1 files changed, 304 insertions, 0 deletions
diff --git a/kernel/bpf/bpf_insn_array.c b/kernel/bpf/bpf_insn_array.c
new file mode 100644
index 000000000000..c96630cb75bf
--- /dev/null
+++ b/kernel/bpf/bpf_insn_array.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2025 Isovalent */
+
+#include <linux/bpf.h>
+
+struct bpf_insn_array {
+	struct bpf_map map;
+	atomic_t used;
+	long *ips;
+	DECLARE_FLEX_ARRAY(struct bpf_insn_array_value, values);
+};
+
+#define cast_insn_array(MAP_PTR) \
+	container_of((MAP_PTR), struct bpf_insn_array, map)
+
+#define INSN_DELETED ((u32)-1)
+
+static inline u64 insn_array_alloc_size(u32 max_entries)
+{
+	const u64 base_size = sizeof(struct bpf_insn_array);
+	const u64 entry_size = sizeof(struct bpf_insn_array_value);
+
+	return base_size + max_entries * (entry_size + sizeof(long));
+}
+
+static int insn_array_alloc_check(union bpf_attr *attr)
+{
+	u32 value_size = sizeof(struct bpf_insn_array_value);
+
+	if (attr->max_entries == 0 || attr->key_size != 4 ||
+	    attr->value_size != value_size || attr->map_flags != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void insn_array_free(struct bpf_map *map)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+
+	bpf_map_area_free(insn_array);
+}
+
+static struct bpf_map *insn_array_alloc(union bpf_attr *attr)
+{
+	u64 size = insn_array_alloc_size(attr->max_entries);
+	struct bpf_insn_array *insn_array;
+
+	insn_array = bpf_map_area_alloc(size, NUMA_NO_NODE);
+	if (!insn_array)
+		return ERR_PTR(-ENOMEM);
+
+	/* ips are allocated right after the insn_array->values[] array */
+	insn_array->ips = (void *)&insn_array->values[attr->max_entries];
+
+	bpf_map_init_from_attr(&insn_array->map, attr);
+
+	/* BPF programs aren't allowed to write to the map */
+	insn_array->map.map_flags |= BPF_F_RDONLY_PROG;
+
+	return &insn_array->map;
+}
+
+static void *insn_array_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	u32 index = *(u32 *)key;
+
+	if (unlikely(index >= insn_array->map.max_entries))
+		return NULL;
+
+	return &insn_array->values[index];
+}
+
+static long insn_array_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	u32 index = *(u32 *)key;
+	struct bpf_insn_array_value val = {};
+
+	if (unlikely(index >= insn_array->map.max_entries))
+		return -E2BIG;
+
+	if (unlikely(map_flags & BPF_NOEXIST))
+		return -EEXIST;
+
+	copy_map_value(map, &val, value);
+	if (val.jitted_off || val.xlated_off)
+		return -EINVAL;
+
+	insn_array->values[index].orig_off = val.orig_off;
+
+	return 0;
+}
+
+static long insn_array_delete_elem(struct bpf_map *map, void *key)
+{
+	return -EINVAL;
+}
+
+static int insn_array_check_btf(const struct bpf_map *map,
+			      const struct btf *btf,
+			      const struct btf_type *key_type,
+			      const struct btf_type *value_type)
+{
+	if (!btf_type_is_i32(key_type))
+		return -EINVAL;
+
+	if (!btf_type_is_i64(value_type))
+		return -EINVAL;
+
+	return 0;
+}
+
+static u64 insn_array_mem_usage(const struct bpf_map *map)
+{
+	return insn_array_alloc_size(map->max_entries);
+}
+
+static int insn_array_map_direct_value_addr(const struct bpf_map *map, u64 *imm, u32 off)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+
+	if ((off % sizeof(long)) != 0 ||
+	    (off / sizeof(long)) >= map->max_entries)
+		return -EINVAL;
+
+	/* from BPF's point of view, this map is a jump table */
+	*imm = (unsigned long)insn_array->ips + off;
+
+	return 0;
+}
+
+BTF_ID_LIST_SINGLE(insn_array_btf_ids, struct, bpf_insn_array)
+
+const struct bpf_map_ops insn_array_map_ops = {
+	.map_alloc_check = insn_array_alloc_check,
+	.map_alloc = insn_array_alloc,
+	.map_free = insn_array_free,
+	.map_get_next_key = bpf_array_get_next_key,
+	.map_lookup_elem = insn_array_lookup_elem,
+	.map_update_elem = insn_array_update_elem,
+	.map_delete_elem = insn_array_delete_elem,
+	.map_check_btf = insn_array_check_btf,
