linux-kernel - Re: Request for help: what did I do wrong with idtentry?

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Date:	Sat, 15 Nov 2014 19:28:06 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andi Kleen <andi@...stfloor.org>,
	Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Request for help: what did I do wrong with idtentry?

> I'm not
> completely thrilled with what it does to double_fault, though.  If we
> somehow get a double fault caused by an interrupt hitting userspace
> with a bad kernel_stack, then we'll end up page faulting in the
> double_fault prologue.  I'm not convinced that this is worth worrying
> about.  It would be easy enough to fix, though, even if it would
> further uglify the code.

If you're "cleaning up" good and working code the functionality should
be the same as before. The old code handled this situation fine. 
So your new code should handle this too.

In general yes handling all the corner cases makes code ugly.
That is how the existing code got how it became.

-Andi

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