bpf: Introduce kprobe_multi session attach #6922
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Adding support to attach bpf program for entry and return probe of the same function. This is common use case which at the moment requires to create two kprobe multi links. Adding new BPF_TRACE_KPROBE_SESSION attach type that instructs kernel to attach single link program to both entry and exit probe. It's possible to control execution of the bpf program on return probe simply by returning zero or non zero from the entry bpf program execution to execute or not the bpf program on return probe respectively. Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding struct bpf_session_run_ctx object to hold session related data, which is atm is_return bool and data pointer coming in following changes. Placing bpf_session_run_ctx layer in between bpf_run_ctx and bpf_kprobe_multi_run_ctx so the session data can be retrieved regardless of if it's kprobe_multi or uprobe_multi link, which support is coming in future. This way both kprobe_multi and uprobe_multi can use same kfuncs to access the session data. Adding bpf_session_is_return kfunc that returns true if the bpf program is executed from the exit probe of the kprobe multi link attached in wrapper mode. It returns false otherwise. Adding new kprobe hook for kprobe program type. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding support for cookie within the session of kprobe multi entry and return program. The session cookie is u64 value and can be retrieved be new kfunc bpf_session_cookie, which returns pointer to the cookie value. The bpf program can use the pointer to store (on entry) and load (on return) the value. The cookie value is implemented via fprobe feature that allows to share values between entry and return ftrace fprobe callbacks. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding support to attach program in kprobe session mode
with bpf_program__attach_kprobe_multi_opts function.
Adding session bool to bpf_kprobe_multi_opts struct that allows
to load and attach the bpf program via kprobe session.
the attachment to create kprobe multi session.
Also adding new program loader section that allows:
SEC("kprobe.session/bpf_fentry_test*")
and loads/attaches kprobe program as kprobe session.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding kprobe session attach type name to attach_type_name, so libbpf_bpf_attach_type_str returns proper string name for BPF_TRACE_KPROBE_SESSION attach type. Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding kprobe session test and testing that the entry program return value controls execution of the return probe program. Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding kprobe session test that verifies the cookie value get properly propagated from entry to return program. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=849243 irrelevant now. Closing PR. |
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Pull request for series with
subject: bpf: Introduce kprobe_multi session attach
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=849243