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Date: Mon, 6 Jan 2003 19:17:37 +0100
From: Luca Barbieri <ldb@ldb.ods.org>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Linux-Kernel ML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Set TIF_IRET in more places
Message-ID: <20030106181737.GA6867@ldb>
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	Linux-Kernel ML <linux-kernel@vger.kernel.org>
References: <20030106144601.GA2447@ldb> <Pine.LNX.4.44.0301060755510.2084-100000@home.transmeta.com>
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I've looked again at it and it is actually less problematic that I
first thought but I still see the following two cases:

1. vfork seems to not set any TIF_ flags so a ptracer setting regs
while a vforking task is stopped in ptrace_notify called from vfork
would result in clobbered %ecx and %edx.

2. A ptracer could use %ecx or %edx to pass information to signal
handlers and this would not work with the current [rt_]sigsuspend.

These only need setting TIF_IRET on ptrace setregs though.

There is also the very small advantage of being able to hardcode
SYSENTER_RETURN as the return eip for sysexit if TIF_IRET is set in
all the 3 places.

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