From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 kernel/bpf/arraymap.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 kernel/bpf/arraymap.c

(limited to 'kernel/bpf/arraymap.c')

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
new file mode 100644
index 000000000..8a6616583
--- /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 const 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 array_type __read_mostly = {
+	.ops = &array_ops,
+	.type = BPF_MAP_TYPE_ARRAY,
+};
+
+static int __init register_array_map(void)
+{
+	bpf_register_map_type(&array_type);
+	return 0;
+}
+late_initcall(register_array_map);
-- 
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