From: Borislav Petkov <bp@alien8.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Brian Gerst <brgerst@gmail.com>, X86 ML <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [RFC PATCH] x86: Make sure verify_cpu has a good stack
Date: Wed, 2 Mar 2016 20:50:53 +0100 [thread overview]
Message-ID: <20160302195053.GG8362@pd.tnic> (raw)
In-Reply-To: <56D73349.3020609@zytor.com>
On Wed, Mar 02, 2016 at 10:39:05AM -0800, H. Peter Anvin wrote:
> Well, we definitely should use %rip-relative addressing if we can.
Right you are.
> However, even so I believe this breaks if the kernel is loaded anywhere
> but its default load address. I think we need to do something like:
>
> movq stack_start(%rip), %rax
> leaq __START_KERNEL_map(%rip), %rdx
> subq %rdx, %rax
> movq %rax, %rsp
>
> The use of temporary registers avoids clobbering a valid stack pointer
> for even a single instruction if we are given one.
Yeah, we should be prudent and make this as sturdy as possible. I did this:
CONFIG_PHYSICAL_START=0x100beef
and it aligned startup_64 up to ffffffff82000000. It seems to boot fine
in kvm. But better safe than sorry.
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
next prev parent reply other threads:[~2016-03-02 19:51 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 11:20 [RFC PATCH] x86: Make sure verify_cpu has a good stack Borislav Petkov
2016-03-02 15:55 ` Mika Penttilä
2016-03-02 16:15 ` Borislav Petkov
2016-03-02 16:38 ` Mika Penttilä
2016-03-02 16:55 ` Borislav Petkov
2016-03-02 17:44 ` Mika Penttilä
2016-03-02 16:22 ` Brian Gerst
2016-03-02 16:25 ` Borislav Petkov
2016-03-02 17:53 ` H. Peter Anvin
2016-03-02 18:15 ` Borislav Petkov
2016-03-02 18:25 ` H. Peter Anvin
2016-03-02 18:39 ` H. Peter Anvin
2016-03-02 19:50 ` Borislav Petkov [this message]
2016-03-02 20:46 ` Borislav Petkov
2016-03-02 21:35 ` H. Peter Anvin
2016-03-02 21:46 ` Borislav Petkov
2016-03-02 21:54 ` H. Peter Anvin
2016-03-02 22:09 ` Borislav Petkov
2016-03-02 22:11 ` H. Peter Anvin
2016-03-02 22:28 ` Borislav Petkov
2016-03-02 22:32 ` H. Peter Anvin
2016-03-02 22:40 ` Borislav Petkov
2016-03-03 0:13 ` Yinghai Lu
2016-03-03 1:00 ` Yinghai Lu
2016-03-03 2:50 ` Yinghai Lu
2016-03-03 12:28 ` Borislav Petkov
2016-03-03 15:26 ` H. Peter Anvin
2016-03-03 16:29 ` Borislav Petkov
2016-03-03 20:22 ` H. Peter Anvin
2016-03-03 20:54 ` Borislav Petkov
2016-03-03 21:22 ` H. Peter Anvin
2016-03-03 21:38 ` Borislav Petkov
2016-03-04 1:18 ` Yinghai Lu
2016-03-04 2:25 ` Yinghai Lu
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