linux-kernel - Re: is TIF_NOTIFY

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: <20070522090210.1388ff3e.akpm@linux-foundation.org>
Date:	Tue, 22 May 2007 09:02:10 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	eranian@....hp.com
Cc:	linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org,
	ak@...e.de, tony.luck@...el.com
Subject: Re: is TIF_NOTIFY_RESUME used?

On Tue, 22 May 2007 05:47:13 -0700
Stephane Eranian <eranian@....hp.com> wrote:

> Hello,
> 
> For perfmon, we need a couple of TIF bits. It seems that with 2.6.22-rc2
> there is now a TIF_RESTORE_SIGMASK which uses the last remaining bit in the
> first 7 bits of the thread flag. Many architectures, including IA-64, rely
> on the fact that some of the TIF flags (TIF_ALL_WORKMASK or TIF_ALL_WORK)
> tested on kernel exit reside in the low 8-bit or 7-bit because they use
> instructions (such as add r1=imm8,r2 on IA-64) which operate on 8 or 7 bit
> immediate.
> 
> On IA-64, adding that one perfmon flag (as bit 7) would cause some
> restructuring in the kernel exit path but also in all the lightweight syscall
> handlers.
> 
> I looked at all the low order TIF flags and found that TIF_NOTIFY_RESUME 
> was never set nor used anywhere in any architecture. Is that really the case?
> 
> If so, we could get rid of it and free up one low-order TIF bit.
> 

My grepping argees with yours.  The only place where TIF_NOTIFY_RESUME gets
altered is in ./arch/ia64/kernel/perfmon.c.
-
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/