Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2540 insertions, 0 deletions

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
new file mode 100644
index 000000000..88c71de0a
--- /dev/null
+++ b/kernel/bpf/hashtab.c
@@ -0,0 +1,2540 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ * Copyright (c) 2016 Facebook
+ */
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/jhash.h>
+#include <linux/filter.h>
+#include <linux/rculist_nulls.h>
+#include <linux/random.h>
+#include <uapi/linux/btf.h>
+#include <linux/rcupdate_trace.h>
+#include <linux/btf_ids.h>
+#include "percpu_freelist.h"
+#include "bpf_lru_list.h"
+#include "map_in_map.h"
+#include <linux/bpf_mem_alloc.h>
+
+#define HTAB_CREATE_FLAG_MASK						\
+	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\
+	 BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED)
+
+#define BATCH_OPS(_name)			\
+	.map_lookup_batch =			\
+	_name##_map_lookup_batch,		\
+	.map_lookup_and_delete_batch =		\
+	_name##_map_lookup_and_delete_batch,	\
+	.map_update_batch =			\
+	generic_map_update_batch,		\
+	.map_delete_batch =			\
+	generic_map_delete_batch
+
+/*
+ * The bucket lock has two protection scopes:
+ *
+ * 1) Serializing concurrent operations from BPF programs on different
+ *    CPUs
+ *
+ * 2) Serializing concurrent operations from BPF programs and sys_bpf()
+ *
+ * BPF programs can execute in any context including perf, kprobes and
+ * tracing. As there are almost no limits where perf, kprobes and tracing
+ * can be invoked from the lock operations need to be protected against
+ * deadlocks. Deadlocks can be caused by recursion and by an invocation in
+ * the lock held section when functions which acquire this lock are invoked
+ * from sys_bpf(). BPF recursion is prevented by incrementing the per CPU
+ * variable bpf_prog_active, which prevents BPF programs attached to perf
+ * events, kprobes and tracing to be invoked before the prior invocation
+ * from one of these contexts completed. sys_bpf() uses the same mechanism
+ * by pinning the task to the current CPU and incrementing the recursion
+ * protection across the map operation.
+ *
+ * This has subtle implications on PREEMPT_RT. PREEMPT_RT forbids certain
+ * operations like memory allocations (even with GFP_ATOMIC) from atomic
+ * contexts. This is required because even with GFP_ATOMIC the memory
+ * allocator calls into code paths which acquire locks with long held lock
+ * sections. To ensure the deterministic behaviour these locks are regular
+ * spinlocks, which are converted to 'sleepable' spinlocks on RT. The only
+ * true atomic contexts on an RT kernel are the low level hardware
+ * handling, scheduling, low level interrupt handling, NMIs etc. None of
+ * these contexts should ever do memory allocations.
+ *
+ * As regular device interrupt handlers and soft interrupts are forced into
+ * thread context, the existing code which does
+ *   spin_lock*(); alloc(GFP_ATOMIC); spin_unlock*();
+ * just works.
+ *
+ * In theory the BPF locks could be converted to regular spinlocks as well,
+ * but the bucket locks and percpu_freelist locks can be taken from
+ * arbitrary contexts (perf, kprobes, tracepoints) which are required to be
+ * atomic contexts even on RT. Before the introduction of bpf_mem_alloc,
+ * it is only safe to use raw spinlock for preallocated hash map on a RT kernel,
+ * because there is no memory allocation within the lock held sections. However
+ * after hash map was fully converted to use bpf_mem_alloc, there will be
+ * non-synchronous memory allocation for non-preallocated hash map, so it is
+ * safe to always use raw spinlock for bucket lock.
+ */
+struct bucket {
+	struct hlist_nulls_head head;
+	raw_spinlock_t raw_lock;
+};
+
+#define HASHTAB_MAP_LOCK_COUNT 8
+#define HASHTAB_MAP_LOCK_MASK (HASHTAB_MAP_LOCK_COUNT - 1)
+
+struct bpf_htab {
+	struct bpf_map map;
+	struct bpf_mem_alloc ma;
+	struct bpf_mem_alloc pcpu_ma;
+	struct bucket *buckets;
+	void *elems;
+	union {
+		struct pcpu_freelist freelist;
+		struct bpf_lru lru;
+	};
+	struct htab_elem *__percpu *extra_elems;
+	/* number of elements in non-preallocated hashtable are kept
+	 * in either pcount or count
+	 */
+	struct percpu_counter pcount;
+	atomic_t count;
+	bool use_percpu_counter;
+	u32 n_buckets;	/* number of hash buckets */
+	u32 elem_size;	/* size of each element in bytes */
+	u32 hashrnd;
+	struct lock_class_key lockdep_key;
+	int __percpu *map_locked[HASHTAB_MAP_LOCK_COUNT];
+};
+
+/* each htab element is struct htab_elem + key + value */
+struct htab_elem {
+	union {
+		struct hlist_nulls_node hash_node;
+		struct {
+			void *padding;
+			union {
+				struct pcpu_freelist_node fnode;
+				struct htab_elem *batch_flink;
+			};
+		};
+	};
+	union {
+		/* pointer to per-cpu pointer */
+		void *ptr_to_pptr;
+		struct bpf_lru_node lru_node;
+	};
+	u32 hash;
+	char key[] __aligned(8);
+};
+
+static inline bool htab_is_prealloc(const struct bpf_htab *htab)
+{
+	return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
+}
+
+static void htab_init_buckets(struct bpf_htab *htab)
+{
+	unsigned int i;
+
+	for (i = 0; i < htab->n_buckets; i++) {
+		INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
+		raw_spin_lock_init(&htab->buckets[i].raw_lock);
+		lockdep_set_class(&htab->buckets[i].raw_lock,
+					  &htab->lockdep_key);
+		cond_resched();
+	}
+}
+
+static inline int htab_lock_bucket(const struct bpf_htab *htab,
+				   struct bucket *b, u32 hash,
+				   unsigned long *pflags)
+{
+	unsigned long flags;
+
+	hash = hash & min_t(u32, HASHTAB_MAP_LOCK_MASK, htab->n_buckets - 1);
+
+	preempt_disable();
+	local_irq_save(flags);
+	if (unlikely(__this_cpu_inc_return(*(htab->map_locked[hash])) != 1)) {
+		__this_cpu_dec(*(htab->map_locked[hash]));
+		local_irq_restore(flags);
+		preempt_enable();
+		return -EBUSY;
+	}
+
+	raw_spin_lock(&b->raw_lock);
+	*pflags = flags;
+
+	return 0;
+}
+
+static inline void htab_unlock_bucket(const struct bpf_htab *htab,
+				      struct bucket *b, u32 hash,
+				      unsigned long flags)
+{
+	hash = hash & min_t(u32, HASHTAB_MAP_LOCK_MASK, htab->n_buckets - 1);
+	raw_spin_unlock(&b->raw_lock);
+	__this_cpu_dec(*(htab->map_locked[hash]));
+	local_irq_restore(flags);
+	preempt_enable();
+}
+
+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 ||
+		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
+}
+
+static bool htab_is_percpu(const struct bpf_htab *htab)
+{
+	return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
+}
+
+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 *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
+{
+	return *(void **)(l->key + roundup(map->key_size, 8));
+}
+
+static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
+{
+	return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);
+}
+
+static bool htab_has_extra_elems(struct bpf_htab *htab)
+{
+	return !htab_is_percpu(htab) && !htab_is_lru(htab);
+}
+
+static void htab_free_prealloced_timers(struct bpf_htab *htab)
+{
+	u32 num_entries = htab->map.max_entries;
+	int i;
+
+	if (!map_value_has_timer(&htab->map))
+		return;
+	if (htab_has_extra_elems(htab))
+		num_entries += num_possible_cpus();
+
+	for (i = 0; i < num_entries; i++) {
+		struct htab_elem *elem;
+
+		elem = get_htab_elem(htab, i);
+		bpf_timer_cancel_and_free(elem->key +
+					  round_up(htab->map.key_size, 8) +
+					  htab->map.timer_off);
+		cond_resched();
+	}
+}
+
+static void htab_free_prealloced_kptrs(struct bpf_htab *htab)
+{
+	u32 num_entries = htab->map.max_entries;
+	int i;
+
+	if (!map_value_has_kptrs(&htab->map))
+		return;
+	if (htab_has_extra_elems(htab))
+		num_entries += num_possible_cpus();
+
+	for (i = 0; i < num_entries; i++) {
+		struct htab_elem *elem;
+
+		elem = get_htab_elem(htab, i);
+		bpf_map_free_kptrs(&htab->map, elem->key + round_up(htab->map.key_size, 8));
+		cond_resched();
+	}
+}
+
+static void htab_free_elems(struct bpf_htab *htab)
+{
+	int i;
+
+	if (!htab_is_percpu(htab))
+		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);
+		cond_resched();
+	}
+free_elems:
+	bpf_map_area_free(htab->elems);
+}
+
+/* The LRU list has a lock (lru_lock). Each htab bucket has a lock
+ * (bucket_lock). If both locks need to be acquired together, the lock
+ * order is always lru_lock -> bucket_lock and this only happens in
+ * bpf_lru_list.c logic. For example, certain code path of
+ * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(),
+ * will acquire lru_lock first followed by acquiring bucket_lock.
