linux-kernel - Re: [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples

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: <50181FDC.4030200@zytor.com>
Date:	Tue, 31 Jul 2012 11:11:40 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...nel.org>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	eranian@...gle.com, linux-kernel@...r.kernel.org,
	fweisbec@...il.com, akpm@...ux-foundation.org, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org,
	Robert Richter <robert.richter@....com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples

On 07/10/2012 02:48 AM, Ingo Molnar wrote:
>
> We could read out the current GDT [the SGDT instruction] instead
> of looking at gdt_page.
>
> Then we'd have to decode that descriptor, the limit. Decide
> whether the selector points to the GDT or LDT. All the fun x86
> legacies that we mostly forgot already after two decades of
> running the kernel in flat linear mode...
>

In 32-bit mode there are actually instructions that do that work for you.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
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/