linux-kernel - Re: [PATCH v2 0/2] x86/asm: avoid register pressure from static_cpu

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Message-ID: <YTtcjhrWS8e9VfWG@zn.tnic>
Date:   Fri, 10 Sep 2021 15:24:30 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "H. Peter Anvin (Intel)" <hpa@...or.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        x86@...nel.org
Subject: Re: [PATCH v2 0/2] x86/asm: avoid register pressure from
 static_cpu_has()

On Fri, Sep 10, 2021 at 11:16:47AM +0200, Borislav Petkov wrote:
> Right, maybe I'm missing something but what is wrong with the immediate
> addressing variant, i.e., that thing:
> 
> 	testb  $0x8,0xffffffff89346eea
> 
> and you need to *force* %rip-relative?

To answer my own question after peterz asked: that hardcoded address
won't work with KASLR, ofc.

-- 
Regards/Gruss,
    Boris.

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