From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Juergen Gross <jgross@suse.com>, Nicolai Stange <nstange@suse.de>,
Greg KH <gregkh@linuxfoundation.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
jpoimboe@redhat.com, Ben Hutchings <ben@decadent.org.uk>
Subject: Re: Build warnings in Xen 5.15.y and 5.10.y with retbleed backports
Date: Mon, 18 Jul 2022 09:36:26 -0400 [thread overview]
Message-ID: <7e075c90-5adb-856a-36fb-73a8d424cd0b@oracle.com> (raw)
In-Reply-To: <6eea38ab-17d2-7bdc-1277-9964a3828a9e@suse.com>
On 7/17/22 1:20 AM, Juergen Gross wrote:
>
> What about filling the complete hypercall page just with "int 3" or "ud2"?
>
> Any try to do a hypercall before the hypercall page has been initialized
> is a bug anyway. What good can come from calling a function which will
> return a basically random value instead of doing a privileged operation?
>
This is all about objtool, that's why 'ret' was added there originally by f4b4bc10b0b8 ("x86/xen: Support objtool vmlinux.o validation in xen-head.S").
Before that it was all 'nop' which is similar to what you are suggesting ('int3' or 'ud2' would of course be better)
-boris
prev parent reply other threads:[~2022-07-18 13:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 16:38 Greg KH
2022-07-12 19:19 ` Boris Ostrovsky
2022-07-12 19:31 ` Greg KH
2022-07-12 20:22 ` Boris Ostrovsky
2022-07-16 16:35 ` Nicolai Stange
2022-07-16 22:47 ` Boris Ostrovsky
2022-07-17 5:20 ` Juergen Gross
2022-07-18 13:36 ` Boris Ostrovsky [this message]
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