diff options
Diffstat (limited to 'kernel/bpf/arraymap.c')
| -rw-r--r-- | kernel/bpf/arraymap.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c new file mode 100644 index 000000000000..9eb4d8a7cd87 --- /dev/null +++ b/kernel/bpf/arraymap.c @@ -0,0 +1,156 @@ +/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include <linux/bpf.h> +#include <linux/err.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> +#include <linux/mm.h> + +struct bpf_array { + struct bpf_map map; + u32 elem_size; + char value[0] __aligned(8); +}; + +/* Called from syscall */ +static struct bpf_map *array_map_alloc(union bpf_attr *attr) +{ + struct bpf_array *array; + u32 elem_size, array_size; + + /* check sanity of attributes */ + if (attr->max_entries == 0 || attr->key_size != 4 || + attr->value_size == 0) + return ERR_PTR(-EINVAL); + + elem_size = round_up(attr->value_size, 8); + + /* check round_up into zero and u32 overflow */ + if (elem_size == 0 || + attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size) + return ERR_PTR(-ENOMEM); + + array_size = sizeof(*array) + attr->max_entries * elem_size; + + /* allocate all map elements and zero-initialize them */ + array = kzalloc(array_size, GFP_USER | __GFP_NOWARN); + if (!array) { + array = vzalloc(array_size); + if (!array) + return ERR_PTR(-ENOMEM); + } + + /* copy mandatory map attributes */ + array->map.key_size = attr->key_size; + array->map.value_size = attr->value_size; + array->map.max_entries = attr->max_entries; + + array->elem_size = elem_size; + + 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 (index >= array->map.max_entries) + return NULL; + + return array->value + array->elem_size * index; +} + +/* 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 = *(u32 *)key; + 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; +} + +/* 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; + + if (map_flags > BPF_EXIST) + /* unknown flags */ + return -EINVAL; + + if (index >= array->map.max_entries) + /* all elements were pre-allocated, cannot insert a new one */ + return -E2BIG; + + if (map_flags == BPF_NOEXIST) + /* all elements already exist */ + return -EEXIST; + + memcpy(array->value + array->elem_size * index, value, array->elem_size); + return 0; +} + +/* Called from syscall or from eBPF program */ +static int array_map_delete_elem(struct bpf_map *map, void *key) +{ + return -EINVAL; +} + +/* 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); + + /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, + * so the programs (can be more than one that used this map) were + * disconnected from events. Wait for outstanding programs to complete + * and free the array + */ + synchronize_rcu(); + + kvfree(array); +} + +static struct bpf_map_ops array_ops = { + .map_alloc = array_map_alloc, + .map_free = array_map_free, + .map_get_next_key = array_map_get_next_key, + .map_lookup_elem = array_map_lookup_elem, + .map_update_elem = array_map_update_elem, + .map_delete_elem = array_map_delete_elem, +}; + +static struct bpf_map_type_list tl = { + .ops = &array_ops, + .type = BPF_MAP_TYPE_ARRAY, +}; + +static int __init register_array_map(void) +{ + bpf_register_map_type(&tl); + return 0; +} +late_initcall(register_array_map); |