Upstream cilium GetMapInfo

[lmb]

Cilium has a cool function that parses map attributes from /proc: https://github.com/cilium/cilium/blob/12fe19d26afd005aa0e0e4c312f81b52af919b82/pkg/bpf/map_linux.go#L282

We should incorporate this into LoadPinnedMap, to make it work on kernels < 4.14.

[lmb]

@joestringer do you think you could take a stab at this?

[joestringer]

Sure, it's all just a matter of finding the time ;)

[whl739]

And GetProgInfoByFD ? (https://github.com/cilium/cilium/blob/master/pkg/bpf/prog_linux.go#L106)

[lmb]

That's what LoadPinned(Map|Program) use right now. This issue is about adding a fall back for older kernels that don't have the function.

[whl739]

Got it.
But how can i use APIs like GetMapInfo or GetProgInfo, they are private in syscalls.go(for example, bpfGetMapInfoByFD).

[joestringer]

@whl739 Does LoadPinnedMap() / LoadPinnedProgram() do what you want? I believe that these are effectively the higher level API for the same thing.

[whl739]

@joestringer you are right, these APIs are enough if i only want to get the map/prog.
But if i want to get more info about map/prog, such as type bpfMapInfo struct and type bpfProgInfo struct defined in syscalls.go, i didn't find any API can do that, did i miss something?

[lmb]

You can use https://godoc.org/github.com/cilium/ebpf#Map.ABI to access some of the information from the syscalls. Please create a separate issue explaining what you want to achieve if that isn't enough for your use case.

[whl739]

Thanks for your kind help. I'll create a new issue.