bpf: Add BPF_MAP_TYPE_LRU_HASH (29ba732a) · Commits · e / devices / android_kernel_oneplus_sm7250

include/uapi/linux/bpf.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -85,6 +85,7 @@ enum bpf_map_type {
		BPF_MAP_TYPE_PERCPU_ARRAY,
		BPF_MAP_TYPE_STACK_TRACE,
		BPF_MAP_TYPE_CGROUP_ARRAY,
		BPF_MAP_TYPE_LRU_HASH,
		};

		enum bpf_prog_type {
		@@ -106,6 +107,13 @@ enum bpf_prog_type {
		#define BPF_EXIST 2 /* update existing element */

		#define BPF_F_NO_PREALLOC (1U << 0)
		/* Instead of having one common LRU list in the
		* BPF_MAP_TYPE_LRU_HASH map, use a percpu LRU list
		* which can scale and perform better.
		* Note, the LRU nodes (including free nodes) cannot be moved
		* across different LRU lists.
		*/
		#define BPF_F_NO_COMMON_LRU (1U << 1)

		union bpf_attr {
		struct { /* anonymous struct used by BPF_MAP_CREATE command */

kernel/bpf/hashtab.c

+252 −14

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <linux/filter.h>
		#include <linux/vmalloc.h>
		#include "percpu_freelist.h"
		#include "bpf_lru_list.h"

		struct bucket {
		struct hlist_head head;
		@@ -25,7 +26,10 @@ struct bpf_htab {
		struct bpf_map map;
		struct bucket *buckets;
		void *elems;
		union {
		struct pcpu_freelist freelist;
		struct bpf_lru lru;
		};
		void __percpu *extra_elems;
		atomic_t count; /* number of elements in this hashtable */
		u32 n_buckets; /* number of hash buckets */
		@@ -48,11 +52,19 @@ struct htab_elem {
		union {
		struct rcu_head rcu;
		enum extra_elem_state state;
		struct bpf_lru_node lru_node;
		};
		u32 hash;
		char key[0] __aligned(8);
		};

		static bool htab_lru_map_delete_node(void arg, struct bpf_lru_node node);

		static bool htab_is_lru(const struct bpf_htab *htab)
		{
		return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH;
		}

		static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
		void __percpu *pptr)
		{
		@@ -87,7 +99,22 @@ static void htab_free_elems(struct bpf_htab *htab)
		vfree(htab->elems);
		}

		static int prealloc_elems_and_freelist(struct bpf_htab *htab)
		static struct htab_elem prealloc_lru_pop(struct bpf_htab htab, void *key,
		u32 hash)
		{
		struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
		struct htab_elem *l;

		if (node) {
		l = container_of(node, struct htab_elem, lru_node);
		memcpy(l->key, key, htab->map.key_size);
		return l;
		}

		return NULL;
		}

		static int prealloc_init(struct bpf_htab *htab)
		{
		int err = -ENOMEM, i;

		@@ -110,12 +137,27 @@ static int prealloc_elems_and_freelist(struct bpf_htab *htab)
		}

		skip_percpu_elems:
		if (htab_is_lru(htab))
		err = bpf_lru_init(&htab->lru,
		htab->map.map_flags & BPF_F_NO_COMMON_LRU,
		offsetof(struct htab_elem, hash) -
		offsetof(struct htab_elem, lru_node),
		htab_lru_map_delete_node,
		htab);
		else
		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);
		if (htab_is_lru(htab))
		bpf_lru_populate(&htab->lru, htab->elems,
		offsetof(struct htab_elem, lru_node),
		htab->elem_size, htab->map.max_entries);
		else
		pcpu_freelist_populate(&htab->freelist, htab->elems,
		htab->elem_size, htab->map.max_entries);

		return 0;

		free_elems:
		@@ -123,6 +165,16 @@ static int prealloc_elems_and_freelist(struct bpf_htab *htab)
		return err;
		}

		static void prealloc_destroy(struct bpf_htab *htab)
		{
		htab_free_elems(htab);

		if (htab_is_lru(htab))
		bpf_lru_destroy(&htab->lru);
		else
		pcpu_freelist_destroy(&htab->freelist);
		}

