From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@suse.de>
Cc: Baoquan He <bhe@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
Yinghai Lu <yinghai@kernel.org>,
Thomas Garnier <thgarnie@google.com>,
Alexander Kuleshov <kuleshovmail@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
"Luis R. Rodriguez" <mcgrof@kernel.org>,
Dave Anderson <anderson@redhat.com>,
Dave Young <dyoung@redhat.com>
Subject: Re: [PATCH v3 1/3] x86/64: Make kernel text mapping always take one whole page table in early boot code
Date: Thu, 5 Jan 2017 11:35:57 -0800 [thread overview]
Message-ID: <CAGXu5j++vFs-+3J3nFC-M_7xG429DC8acV3YYRLNp-9ySt=oMg@mail.gmail.com> (raw)
In-Reply-To: <20170105140112.amu3msg3hp7ome7v@pd.tnic>
On Thu, Jan 5, 2017 at 6:01 AM, Borislav Petkov <bp@suse.de> wrote:
> On Thu, Jan 05, 2017 at 11:28:00AM +0800, Baoquan He wrote:
>> Possibly people worry more that no enough space left for kernel modules
>> mapping whthin 1G, just a guess. I am fine with making text mapping size
>> 1G by default. Kees must know more about the 1G only if kaslr enabled.
>
> So I'm thinking practically kaslr will be enabled on the majority
> of the systems anyway so we will have 1G text mapping size on most.
> The question is, are there any downsides/issues with making that the
> default.
>
> hpa, do you see any problems with it?
The only reason I had it as an option was for kernel module space. It
wasn't clear to me at the time if enough space remained for modules in
all use-cases. It seems like probably there is, so I have no objection
to making the mapping 1G unconditionally.
-Kees
--
Kees Cook
Nexus Security
next prev parent reply other threads:[~2017-01-05 19:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-04 8:37 [PATCH v3 0/3] Determine kernel image mapping size at runtime for x86_64 Baoquan He
2017-01-04 8:37 ` [PATCH v3 1/3] x86/64: Make kernel text mapping always take one whole page table in early boot code Baoquan He
2017-01-04 13:00 ` Boris Petkov
2017-01-05 3:28 ` Baoquan He
2017-01-05 14:01 ` Borislav Petkov
2017-01-05 19:35 ` Kees Cook [this message]
2017-01-05 20:52 ` Borislav Petkov
2017-01-06 9:35 ` Baoquan He
2017-01-04 8:37 ` [PATCH v3 2/3] x86/64: Introduce a new constant KERNEL_MAPPING_SIZE Baoquan He
2017-01-04 8:37 ` [PATCH v3 3/3] x86/64/KASLR: Determine the kernel mapping size at run time Baoquan He
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