Re: [PATCH bpf-next 2/3] libbpf: Add support for program extensions
From: Andrii Nakryiko <hidden>
Date: 2020-01-20 22:51:55
Also in:
bpf
On Fri, Jan 17, 2020 at 4:47 PM Alexei Starovoitov [off-list ref] wrote:
Add minimal support for program extensions. bpf_object_open_opts() needs to be
called with attach_prog_fd = target_prog_fd and BPF program extension needs to
have in .c file section definition like SEC("replace/func_to_be_replaced").
libbpf will search for "func_to_be_replaced" in the target_prog_fd's BTF and
will pass it in attach_btf_id to the kernel. This approach works for tests, but
more compex use case may need to request function name (and attach_btf_id that
kernel sees) to be more dynamic. Such API will be added in future patches.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
tools/include/uapi/linux/bpf.h | 1 +
tools/lib/bpf/bpf.c | 3 ++-
tools/lib/bpf/libbpf.c | 14 +++++++++++---
tools/lib/bpf/libbpf.h | 2 ++
tools/lib/bpf/libbpf.map | 2 ++
tools/lib/bpf/libbpf_probes.c | 1 +
6 files changed, 19 insertions(+), 4 deletions(-)[...]
quoted hunk ↗ jump to hunk
enum bpf_attach_type bpf_program__get_expected_attach_type(struct bpf_program *prog)@@ -6265,6 +6269,10 @@ static const struct bpf_sec_def section_defs[] = { .expected_attach_type = BPF_TRACE_FEXIT, .is_attach_btf = true, .attach_fn = attach_trace), + SEC_DEF("replace/", EXT,
how about freplace/, similar to fentry/fexit?
+ .expected_attach_type = 0,
no need, it will be zero, if not specified here
+ .is_attach_btf = true,
+ .attach_fn = attach_trace),
BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),[...]