Add target-less tracing SEC() definitions #2845
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Master branch: 658d876 |
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Master branch: 097caa8 |
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In a lot of cases the target of kprobe/kretprobe, tracepoint, raw
tracepoint, etc BPF program might not be known at the compilation time
and will be discovered at runtime. This was always a supported case by
libbpf, with APIs like bpf_program__attach_{kprobe,tracepoint,etc}()
accepting full target definition, regardless of what was defined in
SEC() definition in BPF source code.
Unfortunately, up till now libbpf still enforced users to specify at
least something for the fake target, e.g., SEC("kprobe/whatever"), which
is cumbersome and somewhat misleading.
This patch allows target-less SEC() definitions for basic tracing BPF
program types:
- kprobe/kretprobe;
- multi-kprobe/multi-kretprobe;
- tracepoints;
- raw tracepoints.
Such target-less SEC() definitions are meant to specify declaratively
proper BPF program type only. Attachment of them will have to be handled
programmatically using correct APIs. As such, skeleton's auto-attachment
of such BPF programs is skipped and generic bpf_program__attach() will
fail, if attempted, due to the lack of enough target information.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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Master branch: 658d876 |
Similar to previous patch, support target-less definitions like
SEC("fentry"), SEC("freplace"), etc. For such BTF-backed program types
it is expected that user will specify BTF target programmatically at
runtime using bpf_program__set_attach_target() *before* load phase. If
not, libbpf will report this as an error.
Aslo use SEC_ATTACH_BTF flag instead of explicitly listing a set of
types that are expected to require attach_btf_id. This was an accidental
omission during custom SEC() support refactoring.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Add new or modify existing SEC() definitions to be target-less and validate that libbpf handles such program definitions correctly. For kprobe/kretprobe we also add explicit test that generic bpf_program__attach() works in cases when kprobe definition contains proper target. It wasn't previously tested as selftests code always explicitly specified the target regardless. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Song Liu <songliubraving@fb.com>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=630550 expired. Closing PR. |
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Pull request for series with
subject: Add target-less tracing SEC() definitions
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=630550