On Fri, Feb 11, 2022 at 01:14:50PM -0800, Andrii Nakryiko wrote:
> Add a selftest validating various aspects of libbpf's handling of custom
> SEC() handlers. It also demonstrates how libraries can ensure very early
> callbacks registration and unregistration using
> __attribute__((constructor))/__attribute__((destructor)) functions.
>
> Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> .../bpf/prog_tests/custom_sec_handlers.c | 176 ++++++++++++++++++
> .../bpf/progs/test_custom_sec_handlers.c | 63 +++++++
> 2 files changed, 239 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
> new file mode 100644
> index 000000000000..28264528280d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
> @@ -0,0 +1,176 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2022 Facebook */
> +
> +#include <test_progs.h>
> +#include "test_custom_sec_handlers.skel.h"
> +
> +#define COOKIE_ABC1 1
> +#define COOKIE_ABC2 2
> +#define COOKIE_CUSTOM 3
> +#define COOKIE_FALLBACK 4
> +#define COOKIE_KPROBE 5
> +
> +static int custom_init_prog(struct bpf_program *prog, long cookie)
> +{
> + if (cookie == COOKIE_ABC1)
> + bpf_program__set_autoload(prog, false);
> +
> + return 0;
> +}
What is the value of init_fn callback?
afaict it was and still unused in libbpf.
The above example doesn't make a compelling case, since set_autoload
can be done out of preload callback.
Maybe drop init_fn for now and extend libbpf_prog_handler_opts
when there is actual need for it?
