linux-kernel - Re: [PATCH v2 1/6] x86/bugs: Add asm helpers for executing VERW

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Message-ID: <20231024173015.w5qw767akvcdwmiv@desk>
Date:   Tue, 24 Oct 2023 10:30:15 -0700
From:   Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>, tony.luck@...el.com,
        ak@...ux.intel.com, tim.c.chen@...ux.intel.com,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        kvm@...r.kernel.org,
        Alyssa Milburn <alyssa.milburn@...ux.intel.com>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        antonio.gomez.iglesias@...ux.intel.com,
        Alyssa Milburn <alyssa.milburn@...el.com>
Subject: Re: [PATCH  v2 1/6] x86/bugs: Add asm helpers for executing VERW

On Tue, Oct 24, 2023 at 07:02:48PM +0200, Peter Zijlstra wrote:
> On Tue, Oct 24, 2023 at 09:45:20AM -0700, Pawan Gupta wrote:
> 
> > > > modules being within 4GB of kernel.
> 
> FWIW, it's 2G, it's a s32 displacement, the highest most address can
> jump 2g down, while the lowest most address can jump 2g up. Leaving a 2G
> directly addressable range.
> 
> And yeah, we ensure kernel text and modules are inside that 2G range.

Ah, okay. Thanks for the info.