		static int alloc_extra_elems(struct bpf_htab *htab)
		{
		void __percpu *pptr;
		@@ -144,14 +196,34 @@ static int alloc_extra_elems(struct bpf_htab *htab)
		static struct bpf_map htab_map_alloc(union bpf_attr attr)
		{
		bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_HASH;
		bool lru = attr->map_type == BPF_MAP_TYPE_LRU_HASH;
		/* percpu_lru means each cpu has its own LRU list.
		* it is different from BPF_MAP_TYPE_PERCPU_HASH where
		* the map's value itself is percpu. percpu_lru has
		* nothing to do with the map's value.
		*/
		bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
		bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
		struct bpf_htab *htab;
		int err, i;
		u64 cost;

		if (attr->map_flags & ~BPF_F_NO_PREALLOC)
		if (lru && !capable(CAP_SYS_ADMIN))
		/* LRU implementation is much complicated than other
		* maps. Hence, limit to CAP_SYS_ADMIN for now.
		*/
		return ERR_PTR(-EPERM);

		if (attr->map_flags & ~(BPF_F_NO_PREALLOC \| BPF_F_NO_COMMON_LRU))
		/* reserved bits should not be used */
		return ERR_PTR(-EINVAL);

		if (!lru && percpu_lru)
		return ERR_PTR(-EINVAL);

		if (lru && !prealloc)
		return ERR_PTR(-ENOTSUPP);

		htab = kzalloc(sizeof(*htab), GFP_USER);
		if (!htab)
		return ERR_PTR(-ENOMEM);
		@@ -171,6 +243,18 @@ static struct bpf_map htab_map_alloc(union bpf_attr attr)
		htab->map.value_size == 0)
		goto free_htab;

		if (percpu_lru) {
		/* ensure each CPU's lru list has >=1 elements.
		* since we are at it, make each lru list has the same
		* number of elements.
		*/
		htab->map.max_entries = roundup(attr->max_entries,
		num_possible_cpus());
		if (htab->map.max_entries < attr->max_entries)
		htab->map.max_entries = rounddown(attr->max_entries,
		num_possible_cpus());
		}

		/* hash table size must be power of 2 */
		htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);

		@@ -241,14 +325,17 @@ static struct bpf_map htab_map_alloc(union bpf_attr attr)
		raw_spin_lock_init(&htab->buckets[i].lock);
		}

		if (!percpu) {
		if (!percpu && !lru) {
		/* lru itself can remove the least used element, so
		* there is no need for an extra elem during map_update.
		*/
		err = alloc_extra_elems(htab);
		if (err)
		goto free_buckets;
		}

		if (!(attr->map_flags & BPF_F_NO_PREALLOC)) {
		err = prealloc_elems_and_freelist(htab);
		if (prealloc) {
		err = prealloc_init(htab);
		if (err)
		goto free_extra_elems;
		}
		@@ -323,6 +410,46 @@ static void htab_map_lookup_elem(struct bpf_map map, void *key)
		return NULL;
		}

		static void htab_lru_map_lookup_elem(struct bpf_map map, void *key)
		{
		struct htab_elem *l = __htab_map_lookup_elem(map, key);

		if (l) {
		bpf_lru_node_set_ref(&l->lru_node);
		return l->key + round_up(map->key_size, 8);
		}

		return NULL;
		}

		/* It is called from the bpf_lru_list when the LRU needs to delete
		* older elements from the htab.
		*/
		static bool htab_lru_map_delete_node(void arg, struct bpf_lru_node node)
		{
		struct bpf_htab htab = (struct bpf_htab )arg;
		struct htab_elem l, tgt_l;
		struct hlist_head *head;
		unsigned long flags;
		struct bucket *b;

		tgt_l = container_of(node, struct htab_elem, lru_node);
		b = __select_bucket(htab, tgt_l->hash);
		head = &b->head;

		raw_spin_lock_irqsave(&b->lock, flags);

		hlist_for_each_entry_rcu(l, head, hash_node)
		if (l == tgt_l) {
		hlist_del_rcu(&l->hash_node);
		break;
		}

		raw_spin_unlock_irqrestore(&b->lock, flags);

		return l == tgt_l;
		}

		/* Called from syscall */
		static int htab_map_get_next_key(struct bpf_map map, void key, void *next_key)
		{
		@@ -579,6 +706,70 @@ static int htab_map_update_elem(struct bpf_map map, void key, void *value,
		return ret;
		}

		static int htab_lru_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 = NULL;
		struct hlist_head *head;
		unsigned long flags;
		struct bucket *b;
		u32 key_size, hash;
		int ret;

		if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

		WARN_ON_ONCE(!rcu_read_lock_held());

		key_size = map->key_size;

		hash = htab_map_hash(key, key_size);

		b = __select_bucket(htab, hash);
		head = &b->head;

