/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ * Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
#include <linux/jhash.h>
#include <linux/filter.h>
#include <linux/vmalloc.h>
+#include "percpu_freelist.h"
struct bucket {
struct hlist_head head;
struct bpf_htab {
struct bpf_map map;
struct bucket *buckets;
+ void *elems;
+ struct pcpu_freelist freelist;
atomic_t 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;
union {
- u32 hash;
- u32 key_size;
+ struct hlist_node hash_node;
+ struct bpf_htab *htab;
+ struct pcpu_freelist_node fnode;
};
+ struct rcu_head rcu;
+ u32 hash;
char key[0] __aligned(8);
};
+static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
+ void __percpu *pptr)
+{
+ *(void __percpu **)(l->key + key_size) = pptr;
+}
+
+static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
+{
+ return *(void __percpu **)(l->key + key_size);
+}
+
+static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
+{
+ return (struct htab_elem *) (htab->elems + i * htab->elem_size);
+}
+
+static void htab_free_elems(struct bpf_htab *htab)
+{
+ int i;
+
+ if (htab->map.map_type != BPF_MAP_TYPE_PERCPU_HASH)
+ goto free_elems;
+
+ for (i = 0; i < htab->map.max_entries; i++) {
+ void __percpu *pptr;
+
+ pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
+ htab->map.key_size);
+ free_percpu(pptr);
+ }
+free_elems:
+ vfree(htab->elems);
+}
+
+static int prealloc_elems_and_freelist(struct bpf_htab *htab)
+{
+ int err = -ENOMEM, i;
+
+ htab->elems = vzalloc(htab->elem_size * htab->map.max_entries);
+ if (!htab->elems)
+ return -ENOMEM;
+
+ if (htab->map.map_type != BPF_MAP_TYPE_PERCPU_HASH)
+ goto skip_percpu_elems;
+
+ for (i = 0; i < htab->map.max_entries; i++) {
+ u32 size = round_up(htab->map.value_size, 8);
+ void __percpu *pptr;
+
+ pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
+ if (!pptr)
+ goto free_elems;
+ htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
+ pptr);
+ }
+
+skip_percpu_elems:
+ err = pcpu_freelist_init(&htab->freelist);
+ if (err)
+ goto free_elems;
+
+ pcpu_freelist_populate(&htab->freelist, htab->elems, htab->elem_size,
+ htab->map.max_entries);
+ return 0;
+
+free_elems:
+ htab_free_elems(htab);
+ return err;
+}
+
/* Called from syscall */
static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
{
int err, i;
u64 cost;
+ if (attr->map_flags & ~BPF_F_NO_PREALLOC)
+ /* reserved bits should not be used */
+ return ERR_PTR(-EINVAL);
+
htab = kzalloc(sizeof(*htab), GFP_USER);
if (!htab)
return ERR_PTR(-ENOMEM);
htab->map.key_size = attr->key_size;
htab->map.value_size = attr->value_size;
htab->map.max_entries = attr->max_entries;
+ htab->map.map_flags = attr->map_flags;
/* check sanity of attributes.
* value_size == 0 may be allowed in the future to use map as a set
if (percpu)
htab->elem_size += sizeof(void *);
else
- htab->elem_size += htab->map.value_size;
+ htab->elem_size += round_up(htab->map.value_size, 8);
/* prevent zero size kmalloc and check for u32 overflow */
if (htab->n_buckets == 0 ||
htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
+ /* if map size is larger than memlock limit, reject it early */
+ err = bpf_map_precharge_memlock(htab->map.pages);
+ if (err)
+ goto free_htab;
+
err = -ENOMEM;
htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct bucket),
GFP_USER | __GFP_NOWARN);
raw_spin_lock_init(&htab->buckets[i].lock);
}
- atomic_set(&htab->count, 0);
+ if (!(attr->map_flags & BPF_F_NO_PREALLOC)) {
+ err = prealloc_elems_and_freelist(htab);
+ if (err)
+ goto free_buckets;
+ }
return &htab->map;
+free_buckets:
+ kvfree(htab->buckets);
free_htab:
kfree(htab);
return ERR_PTR(err);
}
}
- /* itereated over all buckets and all elements */
+ /* iterated over all buckets and all elements */
return -ENOENT;
}
-
-static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
- void __percpu *pptr)
-{
- *(void __percpu **)(l->key + key_size) = pptr;
-}
-
-static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
-{
- return *(void __percpu **)(l->key + key_size);
-}
-
-static void htab_percpu_elem_free(struct htab_elem *l)
+static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
{
- free_percpu(htab_elem_get_ptr(l, l->key_size));
+ if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
+ free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
kfree(l);
+
}
-static void htab_percpu_elem_free_rcu(struct rcu_head *head)
+static void htab_elem_free_rcu(struct rcu_head *head)
{
struct htab_elem *l = container_of(head, struct htab_elem, rcu);
+ struct bpf_htab *htab = l->htab;
- htab_percpu_elem_free(l);
+ /* must increment bpf_prog_active to avoid kprobe+bpf triggering while
