linux-kernel - Re: [PATCH] x86/setup: fix low identity map for >= 2GB kernel range

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Date:	Fri, 6 Nov 2015 15:11:39 +0100
From:	Krzysztof Mazur <krzysiek@...lesie.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Laszlo Ersek <lersek@...hat.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/setup: fix low identity map for >= 2GB kernel range

On Fri, Nov 06, 2015 at 02:27:33PM +0100, Borislav Petkov wrote:
> On Fri, Nov 06, 2015 at 02:18:36PM +0100, Krzysztof Mazur wrote:
> > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> > index a3cccbf..37c8ea8 100644
> > --- a/arch/x86/kernel/setup.c
> > +++ b/arch/x86/kernel/setup.c
> > @@ -1180,7 +1180,7 @@ void __init setup_arch(char **cmdline_p)
> >  	 */
> >  	clone_pgd_range(initial_page_table,
> >  			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
> > -			KERNEL_PGD_PTRS);
> > +			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
> >  #endif
> >  
> >  	tboot_probe();
> 
> http://git.kernel.org/tip/1c5dac914794f0170e1582d8ffdee52d30e0e4dd
> 

Thanks and sorry. Yes, it has been already fixed. I've rechecked only
mainline.

However, I think that there should be
min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY), not just KERNEL_PGD_BOUNDARY
(usually 768 for normal 1G/3G split), because swapper_pg_dir has only
1024 entries and 768+768 is 1536.

Krzysiek
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