linux-kernel - Re: [PATCH Part1 v5 23/38] x86/head/64: set up a startup %gs for stack protector

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Message-ID: <20210827133831.xfdw7z55q6ixpgjg@amd.com>
Date:   Fri, 27 Aug 2021 08:38:31 -0500
From:   Michael Roth <michael.roth@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Brijesh Singh <brijesh.singh@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH Part1 v5 23/38] x86/head/64: set up a startup %gs for
 stack protector

On Wed, Aug 25, 2021 at 06:29:31PM +0200, Borislav Petkov wrote:
> On Wed, Aug 25, 2021 at 10:18:35AM -0500, Michael Roth wrote:
> > On Wed, Aug 25, 2021 at 04:29:13PM +0200, Borislav Petkov wrote:
> > > On Fri, Aug 20, 2021 at 10:19:18AM -0500, Brijesh Singh wrote:
> > > > From: Michael Roth <michael.roth@....com>
> > > > 
> > > > As of commit 103a4908ad4d ("x86/head/64: Disable stack protection for
> > > > head$(BITS).o") kernel/head64.c is compiled with -fno-stack-protector
> > > > to allow a call to set_bringup_idt_handler(), which would otherwise
> > > > have stack protection enabled with CONFIG_STACKPROTECTOR_STRONG. While
> > > > sufficient for that case, this will still cause issues if we attempt to
> 								^^^
> 
> I'm tired of repeating the same review comments with you guys:
> 
> Who's "we"?
> 
> Please use passive voice in your text: no "we" or "I", etc.
> Personal pronouns are ambiguous in text, especially with so many
> parties/companies/etc developing the kernel so let's avoid them please.

That had also been fixed in the commit message fixup that got clobbered, but
I still missed it in one of the comments as well so I'll be more careful of
this.

> 
> How about you pay more attention?

I've been periodically revising/rewording my comments since I saw you're
original comments to Brijesh a few versions back, but it's how I normally
talk when discussing code with people so it keeps managing to sneak back in.

I've added a git hook to check for this and found other instances that need
fixing as well, so hopefully with the help of technology I can get them all
sorted for the next spin.

> 
> > I didn't realize the the 32-bit path was something you were suggesting
> > to have added in this patch, but I'll take a look at that as well.
> 
> If you're going to remove the -no-stack-protector thing for that file,
> then pls remove it for both 32- and 64-bit. I.e., the revert what
> 103a4908ad4d did.

Got it, will do.

> 
> -- 
> Regards/Gruss,
>     Boris.
> 
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