text: // SPDX-License-Identifier: GPL-2.0-only
  /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   * Copyright (c) 2016,2017 Facebook
   */
  #include <linux/bpf.h>
  #include <linux/btf.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/mm.h>
  #include <linux/filter.h>
  #include <linux/perf_event.h>
  #include <uapi/linux/btf.h>
  #include <linux/rcupdate_trace.h>
  
  #include "map_in_map.h"
  
  #define ARRAY_CREATE_FLAG_MASK \
  	(BPF_F_NUMA_NODE | BPF_F_MMAPABLE | BPF_F_ACCESS_MASK | \
  	 BPF_F_PRESERVE_ELEMS | BPF_F_INNER_MAP)
  
  static void bpf_array_free_percpu(struct bpf_array *array)
  {
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++) {
  		free_percpu(array->pptrs[i]);
  		cond_resched();
  	}
  }
  
  static int bpf_array_alloc_percpu(struct bpf_array *array)
  {
  	void __percpu *ptr;
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++) {
  		ptr = bpf_map_alloc_percpu(&array->map, array->elem_size, 8,
  					   GFP_USER | __GFP_NOWARN);
  		if (!ptr) {
  			bpf_array_free_percpu(array);
  			return -ENOMEM;
  		}
  		array->pptrs[i] = ptr;
  		cond_resched();
  	}
  
  	return 0;
  }
  
  /* Called from syscall */
  int array_map_alloc_check(union bpf_attr *attr)
  {
  	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
  	int numa_node = bpf_map_attr_numa_node(attr);
  
  	/* check sanity of attributes */
  	if (attr->max_entries == 0 || attr->key_size != 4 ||
  	    attr->value_size == 0 ||
  	    attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
  	    !bpf_map_flags_access_ok(attr->map_flags) ||
  	    (percpu && numa_node != NUMA_NO_NODE))
  		return -EINVAL;
  
  	if (attr->map_type != BPF_MAP_TYPE_ARRAY &&
  	    attr->map_flags & (BPF_F_MMAPABLE | BPF_F_INNER_MAP))
  		return -EINVAL;
  
  	if (attr->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
  	    attr->map_flags & BPF_F_PRESERVE_ELEMS)
  		return -EINVAL;
  
  	if (attr->value_size > KMALLOC_MAX_SIZE)
  		/* if value_size is bigger, the user space won't be able to
  		 * access the elements.
  		 */
  		return -E2BIG;
  
  	return 0;
  }
  
  static struct bpf_map *array_map_alloc(union bpf_attr *attr)
  {
  	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
  	int numa_node = bpf_map_attr_numa_node(attr);
  	u32 elem_size, index_mask, max_entries;
  	bool bypass_spec_v1 = bpf_bypass_spec_v1();
  	u64 array_size, mask64;
  	struct bpf_array *array;
  
  	elem_size = round_up(attr->value_size, 8);
  
  	max_entries = attr->max_entries;
  
  	/* On 32 bit archs roundup_pow_of_two() with max_entries that has
  	 * upper most bit set in u32 space is undefined behavior due to
  	 * resulting 1U << 32, so do it manually here in u64 space.
  	 */
  	mask64 = fls_long(max_entries - 1);
  	mask64 = 1ULL << mask64;
  	mask64 -= 1;
  
  	index_mask = mask64;
  	if (!bypass_spec_v1) {
  		/* round up array size to nearest power of 2,
  		 * since cpu will speculate within index_mask limits
  		 */
  		max_entries = index_mask + 1;
  		/* Check for overflows. */
  		if (max_entries < attr->max_entries)
  			return ERR_PTR(-E2BIG);
  	}
  
  	array_size = sizeof(*array);
  	if (percpu) {
  		array_size += (u64) max_entries * sizeof(void *);
  	} else {
  		/* rely on vmalloc() to return page-aligned memory and
  		 * ensure array->value is exactly page-aligned
  		 */
  		if (attr->map_flags & BPF_F_MMAPABLE) {
  			array_size = PAGE_ALIGN(array_size);
  			array_size += PAGE_ALIGN((u64) max_entries * elem_size);
  		} else {
  			array_size += (u64) max_entries * elem_size;
  		}
  	}
  
  	/* allocate all map elements and zero-initialize them */
  	if (attr->map_flags & BPF_F_MMAPABLE) {
  		void *data;
  
  		/* kmalloc'ed memory can't be mmap'ed, use explicit vmalloc */
  		data = bpf_map_area_mmapable_alloc(array_size, numa_node);
  		if (!data)
  			return ERR_PTR(-ENOMEM);
  		array = data + PAGE_ALIGN(sizeof(struct bpf_array))
  			- offsetof(struct bpf_array, value);
  	} else {
  		array = bpf_map_area_alloc(array_size, numa_node);
  	}
  	if (!array)
  		return ERR_PTR(-ENOMEM);
  	array->index_mask = index_mask;
  	array->map.bypass_spec_v1 = bypass_spec_v1;
  