+ *
+ * In hashtab.c, to avoid deadlock, lock acquisition of
+ * bucket_lock followed by lru_lock is not allowed. In such cases,
+ * bucket_lock needs to be released first before acquiring lru_lock.
+ */
+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)
+{
+	u32 num_entries = htab->map.max_entries;
+	int err = -ENOMEM, i;
+
+	if (htab_has_extra_elems(htab))
+		num_entries += num_possible_cpus();
+
+	htab->elems = bpf_map_area_alloc((u64)htab->elem_size * num_entries,
+					 htab->map.numa_node);
+	if (!htab->elems)
+		return -ENOMEM;
+
+	if (!htab_is_percpu(htab))
+		goto skip_percpu_elems;
+
+	for (i = 0; i < num_entries; i++) {
+		u32 size = round_up(htab->map.value_size, 8);
+		void __percpu *pptr;
+
+		pptr = bpf_map_alloc_percpu(&htab->map, 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);
+		cond_resched();
+	}
+
+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;
+
+	if (htab_is_lru(htab))
+		bpf_lru_populate(&htab->lru, htab->elems,
+				 offsetof(struct htab_elem, lru_node),
+				 htab->elem_size, num_entries);
+	else
+		pcpu_freelist_populate(&htab->freelist,
+				       htab->elems + offsetof(struct htab_elem, fnode),
+				       htab->elem_size, num_entries);
+
+	return 0;
+
+free_elems:
+	htab_free_elems(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)
+{
+	struct htab_elem *__percpu *pptr, *l_new;
+	struct pcpu_freelist_node *l;
+	int cpu;
+
+	pptr = bpf_map_alloc_percpu(&htab->map, sizeof(struct htab_elem *), 8,
+				    GFP_USER | __GFP_NOWARN);
+	if (!pptr)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		l = pcpu_freelist_pop(&htab->freelist);
+		/* pop will succeed, since prealloc_init()
+		 * preallocated extra num_possible_cpus elements
+		 */
+		l_new = container_of(l, struct htab_elem, fnode);
+		*per_cpu_ptr(pptr, cpu) = l_new;
+	}
+	htab->extra_elems = pptr;
+	return 0;
+}
+
+/* Called from syscall */
+static int htab_map_alloc_check(union bpf_attr *attr)
+{
+	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
+	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
+		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_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);
+	bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
+	int numa_node = bpf_map_attr_numa_node(attr);
+
+	BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
+		     offsetof(struct htab_elem, hash_node.pprev));
+
+	if (lru && !bpf_capable())
+		/* LRU implementation is much complicated than other
+		 * maps.  Hence, limit to CAP_BPF.
+		 */
+		return -EPERM;
+
+	if (zero_seed && !capable(CAP_SYS_ADMIN))
+		/* Guard against local DoS, and discourage production use. */
+		return -EPERM;
+
+	if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK ||
+	    !bpf_map_flags_access_ok(attr->map_flags))
+		return -EINVAL;
+
+	if (!lru && percpu_lru)
+		return -EINVAL;
+
+	if (lru && !prealloc)
+		return -ENOTSUPP;
+
+	if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
+		return -EINVAL;
+
+	/* check sanity of attributes.
+	 * value_size == 0 may be allowed in the future to use map as a set
+	 */
+	if (attr->max_entries == 0 || attr->key_size == 0 ||
+	    attr->value_size == 0)
+		return -EINVAL;
+
+	if ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE -
+	   sizeof(struct htab_elem))
+		/* if key_size + value_size is bigger, the user space won't be
+		 * able to access the elements via bpf syscall. This check
+		 * also makes sure that the elem_size doesn't overflow and it's
+		 * kmalloc-able later in htab_map_update_elem()
+		 */
+		return -E2BIG;
+
+	return 0;
+}
+
+static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
+{
+	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
+	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
+		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_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;
+
+	htab = bpf_map_area_alloc(sizeof(*htab), NUMA_NO_NODE);
+	if (!htab)
+		return ERR_PTR(-ENOMEM);
+
+	lockdep_register_key(&htab->lockdep_key);
+
+	bpf_map_init_from_attr(&htab->map, attr);
+
+	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);
+
+	htab->elem_size = sizeof(struct htab_elem) +
+			  round_up(htab->map.key_size, 8);
+	if (percpu)
+		htab->elem_size += sizeof(void *);
+	else
+		htab->elem_size += round_up(htab->map.value_size, 8);
+
+	err = -E2BIG;
+	/* prevent zero size kmalloc and check for u32 overflow */
+	if (htab->n_buckets == 0 ||
+	    htab->n_buckets > U32_MAX / sizeof(struct bucket))
+		goto free_htab;
+
+	err = -ENOMEM;
+	htab->buckets = bpf_map_area_alloc(htab->n_buckets *
+					   sizeof(struct bucket),
+					   htab->map.numa_node);
+	if (!htab->buckets)
+		goto free_htab;
+
+	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++) {
+		htab->map_locked[i] = bpf_map_alloc_percpu(&htab->map,
+							   sizeof(int),
+							   sizeof(int),
+							   GFP_USER);
+		if (!htab->map_locked[i])
+			goto free_map_locked;
+	}
+
+	if (htab->map.map_flags & BPF_F_ZERO_SEED)
+		htab->hashrnd = 0;
+	else
+		htab->hashrnd = get_random_u32();
+
+	htab_init_buckets(htab);
+
+/* compute_batch_value() computes batch value as num_online_cpus() * 2
+ * and __percpu_counter_compare() needs
+ * htab->max_entries - cur_number_of_elems to be more than batch * num_online_cpus()
+ * for percpu_counter to be faster than atomic_t. In practice the average bpf
+ * hash map size is 10k, which means that a system with 64 cpus will fill
+ * hashmap to 20% of 10k before percpu_counter becomes ineffective. Therefore
+ * define our own batch count as 32 then 10k hash map can be filled up to 80%:
+ * 10k - 8k > 32 _batch_ * 64 _cpus_
+ * and __percpu_counter_compare() will still be fast. At that point hash map
+ * collisions will dominate its performance anyway. Assume that hash map filled
+ * to 50+% isn't going to be O(1) and use the following formula to choose
+ * between percpu_counter and atomic_t.
