linux-kernel - Re: [PATCH v3 5/6] x86-64: Move vread_tsc into a new file with sensible options

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, 10 May 2011 16:36:02 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Andy Lutomirski <luto@....EDU>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 5/6] x86-64: Move vread_tsc into a new file with
 sensible options

On Tue, 2011-05-10 at 10:15 -0400, Andy Lutomirski wrote:
> vread_tsc is short and hot, and it's userspace code so the usual
> reasons to keep frame pointers around, enable -pg, and turn off
> sibling calls don't apply.
> 
I really don't like that, turning off frame pointers here means that if
your profiler interrupt hits while in the vDSO the user-space backtrace
is dead.

Please leave the frame pointer in. Esp on x86_64 the cost of keeping the
framepointer isn't much at all since it isn't nearly as register starved
as i386.

I'm fine with stripping -pg, that is indeed useless for the vDSO.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/