  	/* copy mandatory map attributes */
  	bpf_map_init_from_attr(&array->map, attr);
  	array->elem_size = elem_size;
  
  	if (percpu && bpf_array_alloc_percpu(array)) {
  		bpf_map_area_free(array);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	return &array->map;
  }
  
  /* Called from syscall or from eBPF program */
  static void *array_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  
  	if (unlikely(index >= array->map.max_entries))
  		return NULL;
  
  	return array->value + array->elem_size * (index & array->index_mask);
  }
  
  static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm,
  				       u32 off)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  
  	if (map->max_entries != 1)
  		return -ENOTSUPP;
  	if (off >= map->value_size)
  		return -EINVAL;
  
  	*imm = (unsigned long)array->value;
  	return 0;
  }
  
  static int array_map_direct_value_meta(const struct bpf_map *map, u64 imm,
  				       u32 *off)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u64 base = (unsigned long)array->value;
  	u64 range = array->elem_size;
  
  	if (map->max_entries != 1)
  		return -ENOTSUPP;
  	if (imm < base || imm >= base + range)
  		return -ENOENT;
  
  	*off = imm - base;
  	return 0;
  }
  
  /* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
  static int array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	struct bpf_insn *insn = insn_buf;
  	u32 elem_size = round_up(map->value_size, 8);
  	const int ret = BPF_REG_0;
  	const int map_ptr = BPF_REG_1;
  	const int index = BPF_REG_2;
  
  	if (map->map_flags & BPF_F_INNER_MAP)
  		return -EOPNOTSUPP;
  
  	*insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
  	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
  	if (!map->bypass_spec_v1) {
  		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
  		*insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
  	} else {
  		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
  	}
  
  	if (is_power_of_2(elem_size)) {
  		*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
  	} else {
  		*insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
  	}
  	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
  	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
  	*insn++ = BPF_MOV64_IMM(ret, 0);
  	return insn - insn_buf;
  }
  
  /* Called from eBPF program */
  static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  
  	if (unlikely(index >= array->map.max_entries))
  		return NULL;
  
  	return this_cpu_ptr(array->pptrs[index & array->index_mask]);
  }
  
  int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	void __percpu *pptr;
  	int cpu, off = 0;
  	u32 size;
  
  	if (unlikely(index >= array->map.max_entries))
  		return -ENOENT;
  
  	/* 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();
  	pptr = array->pptrs[index & array->index_mask];
  	for_each_possible_cpu(cpu) {
  		bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
  		off += size;
  	}
  	rcu_read_unlock();
  	return 0;
  }
  
  /* Called from syscall */
  static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = key ? *(u32 *)key : U32_MAX;
  	u32 *next = (u32 *)next_key;
  
  	if (index >= array->map.max_entries) {
  		*next = 0;
  		return 0;
  	}
  
  	if (index == array->map.max_entries - 1)
  		return -ENOENT;
  
  	*next = index + 1;
  	return 0;
  }
  
  static void check_and_free_timer_in_array(struct bpf_array *arr, void *val)
  {
  	if (unlikely(map_value_has_timer(&arr->map)))
  		bpf_timer_cancel_and_free(val + arr->map.timer_off);
  }
  
  /* Called from syscall or from eBPF program */
  static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
  				 u64 map_flags)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	char *val;
  
  	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
  		/* unknown flags */
  		return -EINVAL;
  
  	if (unlikely(index >= array->map.max_entries))
  		/* all elements were pre-allocated, cannot insert a new one */
  		return -E2BIG;
  
  	if (unlikely(map_flags & BPF_NOEXIST))
  		/* all elements already exist */
  		return -EEXIST;
  
  	if (unlikely((map_flags & BPF_F_LOCK) &&
  		     !map_value_has_spin_lock(map)))
  		return -EINVAL;
  
  	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
  		memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
  		       value, map->value_size);
  	} else {
  		val = array->value +
  			array->elem_size * (index & array->index_mask);
  		if (map_flags & BPF_F_LOCK)
  			copy_map_value_locked(map, val, value, false);
  		else
  			copy_map_value(map, val, value);
  		check_and_free_timer_in_array(array, val);
  	}
  	return 0;
  }
  
  int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
  			    u64 map_flags)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	void __percpu *pptr;
  	int cpu, off = 0;
  	u32 size;
  
  	if (unlikely(map_flags > BPF_EXIST))
  		/* unknown flags */
  		return -EINVAL;
  
  	if (unlikely(index >= array->map.max_entries))
  		/* all elements were pre-allocated, cannot insert a new one */
  		return -E2BIG;
  
  	if (unlikely(map_flags == BPF_NOEXIST))
  		/* all elements already exist */
  		return -EEXIST;
  
  	/* the user space will provide round_up(value_size, 8) bytes that
  	 * will be copied into per-cpu area. bpf programs can only access
  	 * value_size of it. During lookup the same extra bytes will be
  	 * returned or zeros which were zero-filled by percpu_alloc,
  	 * so no kernel data leaks possible
  	 */
  	size = round_up(map->value_size, 8);
  	rcu_read_lock();
  	pptr = array->pptrs[index & array->index_mask];
  	for_each_possible_cpu(cpu) {
  		bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
  		off += size;
  	}
  	rcu_read_unlock();
  	return 0;
  }
  
