linux-kernel - Re: [Xen-devel] [PATCH 11/13] x86/paravirt: Add paravirt alternatives infrastructure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <44a2cbeb-7424-0a2a-7f9c-b669e049bded@oracle.com>
Date:   Tue, 17 Oct 2017 16:36:00 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Andrew Cooper <andrew.cooper3@...rix.com>,
        Juergen Gross <jgross@...e.com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        Mike Galbraith <efault@....de>, xen-devel@...ts.xenproject.org,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Sasha Levin <alexander.levin@...izon.com>,
        Chris Wright <chrisw@...s-sol.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        live-patching@...r.kernel.org, Alok Kataria <akataria@...are.com>,
        virtualization@...ts.linux-foundation.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [Xen-devel] [PATCH 11/13] x86/paravirt: Add paravirt alternatives
 infrastructure

On 10/17/2017 04:17 PM, Josh Poimboeuf wrote:
> On Tue, Oct 17, 2017 at 11:36:57AM -0400, Boris Ostrovsky wrote:
>> On 10/17/2017 10:36 AM, Josh Poimboeuf wrote:
>>> Maybe we can add a new field to the alternatives entry struct which
>>> specifies the offset to the CALL instruction, so apply_alternatives()
>>> can find it.
>> We'd also have to assume that the restore part of an alternative entry
>> is the same size as the save part. Which is true now.
> Why?
>

Don't you need to know the size of the instruction without save and
restore part?

+ if (a->replacementlen == 6 && *insnbuf == 0xff && *(insnbuf+1) == 0x15)

Otherwise you'd need another field for the actual instruction length.

-boris