Message-ID: <47CF0BA8.8040204@zytor.com>
Date: Wed, 05 Mar 2008 13:07:52 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Jan Hubicka <hubicka@ucw.cz>
CC: Joe Buck <Joe.Buck@synopsys.COM>, Michael Matz <matz@suse.de>,
       Aurelien Jarno <aurelien@aurel32.net>, linux-kernel@vger.kernel.org,
       gcc@gcc.gnu.org
Subject: Re: Linux doesn't follow x86/x86-64 ABI wrt direction flag
References: <20080305153020.GA24631@volta.aurel32.net> <47CEC3AA.6080709@zytor.com> <20080305195834.GA17267@synopsys.com> <20080305202319.GA17053@volta.aurel32.net> <Pine.LNX.4.64.0803052133400.20583@wotan.suse.de> <20080305204234.GB17267@synopsys.com> <20080305204945.GB14011@atrey.karlin.mff.cuni.cz>
In-Reply-To: <20080305204945.GB14011@atrey.karlin.mff.cuni.cz>
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Jan Hubicka wrote:
>> Yes, if there are four kernels that get it "wrong", that effectively means
>> that the ABI document doesn't describe reality and gcc has to adjust.
> 
> Kernels almost never follow ABI used by applications to last detail.
> Linux kernel is disabling red zone and use kernel code model, yet the
> ABI is not going to be adjusted for that.
> 
> This is resonably easy to fix on kernel side in signal handling, or by
> removing std usage completely (I believe it is not performance win, but
> some benchmarking would be needed to double check)

That's not the issue.  The issue is that the kernel leaks the DF from 
the code that took a signal to the signal handler.

	-hpa
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