From: Daniel Borkmann <daniel@iogearbox.net>
To: David Daney <david.daney@cavium.com>,
Alexei Starovoitov <ast@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: Re: [PATCH 2/4] test_bpf: Add test to make conditional jump cross a large number of insns.
Date: Wed, 14 Jun 2017 02:20:09 +0200 [thread overview]
Message-ID: <59408139.6010302@iogearbox.net> (raw)
In-Reply-To: <20170613234938.4823-3-david.daney@cavium.com>
On 06/14/2017 01:49 AM, David Daney wrote:
> On MIPS, conditional branches can only span 32k instructions. To
> exceed this limit in the JIT with the BPF maximum of 4k insns, we need
> to choose eBPF insns that expand to more than 8 machine instructions.
> Use BPF_LD_ABS as it is quite complex. This forces the JIT to invert
> the sense of the branch to branch around a long jump to the end.
>
> This (somewhat) verifies that the branch inversion logic and target
> address calculation of the long jumps are done correctly.
>
> Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
next prev parent reply other threads:[~2017-06-14 0:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-13 23:49 [PATCH 0/4] bpf: Changes needed (or desired) for MIPS support David Daney
2017-06-13 23:49 ` [PATCH 1/4] tools: bpf_jit_disasm: Handle large images David Daney
2017-06-14 0:19 ` Daniel Borkmann
2017-06-13 23:49 ` [PATCH 2/4] test_bpf: Add test to make conditional jump cross a large number of insns David Daney
2017-06-14 0:20 ` Daniel Borkmann [this message]
2017-06-13 23:49 ` [PATCH 3/4] bpf: Add MIPS support to samples/bpf David Daney
2017-06-14 0:20 ` Daniel Borkmann
2017-06-13 23:49 ` [PATCH 4/4] samples/bpf: Fix tracex5 to work with MIPS syscalls David Daney
2017-06-14 0:21 ` Daniel Borkmann
2017-06-14 0:22 ` [PATCH 0/4] bpf: Changes needed (or desired) for MIPS support Daniel Borkmann
2017-06-14 15:54 ` David Daney
2017-06-14 19:03 ` David Miller
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