+ */
+#define PERCPU_COUNTER_BATCH 32
+	if (attr->max_entries / 2 > num_online_cpus() * PERCPU_COUNTER_BATCH)
+		htab->use_percpu_counter = true;
+
+	if (htab->use_percpu_counter) {
+		err = percpu_counter_init(&htab->pcount, 0, GFP_KERNEL);
+		if (err)
+			goto free_map_locked;
+	}
+
+	if (prealloc) {
+		err = prealloc_init(htab);
+		if (err)
+			goto free_map_locked;
+
+		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_prealloc;
+		}
+	} else {
+		err = bpf_mem_alloc_init(&htab->ma, htab->elem_size, false);
+		if (err)
+			goto free_map_locked;
+		if (percpu) {
+			err = bpf_mem_alloc_init(&htab->pcpu_ma,
+						 round_up(htab->map.value_size, 8), true);
+			if (err)
+				goto free_map_locked;
+		}
+	}
+
+	return &htab->map;
+
+free_prealloc:
+	prealloc_destroy(htab);
+free_map_locked:
+	if (htab->use_percpu_counter)
+		percpu_counter_destroy(&htab->pcount);
+	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
+		free_percpu(htab->map_locked[i]);
+	bpf_map_area_free(htab->buckets);
+	bpf_mem_alloc_destroy(&htab->pcpu_ma);
+	bpf_mem_alloc_destroy(&htab->ma);
+free_htab:
+	lockdep_unregister_key(&htab->lockdep_key);
+	bpf_map_area_free(htab);
+	return ERR_PTR(err);
+}
+
+static inline u32 htab_map_hash(const void *key, u32 key_len, u32 hashrnd)
+{
+	return jhash(key, key_len, hashrnd);
+}
+
+static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
+{
+	return &htab->buckets[hash & (htab->n_buckets - 1)];
+}
+
+static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
+{
+	return &__select_bucket(htab, hash)->head;
+}
+
+/* this lookup function can only be called with bucket lock taken */
+static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
+					 void *key, u32 key_size)
+{
+	struct hlist_nulls_node *n;
+	struct htab_elem *l;
+
+	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
+		if (l->hash == hash && !memcmp(&l->key, key, key_size))
+			return l;
+
+	return NULL;
+}
+
+/* can be called without bucket lock. it will repeat the loop in
+ * the unlikely event when elements moved from one bucket into another
+ * while link list is being walked
+ */
+static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
+					       u32 hash, void *key,
+					       u32 key_size, u32 n_buckets)
+{
+	struct hlist_nulls_node *n;
+	struct htab_elem *l;
+
+again:
+	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
+		if (l->hash == hash && !memcmp(&l->key, key, key_size))
+			return l;
+
+	if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
+		goto again;
+
+	return NULL;
+}
+
+/* Called from syscall or from eBPF program directly, so
+ * arguments have to match bpf_map_lookup_elem() exactly.
+ * The return value is adjusted by BPF instructions
+ * in htab_map_gen_lookup().
+ */
+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_nulls_head *head;
+	struct htab_elem *l;
+	u32 hash, key_size;
+
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	head = select_bucket(htab, hash);
+
+	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
+
+	return l;
+}
+
+static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct htab_elem *l = __htab_map_lookup_elem(map, key);
+
+	if (l)
+		return l->key + round_up(map->key_size, 8);
+
+	return NULL;
+}
+
+/* inline bpf_map_lookup_elem() call.
+ * Instead of:
+ * bpf_prog
+ *   bpf_map_lookup_elem
+ *     map->ops->map_lookup_elem
+ *       htab_map_lookup_elem
+ *         __htab_map_lookup_elem
+ * do:
+ * bpf_prog
+ *   __htab_map_lookup_elem
+ */
+static int htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
+{
+	struct bpf_insn *insn = insn_buf;
+	const int ret = BPF_REG_0;
+
+	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
+		     (void *(*)(struct bpf_map *map, void *key))NULL));
+	*insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
+	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
+	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
+				offsetof(struct htab_elem, key) +
+				round_up(map->key_size, 8));
+	return insn - insn_buf;
+}
+
+static __always_inline void *__htab_lru_map_lookup_elem(struct bpf_map *map,
+							void *key, const bool mark)
+{
+	struct htab_elem *l = __htab_map_lookup_elem(map, key);
+
+	if (l) {
+		if (mark)
+			bpf_lru_node_set_ref(&l->lru_node);
+		return l->key + round_up(map->key_size, 8);
+	}
+
+	return NULL;
+}
+
+static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	return __htab_lru_map_lookup_elem(map, key, true);
+}
+
+static void *htab_lru_map_lookup_elem_sys(struct bpf_map *map, void *key)
+{
+	return __htab_lru_map_lookup_elem(map, key, false);
+}
+
+static int htab_lru_map_gen_lookup(struct bpf_map *map,
+				   struct bpf_insn *insn_buf)
+{
+	struct bpf_insn *insn = insn_buf;
+	const int ret = BPF_REG_0;
+	const int ref_reg = BPF_REG_1;
+
+	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
+		     (void *(*)(struct bpf_map *map, void *key))NULL));
+	*insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
+	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
+	*insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
+			      offsetof(struct htab_elem, lru_node) +
+			      offsetof(struct bpf_lru_node, ref));
+	*insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
+	*insn++ = BPF_ST_MEM(BPF_B, ret,
+			     offsetof(struct htab_elem, lru_node) +
+			     offsetof(struct bpf_lru_node, ref),
+			     1);
+	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
+				offsetof(struct htab_elem, key) +
+				round_up(map->key_size, 8));
+	return insn - insn_buf;
+}
+
+static void check_and_free_fields(struct bpf_htab *htab,
+				  struct htab_elem *elem)
+{
+	void *map_value = elem->key + round_up(htab->map.key_size, 8);
+
+	if (map_value_has_timer(&htab->map))
+		bpf_timer_cancel_and_free(map_value + htab->map.timer_off);
+	if (map_value_has_kptrs(&htab->map))
+		bpf_map_free_kptrs(&htab->map, map_value);
+}
+
+/* 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 = arg;
+	struct htab_elem *l = NULL, *tgt_l;
+	struct hlist_nulls_head *head;
+	struct hlist_nulls_node *n;
+	unsigned long flags;
+	struct bucket *b;
+	int ret;
+
+	tgt_l = container_of(node, struct htab_elem, lru_node);
+	b = __select_bucket(htab, tgt_l->hash);
+	head = &b->head;
+
+	ret = htab_lock_bucket(htab, b, tgt_l->hash, &flags);
+	if (ret)
+		return false;
+
+	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
+		if (l == tgt_l) {
+			hlist_nulls_del_rcu(&l->hash_node);
+			check_and_free_fields(htab, l);
+			break;
+		}
+
+	htab_unlock_bucket(htab, b, tgt_l->hash, flags);
+
+	return l == tgt_l;
+}
+
+/* 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_nulls_head *head;
+	struct htab_elem *l, *next_l;
+	u32 hash, key_size;
+	int i = 0;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	key_size = map->key_size;
+
+	if (!key)
+		goto find_first_elem;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	head = select_bucket(htab, hash);
+
+	/* lookup the key */
+	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
+
+	if (!l)
+		goto find_first_elem;
+
+	/* key was found, get next key in the same bucket */
+	next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_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_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_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;
+		}
+	}
+
+	/* iterated over all buckets and all elements */
+	return -ENOENT;
+}
+
+static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
+{
+	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
+		bpf_mem_cache_free(&htab->pcpu_ma, l->ptr_to_pptr);
+	check_and_free_fields(htab, l);
+	bpf_mem_cache_free(&htab->ma, l);
+}
+
+static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)
+{
+	struct bpf_map *map = &htab->map;
+	void *ptr;
+
+	if (map->ops->map_fd_put_ptr) {
+		ptr = fd_htab_map_get_ptr(map, l);
+		map->ops->map_fd_put_ptr(map, ptr, true);
+	}
+}
+
+static bool is_map_full(struct bpf_htab *htab)
+{
+	if (htab->use_percpu_counter)
+		return __percpu_counter_compare(&htab->pcount, htab->map.max_entries,
+						PERCPU_COUNTER_BATCH) >= 0;
+	return atomic_read(&htab->count) >= htab->map.max_entries;
+}
+
+static void inc_elem_count(struct bpf_htab *htab)
+{
+	if (htab->use_percpu_counter)
+		percpu_counter_add_batch(&htab->pcount, 1, PERCPU_COUNTER_BATCH);
+	else
+		atomic_inc(&htab->count);
+}
+
+static void dec_elem_count(struct bpf_htab *htab)
+{
+	if (htab->use_percpu_counter)
+		percpu_counter_add_batch(&htab->pcount, -1, PERCPU_COUNTER_BATCH);
+	else
+		atomic_dec(&htab->count);
+}
+
+
+static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
+{
+	htab_put_fd_value(htab, l);
+
+	if (htab_is_prealloc(htab)) {
+		check_and_free_fields(htab, l);
+		__pcpu_freelist_push(&htab->freelist, &l->fnode);
+	} else {
+		dec_elem_count(htab);
+		htab_elem_free(htab, l);
+	}
+}
+
+static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
+			    void *value, bool onallcpus)
+{
+	if (!onallcpus) {
+		/* copy true value_size bytes */
+		memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
+	} else {
+		u32 size = round_up(htab->map.value_size, 8);
+		int off = 0, cpu;
+
+		for_each_possible_cpu(cpu) {
+			bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
+					value + off, size);
+			off += size;
+		}
+	}
+}
+
+static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,
+			    void *value, bool onallcpus)
+{
+	/* When not setting the initial value on all cpus, zero-fill element
+	 * values for other cpus. Otherwise, bpf program has no way to ensure
+	 * known initial values for cpus other than current one
+	 * (onallcpus=false always when coming from bpf prog).
