linux-kernel - Re: [PATCH] clk: Warn (and therefore taint the kernel) on clk_ignore

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: <efd38edbed2743a258bbec7e80ff2238.sboyd@kernel.org>
Date: Tue, 04 Mar 2025 11:34:19 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Florian Fainelli <florian.fainelli@...adcom.com>
Cc: Konrad Dybcio <konradybcio@...nel.org>, Michael Turquette <mturquette@...libre.com>, Marijn Suijten <marijn.suijten@...ainline.org>, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, Bjorn Andersson <bjorn.andersson@....qualcomm.com>, Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH] clk: Warn (and therefore taint the kernel) on clk_ignore_unused

Quoting Dmitry Baryshkov (2025-03-03 15:17:21)
> On Tue, 4 Mar 2025 at 00:16, Florian Fainelli
> <florian.fainelli@...adcom.com> wrote:
> >
> > On 3/3/25 14:48, Stephen Boyd wrote:
> > > Quoting Konrad Dybcio (2025-02-01 08:52:30)
[...]
> > >>
> > >> The clock subsystem plays a crucial part in this quest, as even if
> > >> the clock controllers themselves don't draw a lot of power when on
> > >> (comparatively), improper description of clock requirements has been
> > >> the #1 cause of incomplete/incorrect devicetree bindings in my
> > >> experience.
> > >
> > > What is a user supposed to do about this warning stack? We already print
> > > a warning. I don't see us dumping the stack when a driver is unfinished
> > > and doesn't implement runtime PM to save power.
> > >
> >
> > Agreed, I don't think this is tremendously helpful given that it does
> > not even tell you what part is incomplete, it's just a broad warning for
> > the entire system.
> >
> > Assuming you have a clock provided that can be used to turn clocks off,
> > and you did not boot with 'clk_ignore_unused' set on the kernel command
> > line, then you should discover pretty quickly which driver is not
> > managing the clocks as it should no?
> 
> Unfortunately it's sometimes not that easy. And some developers
> pretend that 'clk_ignore_unused' is a viable way to run the system.
> 

Maybe we would be better off with a config option that removes the clk
ignore unused ability entirely. Then you can have a kernel config check
somewhere in the build process that verifies that a user can't even set
the kernel commandline to change the behavior.