From: Kumar Kartikeya Dwivedi KF_IMPLICIT_ARGS kfuncs have a BPF-call prototype and a real kernel target prototype. Add a tracing selftest that attaches fentry and fexit programs to bpf_kfunc_implicit_arg(), runs a syscall BPF program that calls it, and checks that the tracing context exposes both the explicit argument and the implicit prog aux pointer. Signed-off-by: Kumar Kartikeya Dwivedi Co-developed-by: Ihor Solodrai Signed-off-by: Ihor Solodrai --- .../prog_tests/kfunc_implicit_args_tracing.c | 36 +++++++++ .../bpf/progs/kfunc_implicit_args_tracing.c | 77 +++++++++++++++++++ 2 files changed, 113 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/kfunc_implicit_args_tracing.c create mode 100644 tools/testing/selftests/bpf/progs/kfunc_implicit_args_tracing.c diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_implicit_args_tracing.c b/tools/testing/selftests/bpf/prog_tests/kfunc_implicit_args_tracing.c new file mode 100644 index 000000000000..61cc5aaba025 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/kfunc_implicit_args_tracing.c @@ -0,0 +1,36 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include "kfunc_implicit_args_tracing.skel.h" + +void test_kfunc_implicit_args_tracing(void) +{ + struct kfunc_implicit_args_tracing *skel; + LIBBPF_OPTS(bpf_test_run_opts, topts); + int err, fd; + + skel = kfunc_implicit_args_tracing__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_and_load")) + return; + + err = kfunc_implicit_args_tracing__attach(skel); + if (!ASSERT_OK(err, "attach")) + goto cleanup; + + fd = bpf_program__fd(skel->progs.trigger_implicit_arg); + err = bpf_prog_test_run_opts(fd, &topts); + if (!ASSERT_OK(err, "test_run")) + goto cleanup; + + ASSERT_EQ(topts.retval, 5, "kfunc_retval"); + ASSERT_EQ(skel->bss->fentry_arg_cnt, 2, "fentry_arg_cnt"); + ASSERT_NEQ(skel->bss->fentry_aux_arg, 0, "fentry_aux_arg"); + ASSERT_EQ(skel->bss->fentry_result, 1, "fentry_result"); + ASSERT_EQ(skel->bss->fexit_arg_cnt, 2, "fexit_arg_cnt"); + ASSERT_NEQ(skel->bss->fexit_aux_arg, 0, "fexit_aux_arg"); + ASSERT_EQ(skel->bss->fexit_result, 1, "fexit_result"); + +cleanup: + kfunc_implicit_args_tracing__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/kfunc_implicit_args_tracing.c b/tools/testing/selftests/bpf/progs/kfunc_implicit_args_tracing.c new file mode 100644 index 000000000000..995f8b8b5b9e --- /dev/null +++ b/tools/testing/selftests/bpf/progs/kfunc_implicit_args_tracing.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include +#include + +extern int bpf_kfunc_implicit_arg(int a) __weak __ksym; + +char _license[] SEC("license") = "GPL"; + +/* Shared arg checks; reports arg count and aux, returns 1 on success. */ +static __always_inline __u64 +check_implicit_args(void *ctx, __u64 *arg_cnt, __u64 *aux_arg) +{ + __u64 a = 0, aux = 0, z = 0; + __u64 result; + __s64 err; + + *arg_cnt = bpf_get_func_arg_cnt(ctx); + result = *arg_cnt == 2; + + err = bpf_get_func_arg(ctx, 0, &a); + result &= err == 0 && (int)a == 5; + + err = bpf_get_func_arg(ctx, 1, &aux); + *aux_arg = aux; + result &= err == 0 && aux != 0; + + err = bpf_get_func_arg(ctx, 2, &z); + result &= err == -EINVAL; + + return result; +} + +__u64 fentry_result; +__u64 fentry_arg_cnt; +__u64 fentry_aux_arg; + +SEC("fentry/bpf_kfunc_implicit_arg") +int BPF_PROG(trace_implicit_arg_fentry) +{ + __u64 ret = 0; + __s64 err; + + fentry_result = check_implicit_args(ctx, &fentry_arg_cnt, &fentry_aux_arg); + + err = bpf_get_func_ret(ctx, &ret); + fentry_result &= err == -EOPNOTSUPP; + + return 0; +} + +__u64 fexit_result; +__u64 fexit_arg_cnt; +__u64 fexit_aux_arg; + +SEC("fexit/bpf_kfunc_implicit_arg") +int BPF_PROG(trace_implicit_arg_fexit) +{ + __u64 ret = 0; + __s64 err; + + fexit_result = check_implicit_args(ctx, &fexit_arg_cnt, &fexit_aux_arg); + + err = bpf_get_func_ret(ctx, &ret); + fexit_result &= err == 0 && ret == 5; + + return 0; +} + +SEC("syscall") +int trigger_implicit_arg(void *ctx) +{ + return bpf_kfunc_implicit_arg(5); +} -- 2.55.0