aya::programs::uprobe: add support for cookies

[ajwerner]

Fixes #1132.

Note that this change does not add support in the public API for kprobes or tracepoints, but it's a trivial matter of plumbing.

Along the way, the Uprobe::attach API is cleaned up to make the attachment location more coherent. The logic being: if we're going to be breaking the API anyway, may as well clean it up a bit.

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[tamird]

You'll need to run CARGO_CFG_BPF_TARGET_ARCH=x86_64 cargo +nightly xtask public-api --bless --target x86_64-unknown-linux-gnu to regenerate the API fixtures I think.

Reviewed 33 of 33 files at r1, all commit messages.
Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @ajwerner)

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aya/src/programs/mod.rs line 223 at r1 (raw file):

    IOError(#[from] io::Error),

    /// Providing a bpf cookie for perf event links is not supported.

pretty far away from "perf event links" here and it's not in the variant name

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test/integration-test/src/tests/uprobe_cookie.rs line 45 at r1 (raw file):

        let read: [u8; 8] = (*read)
            .try_into()
            .with_context(|| format!("data: {:?}", read.len()))

data: {read:x}? IOW do we want the data or just its length?

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aya/src/sys/bpf.rs line 408 at r1 (raw file):

    attach_type: bpf_attach_type,
    flags: u32,
    args: Option<BpfLinkCreateArgs<'_>>,

nice.

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aya/src/sys/bpf.rs line 903 at r1 (raw file):

            link,
            Err((_, e)) if e.raw_os_error() == Some(libc::EBADF),
        )

Might fit on one line

Code quote:

        matches!(
            link,
            Err((_, e)) if e.raw_os_error() == Some(libc::EBADF),
        )

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aya/src/programs/uprobe.rs line 51 at r1 (raw file):

}

/// The location of in the target object file to which the uprobe is attached.

"of in"

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aya/src/programs/uprobe.rs line 62 at r1 (raw file):

}

impl<'a> From<&'a str> for UProbeAttachLocation<'a> {

should there be a From<u64> impl?

[ajwerner]

Thanks for the review!

You'll need to run CARGO_CFG_BPF_TARGET_ARCH=x86_64 cargo +nightly xtask public-api --bless --target x86_64-unknown-linux-gnu to regenerate the API fixtures I think.

Needed a rustup update to get this working, should be good now.

Reviewable status: 27 of 34 files reviewed, 5 unresolved discussions (waiting on @tamird)

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aya/src/programs/mod.rs line 223 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

pretty far away from "perf event links" here and it's not in the variant name

Made the error more specific to the cause rather than the source.

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aya/src/programs/uprobe.rs line 51 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

"of in"

Done.

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aya/src/programs/uprobe.rs line 62 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

should there be a From<u64> impl?

Sure, done.

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aya/src/sys/bpf.rs line 903 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

Might fit on one line

Done.

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test/integration-test/src/tests/uprobe_cookie.rs line 45 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

data: {read:x}? IOW do we want the data or just its length?

Done.

[mergify]

Hey @alessandrod, this pull request changes the Aya Public API and requires your review.

[tamird]

Reviewed 7 of 7 files at r2, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @ajwerner and @alessandrod)

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aya/src/programs/uprobe.rs line 51 at r1 (raw file):

Previously, ajwerner wrote…

Done.

"to which the uprobe is to be attached"?

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test/integration-test/src/tests/uprobe_cookie.rs line 45 at r2 (raw file):

        match read.try_into() {
            Ok(read) => seen.push(u64::from_le_bytes(read)),
            Err(_) => panic!("invalid ring buffer data: {read:x?}"),

Err(std::array::TryFromSliceError { .. }) for the OCD

[ajwerner]

Reviewable status: 32 of 34 files reviewed, 2 unresolved discussions (waiting on @alessandrod and @tamird)

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aya/src/programs/uprobe.rs line 51 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

"to which the uprobe is to be attached"?

Done.

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test/integration-test/src/tests/uprobe_cookie.rs line 45 at r2 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

Err(std::array::TryFromSliceError { .. }) for the OCD

Done.

[tamird]

Reviewed 2 of 2 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @alessandrod)

[alessandrod]

10/10 no notes thanks both!