linux-kernel - Re: [PATCH bpf-next v2 5/8] arm32, bpf: add support for 32-bit signed division

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Message-ID: <ZPmOiF9UsPf8FN5V@shell.armlinux.org.uk>
Date:   Thu, 7 Sep 2023 09:49:12 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Puranjay Mohan <puranjay12@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Shubham Bansal <illusionist.neo@...il.com>,
        Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
        bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 5/8] arm32, bpf: add support for 32-bit
 signed division

On Wed, Sep 06, 2023 at 06:33:17PM +0000, Puranjay Mohan wrote:
> The cpuv4 added a new BPF_SDIV instruction that does signed division.
> The encoding is similar to BPF_DIV but BPF_SDIV sets offset=1.
> 
> ARM32 already supports 32-bit BPF_DIV which can be easily extended to
> support BPF_SDIV as ARM32 has the SDIV instruction. When the CPU is not
> ARM-v7, we implement that SDIV/SMOD with the function call similar to
> the implementation of DIV/MOD.
> 
> Signed-off-by: Puranjay Mohan <puranjay12@...il.com>

Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Thanks, this is a lot more clear!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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