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Message-ID: <CAMzpN2gfiBAeCV_1+9ogh42bMMuDW=qdwd7dYp49-=zY3kzBaA@mail.gmail.com>
Date: Tue, 19 May 2020 09:58:18 -0400
From: Brian Gerst <brgerst@...il.com>
To: Joerg Roedel <joro@...tes.org>
Cc: "the arch/x86 maintainers" <x86@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Hellstrom <thellstrom@...are.com>,
Jiri Slaby <jslaby@...e.cz>,
Dan Williams <dan.j.williams@...el.com>,
Tom Lendacky <thomas.lendacky@....com>,
Juergen Gross <jgross@...e.com>,
Kees Cook <keescook@...omium.org>,
David Rientjes <rientjes@...gle.com>,
Cfir Cohen <cfir@...gle.com>,
Erdem Aktas <erdemaktas@...gle.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mike Stunes <mstunes@...are.com>,
Joerg Roedel <jroedel@...e.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
kvm list <kvm@...r.kernel.org>,
Linux Virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH v3 35/75] x86/head/64: Build k/head64.c with -fno-stack-protector
On Tue, Apr 28, 2020 at 11:28 AM Joerg Roedel <joro@...tes.org> wrote:
>
> From: Joerg Roedel <jroedel@...e.de>
>
> The code inserted by the stack protector does not work in the early
> boot environment because it uses the GS segment, at least with memory
> encryption enabled. Make sure the early code is compiled without this
> feature enabled.
>
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
> arch/x86/kernel/Makefile | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index ba89cabe5fcf..1192de38fa56 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -35,6 +35,10 @@ ifdef CONFIG_FRAME_POINTER
> OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y
> endif
>
> +# make sure head64.c is built without stack protector
> +nostackp := $(call cc-option, -fno-stack-protector)
> +CFLAGS_head64.o := $(nostackp)
> +
> # If instrumentation of this dir is enabled, boot hangs during first second.
> # Probably could be more selective here, but note that files related to irqs,
> # boot, dumpstack/stacktrace, etc are either non-interesting or can lead to
The proper fix would be to initialize MSR_GS_BASE earlier.
--
Brian Gerst
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