linux-kernel - Re: [PATCH] Add a text

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Message-ID: <20131129200532.GA13561@redhat.com>
Date:	Fri, 29 Nov 2013 21:05:32 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	x86@...nel.org, Andi Kleen <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH] Add a text_poke syscall v2

On 11/29, Andi Kleen wrote:
>
> > Andi, et al. I am going to discuss the things I do not really
> > understand, probably this can't make any sense, but...
>
> I think it's enough to set the dirty bit in the underlying
> struct page, no need to play games with the PTE.

Ah, sorry for confusion, I guess you misunderstood.

I meant, perhaps sys_text_poke() doesn't the in-kernel text_poke
machinery altogether?

Can't we invalidate pte (so that any user will stuck in page fault),
update the page(s), restore the pte and drop the locks?

This way sys_text_poke() won't be x86-specific, and it will be per-mm.

Oleg.

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