linux-kernel - Re: [RFC PATCH v2] ftrace: support very early function tracing

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: <20171108190727.GL3326@worktop>
Date:   Wed, 8 Nov 2017 20:07:27 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Abderrahmane Benbachir <abderrahmane.benbachir@...ymtl.ca>,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        mathieu.desnoyers@...icios.com,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC PATCH v2] ftrace: support very early function tracing

On Wed, Nov 08, 2017 at 11:07:57AM -0500, Steven Rostedt wrote:
> On Wed, 8 Nov 2017 09:10:58 +0100
> Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > On Tue, Nov 07, 2017 at 09:17:06PM -0500, Steven Rostedt wrote:
> > > > +#ifdef CONFIG_X86_TSC
> > > > +	entry->clock = rdtsc();
> > > > +#else
> > > > +	entry->clock = trace_clock_local();
> > > > +#endif  
> > 
> > > > +#ifdef CONFIG_X86_TSC
> > > > +	cpu_khz = native_calibrate_cpu();
> > > > +#endif  
> > 
> > > > +#ifdef CONFIG_X86_TSC
> > > > +		ns = cycles_to_ns(entry->clock, cpu_khz);
> > > > +#else
> > > > +		ns = entry->clock;
> > > > +#endif  
> > 
> > Yeah, no, not going to happen...
> 
> Agreed.

Depends on how early you need things; ideally you'd be able to use the
stuff from here:

  https://lkml.kernel.org/r/1504116205-355281-1-git-send-email-pasha.tatashin@oracle.com

That is, fix the normal time sources to work earlier instead of building
parallel infrastructure.