netdev - Re: [net-next 01/12] i40e: replace switch-statement to speed-up retpoline-enabled builds

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

Date:   Mon, 29 Apr 2019 13:01:57 -0700
From:   Josh Elsasser <jelsasser@...neta.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Björn Töpel <bjorn.topel@...el.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        nhorman@...hat.com, sassmann@...hat.com,
        Andrew Bowers <andrewx.bowers@...el.com>
Subject: Re: [net-next 01/12] i40e: replace switch-statement to speed-up
 retpoline-enabled builds

On Apr 29, 2019, at 12:16 PM, Jeff Kirsher <jeffrey.t.kirsher@...el.com> wrote:

> From: Björn Töpel <bjorn.topel@...el.com>
> 
> GCC will generate jump tables for switch-statements with more than 5
> case statements. An entry into the jump table is an indirect call,
> which means that for CONFIG_RETPOLINE builds, this is rather
> expensive.
> 
> This commit replaces the switch-statement that acts on the XDP program
> result with an if-clause.

Apologies for the noise, but is this patch still required after the
recent threshold bump[0] and later removal[1] of switch-case jump
table generation when building with CONFIG_RETPOLINE?

[0]: https://lore.kernel.org/patchwork/patch/1044863/
[1]: https://lore.kernel.org/patchwork/patch/1054472/

If nothing else the commit message no longer seems accurate.

Regards,
-- Josh