+	 */
+	if (!onallcpus) {
+		u32 size = round_up(htab->map.value_size, 8);
+		int current_cpu = raw_smp_processor_id();
+		int cpu;
+
+		for_each_possible_cpu(cpu) {
+			if (cpu == current_cpu)
+				bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value,
+						size);
+			else
+				memset(per_cpu_ptr(pptr, cpu), 0, size);
+		}
+	} else {
+		pcpu_copy_value(htab, pptr, value, onallcpus);
+	}
+}
+
+static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
+{
+	return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
+	       BITS_PER_LONG == 64;
+}
+
+static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
+					 void *value, u32 key_size, u32 hash,
+					 bool percpu, bool onallcpus,
+					 struct htab_elem *old_elem)
+{
+	u32 size = htab->map.value_size;
+	bool prealloc = htab_is_prealloc(htab);
+	struct htab_elem *l_new, **pl_new;
+	void __percpu *pptr;
+
+	if (prealloc) {
+		if (old_elem) {
+			/* if we're updating the existing element,
+			 * use per-cpu extra elems to avoid freelist_pop/push
+			 */
+			pl_new = this_cpu_ptr(htab->extra_elems);
+			l_new = *pl_new;
+			htab_put_fd_value(htab, old_elem);
+			*pl_new = old_elem;
+		} else {
+			struct pcpu_freelist_node *l;
+
+			l = __pcpu_freelist_pop(&htab->freelist);
+			if (!l)
+				return ERR_PTR(-E2BIG);
+			l_new = container_of(l, struct htab_elem, fnode);
+		}
+	} else {
+		if (is_map_full(htab))
+			if (!old_elem)
+				/* when map is full and update() is replacing
+				 * old element, it's ok to allocate, since
+				 * old element will be freed immediately.
+				 * Otherwise return an error
+				 */
+				return ERR_PTR(-E2BIG);
+		inc_elem_count(htab);
+		l_new = bpf_mem_cache_alloc(&htab->ma);
+		if (!l_new) {
+			l_new = ERR_PTR(-ENOMEM);
+			goto dec_count;
+		}
+	}
+
+	memcpy(l_new->key, key, key_size);
+	if (percpu) {
+		if (prealloc) {
+			pptr = htab_elem_get_ptr(l_new, key_size);
+		} else {
+			/* alloc_percpu zero-fills */
+			pptr = bpf_mem_cache_alloc(&htab->pcpu_ma);
+			if (!pptr) {
+				bpf_mem_cache_free(&htab->ma, l_new);
+				l_new = ERR_PTR(-ENOMEM);
+				goto dec_count;
+			}
+			l_new->ptr_to_pptr = pptr;
+			pptr = *(void **)pptr;
+		}
+
+		pcpu_init_value(htab, pptr, value, onallcpus);
+
+		if (!prealloc)
+			htab_elem_set_ptr(l_new, key_size, pptr);
+	} else if (fd_htab_map_needs_adjust(htab)) {
+		size = round_up(size, 8);
+		memcpy(l_new->key + round_up(key_size, 8), value, size);
+	} else {
+		copy_map_value(&htab->map,
+			       l_new->key + round_up(key_size, 8),
+			       value);
+	}
+
+	l_new->hash = hash;
+	return l_new;
+dec_count:
+	dec_elem_count(htab);
+	return l_new;
+}
+
+static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
+		       u64 map_flags)
+{
+	if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
+		/* elem already exists */
+		return -EEXIST;
+
+	if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
+		/* elem doesn't exist, cannot update it */
+		return -ENOENT;
+
+	return 0;
+}
+
+/* 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 = NULL, *l_old;
+	struct hlist_nulls_head *head;
+	unsigned long flags;
+	struct bucket *b;
+	u32 key_size, hash;
+	int ret;
+
+	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
+		/* unknown flags */
+		return -EINVAL;
+
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	if (unlikely(map_flags & BPF_F_LOCK)) {
+		if (unlikely(!map_value_has_spin_lock(map)))
+			return -EINVAL;
+		/* find an element without taking the bucket lock */
+		l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
+					      htab->n_buckets);
+		ret = check_flags(htab, l_old, map_flags);
+		if (ret)
+			return ret;
+		if (l_old) {
+			/* grab the element lock and update value in place */
+			copy_map_value_locked(map,
+					      l_old->key + round_up(key_size, 8),
+					      value, false);
+			return 0;
+		}
+		/* fall through, grab the bucket lock and lookup again.
+		 * 99.9% chance that the element won't be found,
+		 * but second lookup under lock has to be done.
+		 */
+	}
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		return ret;
+
+	l_old = lookup_elem_raw(head, hash, key, key_size);
+
+	ret = check_flags(htab, l_old, map_flags);
+	if (ret)
+		goto err;
+
+	if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
+		/* first lookup without the bucket lock didn't find the element,
+		 * but second lookup with the bucket lock found it.
+		 * This case is highly unlikely, but has to be dealt with:
+		 * grab the element lock in addition to the bucket lock
+		 * and update element in place
+		 */
+		copy_map_value_locked(map,
+				      l_old->key + round_up(key_size, 8),
+				      value, false);
+		ret = 0;
+		goto err;
+	}
+
+	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
+				l_old);
+	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_nulls_add_head_rcu(&l_new->hash_node, head);
+	if (l_old) {
+		hlist_nulls_del_rcu(&l_old->hash_node);
+		if (!htab_is_prealloc(htab))
+			free_htab_elem(htab, l_old);
+		else
+			check_and_free_fields(htab, l_old);
+	}
+	ret = 0;
+err:
+	htab_unlock_bucket(htab, b, hash, flags);
+	return ret;
+}
+
+static void htab_lru_push_free(struct bpf_htab *htab, struct htab_elem *elem)
+{
+	check_and_free_fields(htab, elem);
+	bpf_lru_push_free(&htab->lru, &elem->lru_node);
+}
+
+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_nulls_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() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	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;
+	copy_map_value(&htab->map,
+		       l_new->key + round_up(map->key_size, 8), value);
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		goto err_lock_bucket;
+
+	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_nulls_add_head_rcu(&l_new->hash_node, head);
+	if (l_old) {
+		bpf_lru_node_set_ref(&l_new->lru_node);
+		hlist_nulls_del_rcu(&l_old->hash_node);
+	}
+	ret = 0;
+
+err:
+	htab_unlock_bucket(htab, b, hash, flags);
+
+err_lock_bucket:
+	if (ret)
+		htab_lru_push_free(htab, l_new);
+	else if (l_old)
+		htab_lru_push_free(htab, l_old);
+
+	return ret;
+}
+
+static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
+					 void *value, u64 map_flags,
+					 bool onallcpus)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct htab_elem *l_new = NULL, *l_old;
+	struct hlist_nulls_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() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		return ret;
+
+	l_old = lookup_elem_raw(head, hash, key, key_size);
+
+	ret = check_flags(htab, l_old, map_flags);
+	if (ret)
+		goto err;
+
+	if (l_old) {
+		/* per-cpu hash map can update value in-place */
+		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
+				value, onallcpus);
+	} else {
+		l_new = alloc_htab_elem(htab, key, value, key_size,
+					hash, true, onallcpus, NULL);
+		if (IS_ERR(l_new)) {
+			ret = PTR_ERR(l_new);
+			goto err;
+		}
+		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
+	}
+	ret = 0;
+err:
+	htab_unlock_bucket(htab, b, hash, flags);
+	return ret;
+}
+
+static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
+					     void *value, u64 map_flags,
+					     bool onallcpus)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct htab_elem *l_new = NULL, *l_old;
+	struct hlist_nulls_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() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	/* For LRU, we need to alloc before taking bucket's
+	 * spinlock because LRU's elem alloc may need
+	 * to remove older elem from htab and this removal
+	 * operation will need a bucket lock.
