linux-kernel - TSC calibration sometimes not correct with RT patch.

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-next>] [day] [month] [year] [list]

Date:	Wed, 25 Jul 2007 09:25:09 +0200
From:	"Henri Hunnekens" <henrihunnekens@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	mingo@...e.hu
Subject: TSC calibration sometimes not correct with RT patch.

I've seen that the calbration of the TSC timer was not always done
correctly, which resulted in incorrect timers.

I found out that local_irq_disable is used before the calibration is
started. However with the RT patch applied this does not mean that the
interrupts are disabled and therefore the calibration may fails when
it's interrupted by an interrupt. Correct me if I'm wrong.

I think that this local_irq_disable must be replaced with the
raw_local_irq_disable which does disable the interrupts.

I'm not able to verify if this solves the problem because it is very
hard to reproduce. Maybe someone can verify if my assumption is
correcly.

Currently I'm using kernel version 2.6.20-RT8, but I've checked that
latest kernel version with the latest RT patch and they have the same
implementation.
-
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/