(map_fd, &next_key, &next_key) == -1 &&
+	       errno == ENOENT);
+
+	/* delete shouldn't succeed */
+	key = 1;
+	assert(bpf_delete_elem(map_fd, &key) == -1 && errno == EINVAL);
+
+	close(map_fd);
+}
+
+#define MAP_SIZE (32 * 1024)
+static void test_map_large(void)
+{
+	struct bigkey {
+		int a;
+		char b[116];
+		long long c;
+	} key;
+	int map_fd, i, value;
+
+	/* allocate 4Mbyte of memory */
+	map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
+				MAP_SIZE);
+	if (map_fd < 0) {
+		printf("failed to create large map '%s'\n", strerror(errno));
+		exit(1);
+	}
+
+	for (i = 0; i < MAP_SIZE; i++) {
+		key = (struct bigkey) {.c = i};
+		value = i;
+		assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == 0);
+	}
+	key.c = -1;
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == -1 &&
+	       errno == E2BIG);
+
+	/* iterate through all elements */
+	for (i = 0; i < MAP_SIZE; i++)
+		assert(bpf_get_next_key(map_fd, &key, &key) == 0);
+	assert(bpf_get_next_key(map_fd, &key, &key) == -1 && errno == ENOENT);
+
+	key.c = 0;
+	assert(bpf_lookup_elem(map_fd, &key, &value) == 0 && value == 0);
+	key.a = 1;
+	assert(bpf_lookup_elem(map_fd, &key, &value) == -1 && errno == ENOENT);
+
+	close(map_fd);
+}
+
+/* fork N children and wait for them to complete */
+static void run_parallel(int tasks, void (*fn)(int i, void *data), void *data)
+{
+	pid_t pid[tasks];
+	int i;
+
+	for (i = 0; i < tasks; i++) {
+		pid[i] = fork();
+		if (pid[i] == 0) {
+			fn(i, data);
+			exit(0);
+		} else if (pid[i] == -1) {
+			printf("couldn't spawn #%d process\n", i);
+			exit(1);
+		}
+	}
+	for (i = 0; i < tasks; i++) {
+		int status;
+
+		assert(waitpid(pid[i], &status, 0) == pid[i]);
+		assert(status == 0);
+	}
+}
+
+static void test_map_stress(void)
+{
+	run_parallel(100, test_hashmap_sanity, NULL);
+	run_parallel(100, test_arraymap_sanity, NULL);
+}
+
+#define TASKS 1024
+#define DO_UPDATE 1
+#define DO_DELETE 0
+static void do_work(int fn, void *data)
+{
+	int map_fd = ((int *)data)[0];
+	int do_update = ((int *)data)[1];
+	int i;
+	int key, value;
+
+	for (i = fn; i < MAP_SIZE; i += TASKS) {
+		key = value = i;
+		if (do_update)
+			assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == 0);
+		else
+			assert(bpf_delete_elem(map_fd, &key) == 0);
+	}
+}
+
+static void test_map_parallel(void)
+{
+	int i, map_fd, key = 0, value = 0;
+	int data[2];
+
+	map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
+				MAP_SIZE);
+	if (map_fd < 0) {
+		printf("failed to create map for parallel test '%s'\n",
+		       strerror(errno));
+		exit(1);
+	}
+
+	data[0] = map_fd;
+	data[1] = DO_UPDATE;
+	/* use the same map_fd in children to add elements to this map
+	 * child_0 adds key=0, key=1024, key=2048, ...
+	 * child_1 adds key=1, key=1025, key=2049, ...
+	 * child_1023 adds key=1023, ...
+	 */
+	run_parallel(TASKS, do_work, data);
+
+	/* check that key=0 is already there */
+	assert(bpf_update_elem(map_fd, &key, &value, BPF_NOEXIST) == -1 &&
+	       errno == EEXIST);
+
+	/* check that all elements were inserted */
+	key = -1;
+	for (i = 0; i < MAP_SIZE; i++)
+		assert(bpf_get_next_key(map_fd, &key, &key) == 0);
+	assert(bpf_get_next_key(map_fd, &key, &key) == -1 && errno == ENOENT);
+
+	/* another check for all elements */
+	for (i = 0; i < MAP_SIZE; i++) {
+		key = MAP_SIZE - i - 1;
+		assert(bpf_lookup_elem(map_fd, &key, &value) == 0 &&
+		       value == key);
+	}
+
+	/* now let's delete all elemenets in parallel */
+	data[1] = DO_DELETE;
+	run_parallel(TASKS, do_work, data);
+
+	/* nothing should be left */
+	key = -1;
+	assert(bpf_get_next_key(map_fd, &key, &key) == -1 && errno == ENOENT);
+}
+
+int main(void)
+{
+	test_hashmap_sanity(0, NULL);
+	test_arraymap_sanity(0, NULL);
+	test_map_large();
+	test_map_parallel();
+	test_map_stress();
+	printf("test_maps: OK\n");
+	return 0;
+}

samples/bpf/test_verifier.c

@@ -261,7 +261,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 			BPF_EXIT_INSN(),
 		},
 		.fixup = {2},
@@ -417,7 +417,7 @@ static struct bpf_test tests[] = {
 			BPF_ALU64_REG(BPF_MOV, BPF_REG_2, BPF_REG_10),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_delete_elem),
 			BPF_EXIT_INSN(),
 		},
 		.errstr = "fd 0 is not pointing to valid bpf_map",
@@ -430,7 +430,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 			BPF_ST_MEM(BPF_DW, BPF_REG_0, 0, 0),
 			BPF_EXIT_INSN(),
 		},
@@ -445,7 +445,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
 			BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0),
 			BPF_EXIT_INSN(),
@@ -461,7 +461,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
 			BPF_ST_MEM(BPF_DW, BPF_REG_0, 0, 0),
 			BPF_EXIT_INSN(),
@@ -548,7 +548,7 @@ static struct bpf_test tests[] = {
 			BPF_ST_MEM(BPF_DW, BPF_REG_2, -56, 0),
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -56),
 			BPF_LD_MAP_FD(BPF_REG_1, 0),
-			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_unspec),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_delete_elem),
 			BPF_EXIT_INSN(),
 		},
 		.fixup = {24},
@@ -659,7 +659,7 @@ static int create_map(void)
 	long long key, value = 0;
 	int map_fd;
 
-	map_fd = bpf_create_map(BPF_MAP_TYPE_UNSPEC, sizeof(key), sizeof(value), 1024);
+	map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value), 1024);
 	if (map_fd < 0) {
 		printf("failed to create map '%s'\n", strerror(errno));
 	}