From: Daniel Borkmann <daniel@iogearbox•net>
To: David Miller <davem@davemloft•net>, sparclinux@vger•kernel.org
Cc: netdev@vger•kernel.org, ast@kernel•org
Subject: Re: [PATCH RFC] sparc64: eBPF JIT
Date: Mon, 17 Apr 2017 20:44:35 +0200 [thread overview]
Message-ID: <58F50D13.3090001@iogearbox.net> (raw)
In-Reply-To: <20170416.233825.1748421481008153466.davem@davemloft.net>
On 04/17/2017 05:38 AM, David Miller wrote:
>
> There are a bunch of things I want to do still, and I know that I have
> to attend to sparc32 more cleanly, but I wanted to post this now that
> I have it passing the BPF testsuite completely:
>
> [24174.315421] test_bpf: Summary: 305 PASSED, 0 FAILED, [297/297 JIT'ed]
Awesome, thanks for working on it! :)
> Only major unimplemented feature is tail calls, which I am very sure I
> can do simply but until something easy to use like test_bpf can
> exercise it I probably won't do it.
There is samples/bpf/sockex3_kern.c, which exercises it. To
run it, it would be (clang/llvm needed due to BPF backend not
available in gcc):
# cd samples/bpf
# make
# ./sockex3
IP src.port -> dst.port bytes packets
127.0.0.1.12865 -> 127.0.0.1.49711 148 2
127.0.0.1.49711 -> 127.0.0.1.12865 108 2
[...]
Inside parse_eth_proto(), it will do tail calls based on the
eth protocol. Over time, we'll move such C based tests over to
tools/testing/selftests/bpf/.
> From my side, what I need to do to turn this into a non-RFC is to sort
> out sparc32. My plan is to take the existing cBPF JIT, rip out all of
> the sparc64 specific bits, and have sparc32 use that. And do it in
> such a way that git bisection is not broken.
Makes sense. That would follow the same model as ppc32/64.
> As a future optimization I'd like to add support for emitting cbcond
> instructions on newer chips.
>
> This implementation grabs a register window all the time, and we could
> avoid that and use a leaf function in certatin situations. The
> register layout is also not optimal, and one side effect is that we
> have to move the argument registers over during function calls.
>
> Signed-off-by: David S. Miller <davem@davemloft•net>
[...]
> +/* Map BPF registers to SPARC registers */
> +static const int bpf2sparc[] = {
> + /* return value from in-kernel function, and exit value from eBPF */
> + [BPF_REG_0] = I5,
> +
> + /* arguments from eBPF program to in-kernel function */
> + [BPF_REG_1] = I0,
> + [BPF_REG_2] = I1,
> + [BPF_REG_3] = I2,
> + [BPF_REG_4] = I3,
> + [BPF_REG_5] = I4,
> +
> + /* callee saved registers that in-kernel function will preserve */
> + [BPF_REG_6] = L0,
> + [BPF_REG_7] = L1,
> + [BPF_REG_8] = L2,
> + [BPF_REG_9] = L3,
> +
> + /* read-only frame pointer to access stack */
> + [BPF_REG_FP] = FP,
On a quick initial glance, you also need to map BPF_REG_AX. If
I understand the convention correctly, you could use L7 for that.
You can test for it through tools/testing/selftests/bpf/test_kmod.sh
which exercises the test_bpf.ko under various sysctl combinations as
part of the BPF selftest suite.
> + /* temporary register for internal BPF JIT */
> + [TMP_REG_1] = G1,
> + [TMP_REG_2] = G3,
> + [TMP_REG_3] = L6,
> +
> + [SKB_HLEN_REG] = L4,
> + [SKB_DATA_REG] = L5,
> +};
Thanks a lot!
Daniel
next prev parent reply other threads:[~2017-04-17 18:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 3:38 [PATCH RFC] sparc64: eBPF JIT David Miller
2017-04-17 18:44 ` Daniel Borkmann [this message]
2017-04-17 19:03 ` David Miller
2017-04-17 20:55 ` Daniel Borkmann
2017-04-17 20:12 ` David Miller
2017-04-21 16:46 ` David Miller
2017-04-21 16:50 ` Daniel Borkmann
2017-04-21 18:49 ` Alexei Starovoitov
2017-04-21 19:02 ` David Miller
2017-04-21 19:26 ` Alexei Starovoitov
2017-04-21 19:41 ` David Miller
2017-04-17 23:27 ` Alexei Starovoitov
2017-04-18 1:12 ` David Miller
2017-04-18 5:44 ` Alexei Starovoitov
2017-04-18 18:37 ` David Miller
2017-04-18 22:57 ` Alexei Starovoitov
2017-04-19 2:27 ` David Miller
2017-04-22 1:19 ` David Miller
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