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bpf_iter and cgroup support #110

Merged
merged 2 commits into from
Jun 17, 2020
Merged

bpf_iter and cgroup support #110

merged 2 commits into from
Jun 17, 2020

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lmb
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@lmb lmb commented Jun 16, 2020

Use the low-level APIs to construct high-level Links for attaching to cgroups and bpf_iter. Especially the cgroup support is interesting, because it falls back to BPF_PROG_ATTACH after trying bpf_link on older kernel.

New API:

 var ErrNotSupported = internal.ErrNotSupported
 func RawAttachProgram(opts RawAttachProgramOptions) error
 func RawDetachProgram(opts RawDetachProgramOptions) error
+type CgroupOptions struct{ ... }
+type Iter struct{ ... }
+    func AttachIter(opts IterOptions) (*Iter, error)
+    func LoadPinnedIter(fileName string) (*Iter, error)
+type IterOptions struct{ ... }
 type Link interface{ ... }
+    func AttachCgroup(opts CgroupOptions) (Link, error)
+    func LoadPinnedCgroup(fileName string) (Link, error)
 type RawAttachProgramOptions struct{ ... }
 type RawDetachProgramOptions struct{ ... }
 type RawLink struct{ ... }

lmb added 2 commits June 16, 2020 15:16
@lmb
link: add support for attaching to cgroups
6b52926 
Use the BPF_PROG_ATTACH and bpf_link infrastructure to implement a
generic way to attach to cgroups. Older kernels will use BPF_PROG_ATTACH,
newer ones bpf_link.
@lmb
link: add bpf_iter support
070fbb0 
bpf_iter allows writing dumpers for various kernel data structures like BPF maps.
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lmb commented Jun 16, 2020

I'm not sure about the LoadPinned* methods. I think it might be possible to write a LoadPinnedLink function which uses BPF_GET_OBJ_INFO (or whatever that is called) to determine what kind of Link we are dealing with, which would make these obsolete.

florianl
florianl approved these changes Jun 16, 2020
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looks good to me! and great work!

Do you think raw_tracepoints should also be in link?

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lmb commented Jun 17, 2020

Yes, if we can make them conform to Link and if we don't need new dependencies.

tklauser
tklauser approved these changes Jun 17, 2020
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Nice!

@lmb lmb merged commit 7acf5cc into master Jun 17, 2020
@lmb lmb deleted the iter-and-cgroup branch June 17, 2020 13:59
This was referenced Dec 3, 2020
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@florianl florianl florianl approved these changes

@tklauser tklauser tklauser approved these changes

@jrfastab jrfastab Awaiting requested review from jrfastab

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3 participants
@lmb @tklauser @florianl