+	.map_mem_usage = insn_array_mem_usage,
+	.map_direct_value_addr = insn_array_map_direct_value_addr,
+	.map_btf_id = &insn_array_btf_ids[0],
+};
+
+static inline bool is_frozen(struct bpf_map *map)
+{
+	guard(mutex)(&map->freeze_mutex);
+
+	return map->frozen;
+}
+
+static bool is_insn_array(const struct bpf_map *map)
+{
+	return map->map_type == BPF_MAP_TYPE_INSN_ARRAY;
+}
+
+static inline bool valid_offsets(const struct bpf_insn_array *insn_array,
+				 const struct bpf_prog *prog)
+{
+	u32 off;
+	int i;
+
+	for (i = 0; i < insn_array->map.max_entries; i++) {
+		off = insn_array->values[i].orig_off;
+
+		if (off >= prog->len)
+			return false;
+
+		if (off > 0) {
+			if (prog->insnsi[off-1].code == (BPF_LD | BPF_DW | BPF_IMM))
+				return false;
+		}
+	}
+
+	return true;
+}
+
+int bpf_insn_array_init(struct bpf_map *map, const struct bpf_prog *prog)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	struct bpf_insn_array_value *values = insn_array->values;
+	int i;
+
+	if (!is_frozen(map))
+		return -EINVAL;
+
+	if (!valid_offsets(insn_array, prog))
+		return -EINVAL;
+
+	/*
+	 * There can be only one program using the map
+	 */
+	if (atomic_xchg(&insn_array->used, 1))
+		return -EBUSY;
+
+	/*
+	 * Reset all the map indexes to the original values.  This is needed,
+	 * e.g., when a replay of verification with different log level should
+	 * be performed.
+	 */
+	for (i = 0; i < map->max_entries; i++)
+		values[i].xlated_off = values[i].orig_off;
+
+	return 0;
+}
+
+int bpf_insn_array_ready(struct bpf_map *map)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	int i;
+
+	for (i = 0; i < map->max_entries; i++) {
+		if (insn_array->values[i].xlated_off == INSN_DELETED)
+			continue;
+		if (!insn_array->ips[i])
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+void bpf_insn_array_release(struct bpf_map *map)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+
+	atomic_set(&insn_array->used, 0);
+}
+
+void bpf_insn_array_adjust(struct bpf_map *map, u32 off, u32 len)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	int i;
+
+	if (len <= 1)
+		return;
+
+	for (i = 0; i < map->max_entries; i++) {
+		if (insn_array->values[i].xlated_off <= off)
+			continue;
+		if (insn_array->values[i].xlated_off == INSN_DELETED)
+			continue;
+		insn_array->values[i].xlated_off += len - 1;
+	}
+}
+
+void bpf_insn_array_adjust_after_remove(struct bpf_map *map, u32 off, u32 len)
+{
+	struct bpf_insn_array *insn_array = cast_insn_array(map);
+	int i;
+
+	for (i = 0; i < map->max_entries; i++) {
+		if (insn_array->values[i].xlated_off < off)
+			continue;
+		if (insn_array->values[i].xlated_off == INSN_DELETED)
+			continue;
+		if (insn_array->values[i].xlated_off < off + len)
+			insn_array->values[i].xlated_off = INSN_DELETED;
+		else
+			insn_array->values[i].xlated_off -= len;
+	}
+}
+
+/*
+ * This function is called by JITs. The image is the real program
+ * image, the offsets array set up the xlated -> jitted mapping.
+ * The offsets[xlated] offset should point to the beginning of
+ * the jitted instruction.
+ */
+void bpf_prog_update_insn_ptrs(struct bpf_prog *prog, u32 *offsets, void *image)
+{
+	struct bpf_insn_array *insn_array;
+	struct bpf_map *map;
+	u32 xlated_off;
+	int i, j;
+
+	if (!offsets || !image)
+		return;
+
+	for (i = 0; i < prog->aux->used_map_cnt; i++) {
+		map = prog->aux->used_maps[i];
+		if (!is_insn_array(map))
+			continue;
+
+		insn_array = cast_insn_array(map);
+		for (j = 0; j < map->max_entries; j++) {
+			xlated_off = insn_array->values[j].xlated_off;
+			if (xlated_off == INSN_DELETED)
+				continue;
+			if (xlated_off < prog->aux->subprog_start)
+				continue;
+			xlated_off -= prog->aux->subprog_start;
+			if (xlated_off >= prog->len)
+				continue;
+
+			insn_array->values[j].jitted_off = offsets[xlated_off];
+			insn_array->ips[j] = (long)(image + offsets[xlated_off]);
+		}
+	}
+}