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From: Jason Andryuk <jandryuk@gmail.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Stefan Bader" <stefan.bader@canonical.com>,
	Xen-devel <xen-devel@lists.xenproject.org>,
	"Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH] x86/build: Unilaterally disable -fcf-protection
Date: Tue, 12 May 2020 22:35:38 -0400	[thread overview]
Message-ID: <CAKf6xpt-WLVOTaca_FncB4XX0PQ2ZbP6GFWQjinAYex=6mptRA@mail.gmail.com> (raw)
In-Reply-To: <20200512191116.6851-1-andrew.cooper3@citrix.com>

On Tue, May 12, 2020 at 3:11 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>
> See comment for details.  Works around a GCC-9 bug which breaks the build on
> Ubuntu.
>
> Reported-by: Jason Andryuk <jandryuk@gmail.com>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Tested-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>

> diff --git a/xen/arch/x86/arch.mk b/xen/arch/x86/arch.mk
> index 2a51553edb..93e30e4bea 100644
> --- a/xen/arch/x86/arch.mk
> +++ b/xen/arch/x86/arch.mk
> @@ -67,6 +67,15 @@ CFLAGS-$(CONFIG_INDIRECT_THUNK) += -mindirect-branch=thunk-extern
>  CFLAGS-$(CONFIG_INDIRECT_THUNK) += -mindirect-branch-register
>  CFLAGS-$(CONFIG_INDIRECT_THUNK) += -fno-jump-tables
>
> +# Xen doesn't support CET-IBT yet.  At a minimum, logic is required to
> +# enable it for supervisor use, but the Livepatch functionality needs
> +# to learn not to overwrite ENDBR64 instructions.

Is the problem that existing functions start with ENDBR64, but the
livepatch overwrites with a "real" instruction?

Regards,
Jason


  reply	other threads:[~2020-05-13  2:36 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 19:11 [PATCH] x86/build: Unilaterally disable -fcf-protection Andrew Cooper
2020-05-13  2:35 ` Jason Andryuk [this message]
2020-05-13 11:01   ` Andrew Cooper
2020-05-13 12:15     ` Jason Andryuk
2020-05-13  9:15 ` Jan Beulich
2020-05-13 13:55 [PATCH] build: Fix build with Ubuntu Andrew Cooper
2020-05-13 13:55 ` [PATCH] x86/build: Unilaterally disable -fcf-protection Andrew Cooper
2020-05-13 14:13   ` Jan Beulich
2020-05-13 14:40     ` Andrew Cooper
2020-05-13 14:54   ` Jason Andryuk

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