linux-kernel - RE: [PATCH v4] trace,x86: add x86 irq vector tracepoints

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: <A5ED84D3BB3A384992CBB9C77DEDA4D413872974@USINDEM103.corp.hds.com>
Date:	Thu, 11 Oct 2012 17:04:03 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Steven Rostedt <rostedt@...dmis.org>
CC:	"Thomas Gleixner (tglx@...utronix.de)" <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"'mingo@...e.hu' (mingo@...e.hu)" <mingo@...e.hu>,
	"x86@...nel.org" <x86@...nel.org>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: RE: [PATCH v4] trace,x86: add x86 irq vector tracepoints

> >
> > I didn't say anything magic, but a table of pointers that are very
> > critical for the system running. Should we implement it with a single
> > switch, like we discussed in San Diego to do with the system call table?
> >
> > That is, have a "normal" table, and a "trace" table. The trace table
> > points to functions that have tracepoints. The first enabler of
> > tracing switches the table to use the tracepoints, and the last
> > disabler switches it back?
> >
> 
> That is certainly a reasonable implementation option.  It is slightly less usable than it is for system calls, though, because the vectors in
> the IDTs are somewhat scrambled and so you can't just do an indirect jump to the original vector content.  This does get messy
> because you also want to preserve registers...
> 

Peter, Steven, 

Thank you for explaining the reason why you think a time penalty should be zero
and discussing its implementation.

I will update my patch so that a time penalty makes zero and submit it shortly.

Seiji
--
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/