From: Daniel Borkmann <daniel@iogearbox.net>
To: Luke Nelson <lukenels@cs.washington.edu>, bpf@vger.kernel.org
Cc: Luke Nelson <luke.r.nels@gmail.com>, Xi Wang <xi.wang@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Zi Shen Lim <zlim.lnx@gmail.com>, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Mark Rutland <mark.rutland@arm.com>,
Enrico Weigelt <info@metux.net>,
Alexios Zavras <alexios.zavras@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marc Zyngier <maz@kernel.org>,
Christoffer Dall <christoffer.dall@linaro.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
clang-built-linux@googlegroups.com
Subject: Re: [RFC PATCH bpf-next 2/3] bpf, arm64: Optimize AND,OR,XOR,JSET BPF_K using arm64 logical immediates
Date: Thu, 7 May 2020 22:19:35 +0200 [thread overview]
Message-ID: <2b05950b-5f7a-e5e7-81fe-27703c3ef77f@iogearbox.net> (raw)
In-Reply-To: <20200507010504.26352-3-luke.r.nels@gmail.com>
On 5/7/20 3:05 AM, Luke Nelson wrote:
> The current code for BPF_{AND,OR,XOR,JSET} BPF_K loads the immediate to
> a temporary register before use.
>
> This patch changes the code to avoid using a temporary register
> when the BPF immediate is encodable using an arm64 logical immediate
> instruction. If the encoding fails (due to the immediate not being
> encodable), it falls back to using a temporary register.
>
> Example of generated code for BPF_ALU32_IMM(BPF_AND, R0, 0x80000001):
>
> without optimization:
>
> 24: mov w10, #0x8000ffff
> 28: movk w10, #0x1
> 2c: and w7, w7, w10
>
> with optimization:
>
> 24: and w7, w7, #0x80000001
>
> Since the encoding process is quite complex, the JIT reuses existing
> functionality in arch/arm64/kernel/insn.c for encoding logical immediates
> rather than duplicate it in the JIT.
>
> Co-developed-by: Xi Wang <xi.wang@gmail.com>
> Signed-off-by: Xi Wang <xi.wang@gmail.com>
> Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Great find, thanks! Given Will wanted to queue them:
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Borkmann <daniel@iogearbox.net>
To: Luke Nelson <lukenels@cs.washington.edu>, bpf@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Song Liu <songliubraving@fb.com>,
Zi Shen Lim <zlim.lnx@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
clang-built-linux@googlegroups.com,
Catalin Marinas <catalin.marinas@arm.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
Xi Wang <xi.wang@gmail.com>, Luke Nelson <luke.r.nels@gmail.com>,
Alexios Zavras <alexios.zavras@intel.com>,
KP Singh <kpsingh@chromium.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Enrico Weigelt <info@metux.net>,
Martin KaFai Lau <kafai@fb.com>,
Christoffer Dall <christoffer.dall@linaro.org>
Subject: Re: [RFC PATCH bpf-next 2/3] bpf, arm64: Optimize AND,OR,XOR,JSET BPF_K using arm64 logical immediates
Date: Thu, 7 May 2020 22:19:35 +0200 [thread overview]
Message-ID: <2b05950b-5f7a-e5e7-81fe-27703c3ef77f@iogearbox.net> (raw)
In-Reply-To: <20200507010504.26352-3-luke.r.nels@gmail.com>
On 5/7/20 3:05 AM, Luke Nelson wrote:
> The current code for BPF_{AND,OR,XOR,JSET} BPF_K loads the immediate to
> a temporary register before use.
>
> This patch changes the code to avoid using a temporary register
> when the BPF immediate is encodable using an arm64 logical immediate
> instruction. If the encoding fails (due to the immediate not being
> encodable), it falls back to using a temporary register.
>
> Example of generated code for BPF_ALU32_IMM(BPF_AND, R0, 0x80000001):
>
> without optimization:
>
> 24: mov w10, #0x8000ffff
> 28: movk w10, #0x1
> 2c: and w7, w7, w10
>
> with optimization:
>
> 24: and w7, w7, #0x80000001
>
> Since the encoding process is quite complex, the JIT reuses existing
> functionality in arch/arm64/kernel/insn.c for encoding logical immediates
> rather than duplicate it in the JIT.
>
> Co-developed-by: Xi Wang <xi.wang@gmail.com>
> Signed-off-by: Xi Wang <xi.wang@gmail.com>
> Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Great find, thanks! Given Will wanted to queue them:
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-05-07 20:19 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 1:05 [RFC PATCH bpf-next 0/3] arm64 BPF JIT Optimizations Luke Nelson
2020-05-07 1:05 ` Luke Nelson
2020-05-07 1:05 ` [RFC PATCH bpf-next 1/3] arm64: insn: Fix two bugs in encoding 32-bit logical immediates Luke Nelson
2020-05-07 1:05 ` Luke Nelson
2020-05-07 8:19 ` Marc Zyngier
2020-05-07 8:19 ` Marc Zyngier
2020-05-07 8:29 ` Will Deacon
2020-05-07 8:29 ` Will Deacon
2020-05-07 9:12 ` Marc Zyngier
2020-05-07 9:12 ` Marc Zyngier
2020-05-07 21:48 ` Luke Nelson
2020-05-07 21:48 ` Luke Nelson
2020-05-08 11:47 ` Will Deacon
2020-05-08 11:47 ` Will Deacon
2020-05-08 18:12 ` Luke Nelson
2020-05-08 18:12 ` Luke Nelson
2020-05-07 1:05 ` [RFC PATCH bpf-next 2/3] bpf, arm64: Optimize AND,OR,XOR,JSET BPF_K using arm64 " Luke Nelson
2020-05-07 1:05 ` [RFC PATCH bpf-next 2/3] bpf, arm64: Optimize AND, OR, XOR, JSET " Luke Nelson
2020-05-07 20:19 ` Daniel Borkmann [this message]
2020-05-07 20:19 ` [RFC PATCH bpf-next 2/3] bpf, arm64: Optimize AND,OR,XOR,JSET " Daniel Borkmann
2020-05-07 1:05 ` [RFC PATCH bpf-next 3/3] bpf, arm64: Optimize ADD,SUB,JMP BPF_K using arm64 add/sub immediates Luke Nelson
2020-05-07 1:05 ` [RFC PATCH bpf-next 3/3] bpf, arm64: Optimize ADD, SUB, JMP " Luke Nelson
2020-05-07 20:22 ` [RFC PATCH bpf-next 3/3] bpf, arm64: Optimize ADD,SUB,JMP " Daniel Borkmann
2020-05-07 20:22 ` Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2b05950b-5f7a-e5e7-81fe-27703c3ef77f@iogearbox.net \
--to=daniel@iogearbox.net \
--cc=alexios.zavras@intel.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=catalin.marinas@arm.com \
--cc=christoffer.dall@linaro.org \
--cc=clang-built-linux@googlegroups.com \
--cc=info@metux.net \
--cc=john.fastabend@gmail.com \
--cc=kafai@fb.com \
--cc=kpsingh@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luke.r.nels@gmail.com \
--cc=lukenels@cs.washington.edu \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=songliubraving@fb.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=xi.wang@gmail.com \
--cc=yhs@fb.com \
--cc=zlim.lnx@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.