linux-kernel - Re: [Xen-devel] [PATCH v2] xen: get rid of paravirt op adjust_exception

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Date:   Tue, 1 Aug 2017 16:52:33 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Andrew Cooper <andrew.cooper3@...rix.com>
Cc:     Juergen Gross <jgross@...e.com>, X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Xen-devel] [PATCH v2] xen: get rid of paravirt op adjust_exception_frame

On Tue, Aug 1, 2017 at 4:38 PM, Andrew Cooper <andrew.cooper3@...rix.com> wrote:
> On 01/08/2017 20:45, Andy Lutomirski wrote:
>> Also, IMO it would be nice to fully finish the job.  Remaining steps are:
>>
>> 1. Unsuck the SYSCALL entries on Xen PV.
>> 2. Unsuck the SYENTER entry on Xen PV.
>> 3. Make a xen_nmi that's actually correct (should be trivial)
>>
>> #1 is here:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_syscall&id=14fee348e3e86c994400d68085217d1232a637d6
>
> If the
>
> /* Zero-extending 32-bit regs, do not remove */
> movl    %eax, %eax
>
> comments are to be believed, then the entry logic needs reordering
> slightly to:
>
> GLOBAL(entry_*_compat_after_hwframe)
>     movl    %eax, %eax    /* Zero-extending 32-bit regs, do not remove */
>     pushq    %rax                /* pt_regs->orig_ax */

D'oh, right.  Juergen, want to make that change?