  /* Called from syscall or from eBPF program */
  static int array_map_delete_elem(struct bpf_map *map, void *key)
  {
  	return -EINVAL;
  }
  
  static void *array_map_vmalloc_addr(struct bpf_array *array)
  {
  	return (void *)round_down((unsigned long)array, PAGE_SIZE);
  }
  
  static void array_map_free_timers(struct bpf_map *map)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	int i;
  
  	if (likely(!map_value_has_timer(map)))
  		return;
  
  	for (i = 0; i < array->map.max_entries; i++)
  		bpf_timer_cancel_and_free(array->value + array->elem_size * i +
  					  map->timer_off);
  }
  
  /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
  static void array_map_free(struct bpf_map *map)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  
  	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
  		bpf_array_free_percpu(array);
  
  	if (array->map.map_flags & BPF_F_MMAPABLE)
  		bpf_map_area_free(array_map_vmalloc_addr(array));
  	else
  		bpf_map_area_free(array);
  }
  
  static void array_map_seq_show_elem(struct bpf_map *map, void *key,
  				    struct seq_file *m)
  {
  	void *value;
  
  	rcu_read_lock();
  
  	value = array_map_lookup_elem(map, key);
  	if (!value) {
  		rcu_read_unlock();
  		return;
  	}
  
  	if (map->btf_key_type_id)
  		seq_printf(m, "%u: ", *(u32 *)key);
  	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
  	seq_puts(m, "\n");
  
  	rcu_read_unlock();
  }
  
  static void percpu_array_map_seq_show_elem(struct bpf_map *map, void *key,
  					   struct seq_file *m)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	void __percpu *pptr;
  	int cpu;
  
  	rcu_read_lock();
  
  	seq_printf(m, "%u: {\n", *(u32 *)key);
  	pptr = array->pptrs[index & array->index_mask];
  	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();
  }
  
  static int array_map_check_btf(const struct bpf_map *map,
  			       const struct btf *btf,
  			       const struct btf_type *key_type,
  			       const struct btf_type *value_type)
  {
  	u32 int_data;
  
  	/* One exception for keyless BTF: .bss/.data/.rodata map */
  	if (btf_type_is_void(key_type)) {
  		if (map->map_type != BPF_MAP_TYPE_ARRAY ||
  		    map->max_entries != 1)
  			return -EINVAL;
  
  		if (BTF_INFO_KIND(value_type->info) != BTF_KIND_DATASEC)
  			return -EINVAL;
  
  		return 0;
  	}
  
  	if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
  		return -EINVAL;
  
  	int_data = *(u32 *)(key_type + 1);
  	/* bpf array can only take a u32 key. This check makes sure
  	 * that the btf matches the attr used during map_create.
  	 */
  	if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
  		return -EINVAL;
  
  	return 0;
  }
  
  static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	pgoff_t pgoff = PAGE_ALIGN(sizeof(*array)) >> PAGE_SHIFT;
  
  	if (!(map->map_flags & BPF_F_MMAPABLE))
  		return -EINVAL;
  
  	if (vma->vm_pgoff * PAGE_SIZE + (vma->vm_end - vma->vm_start) >
  	    PAGE_ALIGN((u64)array->map.max_entries * array->elem_size))
  		return -EINVAL;
  
  	return remap_vmalloc_range(vma, array_map_vmalloc_addr(array),
  				   vma->vm_pgoff + pgoff);
  }
  
  static bool array_map_meta_equal(const struct bpf_map *meta0,
  				 const struct bpf_map *meta1)
  {
  	if (!bpf_map_meta_equal(meta0, meta1))
  		return false;
  	return meta0->map_flags & BPF_F_INNER_MAP ? true :
  	       meta0->max_entries == meta1->max_entries;
  }
  
  struct bpf_iter_seq_array_map_info {
  	struct bpf_map *map;
  	void *percpu_value_buf;
  	u32 index;
  };
  
  static void *bpf_array_map_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	struct bpf_iter_seq_array_map_info *info = seq->private;
  	struct bpf_map *map = info->map;
  	struct bpf_array *array;
  	u32 index;
  
  	if (info->index >= map->max_entries)
  		return NULL;
  
  	if (*pos == 0)
  		++*pos;
  	array = container_of(map, struct bpf_array, map);
  	index = info->index & array->index_mask;
  	if (info->percpu_value_buf)
  	       return array->pptrs[index];
  	return array->value + array->elem_size * index;
  }
  
  static void *bpf_array_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	struct bpf_iter_seq_array_map_info *info = seq->private;
  	struct bpf_map *map = info->map;
  	struct bpf_array *array;
  	u32 index;
  
