netdev - Re: [PATCH net-next 3/3] ptp: idt82p33: optimize _idt82p33

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20201105170204.GA5258@hoboy.vegasvil.org>
Date:   Thu, 5 Nov 2020 09:02:04 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     min.li.xe@...esas.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] ptp: idt82p33: optimize _idt82p33_adjfine

On Thu, Nov 05, 2020 at 02:35:56AM +0200, Vladimir Oltean wrote:
> On the other hand and with all due respect, saying that it may have been
> 'buggy on some archs back in the day' and then not bringing any evidence
> is a bit of a strange claim to make.

You're right.  I made the effort to look back into the days of v3.0,
and the only thing I could find is that the 32 bit implementation of
div_s64 does extra operations and invokes an additional function call.
But the difference in performance, if any, is probably not very large.

> I am actively using div_s64 in drivers/net/dsa/sja1105/sja1105_ptp.c
> successfully on arm and arm64.

Yeah, I see div_s64 has found its way into the ntp code, too, so it
must be fine.

Thanks,
Richard