linux-kernel - Re: [PATCH 4/8] x86: Add support for rd/wr fs/gs base

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Date:	Sat, 11 Apr 2015 00:52:56 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Andi Kleen <ak@...ux.intel.com>, Andi Kleen <andi@...stfloor.org>,
	X86 ML <x86@...nel.org>, Andrew Lutomirski <luto@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 4/8] x86: Add support for rd/wr fs/gs base

> I think all of this stems from unfortunate naming.  DEBUG_STACK isn't
> one stack -- it's a debug stack *array*.  The IST shift mechanism
> means that we can use different entries in that array as our stacks
> depending on how deeply nested we are.

It's not. It was always intended as one stack. It still is, for anyone
not nesting debuggers (which afaik doesn't happen in-tree, it was
only for Jan Beulich's magic debugger)

I wrote the original code, so I should know.

-Andi


-- 
ak@...ux.intel.com -- Speaking for myself only.
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