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Date: Mon, 27 Nov 2000 00:38:44 +0100
From: Andrea Arcangeli <andrea@suse.de>
To: Pavel Machek <pavel@suse.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>
Subject: Re: kernel_thread bogosity
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In-Reply-To: <20001126232932.A4052@bug.ucw.cz>; from pavel@suse.cz on Sun, Nov 26, 2000 at 11:29:32PM +0100
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On Sun, Nov 26, 2000 at 11:29:32PM +0100, Pavel Machek wrote:
> Is this different on x86-64 in long mode?

Yes, in 64bit mode ss:rsp is restore unconditionally. In compatibility and
legacy modes it's restored only if the CPL changes.

kernel never runs in compatibility mode (and userspace never runs iret) so in
kernel_thread we know x86-64 always restores ss:rsp from the stack.

You should find this as a familiar behaviour as you just tried to pass a stack
via kernel_thread in your latest patch against cvs :).

Andrea
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