linux-kernel - Re: [patch 01/20] idle: Move x86ism out of generic code

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: <alpine.DEB.2.11.1602292105410.3638@nanos>
Date:	Mon, 29 Feb 2016 21:06:10 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Will Deacon <will.deacon@....com>
cc:	Brian Gerst <brgerst@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Peter Anvin <hpa@...or.com>, Oleg Nesterov <oleg@...hat.com>,
	linux-arch@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Rafael Wysocki <rafael.j.wysocki@...el.com>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	"Srivatsa S. Bhat" <srivatsa@....edu>,
	Sebastian Siewior <bigeasy@...utronix.de>,
	Paul Turner <pjt@...gle.com>,
	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>
Subject: Re: [patch 01/20] idle: Move x86ism out of generic code

On Mon, 29 Feb 2016, Will Deacon wrote:

> On Mon, Feb 29, 2016 at 08:35:41PM +0100, Thomas Gleixner wrote:
> > On Sat, 27 Feb 2016, Brian Gerst wrote:
> > > >         arch_cpu_idle_prepare();
> > > >         cpu_idle_loop();
> > > >  }
> > > 
> > > Does this actually work with stack protector enabled?
> > > boot_init_stack_canary() is inlined while arch_cpu_idle_prepare() is
> > > not.
> > 
> > Stupid me. No it does of course not. I could have sworn that I tested that,
> > but obvioulsy not.
> > 
> > I drop that patch, but actually the real question is whether we can drop that
> > '#ifdef x86' around that boot_init_stack_canary() invocation.
> > 
> > AFAICT, neither arm, arm64 nor mips and sh call it on anything else than the
> > boot cpu. I can't see why that would be an issue on those architectures and
> > why it would be a problem if the boot cpu calls it again here.
> > 
> > CC'ed the relevant maintainers. Is there any issue with the patch below?
> 
> On arm[64], the canary is unfortunately global, so I don't think it would
> be safe to update it live like this without effectively stopping the
> machine and forcing everybody into idle.

Thanks for clarification.

       Thomas