netdev - Re: [PATCH] ARM: net: bpf: improve prologue code sequence

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Message-ID: <20191211135615.GA25011@linux.fritz.box>
Date:   Wed, 11 Dec 2019 14:56:15 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Russell King <rmk+kernel@...linux.org.uk>
Cc:     Shubham Bansal <illusionist.neo@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ARM: net: bpf: improve prologue code sequence

On Mon, Dec 09, 2019 at 11:17:30AM +0000, Russell King wrote:
> Improve the prologue code sequence to be able to take advantage of
> 64-bit stores, changing the code from:
> 
>   push    {r4, r5, r6, r7, r8, r9, fp, lr}
>   mov     fp, sp
>   sub     ip, sp, #80     ; 0x50
>   sub     sp, sp, #600    ; 0x258
>   str     ip, [fp, #-100] ; 0xffffff9c
>   mov     r6, #0
>   str     r6, [fp, #-96]  ; 0xffffffa0
>   mov     r4, #0
>   mov     r3, r4
>   mov     r2, r0
>   str     r4, [fp, #-104] ; 0xffffff98
>   str     r4, [fp, #-108] ; 0xffffff94
> 
> to the tighter:
> 
>   push    {r4, r5, r6, r7, r8, r9, fp, lr}
>   mov     fp, sp
>   mov     r3, #0
>   sub     r2, sp, #80     ; 0x50
>   sub     sp, sp, #600    ; 0x258
>   strd    r2, [fp, #-100] ; 0xffffff9c
>   mov     r2, #0
>   strd    r2, [fp, #-108] ; 0xffffff94
>   mov     r2, r0
> 
> resulting in a saving of three instructions.
> 
> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>

Applied, thanks!