+ * we're calling kfree, otherwise deadlock is possible if kprobes
+ * are placed somewhere inside of slub
+ */
+ preempt_disable();
+ __this_cpu_inc(bpf_prog_active);
+ htab_elem_free(htab, l);
+ __this_cpu_dec(bpf_prog_active);
+ preempt_enable();
}
-static void free_htab_elem(struct htab_elem *l, bool percpu, u32 key_size)
+static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
{
- if (percpu) {
- l->key_size = key_size;
- call_rcu(&l->rcu, htab_percpu_elem_free_rcu);
+ if (!(htab->map.map_flags & BPF_F_NO_PREALLOC)) {
+ pcpu_freelist_push(&htab->freelist, &l->fnode);
} else {
- kfree_rcu(l, rcu);
+ atomic_dec(&htab->count);
+ l->htab = htab;
+ call_rcu(&l->rcu, htab_elem_free_rcu);
}
}
bool percpu, bool onallcpus)
{
u32 size = htab->map.value_size;
+ bool prealloc = !(htab->map.map_flags & BPF_F_NO_PREALLOC);
struct htab_elem *l_new;
void __percpu *pptr;
- l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN);
- if (!l_new)
- return NULL;
+ if (prealloc) {
+ l_new = (struct htab_elem *)pcpu_freelist_pop(&htab->freelist);
+ if (!l_new)
+ return ERR_PTR(-E2BIG);
+ } else {
+ if (atomic_inc_return(&htab->count) > htab->map.max_entries) {
+ atomic_dec(&htab->count);
+ return ERR_PTR(-E2BIG);
+ }
+ l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN);
+ if (!l_new)
+ return ERR_PTR(-ENOMEM);
+ }
memcpy(l_new->key, key, key_size);
if (percpu) {
/* round up value_size to 8 bytes */
size = round_up(size, 8);
- /* alloc_percpu zero-fills */
- pptr = __alloc_percpu_gfp(size, 8, GFP_ATOMIC | __GFP_NOWARN);
- if (!pptr) {
- kfree(l_new);
- return NULL;
+ if (prealloc) {
+ pptr = htab_elem_get_ptr(l_new, key_size);
+ } else {
+ /* alloc_percpu zero-fills */
+ pptr = __alloc_percpu_gfp(size, 8,
+ GFP_ATOMIC | __GFP_NOWARN);
+ if (!pptr) {
+ kfree(l_new);
+ return ERR_PTR(-ENOMEM);
+ }
}
if (!onallcpus) {
off += size;
}
}
- htab_elem_set_ptr(l_new, key_size, pptr);
+ if (!prealloc)
+ htab_elem_set_ptr(l_new, key_size, pptr);
} else {
memcpy(l_new->key + round_up(key_size, 8), value, size);
}
static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
u64 map_flags)
{
- if (!l_old && unlikely(atomic_read(&htab->count) >= htab->map.max_entries))
- /* if elem with this 'key' doesn't exist and we've reached
- * max_entries limit, fail insertion of new elem
- */
- return -E2BIG;
-
if (l_old && map_flags == BPF_NOEXIST)
/* elem already exists */
return -EEXIST;
hash = htab_map_hash(key, key_size);
- /* allocate new element outside of the lock, since
- * we're most likley going to insert it
- */
- l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false);
- if (!l_new)
- return -ENOMEM;
-
b = __select_bucket(htab, hash);
head = &b->head;
if (ret)
goto err;
+ l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false);
+ if (IS_ERR(l_new)) {
+ /* all pre-allocated elements are in use or memory exhausted */
+ ret = PTR_ERR(l_new);
+ 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 {
- atomic_inc(&htab->count);
+ free_htab_elem(htab, l_old);
}
- raw_spin_unlock_irqrestore(&b->lock, flags);
- return 0;
+ ret = 0;
err:
raw_spin_unlock_irqrestore(&b->lock, flags);
- kfree(l_new);
return ret;
}
} else {
l_new = alloc_htab_elem(htab, key, value, key_size,
hash, true, onallcpus);
- if (!l_new) {
- ret = -ENOMEM;
+ if (IS_ERR(l_new)) {
+ ret = PTR_ERR(l_new);
goto err;
}
hlist_add_head_rcu(&l_new->hash_node, head);
- atomic_inc(&htab->count);
}
ret = 0;
err:
static int htab_map_delete_elem(struct bpf_map *map, void *key)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- bool percpu = map->map_type == BPF_MAP_TYPE_PERCPU_HASH;
struct hlist_head *head;
struct bucket *b;
struct htab_elem *l;
if (l) {
hlist_del_rcu(&l->hash_node);
- atomic_dec(&htab->count);
- free_htab_elem(l, percpu, key_size);
+ free_htab_elem(htab, l);
ret = 0;
}
hlist_for_each_entry_safe(l, n, head, hash_node) {
hlist_del_rcu(&l->hash_node);
- atomic_dec(&htab->count);
- if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH) {
- l->key_size = htab->map.key_size;
- htab_percpu_elem_free(l);
- } else {
- kfree(l);
- }
+ htab_elem_free(htab, l);
}
}
}
-
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
*/
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
+ /* some of free_htab_elem() callbacks for elements of this map may
+ * not have executed. Wait for them.
*/
- delete_all_elements(htab);
+ rcu_barrier();
+ if (htab->map.map_flags & BPF_F_NO_PREALLOC) {
+ delete_all_elements(htab);
+ } else {
+ htab_free_elems(htab);
+ pcpu_freelist_destroy(&htab->freelist);
+ }
kvfree(htab->buckets);
kfree(htab);
}
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