Commit 2569c7b8 authored Apr 20, 2023 by Feng Zhou Committed by Alexei Starovoitov Apr 19, 2023

bpf: support access variable length array of integer type



After this commit:
bpf: Support variable length array in tracing programs (9c5f8a10)
Trace programs can access variable length array, but for structure
type. This patch adds support for integer type.

Example:
Hook load_balance
struct sched_domain {
	...
	unsigned long span[];
}

The access: sd->span[0].

Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
Link: https://lore.kernel.org/r/20230420032735.27760-2-zhoufeng.zf@bytedance.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 2ddade32

kernel/bpf/btf.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -6157,11 +6157,13 @@ static int btf_struct_walk(struct bpf_verifier_log log, const struct btf btf,
		if (off < moff)
		goto error;

		/* Only allow structure for now, can be relaxed for
		* other types later.
		*/
		/* allow structure and integer */
		t = btf_type_skip_modifiers(btf, array_elem->type,
		NULL);

		if (btf_type_is_int(t))
		return WALK_SCALAR;

		if (!btf_type_is_struct(t))
		goto error;