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Uprobe path#12431

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olsajiri wants to merge 7 commits into
kernel-patches:bpf-next_basefrom
olsajiri:uprobe_path
Draft

Uprobe path#12431
olsajiri wants to merge 7 commits into
kernel-patches:bpf-next_basefrom
olsajiri:uprobe_path

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Kernel Patches Daemon and others added 7 commits June 9, 2026 21:29
Resolve the uprobe_multi user path with user_path_at() instead of copying
the string with strndup_user() and passing it to kern_path(). This removes
the temporary allocation and keeps the lookup logic in one helper.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Allow uprobe_multi link to identify the target binary by an already
opened file descriptor.

Adding new BPF_F_UPROBE_MULTI_PATH_FD flag and the path_fd field for
the attr.link_create.uprobe_multi struct.

When the flag is set, we resolve the target from path_fd, without the
flag, we keep the existing string path behavior.

I don't see a use case for supporting O_PATH file descriptors, because
we need to read the binary first to get probes offsets, so I'm using
the CLASS(fd, f), which fails for O_PATH fds.

Assisted-by: Codex:GPT-5.4
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding the path_fd field to struct bpf_link_create_opts and passing it
through kernel attr interface.

Assisted-by: Codex:GPT-5.4
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Add a uprobe_multi link API selftest that opens /proc/self/exe and passes
the resulting descriptor through opts.uprobe_multi.path_fd with
BPF_F_UPROBE_MULTI_PATH_FD set.

Assisted-by: Codex:GPT-5.4
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding tests to attach_api_fails suite to make sure we fail
wrong setup for path_fd usage.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
We verify info.uprobe_multi.flags against wrong kprobe-multi flag
(BPF_F_KPROBE_MULTI_RETURN). It's the same value as the correct
flag (BPF_F_UPROBE_MULTI_RETURN), so there's not functional change.

Fixes: 147c693 ("selftests/bpf: Add link_info test for uprobe_multi link")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
@kernel-patches-daemon-bpf kernel-patches-daemon-bpf Bot force-pushed the bpf-next_base branch 2 times, most recently from d9ed865 to 1b36123 Compare June 10, 2026 23:23
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