  	++*pos;
  	++info->index;
  	if (info->index >= map->max_entries)
  		return NULL;
  
  	array = container_of(map, struct bpf_array, map);
  	index = info->index & array->index_mask;
  	if (info->percpu_value_buf)
  	       return array->pptrs[index];
  	return array->value + array->elem_size * index;
  }
  
  static int __bpf_array_map_seq_show(struct seq_file *seq, void *v)
  {
  	struct bpf_iter_seq_array_map_info *info = seq->private;
  	struct bpf_iter__bpf_map_elem ctx = {};
  	struct bpf_map *map = info->map;
  	struct bpf_iter_meta meta;
  	struct bpf_prog *prog;
  	int off = 0, cpu = 0;
  	void __percpu **pptr;
  	u32 size;
  
  	meta.seq = seq;
  	prog = bpf_iter_get_info(&meta, v == NULL);
  	if (!prog)
  		return 0;
  
  	ctx.meta = &meta;
  	ctx.map = info->map;
  	if (v) {
  		ctx.key = &info->index;
  
  		if (!info->percpu_value_buf) {
  			ctx.value = v;
  		} else {
  			pptr = v;
  			size = round_up(map->value_size, 8);
  			for_each_possible_cpu(cpu) {
  				bpf_long_memcpy(info->percpu_value_buf + off,
  						per_cpu_ptr(pptr, cpu),
  						size);
  				off += size;
  			}
  			ctx.value = info->percpu_value_buf;
  		}
  	}
  
  	return bpf_iter_run_prog(prog, &ctx);
  }
  
  static int bpf_array_map_seq_show(struct seq_file *seq, void *v)
  {
  	return __bpf_array_map_seq_show(seq, v);
  }
  
  static void bpf_array_map_seq_stop(struct seq_file *seq, void *v)
  {
  	if (!v)
  		(void)__bpf_array_map_seq_show(seq, NULL);
  }
  
  static int bpf_iter_init_array_map(void *priv_data,
  				   struct bpf_iter_aux_info *aux)
  {
  	struct bpf_iter_seq_array_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_ARRAY) {
  		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;
  	}
  
  	seq_info->map = map;
  	return 0;
  }
  
  static void bpf_iter_fini_array_map(void *priv_data)
  {
  	struct bpf_iter_seq_array_map_info *seq_info = priv_data;
  
  	kfree(seq_info->percpu_value_buf);
  }
  
  static const struct seq_operations bpf_array_map_seq_ops = {
  	.start	= bpf_array_map_seq_start,
  	.next	= bpf_array_map_seq_next,
  	.stop	= bpf_array_map_seq_stop,
  	.show	= bpf_array_map_seq_show,
  };
  
  static const struct bpf_iter_seq_info iter_seq_info = {
  	.seq_ops		= &bpf_array_map_seq_ops,
  	.init_seq_private	= bpf_iter_init_array_map,
  	.fini_seq_private	= bpf_iter_fini_array_map,
  	.seq_priv_size		= sizeof(struct bpf_iter_seq_array_map_info),
  };
  
  static int bpf_for_each_array_elem(struct bpf_map *map, void *callback_fn,
  				   void *callback_ctx, u64 flags)
  {
  	u32 i, key, num_elems = 0;
  	struct bpf_array *array;
  	bool is_percpu;
  	u64 ret = 0;
  	void *val;
  
  	if (flags != 0)
  		return -EINVAL;
  
  	is_percpu = map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
  	array = container_of(map, struct bpf_array, map);
  	if (is_percpu)
  		migrate_disable();
  	for (i = 0; i < map->max_entries; i++) {
  		if (is_percpu)
  			val = this_cpu_ptr(array->pptrs[i]);
  		else
  			val = array->value + array->elem_size * i;
  		num_elems++;
  		key = i;
  		ret = BPF_CAST_CALL(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)
  			break;
  	}
  
  	if (is_percpu)
  		migrate_enable();
  	return num_elems;
  }
  
  static int array_map_btf_id;
  const struct bpf_map_ops array_map_ops = {
  	.map_meta_equal = array_map_meta_equal,
  	.map_alloc_check = array_map_alloc_check,
  	.map_alloc = array_map_alloc,
  	.map_free = array_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_release_uref = array_map_free_timers,
  	.map_lookup_elem = array_map_lookup_elem,
  	.map_update_elem = array_map_update_elem,
  	.map_delete_elem = array_map_delete_elem,
  	.map_gen_lookup = array_map_gen_lookup,
  	.map_direct_value_addr = array_map_direct_value_addr,
  	.map_direct_value_meta = array_map_direct_value_meta,
  	.map_mmap = array_map_mmap,
  	.map_seq_show_elem = array_map_seq_show_elem,
  	.map_check_btf = array_map_check_btf,
  	.map_lookup_batch = generic_map_lookup_batch,
  	.map_update_batch = generic_map_update_batch,
  	.map_set_for_each_callback_args = map_set_for_each_callback_args,
  	.map_for_each_callback = bpf_for_each_array_elem,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &array_map_btf_id,
  	.iter_seq_info = &iter_seq_info,
  };
  
