From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Brian Gerst <brgerst@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
the arch/x86 maintainers <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@amacapital.net>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Borislav Petkov <bp@suse.de>, Andi Kleen <ak@linux.intel.com>,
Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv2, RFC] x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G
Date: Mon, 16 Oct 2017 11:55:40 +0300 [thread overview]
Message-ID: <20171016085540.tn2tf4hgpeotvvon@node.shutemov.name> (raw)
In-Reply-To: <CAMzpN2iU07o8rBzZMpDv1gB00HUc2CRR1o3m=EuiQ6E16QcPFg@mail.gmail.com>
On Sat, Oct 14, 2017 at 01:19:08PM -0400, Brian Gerst wrote:
> From what we've seen with the TLB flush rework, having potential
> garbage in the page tables that speculative reads can see can cause
> bad things like machine checks. It would be best to have a second
> temporary page just for the page table (and properly cleared).
Hm. Interesting. Is there a place where I can read more about this?
> The trampoline also needs its own stack, in case the stack pointer was
> above 4G.
You are right, we need new stack. I've missed that.
> That could be at the end of the code page, since you only need 8 bytes.
When I wrote about 8 bytes, I referred the usage of page table, not code.
We use more than 8 bytes of code, but this should enough in the page.
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2017-10-16 8:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-13 12:23 [PATCHv2, RFC] x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G Kirill A. Shutemov
2017-10-14 7:33 ` Ingo Molnar
2017-10-14 15:37 ` Kirill A. Shutemov
2017-10-14 17:19 ` Brian Gerst
2017-10-16 8:55 ` Kirill A. Shutemov [this message]
2017-10-16 13:12 ` Brian Gerst
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