+	 */
+	if (map_flags != BPF_EXIST) {
+		l_new = prealloc_lru_pop(htab, key, hash);
+		if (!l_new)
+			return -ENOMEM;
+	}
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		goto err_lock_bucket;
+
+	l_old = lookup_elem_raw(head, hash, key, key_size);
+
+	ret = check_flags(htab, l_old, map_flags);
+	if (ret)
+		goto err;
+
+	if (l_old) {
+		bpf_lru_node_set_ref(&l_old->lru_node);
+
+		/* per-cpu hash map can update value in-place */
+		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
+				value, onallcpus);
+	} else {
+		pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),
+				value, onallcpus);
+		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
+		l_new = NULL;
+	}
+	ret = 0;
+err:
+	htab_unlock_bucket(htab, b, hash, flags);
+err_lock_bucket:
+	if (l_new)
+		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
+	return ret;
+}
+
+static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
+				       void *value, u64 map_flags)
+{
+	return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
+}
+
+static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
+					   void *value, u64 map_flags)
+{
+	return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
+						 false);
+}
+
+/* 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_nulls_head *head;
+	struct bucket *b;
+	struct htab_elem *l;
+	unsigned long flags;
+	u32 hash, key_size;
+	int ret;
+
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		return ret;
+
+	l = lookup_elem_raw(head, hash, key, key_size);
+
+	if (l) {
+		hlist_nulls_del_rcu(&l->hash_node);
+		free_htab_elem(htab, l);
+	} else {
+		ret = -ENOENT;
+	}
+
+	htab_unlock_bucket(htab, b, hash, flags);
+	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_nulls_head *head;
+	struct bucket *b;
+	struct htab_elem *l;
+	unsigned long flags;
+	u32 hash, key_size;
+	int ret;
+
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
+		     !rcu_read_lock_bh_held());
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	ret = htab_lock_bucket(htab, b, hash, &flags);
+	if (ret)
+		return ret;
+
+	l = lookup_elem_raw(head, hash, key, key_size);
+
+	if (l)
+		hlist_nulls_del_rcu(&l->hash_node);
+	else
+		ret = -ENOENT;
+
+	htab_unlock_bucket(htab, b, hash, flags);
+	if (l)
+		htab_lru_push_free(htab, l);
+	return ret;
+}
+
+static void delete_all_elements(struct bpf_htab *htab)
+{
+	int i;
+
+	/* It's called from a worker thread, so disable migration here,
+	 * since bpf_mem_cache_free() relies on that.
+	 */
+	migrate_disable();
+	for (i = 0; i < htab->n_buckets; i++) {
+		struct hlist_nulls_head *head = select_bucket(htab, i);
+		struct hlist_nulls_node *n;
+		struct htab_elem *l;
+
+		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
+			hlist_nulls_del_rcu(&l->hash_node);
+			htab_elem_free(htab, l);
+		}
+	}
+	migrate_enable();
+}
+
+static void htab_free_malloced_timers(struct bpf_htab *htab)
+{
+	int i;
+
+	rcu_read_lock();
+	for (i = 0; i < htab->n_buckets; i++) {
+		struct hlist_nulls_head *head = select_bucket(htab, i);
+		struct hlist_nulls_node *n;
+		struct htab_elem *l;
+
+		hlist_nulls_for_each_entry(l, n, head, hash_node) {
+			/* We don't reset or free kptr on uref dropping to zero,
+			 * hence just free timer.
+			 */
+			bpf_timer_cancel_and_free(l->key +
+						  round_up(htab->map.key_size, 8) +
+						  htab->map.timer_off);
+		}
+		cond_resched_rcu();
+	}
+	rcu_read_unlock();
+}
+
+static void htab_map_free_timers(struct bpf_map *map)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+
+	/* We don't reset or free kptr on uref dropping to zero. */
+	if (!map_value_has_timer(&htab->map))
+		return;
+	if (!htab_is_prealloc(htab))
+		htab_free_malloced_timers(htab);
+	else
+		htab_free_prealloced_timers(htab);
+}
+
+/* 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);
+	int i;
+
+	/* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback.
+	 * bpf_free_used_maps() is called after bpf prog is no longer executing.
+	 * There is no need to synchronize_rcu() here to protect map elements.
+	 */
+
+	/* htab no longer uses call_rcu() directly. bpf_mem_alloc does it
+	 * underneath and is reponsible for waiting for callbacks to finish
+	 * during bpf_mem_alloc_destroy().
+	 */
+	if (!htab_is_prealloc(htab)) {
+		delete_all_elements(htab);
+	} else {
+		htab_free_prealloced_kptrs(htab);
+		prealloc_destroy(htab);
+	}
+
+	bpf_map_free_kptr_off_tab(map);
+	free_percpu(htab->extra_elems);
+	bpf_map_area_free(htab->buckets);
+	bpf_mem_alloc_destroy(&htab->pcpu_ma);
+	bpf_mem_alloc_destroy(&htab->ma);
+	if (htab->use_percpu_counter)
+		percpu_counter_destroy(&htab->pcount);
+	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
+		free_percpu(htab->map_locked[i]);
+	lockdep_unregister_key(&htab->lockdep_key);
+	bpf_map_area_free(htab);
+}
+
+static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
+				   struct seq_file *m)
+{
+	void *value;
+
+	rcu_read_lock();
+
+	value = htab_map_lookup_elem(map, key);
+	if (!value) {
+		rcu_read_unlock();
+		return;
+	}
+
+	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
+	seq_puts(m, ": ");
+	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
+	seq_puts(m, "\n");
+
+	rcu_read_unlock();
+}
+
+static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
+					     void *value, bool is_lru_map,
+					     bool is_percpu, u64 flags)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_nulls_head *head;
+	unsigned long bflags;
+	struct htab_elem *l;
+	u32 hash, key_size;
+	struct bucket *b;
+	int ret;
+
+	key_size = map->key_size;
+
+	hash = htab_map_hash(key, key_size, htab->hashrnd);
+	b = __select_bucket(htab, hash);
+	head = &b->head;
+
+	ret = htab_lock_bucket(htab, b, hash, &bflags);
+	if (ret)
+		return ret;
+
+	l = lookup_elem_raw(head, hash, key, key_size);
+	if (!l) {
+		ret = -ENOENT;
+	} else {
+		if (is_percpu) {
+			u32 roundup_value_size = round_up(map->value_size, 8);
+			void __percpu *pptr;
+			int off = 0, cpu;
+
+			pptr = htab_elem_get_ptr(l, key_size);
+			for_each_possible_cpu(cpu) {
+				bpf_long_memcpy(value + off,
+						per_cpu_ptr(pptr, cpu),
+						roundup_value_size);
+				off += roundup_value_size;
+			}
+		} else {
+			u32 roundup_key_size = round_up(map->key_size, 8);
+
+			if (flags & BPF_F_LOCK)
+				copy_map_value_locked(map, value, l->key +
+						      roundup_key_size,
+						      true);
+			else
+				copy_map_value(map, value, l->key +
+					       roundup_key_size);
+			/* Zeroing special fields in the temp buffer */
+			check_and_init_map_value(map, value);
+		}
+
+		hlist_nulls_del_rcu(&l->hash_node);
+		if (!is_lru_map)
+			free_htab_elem(htab, l);
+	}
+
+	htab_unlock_bucket(htab, b, hash, bflags);
+
+	if (is_lru_map && l)
+		htab_lru_push_free(htab, l);
+
+	return ret;
+}
+
+static int htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
+					   void *value, u64 flags)
+{
+	return __htab_map_lookup_and_delete_elem(map, key, value, false, false,
+						 flags);
+}
+
+static int htab_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
+						  void *key, void *value,
+						  u64 flags)
+{
+	return __htab_map_lookup_and_delete_elem(map, key, value, false, true,
+						 flags);
+}
+
+static int htab_lru_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
+					       void *value, u64 flags)
+{
+	return __htab_map_lookup_and_delete_elem(map, key, value, true, false,
+						 flags);
+}
+
+static int htab_lru_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
+						      void *key, void *value,
+						      u64 flags)
+{
+	return __htab_map_lookup_and_delete_elem(map, key, value, true, true,
+						 flags);
+}
+
+static int
+__htab_map_lookup_and_delete_batch(struct bpf_map *map,
+				   const union bpf_attr *attr,
+				   union bpf_attr __user *uattr,
+				   bool do_delete, bool is_lru_map,
+				   bool is_percpu)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	u32 bucket_cnt, total, key_size, value_size, roundup_key_size;
+	void *keys = NULL, *values = NULL, *value, *dst_key, *dst_val;
+	void __user *uvalues = u64_to_user_ptr(attr->batch.values);
+	void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
+	void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);
+	u32 batch, max_count, size, bucket_size, map_id;
+	struct htab_elem *node_to_free = NULL;
+	u64 elem_map_flags, map_flags;
+	struct hlist_nulls_head *head;
+	struct hlist_nulls_node *n;
+	unsigned long flags = 0;
+	bool locked = false;
+	struct htab_elem *l;
+	struct bucket *b;
+	int ret = 0;
+
+	elem_map_flags = attr->batch.elem_flags;
+	if ((elem_map_flags & ~BPF_F_LOCK) ||
+	    ((elem_map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map)))
+		return -EINVAL;
+
+	map_flags = attr->batch.flags;
+	if (map_flags)
+		return -EINVAL;
+
+	max_count = attr->batch.count;
+	if (!max_count)
+		return 0;
+
+	if (put_user(0, &uattr->batch.count))
+		return -EFAULT;
+
+	batch = 0;
+	if (ubatch && copy_from_user(&batch, ubatch, sizeof(batch)))
+		return -EFAULT;
+
+	if (batch >= htab->n_buckets)
+		return -ENOENT;
+
+	key_size = htab->map.key_size;
+	roundup_key_size = round_up(htab->map.key_size, 8);
+	value_size = htab->map.value_size;
+	size = round_up(value_size, 8);
+	if (is_percpu)
+		value_size = size * num_possible_cpus();
+	total = 0;
+	/* while experimenting with hash tables with sizes ranging from 10 to
+	 * 1000, it was observed that a bucket can have up to 5 entries.
