linux-kernel - Re: [v2 5/7] x86: Add emulation code for UMIP instructions

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Message-ID: <1482885636.106950.30.camel@ranerica-desktop>
Date:   Tue, 27 Dec 2016 16:40:36 -0800
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-msdos@...r.kernel.org, wine-devel@...ehq.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "H . Peter Anvin" <hpa@...or.com>, Brian Gerst <brgerst@...il.com>,
        Chen Yucong <slaoub@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        "Ravi V . Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tony Luck <tony.luck@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Liang Z . Li" <liang.z.li@...el.com>,
        Alexandre Julliard <julliard@...ehq.org>,
        Stas Sergeev <stsp@...t.ru>
Subject: Re: [v2 5/7] x86: Add emulation code for UMIP instructions

On Mon, 2016-12-26 at 00:49 +0900, Masami Hiramatsu wrote:
> On Fri, 23 Dec 2016 17:37:43 -0800
> Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> wrote:
> 
> > +static int __identify_insn(struct insn *insn)
> > +{
> > +	/* by getting modrm we also get the opcode */
> > +	insn_get_modrm(insn);
> > +	if (insn->opcode.bytes[0] != 0xf)
> > +		return -EINVAL;
> > +
> > +	if (insn->opcode.bytes[1] == 0x1) {
> > +		switch (X86_MODRM_REG(insn->modrm.value)) {
> > +		case 0:
> > +			return UMIP_SGDT;
> > +		case 1:
> > +			return UMIP_SIDT;
> > +		case 4:
> > +			return UMIP_SMSW;
> > +		default:
> > +			return -EINVAL;
> > +		}
> > +	} else if (insn->opcode.bytes[1] == 0x0) {
> > +		if (X86_MODRM_REG(insn->modrm.value) == 0)
> > +			return UMIP_SLDT;
> > +		else if (X86_MODRM_REG(insn->modrm.value) == 1)
> > +			return UMIP_STR;
> > +		else
> > +			return -EINVAL;
> > +	}
> 
> gcc detected an error here, you may need return "-EINVAL".

I will make this change. I removed this EINVAL at the last minute as it
didn't look right. It was indeed right.

Thanks and BR,
Ricardo
> 
> Thanks,
> 
> 
>