linux-kernel - Re: [PATCH bpf-next v3 6/9] arm32, bpf: add support for 64 bit division instruction

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Message-ID: <ZPrdBeHZp8nsBsRq@shell.armlinux.org.uk>
Date:   Fri, 8 Sep 2023 09:36:21 +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 v3 6/9] arm32, bpf: add support for 64 bit
 division instruction

On Thu, Sep 07, 2023 at 11:05:47PM +0000, Puranjay Mohan wrote:
> ARM32 doesn't have instructions to do 64-bit/64-bit divisions. So, to
> implement the following instructions:
> BPF_ALU64 | BPF_DIV
> BPF_ALU64 | BPF_MOD
> BPF_ALU64 | BPF_SDIV
> BPF_ALU64 | BPF_SMOD
> 
> We implement the above instructions by doing function calls to div64_u64()
> and div64_u64_rem() for unsigned division/mod and calls to div64_s64()
> for signed division/mod.
> 
> Signed-off-by: Puranjay Mohan <puranjay12@...il.com>

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

Thanks!

-- 
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