  static int percpu_array_map_btf_id;
  const struct bpf_map_ops percpu_array_map_ops = {
  	.map_meta_equal = bpf_map_meta_equal,
  	.map_alloc_check = array_map_alloc_check,
  	.map_alloc = array_map_alloc,
  	.map_free = array_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = percpu_array_map_lookup_elem,
  	.map_update_elem = array_map_update_elem,
  	.map_delete_elem = array_map_delete_elem,
  	.map_seq_show_elem = percpu_array_map_seq_show_elem,
  	.map_check_btf = array_map_check_btf,
  	.map_lookup_batch = generic_map_lookup_batch,
  	.map_update_batch = generic_map_update_batch,
  	.map_set_for_each_callback_args = map_set_for_each_callback_args,
  	.map_for_each_callback = bpf_for_each_array_elem,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &percpu_array_map_btf_id,
  	.iter_seq_info = &iter_seq_info,
  };
  
  static int fd_array_map_alloc_check(union bpf_attr *attr)
  {
  	/* only file descriptors can be stored in this type of map */
  	if (attr->value_size != sizeof(u32))
  		return -EINVAL;
  	/* Program read-only/write-only not supported for special maps yet. */
  	if (attr->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG))
  		return -EINVAL;
  	return array_map_alloc_check(attr);
  }
  
  static void fd_array_map_free(struct bpf_map *map)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	int i;
  
  	/* make sure it's empty */
  	for (i = 0; i < array->map.max_entries; i++)
  		BUG_ON(array->ptrs[i] != NULL);
  
  	bpf_map_area_free(array);
  }
  
  static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	return ERR_PTR(-EOPNOTSUPP);
  }
  
  /* only called from syscall */
  int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
  {
  	void **elem, *ptr;
  	int ret =  0;
  
  	if (!map->ops->map_fd_sys_lookup_elem)
  		return -ENOTSUPP;
  
  	rcu_read_lock();
  	elem = array_map_lookup_elem(map, key);
  	if (elem && (ptr = READ_ONCE(*elem)))
  		*value = map->ops->map_fd_sys_lookup_elem(ptr);
  	else
  		ret = -ENOENT;
  	rcu_read_unlock();
  
  	return ret;
  }
  
  /* only called from syscall */
  int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
  				 void *key, void *value, u64 map_flags)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	void *new_ptr, *old_ptr;
  	u32 index = *(u32 *)key, ufd;
  
  	if (map_flags != BPF_ANY)
  		return -EINVAL;
  
  	if (index >= array->map.max_entries)
  		return -E2BIG;
  
  	ufd = *(u32 *)value;
  	new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
  	if (IS_ERR(new_ptr))
  		return PTR_ERR(new_ptr);
  
  	if (map->ops->map_poke_run) {
  		mutex_lock(&array->aux->poke_mutex);
  		old_ptr = xchg(array->ptrs + index, new_ptr);
  		map->ops->map_poke_run(map, index, old_ptr, new_ptr);
  		mutex_unlock(&array->aux->poke_mutex);
  	} else {
  		old_ptr = xchg(array->ptrs + index, new_ptr);
  	}
  
  	if (old_ptr)
  		map->ops->map_fd_put_ptr(old_ptr);
  	return 0;
  }
  
  static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	void *old_ptr;
  	u32 index = *(u32 *)key;
  
  	if (index >= array->map.max_entries)
  		return -E2BIG;
  
  	if (map->ops->map_poke_run) {
  		mutex_lock(&array->aux->poke_mutex);
  		old_ptr = xchg(array->ptrs + index, NULL);
  		map->ops->map_poke_run(map, index, old_ptr, NULL);
  		mutex_unlock(&array->aux->poke_mutex);
  	} else {
  		old_ptr = xchg(array->ptrs + index, NULL);
  	}
  
  	if (old_ptr) {
  		map->ops->map_fd_put_ptr(old_ptr);
  		return 0;
  	} else {
  		return -ENOENT;
  	}
  }
  
  static void *prog_fd_array_get_ptr(struct bpf_map *map,
  				   struct file *map_file, int fd)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	struct bpf_prog *prog = bpf_prog_get(fd);
  
  	if (IS_ERR(prog))
  		return prog;
  
  	if (!bpf_prog_array_compatible(array, prog)) {
  		bpf_prog_put(prog);
  		return ERR_PTR(-EINVAL);
  	}
  
  	return prog;
  }
  
  static void prog_fd_array_put_ptr(void *ptr)
  {
  	bpf_prog_put(ptr);
  }
  
  static u32 prog_fd_array_sys_lookup_elem(void *ptr)
  {
  	return ((struct bpf_prog *)ptr)->aux->id;
  }
  
