linux-kernel - Re: [PATCH v2 2/2] scripts: ftrace - move the nop-processing in ftrace

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]

Message-ID: <20211116081020.GW174703@worktop.programming.kicks-ass.net>
Date:   Tue, 16 Nov 2021 09:10:20 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Yinan Liu <yinan@...ux.alibaba.com>
Cc:     rostedt@...dmis.org, mark-pk.tsai@...iatek.com, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] scripts: ftrace - move the nop-processing in
 ftrace_init to compile time

On Tue, Nov 16, 2021 at 10:49:42AM +0800, Yinan Liu wrote:
> In some business scenarios, GCC versions are so old that
> optimizations in ftrace cannot be completed, such as
> -mrecord-mcount and -mnop-mcount. The recordmCount in the
> kernel is actually used. In this case, ftrace_init will
> consume a period of time, usually around 9~12ms. Do nop
> substitution in recordmcount.c to speed up ftrace_init.

I really don't buy this.. if you can build a fresh kernel, you can
install a fresh gcc too -- and if you care about performance that's a
very good idea anyway.