From 243d720e2e5320f7ed09034361aa20b74d8eeb03 Mon Sep 17 00:00:00 2001 From: Mykyta Yatsenko Date: Wed, 9 Apr 2025 00:44:16 +0100 Subject: [PATCH 1/2] libbpf: Add getters for BTF.ext func and line info Introducing new libbpf API getters for BTF.ext func and line info, namely: bpf_program__func_info bpf_program__func_info_cnt bpf_program__line_info bpf_program__line_info_cnt This change enables scenarios, when user needs to load bpf_program directly using `bpf_prog_load`, instead of higher-level `bpf_object__load`. Line and func info are required for checking BTF info in verifier; verification may fail without these fields if, for example, program calls `bpf_obj_new`. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250408234417.452565-2-mykyta.yatsenko5@gmail.com --- tools/lib/bpf/libbpf.c | 24 ++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 6 ++++++ tools/lib/bpf/libbpf.map | 4 ++++ 3 files changed, 34 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 37d563e14051..b2591f5cab65 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9446,6 +9446,30 @@ int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log return 0; } +struct bpf_func_info *bpf_program__func_info(const struct bpf_program *prog) +{ + if (prog->func_info_rec_size != sizeof(struct bpf_func_info)) + return libbpf_err_ptr(-EOPNOTSUPP); + return prog->func_info; +} + +__u32 bpf_program__func_info_cnt(const struct bpf_program *prog) +{ + return prog->func_info_cnt; +} + +struct bpf_line_info *bpf_program__line_info(const struct bpf_program *prog) +{ + if (prog->line_info_rec_size != sizeof(struct bpf_line_info)) + return libbpf_err_ptr(-EOPNOTSUPP); + return prog->line_info; +} + +__u32 bpf_program__line_info_cnt(const struct bpf_program *prog) +{ + return prog->line_info_cnt; +} + #define SEC_DEF(sec_pfx, ptype, atype, flags, ...) { \ .sec = (char *)sec_pfx, \ .prog_type = BPF_PROG_TYPE_##ptype, \ diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index e0605403f977..d39f19c8396d 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -940,6 +940,12 @@ LIBBPF_API int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_le LIBBPF_API const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size); LIBBPF_API int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size); +LIBBPF_API struct bpf_func_info *bpf_program__func_info(const struct bpf_program *prog); +LIBBPF_API __u32 bpf_program__func_info_cnt(const struct bpf_program *prog); + +LIBBPF_API struct bpf_line_info *bpf_program__line_info(const struct bpf_program *prog); +LIBBPF_API __u32 bpf_program__line_info_cnt(const struct bpf_program *prog); + /** * @brief **bpf_program__set_attach_target()** sets BTF-based attach target * for supported BPF program types: diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index d8b71f22f197..1205f9a4fe04 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -437,6 +437,10 @@ LIBBPF_1.6.0 { bpf_linker__add_fd; bpf_linker__new_fd; bpf_object__prepare; + bpf_program__func_info; + bpf_program__func_info_cnt; + bpf_program__line_info; + bpf_program__line_info_cnt; btf__add_decl_attr; btf__add_type_attr; } LIBBPF_1.5.0; From b8390dd1e09e1abf73299209e9e7bcc2585b88e6 Mon Sep 17 00:00:00 2001 From: Mykyta Yatsenko Date: Wed, 9 Apr 2025 00:44:17 +0100 Subject: [PATCH 2/2] selftests/bpf: Add BTF.ext line/func info getter tests Add selftests checking that line and func info retrieved by newly added libbpf APIs are the same as returned by kernel via bpf_prog_get_info_by_fd. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250408234417.452565-3-mykyta.yatsenko5@gmail.com --- .../selftests/bpf/prog_tests/test_btf_ext.c | 64 +++++++++++++++++++ .../selftests/bpf/progs/test_btf_ext.c | 22 +++++++ 2 files changed, 86 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_btf_ext.c create mode 100644 tools/testing/selftests/bpf/progs/test_btf_ext.c diff --git a/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c new file mode 100644 index 000000000000..7d1b478c99a0 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c @@ -0,0 +1,64 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms Inc. */ +#include +#include "test_btf_ext.skel.h" +#include "btf_helpers.h" + +static void subtest_line_func_info(void) +{ + struct test_btf_ext *skel; + struct bpf_prog_info info; + struct bpf_line_info line_info[128], *libbpf_line_info; + struct bpf_func_info func_info[128], *libbpf_func_info; + __u32 info_len = sizeof(info), libbbpf_line_info_cnt, libbbpf_func_info_cnt; + int err, fd; + + skel = test_btf_ext__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) + return; + + fd = bpf_program__fd(skel->progs.global_func); + + memset(&info, 0, sizeof(info)); + info.line_info = ptr_to_u64(&line_info); + info.nr_line_info = sizeof(line_info); + info.line_info_rec_size = sizeof(*line_info); + err = bpf_prog_get_info_by_fd(fd, &info, &info_len); + if (!ASSERT_OK(err, "prog_line_info")) + goto out; + + libbpf_line_info = bpf_program__line_info(skel->progs.global_func); + libbbpf_line_info_cnt = bpf_program__line_info_cnt(skel->progs.global_func); + + memset(&info, 0, sizeof(info)); + info.func_info = ptr_to_u64(&func_info); + info.nr_func_info = sizeof(func_info); + info.func_info_rec_size = sizeof(*func_info); + err = bpf_prog_get_info_by_fd(fd, &info, &info_len); + if (!ASSERT_OK(err, "prog_func_info")) + goto out; + + libbpf_func_info = bpf_program__func_info(skel->progs.global_func); + libbbpf_func_info_cnt = bpf_program__func_info_cnt(skel->progs.global_func); + + if (!ASSERT_OK_PTR(libbpf_line_info, "bpf_program__line_info")) + goto out; + if (!ASSERT_EQ(libbbpf_line_info_cnt, info.nr_line_info, "line_info_cnt")) + goto out; + if (!ASSERT_OK_PTR(libbpf_func_info, "bpf_program__func_info")) + goto out; + if (!ASSERT_EQ(libbbpf_func_info_cnt, info.nr_func_info, "func_info_cnt")) + goto out; + ASSERT_MEMEQ(libbpf_line_info, line_info, libbbpf_line_info_cnt * sizeof(*line_info), + "line_info"); + ASSERT_MEMEQ(libbpf_func_info, func_info, libbbpf_func_info_cnt * sizeof(*func_info), + "func_info"); +out: + test_btf_ext__destroy(skel); +} + +void test_btf_ext(void) +{ + if (test__start_subtest("line_func_info")) + subtest_line_func_info(); +} diff --git a/tools/testing/selftests/bpf/progs/test_btf_ext.c b/tools/testing/selftests/bpf/progs/test_btf_ext.c new file mode 100644 index 000000000000..cdf20331db04 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_btf_ext.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2025 Meta Platforms Inc. */ + +#include +#include +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +__noinline static void f0(void) +{ + __u64 a = 1; + + __sink(a); +} + +SEC("xdp") +__u64 global_func(struct xdp_md *xdp) +{ + f0(); + return XDP_DROP; +}