  /* decrement refcnt of all bpf_progs that are stored in this map */
  static void bpf_fd_array_map_clear(struct bpf_map *map)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++)
  		fd_array_map_delete_elem(map, &i);
  }
  
  static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key,
  					 struct seq_file *m)
  {
  	void **elem, *ptr;
  	u32 prog_id;
  
  	rcu_read_lock();
  
  	elem = array_map_lookup_elem(map, key);
  	if (elem) {
  		ptr = READ_ONCE(*elem);
  		if (ptr) {
  			seq_printf(m, "%u: ", *(u32 *)key);
  			prog_id = prog_fd_array_sys_lookup_elem(ptr);
  			btf_type_seq_show(map->btf, map->btf_value_type_id,
  					  &prog_id, m);
  			seq_puts(m, "\n");
  		}
  	}
  
  	rcu_read_unlock();
  }
  
  struct prog_poke_elem {
  	struct list_head list;
  	struct bpf_prog_aux *aux;
  };
  
  static int prog_array_map_poke_track(struct bpf_map *map,
  				     struct bpf_prog_aux *prog_aux)
  {
  	struct prog_poke_elem *elem;
  	struct bpf_array_aux *aux;
  	int ret = 0;
  
  	aux = container_of(map, struct bpf_array, map)->aux;
  	mutex_lock(&aux->poke_mutex);
  	list_for_each_entry(elem, &aux->poke_progs, list) {
  		if (elem->aux == prog_aux)
  			goto out;
  	}
  
  	elem = kmalloc(sizeof(*elem), GFP_KERNEL);
  	if (!elem) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	INIT_LIST_HEAD(&elem->list);
  	/* We must track the program's aux info at this point in time
  	 * since the program pointer itself may not be stable yet, see
  	 * also comment in prog_array_map_poke_run().
  	 */
  	elem->aux = prog_aux;
  
  	list_add_tail(&elem->list, &aux->poke_progs);
  out:
  	mutex_unlock(&aux->poke_mutex);
  	return ret;
  }
  
  static void prog_array_map_poke_untrack(struct bpf_map *map,
  					struct bpf_prog_aux *prog_aux)
  {
  	struct prog_poke_elem *elem, *tmp;
  	struct bpf_array_aux *aux;
  
  	aux = container_of(map, struct bpf_array, map)->aux;
  	mutex_lock(&aux->poke_mutex);
  	list_for_each_entry_safe(elem, tmp, &aux->poke_progs, list) {
  		if (elem->aux == prog_aux) {
  			list_del_init(&elem->list);
  			kfree(elem);
  			break;
  		}
  	}
  	mutex_unlock(&aux->poke_mutex);
  }
  
  static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
  				    struct bpf_prog *old,
  				    struct bpf_prog *new)
  {
  	u8 *old_addr, *new_addr, *old_bypass_addr;
  	struct prog_poke_elem *elem;
  	struct bpf_array_aux *aux;
  
  	aux = container_of(map, struct bpf_array, map)->aux;
  	WARN_ON_ONCE(!mutex_is_locked(&aux->poke_mutex));
  
  	list_for_each_entry(elem, &aux->poke_progs, list) {
  		struct bpf_jit_poke_descriptor *poke;
  		int i, ret;
  
  		for (i = 0; i < elem->aux->size_poke_tab; i++) {
  			poke = &elem->aux->poke_tab[i];
  
  			/* Few things to be aware of:
  			 *
  			 * 1) We can only ever access aux in this context, but
  			 *    not aux->prog since it might not be stable yet and
  			 *    there could be danger of use after free otherwise.
  			 * 2) Initially when we start tracking aux, the program
  			 *    is not JITed yet and also does not have a kallsyms
  			 *    entry. We skip these as poke->tailcall_target_stable
  			 *    is not active yet. The JIT will do the final fixup
  			 *    before setting it stable. The various
  			 *    poke->tailcall_target_stable are successively
  			 *    activated, so tail call updates can arrive from here
  			 *    while JIT is still finishing its final fixup for
  			 *    non-activated poke entries.
  			 * 3) On program teardown, the program's kallsym entry gets
  			 *    removed out of RCU callback, but we can only untrack
  			 *    from sleepable context, therefore bpf_arch_text_poke()
  			 *    might not see that this is in BPF text section and
  			 *    bails out with -EINVAL. As these are unreachable since
  			 *    RCU grace period already passed, we simply skip them.
  			 * 4) Also programs reaching refcount of zero while patching
  			 *    is in progress is okay since we're protected under
  			 *    poke_mutex and untrack the programs before the JIT
  			 *    buffer is freed. When we're still in the middle of
  			 *    patching and suddenly kallsyms entry of the program
  			 *    gets evicted, we just skip the rest which is fine due
  			 *    to point 3).
  			 * 5) Any other error happening below from bpf_arch_text_poke()
  			 *    is a unexpected bug.
  			 */
  			if (!READ_ONCE(poke->tailcall_target_stable))
  				continue;
  			if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
  				continue;
  			if (poke->tail_call.map != map ||
  			    poke->tail_call.key != key)
  				continue;
  
  			old_bypass_addr = old ? NULL : poke->bypass_addr;
  			old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL;
  			new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL;
  
