Re: [PATCH net-next 1/4] bpf: allow bpf programs to tail-call other bpf programs

From: Alexei Starovoitov
Date: Tue May 19 2015 - 20:18:52 EST


On 5/19/15 5:13 PM, Andy Lutomirski wrote:

IMO this is starting to get a bit ugly. Would it be possible to have
the program dereference the subprogram reference itself from the jump
table? There would have to be a verifier type that represents a
reference to a program tail-call entry point, but that seems better
than having this weird indirection.

Which part? I don't think you've looked at examples yet.
network parser has to call itself. Otherwise we cannot parse 10 mpls
labels or TLVs.
Indirection via jump_table also has to be there.
We need to dynamically add and remove programs form this jump table.
It cannot be all static.

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