linux-kernel - Re: [PATCH v2 2/3] x86/entry/64: Teach idtentry to use the IRQ stack

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Message-ID: <20150728095019.GD1612@nazgul.tnic>
Date:	Tue, 28 Jul 2015 11:50:19 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>, linux-kernel@...r.kernel.org,
	Brian Gerst <brgerst@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>, Willy Tarreau <w@....eu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 2/3] x86/entry/64: Teach idtentry to use the IRQ stack

On Fri, Jul 24, 2015 at 10:57:05PM -0700, Andy Lutomirski wrote:
> We don't specifically need IST for things like kprobes, but we do
> want to avoid rare, surprising extra stack usage if a kprobe hits
> with a deep stack.
> 
> Teach idtentry to use the IRQ stack for selected entries.
> 
> This implementation uses the IRQ stack even if we entered from user
> mode.  This disallows tricks like ist_begin_non_atomic.  If we ever
> need such a trick in one of these entries, we can rework this.  For
> now, let's keep it simple.
> 
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/entry/entry_64.S | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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