Alexei Starovoitov says:
====================
pull-request: bpf-next 2018-01-26
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) A number of extensions to tcp-bpf, from Lawrence.
- direct R or R/W access to many tcp_sock fields via bpf_sock_ops
- passing up to 3 arguments to bpf_sock_ops functions
- tcp_sock field bpf_sock_ops_cb_flags for controlling callbacks
- optionally calling bpf_sock_ops program when RTO fires
- optionally calling bpf_sock_ops program when packet is retransmitted
- optionally calling bpf_sock_ops program when TCP state changes
- access to tclass and sk_txhash
- new selftest
2) div/mod exception handling, from Daniel.
One of the ugly leftovers from the early eBPF days is that div/mod
operations based on registers have a hard-coded src_reg == 0 test
in the interpreter as well as in JIT code generators that would
return from the BPF program with exit code 0. This was basically
adopted from cBPF interpreter for historical reasons.
There are multiple reasons why this is very suboptimal and prone
to bugs. To name one: the return code mapping for such abnormal
program exit of 0 does not always match with a suitable program
type's exit code mapping. For example, '0' in tc means action 'ok'
where the packet gets passed further up the stack, which is just
undesirable for such cases (e.g. when implementing policy) and
also does not match with other program types.
After considering _four_ different ways to address the problem,
we adapt the same behavior as on some major archs like ARMv8:
X div 0 results in 0, and X mod 0 results in X. aarch64 and
aarch32 ISA do not generate any traps or otherwise aborts
of program execution for unsigned divides.
Given the options, it seems the most suitable from
all of them, also since major archs have similar schemes in
place. Given this is all in the realm of undefined behavior,
we still have the option to adapt if deemed necessary.
3) sockmap sample refactoring, from John.
4) lpm map get_next_key fixes, from Yonghong.
5) test cleanups, from Alexei and Prashant.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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