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Date:   Fri, 18 Feb 2022 23:58:27 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     "Luck, Tony" <tony.luck@intel.com>
Cc:     Jue Wang <juew@google.com>, "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "patches@lists.linux.dev" <patches@lists.linux.dev>
Subject: Re: [PATCH v2] x86/mce: work around an erratum on fast string copy
 instructions.
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On Fri, Feb 18, 2022 at 10:38:10PM +0000, Luck, Tony wrote:
> > If so, we can sandwich around it with nstrumentation_begin() and _end()...
> 
> I guess so ... this stuff is all Greek to me.

roughly speaking... noinstr simply puts code in a special section
.noinstr.text and objtool checks whether that code calls code outside of
it. And noinstr is off-limits for tracing code.

The begin/end things are for ranges of code and work in a similar way,
see include/linux/instrumentation.h

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette