On Thu, Jan 04, 2024 at 02:39:32PM -0800, andrii@xxxxxxxxxx wrote:
> From: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> 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 even slightly outdated kernels.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.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
jirka
> ---
> .../bpf/prog_tests/bpf_verif_scale.c | 2 +-
> .../selftests/bpf/prog_tests/reg_bounds.c | 2 +-
> tools/testing/selftests/bpf/test_loader.c | 2 +-
> tools/testing/selftests/bpf/test_sock_addr.c | 3 +-
> tools/testing/selftests/bpf/test_verifier.c | 2 +-
> tools/testing/selftests/bpf/testing_helpers.c | 32 +++++++++++++++++--
> tools/testing/selftests/bpf/testing_helpers.h | 2 ++
> 7 files changed, 38 insertions(+), 7 deletions(-)
>
> 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 e770912fc1d2..4c6ada5b270b 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 820d0bcfc474..eb74363f9f70 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 74ceb7877ae2..941778ac2691 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 b0068a9d2cfe..80c42583f597 100644
> --- a/tools/testing/selftests/bpf/test_sock_addr.c
> +++ b/tools/testing/selftests/bpf/test_sock_addr.c
> @@ -19,6 +19,7 @@
> #include <bpf/libbpf.h>
>
> #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 f36e41435be7..50fdc1100a4b 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -1588,7 +1588,7 @@ 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 d2458c1b1671..e1f797c5c501 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.c
> +++ b/tools/testing/selftests/bpf/testing_helpers.c
> @@ -251,6 +251,34 @@ __u32 link_info_prog_id(const struct bpf_link *link, struct bpf_link_info *info)
> }
>
> int extra_prog_load_log_flags = 0;
> +static int prog_test_flags = -1;
> +
> +int testing_prog_flags(void)
> +{
> + 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 (prog_test_flags >= 0)
> + return prog_test_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);
> + }
> + }
> +
> + prog_test_flags = flags;
> + return prog_test_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 35284faff4f2..1caa16f5096c 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.h
> +++ b/tools/testing/selftests/bpf/testing_helpers.h
> @@ -46,4 +46,6 @@ static inline __u64 get_time_ns(void)
> return (u64)t.tv_sec * 1000000000 + t.tv_nsec;
> }
>
> +int testing_prog_flags(void);
> +
> #endif /* __TESTING_HELPERS_H */
> --
> 2.34.1
>
>
