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Message-ID: <20170607043533.GA6341@x1>
Date: Wed, 7 Jun 2017 12:35:33 +0800
From: Baoquan He <bhe@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Russ Anderson <rja@....com>,
Dimitri Sivanich <sivanich@....com>,
"travis@....com" <travis@....com>,
Mike Travis <mike.travis@....com>,
Frank Ramsay <frank.ramsay@....com>,
Thomas Garnier <thgarnie@...gle.com>,
Kees Cook <keescook@...omium.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>
Subject: Re: [PATCH v2 0/2] x86/mm/KASLR: Do not adapt size of the direct
mapping section for SGI UV system
Hi all,
PING!
Is there any further comment or suggetion about this patchset?
Thanks
Baoquan
On 05/20/17 at 08:02pm, Baoquan He wrote:
> This is v2 post.
>
> This patchset is trying to fix a bug that SGI UV system casually hang
> during boot with KASLR enabled. The root cause is that mm KASLR adapts
> size of the direct mapping section only based on the system RAM size.
> Then later when map SGI UV MMIOH region into the direct mapping during
> rest_init() invocation, it might go beyond of the directing mapping
> section and step into VMALLOC or VMEMMAP area, then BUG_ON triggered.
>
> The fix is adding a helper function is_early_uv_system to check UV system
> earlier, then call the helper function in kernel_randomize_memory() to
> check if it's a SGI UV system, if yes, we keep the size of direct mapping
> section to be 64TB just as nokslr.
>
> With this fix, SGI UV system can have 64TB direct mapping size always,
> and the starting address of direct mapping/vmalloc/vmemmap and the padding
> between them can still be randomized to enhance the system security.
>
> v1->v2:
> 1. Mike suggested making is_early_uv_system() an inline function and be
> put in include/asm/uv/uv.h so that they can adjust them easier in the
> future.
>
> 2. Split the v1 code into uv part and mm KASLR part as Mike suggested.
>
> Baoquan He (2):
> x86/UV: Introduce a helper function to check UV system at earlier
> stage
> x86/mm/KASLR: Do not adapt the size of the direct mapping section for
> SGI UV system
>
> arch/x86/include/asm/uv/uv.h | 6 ++++++
> arch/x86/mm/kaslr.c | 3 ++-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> --
> 2.5.5
>
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