linux-kernel - Re: [PATCH] x86/mm/mem_encrypt: Disable all instrumentation for SME early boot code

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Message-ID: <20190429205146.GF2324@zn.tnic>
Date:   Mon, 29 Apr 2019 22:51:46 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Gary R Hook <ghook@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Hook, Gary" <Gary.Hook@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "luto@...nel.org" <luto@...nel.org>,
        Alexander Potapenko <glider@...gle.com>
Subject: Re: [PATCH] x86/mm/mem_encrypt: Disable all instrumentation for SME
 early boot code

On Mon, Apr 29, 2019 at 08:16:07PM +0000, Gary R Hook wrote:
> Yes, option 4 would be a combination of using a local copy of strncmp()

Why the local copy?

> and disabling instrumentation (KASAN, KCOV, whatever) for
> arch/x86/lib/cmdline.c when SME is enabled.

I think this should suffice. You only disable instrumentation when
CONFIG_AMD_MEM_ENCRYPT=y and not do any local copies but use the generic
functions.

Hmm.

-- 
Regards/Gruss,
    Boris.

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