tools/testing/selftests/bpf/progs/test_btf_map_in_map.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/bpf/progs/test_btf_map_in_map.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/bpf/progs/test_btf_map_in_map.c
Extension
.c
Size
3690 bytes
Lines
151
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct inner_map {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 1);
	__type(key, int);
	__type(value, int);
} inner_map1 SEC(".maps"),
  inner_map2 SEC(".maps");

struct inner_map_sz2 {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 2);
	__type(key, int);
	__type(value, int);
} inner_map_sz2 SEC(".maps");

struct outer_arr {
	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
	__uint(max_entries, 3);
	__type(key, int);
	__type(value, int);
	/* it's possible to use anonymous struct as inner map definition here */
	__array(values, struct {
		__uint(type, BPF_MAP_TYPE_ARRAY);
		/* changing max_entries to 2 will fail during load
		 * due to incompatibility with inner_map definition */
		__uint(max_entries, 1);
		__type(key, int);
		__type(value, int);
	});
} outer_arr SEC(".maps") = {
	/* (void *) cast is necessary because we didn't use `struct inner_map`
	 * in __inner(values, ...)
	 * Actually, a conscious effort is required to screw up initialization
	 * of inner map slots, which is a great thing!
	 */
	.values = { (void *)&inner_map1, 0, (void *)&inner_map2 },
};

struct inner_map_sz3 {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(map_flags, BPF_F_INNER_MAP);
	__uint(max_entries, 3);
	__type(key, int);
	__type(value, int);
} inner_map3 SEC(".maps"),
  inner_map4 SEC(".maps");

struct inner_map_sz4 {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(map_flags, BPF_F_INNER_MAP);
	__uint(max_entries, 5);
	__type(key, int);
	__type(value, int);
} inner_map5 SEC(".maps");

struct outer_arr_dyn {
	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
	__uint(max_entries, 3);
	__type(key, int);
	__type(value, int);
	__array(values, struct {
		__uint(type, BPF_MAP_TYPE_ARRAY);
		__uint(map_flags, BPF_F_INNER_MAP);
		__uint(max_entries, 1);
		__type(key, int);
		__type(value, int);
	});
} outer_arr_dyn SEC(".maps") = {
	.values = {
		[0] = (void *)&inner_map3,
		[1] = (void *)&inner_map4,
		[2] = (void *)&inner_map5,
	},
};

struct outer_hash {
	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
	__uint(max_entries, 5);
	__type(key, int);
	/* Here everything works flawlessly due to reuse of struct inner_map
	 * and compiler will complain at the attempt to use non-inner_map
	 * references below. This is great experience.
	 */
	__array(values, struct inner_map);
} outer_hash SEC(".maps") = {
	.values = {
		[0] = &inner_map2,
		[4] = &inner_map1,
	},
};

Annotation

Implementation Notes