linux-kernel - Re: [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros

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Date:   Thu, 25 Nov 2021 15:25:09 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     ira.weiny@...el.com, Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Ira Weiny <ira.weiny@...el.com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-mm@...ck.org
Subject: Re: [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros

On Tue, Aug 03 2021 at 21:32, ira weiny wrote:
> @@ -200,16 +200,14 @@ __setup("init_pkru=", setup_init_pkru);
>   */
>  u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags)
>  {
> -	int pkey_shift = pkey * PKR_BITS_PER_PKEY;
> -
>  	/*  Mask out old bit values */
> -	pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift);
> +	pk_reg &= ~PKR_PKEY_MASK(pkey);
>  
>  	/*  Or in new values */
>  	if (flags & PKEY_DISABLE_ACCESS)
> -		pk_reg |= PKR_AD_BIT << pkey_shift;
> +		pk_reg |= PKR_AD_KEY(pkey);
>  	if (flags & PKEY_DISABLE_WRITE)
> -		pk_reg |= PKR_WD_BIT << pkey_shift;
> +		pk_reg |= PKR_WD_KEY(pkey);

I'm not seeing how this is improving that code. Quite the contrary.

Thanks,

        tglx