Commit 2341d6bb authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
Browse files

selftests/bpf: Test for btf_load command. 



Improve selftest to check that btf_load is working from bpf program.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-8-alexei.starovoitov@gmail.com
parent c571bd75

tools/testing/selftests/bpf/prog_tests/syscall.c

+3 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ struct args { 
	int max_entries;

	int map_fd;

	int prog_fd;

	int btf_fd;

};



void test_syscall(void)
@@ -49,4 +50,6 @@ void test_syscall(void) 
		close(ctx.prog_fd);

	if (ctx.map_fd > 0)

		close(ctx.map_fd);

	if (ctx.btf_fd > 0)

		close(ctx.btf_fd);

}

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

+50 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include <../../../tools/include/linux/filter.h>

#include <linux/btf.h>



char _license[] SEC("license") = "GPL";
@@ -14,8 +15,48 @@ struct args { 
	int max_entries;

	int map_fd;

	int prog_fd;

	int btf_fd;

};



#define BTF_INFO_ENC(kind, kind_flag, vlen) \

	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))

#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)

#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \

	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))

#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \

	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \

	BTF_INT_ENC(encoding, bits_offset, bits)



static int btf_load(void)

{

	struct btf_blob {

		struct btf_header btf_hdr;

		__u32 types[8];

		__u32 str;

	} raw_btf = {

		.btf_hdr = {

			.magic = BTF_MAGIC,

			.version = BTF_VERSION,

			.hdr_len = sizeof(struct btf_header),

			.type_len = sizeof(__u32) * 8,

			.str_off = sizeof(__u32) * 8,

			.str_len = sizeof(__u32),

		},

		.types = {

			/* long */

			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8),  /* [1] */

			/* unsigned long */

			BTF_TYPE_INT_ENC(0, 0, 0, 64, 8),  /* [2] */

		},

	};

	static union bpf_attr btf_load_attr = {

		.btf_size = sizeof(raw_btf),

	};



	btf_load_attr.btf = (long)&raw_btf;

	return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr));

}



SEC("syscall")

int bpf_prog(struct args *ctx)

{
@@ -33,6 +74,8 @@ int bpf_prog(struct args *ctx) 
		.map_type = BPF_MAP_TYPE_HASH,

		.key_size = 8,

		.value_size = 8,

		.btf_key_type_id = 1,

		.btf_value_type_id = 2,

	};

	static union bpf_attr map_update_attr = { .map_fd = 1, };

	static __u64 key = 12;
@@ -43,7 +86,14 @@ int bpf_prog(struct args *ctx) 
	};

	int ret;



	ret = btf_load();

	if (ret <= 0)

		return ret;



	ctx->btf_fd = ret;

	map_create_attr.max_entries = ctx->max_entries;

	map_create_attr.btf_fd = ret;



	prog_load_attr.license = (long) license;

	prog_load_attr.insns = (long) insns;

	prog_load_attr.log_buf = ctx->log_buf;