		/* For LRU, we need to alloc before taking bucket's
		* spinlock because getting free nodes from LRU may need
		* to remove older elements from htab and this removal
		* operation will need a bucket lock.
		*/
		l_new = prealloc_lru_pop(htab, key, hash);
		if (!l_new)
		return -ENOMEM;
		memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);

		/* bpf_map_update_elem() can be called in_irq() */
		raw_spin_lock_irqsave(&b->lock, flags);

		l_old = lookup_elem_raw(head, hash, key, key_size);

		ret = check_flags(htab, l_old, map_flags);
		if (ret)
		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) {
		bpf_lru_node_set_ref(&l_new->lru_node);
		hlist_del_rcu(&l_old->hash_node);
		}
		ret = 0;

		err:
		raw_spin_unlock_irqrestore(&b->lock, flags);

		if (ret)
		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
		else if (l_old)
		bpf_lru_push_free(&htab->lru, &l_old->lru_node);

		return ret;
		}

		static int __htab_percpu_map_update_elem(struct bpf_map map, void key,
		void *value, u64 map_flags,
		bool onallcpus)
		@@ -671,6 +862,39 @@ static int htab_map_delete_elem(struct bpf_map map, void key)
		return ret;
		}

		static int htab_lru_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 bucket *b;
		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);
		b = __select_bucket(htab, hash);
		head = &b->head;

		raw_spin_lock_irqsave(&b->lock, flags);

		l = lookup_elem_raw(head, hash, key, key_size);

		if (l) {
		hlist_del_rcu(&l->hash_node);
		ret = 0;
		}

		raw_spin_unlock_irqrestore(&b->lock, flags);
		if (l)
		bpf_lru_push_free(&htab->lru, &l->lru_node);
		return ret;
		}

		static void delete_all_elements(struct bpf_htab *htab)
		{
		int i;
		@@ -703,12 +927,11 @@ static void htab_map_free(struct bpf_map *map)
		* not have executed. Wait for them.
		*/
		rcu_barrier();
		if (htab->map.map_flags & BPF_F_NO_PREALLOC) {
		if (htab->map.map_flags & BPF_F_NO_PREALLOC)
		delete_all_elements(htab);
		} else {
		htab_free_elems(htab);
		pcpu_freelist_destroy(&htab->freelist);
		}
		else
		prealloc_destroy(htab);

		free_percpu(htab->extra_elems);
		kvfree(htab->buckets);
		kfree(htab);
		@@ -728,6 +951,20 @@ static struct bpf_map_type_list htab_type __read_mostly = {
		.type = BPF_MAP_TYPE_HASH,
		};

		static const struct bpf_map_ops htab_lru_ops = {
		.map_alloc = htab_map_alloc,
		.map_free = htab_map_free,
		.map_get_next_key = htab_map_get_next_key,
		.map_lookup_elem = htab_lru_map_lookup_elem,
		.map_update_elem = htab_lru_map_update_elem,
		.map_delete_elem = htab_lru_map_delete_elem,
		};

		static struct bpf_map_type_list htab_lru_type __read_mostly = {
		.ops = &htab_lru_ops,
		.type = BPF_MAP_TYPE_LRU_HASH,
		};

		/* Called from eBPF program */
		static void htab_percpu_map_lookup_elem(struct bpf_map map, void *key)
		{
		@@ -798,6 +1035,7 @@ static int __init register_htab_map(void)
		{
		bpf_register_map_type(&htab_type);
		bpf_register_map_type(&htab_percpu_type);
		bpf_register_map_type(&htab_lru_type);
		return 0;
		}
		late_initcall(register_htab_map);