+	 */
+	bucket_size = 5;
+
+alloc:
+	/* We cannot do copy_from_user or copy_to_user inside
+	 * the rcu_read_lock. Allocate enough space here.
+	 */
+	keys = kvmalloc_array(key_size, bucket_size, GFP_USER | __GFP_NOWARN);
+	values = kvmalloc_array(value_size, bucket_size, GFP_USER | __GFP_NOWARN);
+	if (!keys || !values) {
+		ret = -ENOMEM;
+		goto after_loop;
+	}
+
+again:
+	bpf_disable_instrumentation();
+	rcu_read_lock();
+again_nocopy:
+	dst_key = keys;
+	dst_val = values;
+	b = &htab->buckets[batch];
+	head = &b->head;
+	/* do not grab the lock unless need it (bucket_cnt > 0). */
+	if (locked) {
+		ret = htab_lock_bucket(htab, b, batch, &flags);
+		if (ret) {
+			rcu_read_unlock();
+			bpf_enable_instrumentation();
+			goto after_loop;
+		}
+	}
+
+	bucket_cnt = 0;
+	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
+		bucket_cnt++;
+
+	if (bucket_cnt && !locked) {
+		locked = true;
+		goto again_nocopy;
+	}
+
+	if (bucket_cnt > (max_count - total)) {
+		if (total == 0)
+			ret = -ENOSPC;
+		/* Note that since bucket_cnt > 0 here, it is implicit
+		 * that the locked was grabbed, so release it.
+		 */
+		htab_unlock_bucket(htab, b, batch, flags);
+		rcu_read_unlock();
+		bpf_enable_instrumentation();
+		goto after_loop;
+	}
+
+	if (bucket_cnt > bucket_size) {
+		bucket_size = bucket_cnt;
+		/* Note that since bucket_cnt > 0 here, it is implicit
+		 * that the locked was grabbed, so release it.
+		 */
+		htab_unlock_bucket(htab, b, batch, flags);
+		rcu_read_unlock();
+		bpf_enable_instrumentation();
+		kvfree(keys);
+		kvfree(values);
+		goto alloc;
+	}
+
+	/* Next block is only safe to run if you have grabbed the lock */
+	if (!locked)
+		goto next_batch;
+
+	hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
+		memcpy(dst_key, l->key, key_size);
+
+		if (is_percpu) {
+			int off = 0, cpu;
+			void __percpu *pptr;
+
+			pptr = htab_elem_get_ptr(l, map->key_size);
+			for_each_possible_cpu(cpu) {
+				bpf_long_memcpy(dst_val + off,
+						per_cpu_ptr(pptr, cpu), size);
+				off += size;
+			}
+		} else {
+			value = l->key + roundup_key_size;
+			if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+				struct bpf_map **inner_map = value;
+
+				 /* Actual value is the id of the inner map */
+				map_id = map->ops->map_fd_sys_lookup_elem(*inner_map);
+				value = &map_id;
+			}
+
+			if (elem_map_flags & BPF_F_LOCK)
+				copy_map_value_locked(map, dst_val, value,
+						      true);
+			else
+				copy_map_value(map, dst_val, value);
+			/* Zeroing special fields in the temp buffer */
+			check_and_init_map_value(map, dst_val);
+		}
+		if (do_delete) {
+			hlist_nulls_del_rcu(&l->hash_node);
+
+			/* bpf_lru_push_free() will acquire lru_lock, which
+			 * may cause deadlock. See comments in function
+			 * prealloc_lru_pop(). Let us do bpf_lru_push_free()
+			 * after releasing the bucket lock.
+			 */
+			if (is_lru_map) {
+				l->batch_flink = node_to_free;
+				node_to_free = l;
+			} else {
+				free_htab_elem(htab, l);
+			}
+		}
+		dst_key += key_size;
+		dst_val += value_size;
+	}
+
+	htab_unlock_bucket(htab, b, batch, flags);
+	locked = false;
+
+	while (node_to_free) {
+		l = node_to_free;
+		node_to_free = node_to_free->batch_flink;
+		htab_lru_push_free(htab, l);
+	}
+
+next_batch:
+	/* If we are not copying data, we can go to next bucket and avoid
+	 * unlocking the rcu.
+	 */
+	if (!bucket_cnt && (batch + 1 < htab->n_buckets)) {
+		batch++;
+		goto again_nocopy;
+	}
+
+	rcu_read_unlock();
+	bpf_enable_instrumentation();
+	if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys,
+	    key_size * bucket_cnt) ||
+	    copy_to_user(uvalues + total * value_size, values,
+	    value_size * bucket_cnt))) {
+		ret = -EFAULT;
+		goto after_loop;
+	}
+
+	total += bucket_cnt;
+	batch++;
+	if (batch >= htab->n_buckets) {
+		ret = -ENOENT;
+		goto after_loop;
+	}
+	goto again;
+
+after_loop:
+	if (ret == -EFAULT)
+		goto out;
+
+	/* copy # of entries and next batch */
+	ubatch = u64_to_user_ptr(attr->batch.out_batch);
+	if (copy_to_user(ubatch, &batch, sizeof(batch)) ||
+	    put_user(total, &uattr->batch.count))
+		ret = -EFAULT;
+
+out:
+	kvfree(keys);
+	kvfree(values);
+	return ret;
+}
+
+static int
+htab_percpu_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
+			     union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
+						  false, true);
+}
+
+static int
+htab_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
+					const union bpf_attr *attr,
+					union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
+						  false, true);
+}
+
+static int
+htab_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
+		      union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
+						  false, false);
+}
+
+static int
+htab_map_lookup_and_delete_batch(struct bpf_map *map,
+				 const union bpf_attr *attr,
+				 union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
+						  false, false);
+}
+
+static int
+htab_lru_percpu_map_lookup_batch(struct bpf_map *map,
+				 const union bpf_attr *attr,
+				 union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
+						  true, true);
+}
+
+static int
+htab_lru_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
+					    const union bpf_attr *attr,
+					    union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
+						  true, true);
+}
+
+static int
+htab_lru_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
+						  true, false);
+}
+
+static int
+htab_lru_map_lookup_and_delete_batch(struct bpf_map *map,
+				     const union bpf_attr *attr,
+				     union bpf_attr __user *uattr)
+{
+	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
+						  true, false);
+}
+
+struct bpf_iter_seq_hash_map_info {
+	struct bpf_map *map;
+	struct bpf_htab *htab;
+	void *percpu_value_buf; // non-zero means percpu hash
+	u32 bucket_id;
+	u32 skip_elems;
+};
+
+static struct htab_elem *
+bpf_hash_map_seq_find_next(struct bpf_iter_seq_hash_map_info *info,
+			   struct htab_elem *prev_elem)
+{
+	const struct bpf_htab *htab = info->htab;
+	u32 skip_elems = info->skip_elems;
+	u32 bucket_id = info->bucket_id;
+	struct hlist_nulls_head *head;
+	struct hlist_nulls_node *n;
+	struct htab_elem *elem;
+	struct bucket *b;
+	u32 i, count;
+
+	if (bucket_id >= htab->n_buckets)
+		return NULL;
+
+	/* try to find next elem in the same bucket */
+	if (prev_elem) {
+		/* no update/deletion on this bucket, prev_elem should be still valid
+		 * and we won't skip elements.