  			if (new) {
  				ret = bpf_arch_text_poke(poke->tailcall_target,
  							 BPF_MOD_JUMP,
  							 old_addr, new_addr);
  				BUG_ON(ret < 0 && ret != -EINVAL);
  				if (!old) {
  					ret = bpf_arch_text_poke(poke->tailcall_bypass,
  								 BPF_MOD_JUMP,
  								 poke->bypass_addr,
  								 NULL);
  					BUG_ON(ret < 0 && ret != -EINVAL);
  				}
  			} else {
  				ret = bpf_arch_text_poke(poke->tailcall_bypass,
  							 BPF_MOD_JUMP,
  							 old_bypass_addr,
  							 poke->bypass_addr);
  				BUG_ON(ret < 0 && ret != -EINVAL);
  				/* let other CPUs finish the execution of program
  				 * so that it will not possible to expose them
  				 * to invalid nop, stack unwind, nop state
  				 */
  				if (!ret)
  					synchronize_rcu();
  				ret = bpf_arch_text_poke(poke->tailcall_target,
  							 BPF_MOD_JUMP,
  							 old_addr, NULL);
  				BUG_ON(ret < 0 && ret != -EINVAL);
  			}
  		}
  	}
  }
  
  static void prog_array_map_clear_deferred(struct work_struct *work)
  {
  	struct bpf_map *map = container_of(work, struct bpf_array_aux,
  					   work)->map;
  	bpf_fd_array_map_clear(map);
  	bpf_map_put(map);
  }
  
  static void prog_array_map_clear(struct bpf_map *map)
  {
  	struct bpf_array_aux *aux = container_of(map, struct bpf_array,
  						 map)->aux;
  	bpf_map_inc(map);
  	schedule_work(&aux->work);
  }
  
  static struct bpf_map *prog_array_map_alloc(union bpf_attr *attr)
  {
  	struct bpf_array_aux *aux;
  	struct bpf_map *map;
  
  	aux = kzalloc(sizeof(*aux), GFP_KERNEL_ACCOUNT);
  	if (!aux)
  		return ERR_PTR(-ENOMEM);
  
  	INIT_WORK(&aux->work, prog_array_map_clear_deferred);
  	INIT_LIST_HEAD(&aux->poke_progs);
  	mutex_init(&aux->poke_mutex);
  	spin_lock_init(&aux->owner.lock);
  
  	map = array_map_alloc(attr);
  	if (IS_ERR(map)) {
  		kfree(aux);
  		return map;
  	}
  
  	container_of(map, struct bpf_array, map)->aux = aux;
  	aux->map = map;
  
  	return map;
  }
  
  static void prog_array_map_free(struct bpf_map *map)
  {
  	struct prog_poke_elem *elem, *tmp;
  	struct bpf_array_aux *aux;
  
  	aux = container_of(map, struct bpf_array, map)->aux;
  	list_for_each_entry_safe(elem, tmp, &aux->poke_progs, list) {
  		list_del_init(&elem->list);
  		kfree(elem);
  	}
  	kfree(aux);
  	fd_array_map_free(map);
  }
  
  /* prog_array->aux->{type,jited} is a runtime binding.
   * Doing static check alone in the verifier is not enough.
   * Thus, prog_array_map cannot be used as an inner_map
   * and map_meta_equal is not implemented.
   */
  static int prog_array_map_btf_id;
  const struct bpf_map_ops prog_array_map_ops = {
  	.map_alloc_check = fd_array_map_alloc_check,
  	.map_alloc = prog_array_map_alloc,
  	.map_free = prog_array_map_free,
  	.map_poke_track = prog_array_map_poke_track,
  	.map_poke_untrack = prog_array_map_poke_untrack,
  	.map_poke_run = prog_array_map_poke_run,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = fd_array_map_lookup_elem,
  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = prog_fd_array_get_ptr,
  	.map_fd_put_ptr = prog_fd_array_put_ptr,
  	.map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
  	.map_release_uref = prog_array_map_clear,
  	.map_seq_show_elem = prog_array_map_seq_show_elem,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &prog_array_map_btf_id,
  };
  
  static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
  						   struct file *map_file)
  {
  	struct bpf_event_entry *ee;
  
  	ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
  	if (ee) {
  		ee->event = perf_file->private_data;
  		ee->perf_file = perf_file;
  		ee->map_file = map_file;
  	}
  
  	return ee;
  }
  
  static void __bpf_event_entry_free(struct rcu_head *rcu)
  {
  	struct bpf_event_entry *ee;
  
  	ee = container_of(rcu, struct bpf_event_entry, rcu);
  	fput(ee->perf_file);
  	kfree(ee);
  }
  
  static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
  {
  	call_rcu(&ee->rcu, __bpf_event_entry_free);
  }
  
  static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
  					 struct file *map_file, int fd)
  {
  	struct bpf_event_entry *ee;
  	struct perf_event *event;
  	struct file *perf_file;
  	u64 value;
  
  	perf_file = perf_event_get(fd);
  	if (IS_ERR(perf_file))
  		return perf_file;
  
