linux-kernel - Re: [PATCH v8 04/12] x86/spectre: Add boot time option to select Spectre v2 mitigation

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Message-ID: <CAGXu5jKQfb8qUnJk-DMMSZS8JW8dsEuG0NQ3ihbLiCP50kLp5w@mail.gmail.com>
Date:   Wed, 24 Jan 2018 11:32:00 +1100
From:   Kees Cook <keescook@...gle.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Jiri Kosina <jikos@...nel.org>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Andi Kleen <ak@...ux.intel.com>, Paul Turner <pjt@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rik van Riel <riel@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>, X86 ML <x86@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v8 04/12] x86/spectre: Add boot time option to select
 Spectre v2 mitigation

On Wed, Jan 24, 2018 at 10:05 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Tue, Jan 23, 2018 at 11:55:05PM +0100, Jiri Kosina wrote:
>> I think we should start recording CFLAGS the kernel has been compiled with
>> anyway; doesn't hurt and might come handy when debugging.
>>
>> /proc/version is probably not the best place ... /proc/cflags?
>
> Yap, I guess I can find that string with hexdump on the kernel binary too :-)

I've wanted this for a while (especially for the coming detected
support for stack protector). Having more than just the clfags is, I
think, important. We'd likely want to record the entire environment
(compiler version, linker version, flags on both, etc).

-Kees

-- 
Kees Cook
Pixel Security