+		 */
+		n = rcu_dereference_raw(hlist_nulls_next_rcu(&prev_elem->hash_node));
+		elem = hlist_nulls_entry_safe(n, struct htab_elem, hash_node);
+		if (elem)
+			return elem;
+
+		/* not found, unlock and go to the next bucket */
+		b = &htab->buckets[bucket_id++];
+		rcu_read_unlock();
+		skip_elems = 0;
+	}
+
+	for (i = bucket_id; i < htab->n_buckets; i++) {
+		b = &htab->buckets[i];
+		rcu_read_lock();
+
+		count = 0;
+		head = &b->head;
+		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
+			if (count >= skip_elems) {
+				info->bucket_id = i;
+				info->skip_elems = count;
+				return elem;
+			}
+			count++;
+		}
+
+		rcu_read_unlock();
+		skip_elems = 0;
+	}
+
+	info->bucket_id = i;
+	info->skip_elems = 0;
+	return NULL;
+}
+
+static void *bpf_hash_map_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct bpf_iter_seq_hash_map_info *info = seq->private;
+	struct htab_elem *elem;
+
+	elem = bpf_hash_map_seq_find_next(info, NULL);
+	if (!elem)
+		return NULL;
+
+	if (*pos == 0)
+		++*pos;
+	return elem;
+}
+
+static void *bpf_hash_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct bpf_iter_seq_hash_map_info *info = seq->private;
+
+	++*pos;
+	++info->skip_elems;
+	return bpf_hash_map_seq_find_next(info, v);
+}
+
+static int __bpf_hash_map_seq_show(struct seq_file *seq, struct htab_elem *elem)
+{
+	struct bpf_iter_seq_hash_map_info *info = seq->private;
+	u32 roundup_key_size, roundup_value_size;
+	struct bpf_iter__bpf_map_elem ctx = {};
+	struct bpf_map *map = info->map;
+	struct bpf_iter_meta meta;
+	int ret = 0, off = 0, cpu;
+	struct bpf_prog *prog;
+	void __percpu *pptr;
+
+	meta.seq = seq;
+	prog = bpf_iter_get_info(&meta, elem == NULL);
+	if (prog) {
+		ctx.meta = &meta;
+		ctx.map = info->map;
+		if (elem) {
+			roundup_key_size = round_up(map->key_size, 8);
+			ctx.key = elem->key;
+			if (!info->percpu_value_buf) {
+				ctx.value = elem->key + roundup_key_size;
+			} else {
+				roundup_value_size = round_up(map->value_size, 8);
+				pptr = htab_elem_get_ptr(elem, map->key_size);
+				for_each_possible_cpu(cpu) {
+					bpf_long_memcpy(info->percpu_value_buf + off,
+							per_cpu_ptr(pptr, cpu),
+							roundup_value_size);
+					off += roundup_value_size;
+				}
+				ctx.value = info->percpu_value_buf;
+			}
+		}
+		ret = bpf_iter_run_prog(prog, &ctx);
+	}
+
+	return ret;
+}
+
+static int bpf_hash_map_seq_show(struct seq_file *seq, void *v)
+{
+	return __bpf_hash_map_seq_show(seq, v);
+}
+
+static void bpf_hash_map_seq_stop(struct seq_file *seq, void *v)
+{
+	if (!v)
+		(void)__bpf_hash_map_seq_show(seq, NULL);
+	else
+		rcu_read_unlock();
+}
+
+static int bpf_iter_init_hash_map(void *priv_data,
+				  struct bpf_iter_aux_info *aux)
+{
+	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
+	struct bpf_map *map = aux->map;
+	void *value_buf;
+	u32 buf_size;
+
+	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
+		buf_size = round_up(map->value_size, 8) * num_possible_cpus();
+		value_buf = kmalloc(buf_size, GFP_USER | __GFP_NOWARN);
+		if (!value_buf)
+			return -ENOMEM;
+
+		seq_info->percpu_value_buf = value_buf;
+	}
+
+	bpf_map_inc_with_uref(map);
+	seq_info->map = map;
+	seq_info->htab = container_of(map, struct bpf_htab, map);
+	return 0;
+}
+
+static void bpf_iter_fini_hash_map(void *priv_data)
+{
+	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
+
+	bpf_map_put_with_uref(seq_info->map);
+	kfree(seq_info->percpu_value_buf);
+}
+
+static const struct seq_operations bpf_hash_map_seq_ops = {
+	.start	= bpf_hash_map_seq_start,
+	.next	= bpf_hash_map_seq_next,
+	.stop	= bpf_hash_map_seq_stop,
+	.show	= bpf_hash_map_seq_show,
+};
+
+static const struct bpf_iter_seq_info iter_seq_info = {
+	.seq_ops		= &bpf_hash_map_seq_ops,
+	.init_seq_private	= bpf_iter_init_hash_map,
+	.fini_seq_private	= bpf_iter_fini_hash_map,
+	.seq_priv_size		= sizeof(struct bpf_iter_seq_hash_map_info),
+};
+
+static int bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_fn,
+				  void *callback_ctx, u64 flags)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_nulls_head *head;
+	struct hlist_nulls_node *n;
+	struct htab_elem *elem;
+	u32 roundup_key_size;
+	int i, num_elems = 0;
+	void __percpu *pptr;
+	struct bucket *b;
+	void *key, *val;
+	bool is_percpu;
+	u64 ret = 0;
+
+	if (flags != 0)
+		return -EINVAL;
+
+	is_percpu = htab_is_percpu(htab);
+
+	roundup_key_size = round_up(map->key_size, 8);
+	/* disable migration so percpu value prepared here will be the
+	 * same as the one seen by the bpf program with bpf_map_lookup_elem().
+	 */
+	if (is_percpu)
+		migrate_disable();
+	for (i = 0; i < htab->n_buckets; i++) {
+		b = &htab->buckets[i];
+		rcu_read_lock();
+		head = &b->head;
+		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
+			key = elem->key;
+			if (is_percpu) {
+				/* current cpu value for percpu map */
+				pptr = htab_elem_get_ptr(elem, map->key_size);
+				val = this_cpu_ptr(pptr);
+			} else {
+				val = elem->key + roundup_key_size;
+			}
+			num_elems++;
+			ret = callback_fn((u64)(long)map, (u64)(long)key,
+					  (u64)(long)val, (u64)(long)callback_ctx, 0);
+			/* return value: 0 - continue, 1 - stop and return */
+			if (ret) {
+				rcu_read_unlock();
+				goto out;
+			}
+		}
+		rcu_read_unlock();
+	}
+out:
+	if (is_percpu)
+		migrate_enable();
+	return num_elems;
+}
+
+BTF_ID_LIST_SINGLE(htab_map_btf_ids, struct, bpf_htab)
+const struct bpf_map_ops htab_map_ops = {
+	.map_meta_equal = bpf_map_meta_equal,
+	.map_alloc_check = htab_map_alloc_check,
+	.map_alloc = htab_map_alloc,
+	.map_free = htab_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_release_uref = htab_map_free_timers,
+	.map_lookup_elem = htab_map_lookup_elem,
+	.map_lookup_and_delete_elem = htab_map_lookup_and_delete_elem,
+	.map_update_elem = htab_map_update_elem,
+	.map_delete_elem = htab_map_delete_elem,
+	.map_gen_lookup = htab_map_gen_lookup,
+	.map_seq_show_elem = htab_map_seq_show_elem,
+	.map_set_for_each_callback_args = map_set_for_each_callback_args,
+	.map_for_each_callback = bpf_for_each_hash_elem,
+	BATCH_OPS(htab),
+	.map_btf_id = &htab_map_btf_ids[0],
+	.iter_seq_info = &iter_seq_info,
+};
+
+const struct bpf_map_ops htab_lru_map_ops = {
+	.map_meta_equal = bpf_map_meta_equal,
+	.map_alloc_check = htab_map_alloc_check,
+	.map_alloc = htab_map_alloc,
+	.map_free = htab_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_release_uref = htab_map_free_timers,
+	.map_lookup_elem = htab_lru_map_lookup_elem,
+	.map_lookup_and_delete_elem = htab_lru_map_lookup_and_delete_elem,
+	.map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
+	.map_update_elem = htab_lru_map_update_elem,
+	.map_delete_elem = htab_lru_map_delete_elem,
+	.map_gen_lookup = htab_lru_map_gen_lookup,
+	.map_seq_show_elem = htab_map_seq_show_elem,
+	.map_set_for_each_callback_args = map_set_for_each_callback_args,
+	.map_for_each_callback = bpf_for_each_hash_elem,
+	BATCH_OPS(htab_lru),
+	.map_btf_id = &htab_map_btf_ids[0],
+	.iter_seq_info = &iter_seq_info,
+};
+
+/* Called from eBPF program */
+static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct htab_elem *l = __htab_map_lookup_elem(map, key);
+
+	if (l)
+		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
+	else
+		return NULL;
+}
+
+static void *htab_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+	struct htab_elem *l;
+
+	if (cpu >= nr_cpu_ids)
+		return NULL;
+
+	l = __htab_map_lookup_elem(map, key);
+	if (l)
+		return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+	else
+		return NULL;
+}
+
+static void *htab_lru_percpu_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 this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
+	}
+
+	return NULL;
+}
+
+static void *htab_lru_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+	struct htab_elem *l;
+
+	if (cpu >= nr_cpu_ids)
+		return NULL;
+
+	l = __htab_map_lookup_elem(map, key);
+	if (l) {
+		bpf_lru_node_set_ref(&l->lru_node);
+		return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+	}
+
+	return NULL;
+}
+
+int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
+{
+	struct htab_elem *l;
+	void __percpu *pptr;
+	int ret = -ENOENT;
+	int cpu, off = 0;
+	u32 size;
+
+	/* per_cpu areas are zero-filled and bpf programs can only
+	 * access 'value_size' of them, so copying rounded areas
+	 * will not leak any kernel data
+	 */
+	size = round_up(map->value_size, 8);
+	rcu_read_lock();
+	l = __htab_map_lookup_elem(map, key);
+	if (!l)
+		goto out;
+	/* We do not mark LRU map element here in order to not mess up
+	 * eviction heuristics when user space does a map walk.