  	ee = ERR_PTR(-EOPNOTSUPP);
  	event = perf_file->private_data;
  	if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
  		goto err_out;
  
  	ee = bpf_event_entry_gen(perf_file, map_file);
  	if (ee)
  		return ee;
  	ee = ERR_PTR(-ENOMEM);
  err_out:
  	fput(perf_file);
  	return ee;
  }
  
  static void perf_event_fd_array_put_ptr(void *ptr)
  {
  	bpf_event_entry_free_rcu(ptr);
  }
  
  static void perf_event_fd_array_release(struct bpf_map *map,
  					struct file *map_file)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	struct bpf_event_entry *ee;
  	int i;
  
  	if (map->map_flags & BPF_F_PRESERVE_ELEMS)
  		return;
  
  	rcu_read_lock();
  	for (i = 0; i < array->map.max_entries; i++) {
  		ee = READ_ONCE(array->ptrs[i]);
  		if (ee && ee->map_file == map_file)
  			fd_array_map_delete_elem(map, &i);
  	}
  	rcu_read_unlock();
  }
  
  static void perf_event_fd_array_map_free(struct bpf_map *map)
  {
  	if (map->map_flags & BPF_F_PRESERVE_ELEMS)
  		bpf_fd_array_map_clear(map);
  	fd_array_map_free(map);
  }
  
  static int perf_event_array_map_btf_id;
  const struct bpf_map_ops perf_event_array_map_ops = {
  	.map_meta_equal = bpf_map_meta_equal,
  	.map_alloc_check = fd_array_map_alloc_check,
  	.map_alloc = array_map_alloc,
  	.map_free = perf_event_fd_array_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = fd_array_map_lookup_elem,
  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = perf_event_fd_array_get_ptr,
  	.map_fd_put_ptr = perf_event_fd_array_put_ptr,
  	.map_release = perf_event_fd_array_release,
  	.map_check_btf = map_check_no_btf,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &perf_event_array_map_btf_id,
  };
  
  #ifdef CONFIG_CGROUPS
  static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
  				     struct file *map_file /* not used */,
  				     int fd)
  {
  	return cgroup_get_from_fd(fd);
  }
  
  static void cgroup_fd_array_put_ptr(void *ptr)
  {
  	/* cgroup_put free cgrp after a rcu grace period */
  	cgroup_put(ptr);
  }
  
  static void cgroup_fd_array_free(struct bpf_map *map)
  {
  	bpf_fd_array_map_clear(map);
  	fd_array_map_free(map);
  }
  
  static int cgroup_array_map_btf_id;
  const struct bpf_map_ops cgroup_array_map_ops = {
  	.map_meta_equal = bpf_map_meta_equal,
  	.map_alloc_check = fd_array_map_alloc_check,
  	.map_alloc = array_map_alloc,
  	.map_free = cgroup_fd_array_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = fd_array_map_lookup_elem,
  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = cgroup_fd_array_get_ptr,
  	.map_fd_put_ptr = cgroup_fd_array_put_ptr,
  	.map_check_btf = map_check_no_btf,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &cgroup_array_map_btf_id,
  };
  #endif
  
  static struct bpf_map *array_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 = array_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 array_of_map_free(struct bpf_map *map)
  {
  	/* map->inner_map_meta is only accessed by syscall which
  	 * is protected by fdget/fdput.
  	 */
  	bpf_map_meta_free(map->inner_map_meta);
  	bpf_fd_array_map_clear(map);
  	fd_array_map_free(map);
  }
  
  static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_map **inner_map = array_map_lookup_elem(map, key);
  
  	if (!inner_map)
  		return NULL;
  
  	return READ_ONCE(*inner_map);
  }
  
  static int array_of_map_gen_lookup(struct bpf_map *map,
  				   struct bpf_insn *insn_buf)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 elem_size = round_up(map->value_size, 8);
  	struct bpf_insn *insn = insn_buf;
  	const int ret = BPF_REG_0;
  	const int map_ptr = BPF_REG_1;
  	const int index = BPF_REG_2;
  
  	*insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
  	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
  	if (!map->bypass_spec_v1) {
  		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
  		*insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
  	} else {
  		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
  	}
  	if (is_power_of_2(elem_size))
  		*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
  	else
  		*insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
  	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
  	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
  	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
  	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
  	*insn++ = BPF_MOV64_IMM(ret, 0);
  
  	return insn - insn_buf;
  }
  
  static int array_of_maps_map_btf_id;
  const struct bpf_map_ops array_of_maps_map_ops = {
  	.map_alloc_check = fd_array_map_alloc_check,
  	.map_alloc = array_of_map_alloc,
  	.map_free = array_of_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = array_of_map_lookup_elem,
  	.map_delete_elem = fd_array_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 = array_of_map_gen_lookup,
  	.map_check_btf = map_check_no_btf,
  	.map_btf_name = "bpf_array",
  	.map_btf_id = &array_of_maps_map_btf_id,
  };
  