GCC 4.3.0 exposes a kernel bug

Note, the fix has gone upstream today:

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commit e40cd10ccff3d9fbffd57b93780bee4b7b9bff51
Author: Aurelien Jarno <aurelien@aurel32.net>
Date:   Wed Mar 5 19:14:24 2008 +0100

    x86: clear DF before calling signal handler
    
    The Linux kernel currently does not clear the direction flag before
    calling a signal handler, whereas the x86/x86-64 ABI requires that.
    
    Linux had this behavior/bug forever, but this becomes a real problem
    with gcc version 4.3, which assumes that the direction flag is
    correctly cleared at the entry of a function.
    
    This patches changes the setup_frame() functions to clear the
    direction before entering the signal handler.
    
    Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    Acked-by: H. Peter Anvin <hpa@zytor.com>