Date: Fri, 29 Sep 2017 13:56:11 +0200
From: Borislav Petkov <bp@suse.de>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Brian Gerst <brgerst@gmail.com>, Chris Metcalf <cmetcalf@mellanox.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Masami Hiramatsu <mhiramat@kernel.org>, Huang Rui <ray.huang@amd.com>,
        Jiri Slaby <jslaby@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Shuah Khan <shuah@kernel.org>, linux-kernel@vger.kernel.org,
        x86@kernel.org, Adam Buchbinder <adam.buchbinder@gmail.com>,
        Colin Ian King <colin.king@canonical.com>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Qiaowei Ren <qiaowei.ren@intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Kees Cook <keescook@chromium.org>,
        Thomas Garnier <thgarnie@google.com>,
        Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v8 12/28] x86/insn-eval: Add utility functions to get
 segment selector
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On Thu, Sep 28, 2017 at 11:06:42PM -0700, Ricardo Neri wrote:
> I agree. In fact, insn_get_seg_base() does not need insn at all. All it needs is
> a INAT_SEG_REG_* index. This would make things clear. UMIP (and callers that
> need to copy_from_user code can do insn_get_seg_base(regs, INAT_SEG_REG_CS). No
> insn needed.

Yap.

> In fact, it is only the insn_get_addr_ref_xx() family of functions that does

I think you mean get_addr_ref_xx() here.

> Do you think the pseudocode above addresses your concerns?
> 
> *insn_get_seg_base() will take a INAT_SEG_REG_* index
> *insn_get_ref_xx() receives an initialized insn that can check for NULL value.
> *a reworked resolve_seg_reg_idx will clearly check if it can use segment
> override prefixes and obtain them. If not, it will use default values.

Makes sense, but send me the final version to take a look at it too.

Thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--