linux-kernel - Re: [RFC PATCH 7/8] x86/lib_user_wait.h: Add APIs for user wait instructions

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:   Tue, 19 Jun 2018 15:36:15 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Fenghua Yu <fenghua.yu@...el.com>, Ingo Molnar <mingo@...hat.com>,
        H Peter Anvin <hpa@...or.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Alan Cox <alan@...ux.intel.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [RFC PATCH 7/8] x86/lib_user_wait.h: Add APIs for user wait
 instructions

On Wed, Jun 20, 2018 at 12:34:32AM +0200, Thomas Gleixner wrote:
> On Tue, 19 Jun 2018, Fenghua Yu wrote:
> > On Tue, Jun 19, 2018 at 11:12:05AM +0200, Thomas Gleixner wrote:
> > > On Fri, 15 Jun 2018, Fenghua Yu wrote:
> > > 
> > > > A few new user wait instructions UMONITOR, UMWAIT, and TPAUSE are
> > > > published in the latest Intel Instruction Set Extensions document.
> > > > 
> > > > Define the APIs for user or kernel to use the instructions.
> > > 
> > > You're not defining APIs. You're adding a pile of misdesigned helper
> > > functions which again add static storage per compilation unit and CPUID
> > > fiddling.
> > > 
> > > If you want to add proper APIs then add the stuff to the VDSO and be done
> > > with it.
> > 
> > The user wait instructions are mainly called by user apps; but they can
> > be used in kernel as well.
> > 
> > I'm planning to provide five APIs to user:
> > 1. If user wait feature is supported
> > 2. nsec to tsc translation
> > 3. umonitor function that exectes UMONITOR instruction
> > 4. umwait function that executes UMWAIT instruction
> > 5. tpause function that executes TPAUSE instruction
> > 
> > Seems 1-2 can be implemented in VDSO. But should I implement 3-5 in
> > VDSO/kernel as well?
> 
> If you want a real API, then yes. If not, then an UAPI header is definitely
> not the place for this.

Sure. I will implement the APIs in VDSO.

Thanks.

-Fenghua