// 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_fields(struct bpf_htab *htab)
{
	u32 num_entries = htab->map.max_entries;
	int i;

	if (IS_ERR_OR_NULL(htab->map.record))
		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);
		if (htab_is_percpu(htab)) {
			void __percpu *pptr = htab_elem_get_ptr(elem, htab->map.key_size);
			int cpu;

			for_each_possible_cpu(cpu) {
				bpf_obj_free_fields(htab->map.record, per_cpu_ptr(pptr, cpu));
				cond_resched();
			}
		} else {
			bpf_obj_free_fields(htab->map.record, elem->key + round_up(htab->map.key_size, 8));
			cond_resched();
		}
		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) {
		bpf_map_inc_elem_count(&htab->map);
		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 (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; roundup_pow_of_two() can overflow
	 * into UB on 32-bit arches, so check that first
	 */
	err = -E2BIG;
	if (htab->map.max_entries > 1UL << 31)
		goto free_htab;

	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);

	/* check for u32 overflow */
	if (htab->n_buckets > U32_MAX / sizeof(struct bucket))
		goto free_htab;

	err = bpf_map_init_elem_count(&htab->map);
	if (err)
		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_elem_count;

	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);

#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_elem_count:
	bpf_map_free_elem_count(&htab->map);
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)
{
	if (likely(key_len % 4 == 0))
		return jhash2(key, key_len / 4, 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)
{
	if (htab_is_percpu(htab)) {
		void __percpu *pptr = htab_elem_get_ptr(elem, htab->map.key_size);
		int cpu;

		for_each_possible_cpu(cpu)
			bpf_obj_free_fields(htab->map.record, per_cpu_ptr(pptr, cpu));
	} else {
		void *map_value = elem->key + round_up(htab->map.key_size, 8);

		bpf_obj_free_fields(htab->map.record, 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);
			bpf_map_dec_elem_count(&htab->map);
			break;
		}

	htab_unlock_bucket(htab, b, tgt_l->hash, flags);

	return l == tgt_l;
}

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) {
		int current_cpu = raw_smp_processor_id();
		int cpu;

		for_each_possible_cpu(cpu) {
			if (cpu == current_cpu)
				copy_map_value_long(&htab->map, per_cpu_ptr(pptr, cpu), value);
			else /* Since elem is preallocated, we cannot touch special fields */
				zero_map_value(&htab->map, per_cpu_ptr(pptr, cpu));
		}
	} 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);
			bpf_map_inc_elem_count(&htab->map);
		}
	} 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 long 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(!btf_record_has_field(map->record, BPF_SPIN_LOCK)))
			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_map_dec_elem_count(&htab->map);
	bpf_lru_push_free(&htab->lru, &elem->lru_node);
}

static long 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 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) {
					copy_map_value_long(map, info->percpu_value_buf + off,
							    per_cpu_ptr(pptr, cpu));
					check_and_init_map_value(map, info->percpu_value_buf + off);
					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),
};

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,
	.map_mem_usage = htab_map_mem_usage,
	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,
	.map_mem_usage = htab_map_mem_usage,
	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) {
		copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu));
		check_and_init_map_value(map, value + off);
		off += size;
	}
	ret = 0;
out:
	rcu_read_unlock();
	return ret;
}