+	 */
+	pptr = htab_elem_get_ptr(l, map->key_size);
+	for_each_possible_cpu(cpu) {
+		bpf_long_memcpy(value + off,
+				per_cpu_ptr(pptr, cpu), size);
+		off += size;
+	}
+	ret = 0;
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
+			   u64 map_flags)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	int ret;
+
+	rcu_read_lock();
+	if (htab_is_lru(htab))
+		ret = __htab_lru_percpu_map_update_elem(map, key, value,
+							map_flags, true);
+	else
+		ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
+						    true);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
+					  struct seq_file *m)
+{
+	struct htab_elem *l;
+	void __percpu *pptr;
+	int cpu;
+
+	rcu_read_lock();
+
+	l = __htab_map_lookup_elem(map, key);
+	if (!l) {
+		rcu_read_unlock();
+		return;
+	}
+
+	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
+	seq_puts(m, ": {\n");
+	pptr = htab_elem_get_ptr(l, map->key_size);
+	for_each_possible_cpu(cpu) {
+		seq_printf(m, "\tcpu%d: ", cpu);
+		btf_type_seq_show(map->btf, map->btf_value_type_id,
+				  per_cpu_ptr(pptr, cpu), m);
+		seq_puts(m, "\n");
+	}
+	seq_puts(m, "}\n");
+
+	rcu_read_unlock();
+}
+
+const struct bpf_map_ops htab_percpu_map_ops = {
+	.map_meta_equal = bpf_map_meta_equal,
+	.map_alloc_check = htab_map_alloc_check,
+	.map_alloc = htab_map_alloc,
+	.map_free = htab_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_lookup_elem = htab_percpu_map_lookup_elem,
+	.map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
+	.map_update_elem = htab_percpu_map_update_elem,
+	.map_delete_elem = htab_map_delete_elem,
+	.map_lookup_percpu_elem = htab_percpu_map_lookup_percpu_elem,
+	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
+	.map_set_for_each_callback_args = map_set_for_each_callback_args,
+	.map_for_each_callback = bpf_for_each_hash_elem,
+	BATCH_OPS(htab_percpu),
+	.map_btf_id = &htab_map_btf_ids[0],
+	.iter_seq_info = &iter_seq_info,
+};
+
+const struct bpf_map_ops htab_lru_percpu_map_ops = {
+	.map_meta_equal = bpf_map_meta_equal,
+	.map_alloc_check = htab_map_alloc_check,
+	.map_alloc = htab_map_alloc,
+	.map_free = htab_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_lookup_elem = htab_lru_percpu_map_lookup_elem,
+	.map_lookup_and_delete_elem = htab_lru_percpu_map_lookup_and_delete_elem,
+	.map_update_elem = htab_lru_percpu_map_update_elem,
+	.map_delete_elem = htab_lru_map_delete_elem,
+	.map_lookup_percpu_elem = htab_lru_percpu_map_lookup_percpu_elem,
+	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
+	.map_set_for_each_callback_args = map_set_for_each_callback_args,
+	.map_for_each_callback = bpf_for_each_hash_elem,
+	BATCH_OPS(htab_lru_percpu),
+	.map_btf_id = &htab_map_btf_ids[0],
+	.iter_seq_info = &iter_seq_info,
+};
+
+static int fd_htab_map_alloc_check(union bpf_attr *attr)
+{
+	if (attr->value_size != sizeof(u32))
+		return -EINVAL;
+	return htab_map_alloc_check(attr);
+}
+
+static void fd_htab_map_free(struct bpf_map *map)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct hlist_nulls_node *n;
+	struct hlist_nulls_head *head;
+	struct htab_elem *l;
+	int i;
+
+	for (i = 0; i < htab->n_buckets; i++) {
+		head = select_bucket(htab, i);
+
+		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
+			void *ptr = fd_htab_map_get_ptr(map, l);
+
+			map->ops->map_fd_put_ptr(map, ptr, false);
+		}
+	}
+
+	htab_map_free(map);
+}
+
+/* only called from syscall */
+int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
+{
+	void **ptr;
+	int ret = 0;
+
+	if (!map->ops->map_fd_sys_lookup_elem)
+		return -ENOTSUPP;
+
+	rcu_read_lock();
+	ptr = htab_map_lookup_elem(map, key);
+	if (ptr)
+		*value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
+	else
+		ret = -ENOENT;
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/* only called from syscall */
+int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
+				void *key, void *value, u64 map_flags)
+{
+	void *ptr;
+	int ret;
+	u32 ufd = *(u32 *)value;
+
+	ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	ret = htab_map_update_elem(map, key, &ptr, map_flags);
+	if (ret)
+		map->ops->map_fd_put_ptr(map, ptr, false);
+
+	return ret;
+}
+
+static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
+{
+	struct bpf_map *map, *inner_map_meta;
+
+	inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
+	if (IS_ERR(inner_map_meta))
+		return inner_map_meta;
+
+	map = htab_map_alloc(attr);
+	if (IS_ERR(map)) {
+		bpf_map_meta_free(inner_map_meta);
+		return map;
+	}
+
+	map->inner_map_meta = inner_map_meta;
+
+	return map;
+}
+
+static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);
+
+	if (!inner_map)
+		return NULL;
+
+	return READ_ONCE(*inner_map);
+}
+
+static int htab_of_map_gen_lookup(struct bpf_map *map,
+				  struct bpf_insn *insn_buf)
+{
+	struct bpf_insn *insn = insn_buf;
+	const int ret = BPF_REG_0;
+
+	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
+		     (void *(*)(struct bpf_map *map, void *key))NULL));
+	*insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
+	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
+	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
+				offsetof(struct htab_elem, key) +
+				round_up(map->key_size, 8));
+	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
+
+	return insn - insn_buf;
+}
+
+static void htab_of_map_free(struct bpf_map *map)
+{
+	bpf_map_meta_free(map->inner_map_meta);
+	fd_htab_map_free(map);
+}
+
+const struct bpf_map_ops htab_of_maps_map_ops = {
+	.map_alloc_check = fd_htab_map_alloc_check,
+	.map_alloc = htab_of_map_alloc,
+	.map_free = htab_of_map_free,
+	.map_get_next_key = htab_map_get_next_key,
+	.map_lookup_elem = htab_of_map_lookup_elem,
+	.map_delete_elem = htab_map_delete_elem,
+	.map_fd_get_ptr = bpf_map_fd_get_ptr,
+	.map_fd_put_ptr = bpf_map_fd_put_ptr,
+	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
+	.map_gen_lookup = htab_of_map_gen_lookup,
+	.map_check_btf = map_check_no_btf,
+	BATCH_OPS(htab),
+	.map_btf_id = &htab_map_btf_ids[0],
+};