From: Andrii Nakryiko Date: Tue, 9 Jan 2024 23:17:38 +0000 (-0800) Subject: selftests/bpf: detect testing prog flags support X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=56d3e44af80c6b4c7cb89a73061ee35d4a7aee18;p=linux.git selftests/bpf: detect testing prog flags support Various tests specify extra testing prog_flags when loading BPF programs, like BPF_F_TEST_RND_HI32, and more recently also BPF_F_TEST_REG_INVARIANTS. While BPF_F_TEST_RND_HI32 is old enough to not cause much problem on older kernels, BPF_F_TEST_REG_INVARIANTS is very fresh and unconditionally specifying it causes selftests to fail on even slightly outdated kernels. This breaks libbpf CI test against 4.9 and 5.15 kernels, it can break some local development (done outside of VM), etc. To prevent this, and guard against similar problems in the future, do runtime detection of supported "testing flags", and only provide those that host kernel recognizes. Acked-by: Song Liu Acked-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240109231738.575844-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c index e770912fc1d24..4c6ada5b270b2 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c @@ -35,7 +35,7 @@ static int check_load(const char *file, enum bpf_prog_type type) } bpf_program__set_type(prog, type); - bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS); + bpf_program__set_flags(prog, testing_prog_flags()); bpf_program__set_log_level(prog, 4 | extra_prog_load_log_flags); err = bpf_object__load(obj); diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c index 820d0bcfc474d..eb74363f9f701 100644 --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c @@ -840,7 +840,7 @@ static int load_range_cmp_prog(struct range x, struct range y, enum op op, .log_level = 2, .log_buf = log_buf, .log_size = log_sz, - .prog_flags = BPF_F_TEST_REG_INVARIANTS, + .prog_flags = testing_prog_flags(), ); /* ; skip exit block below diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c index 72906d27babff..ba57601c2a4d5 100644 --- a/tools/testing/selftests/bpf/test_loader.c +++ b/tools/testing/selftests/bpf/test_loader.c @@ -181,7 +181,7 @@ static int parse_test_spec(struct test_loader *tester, memset(spec, 0, sizeof(*spec)); spec->prog_name = bpf_program__name(prog); - spec->prog_flags = BPF_F_TEST_REG_INVARIANTS; /* by default be strict */ + spec->prog_flags = testing_prog_flags(); btf = bpf_object__btf(obj); if (!btf) { diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c index b0068a9d2cfe9..80c42583f5977 100644 --- a/tools/testing/selftests/bpf/test_sock_addr.c +++ b/tools/testing/selftests/bpf/test_sock_addr.c @@ -19,6 +19,7 @@ #include #include "cgroup_helpers.h" +#include "testing_helpers.h" #include "bpf_util.h" #ifndef ENOTSUPP @@ -679,7 +680,7 @@ static int load_path(const struct sock_addr_test *test, const char *path) bpf_program__set_type(prog, BPF_PROG_TYPE_CGROUP_SOCK_ADDR); bpf_program__set_expected_attach_type(prog, test->expected_attach_type); - bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS); + bpf_program__set_flags(prog, testing_prog_flags()); err = bpf_object__load(obj); if (err) { diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 87519d7fe4c62..1a09fc34d093a 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -1545,7 +1545,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv, if (fixup_skips != skips) return; - pflags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS; + pflags = testing_prog_flags(); if (test->flags & F_LOAD_WITH_STRICT_ALIGNMENT) pflags |= BPF_F_STRICT_ALIGNMENT; if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS) diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c index 53c40f62fdcb8..106ef05586b8f 100644 --- a/tools/testing/selftests/bpf/testing_helpers.c +++ b/tools/testing/selftests/bpf/testing_helpers.c @@ -252,6 +252,34 @@ __u32 link_info_prog_id(const struct bpf_link *link, struct bpf_link_info *info) int extra_prog_load_log_flags = 0; +int testing_prog_flags(void) +{ + static int cached_flags = -1; + static int prog_flags[] = { BPF_F_TEST_RND_HI32, BPF_F_TEST_REG_INVARIANTS }; + static struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int insn_cnt = ARRAY_SIZE(insns), i, fd, flags = 0; + LIBBPF_OPTS(bpf_prog_load_opts, opts); + + if (cached_flags >= 0) + return cached_flags; + + for (i = 0; i < ARRAY_SIZE(prog_flags); i++) { + opts.prog_flags = prog_flags[i]; + fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "flag-test", "GPL", + insns, insn_cnt, &opts); + if (fd >= 0) { + flags |= prog_flags[i]; + close(fd); + } + } + + cached_flags = flags; + return cached_flags; +} + int bpf_prog_test_load(const char *file, enum bpf_prog_type type, struct bpf_object **pobj, int *prog_fd) { @@ -276,7 +304,7 @@ int bpf_prog_test_load(const char *file, enum bpf_prog_type type, if (type != BPF_PROG_TYPE_UNSPEC && bpf_program__type(prog) != type) bpf_program__set_type(prog, type); - flags = bpf_program__flags(prog) | BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS; + flags = bpf_program__flags(prog) | testing_prog_flags(); bpf_program__set_flags(prog, flags); err = bpf_object__load(obj); @@ -299,7 +327,7 @@ int bpf_test_load_program(enum bpf_prog_type type, const struct bpf_insn *insns, { LIBBPF_OPTS(bpf_prog_load_opts, opts, .kern_version = kern_version, - .prog_flags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS, + .prog_flags = testing_prog_flags(), .log_level = extra_prog_load_log_flags, .log_buf = log_buf, .log_size = log_buf_sz, diff --git a/tools/testing/selftests/bpf/testing_helpers.h b/tools/testing/selftests/bpf/testing_helpers.h index 1ed5b9200d661..e099aa4da611e 100644 --- a/tools/testing/selftests/bpf/testing_helpers.h +++ b/tools/testing/selftests/bpf/testing_helpers.h @@ -51,5 +51,6 @@ struct bpf_insn; * e.g. verifier.c:convert_ctx_access() is done. */ int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt); +int testing_prog_flags(void); #endif /* __TESTING_HELPERS_H */