linux-kernel - RE: [cocci] [PATCH v3 3/6] arm64: tlb: Convert the opencoded field modify

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CO1PR11MB5089C0773E3AEAD4BB0A1AFFD6BA2@CO1PR11MB5089.namprd11.prod.outlook.com>
Date: Wed, 23 Apr 2025 16:54:49 +0000
From: "Keller, Jacob E" <jacob.e.keller@...el.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>, Luo Jie
	<quic_luoj@...cinc.com>
CC: Yury Norov <yury.norov@...il.com>, Rasmus Villemoes
	<linux@...musvillemoes.dk>, Julia Lawall <Julia.Lawall@...ia.fr>, "Nicolas
 Palix" <nicolas.palix@...g.fr>, Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Oliver Upton
	<oliver.upton@...ux.dev>, Joey Gouly <joey.gouly@....com>, Suzuki K Poulose
	<suzuki.poulose@....com>, Zenghui Yu <yuzenghui@...wei.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"cocci@...ia.fr" <cocci@...ia.fr>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "kvmarm@...ts.linux.dev"
	<kvmarm@...ts.linux.dev>, "andrew@...n.ch" <andrew@...n.ch>,
	"quic_kkumarcs@...cinc.com" <quic_kkumarcs@...cinc.com>,
	"quic_linchen@...cinc.com" <quic_linchen@...cinc.com>,
	"quic_leiwei@...cinc.com" <quic_leiwei@...cinc.com>,
	"quic_suruchia@...cinc.com" <quic_suruchia@...cinc.com>,
	"quic_pavir@...cinc.com" <quic_pavir@...cinc.com>
Subject: RE: [cocci] [PATCH v3 3/6] arm64: tlb: Convert the opencoded field
 modify



> -----Original Message-----
> From: cocci-request@...ia.fr <cocci-request@...ia.fr> On Behalf Of Russell King
> (Oracle)
> Sent: Thursday, April 17, 2025 11:11 AM
> To: Luo Jie <quic_luoj@...cinc.com>
> Cc: Yury Norov <yury.norov@...il.com>; Rasmus Villemoes
> <linux@...musvillemoes.dk>; Julia Lawall <Julia.Lawall@...ia.fr>; Nicolas Palix
> <nicolas.palix@...g.fr>; Catalin Marinas <catalin.marinas@....com>; Will
> Deacon <will@...nel.org>; Marc Zyngier <maz@...nel.org>; Oliver Upton
> <oliver.upton@...ux.dev>; Joey Gouly <joey.gouly@....com>; Suzuki K Poulose
> <suzuki.poulose@....com>; Zenghui Yu <yuzenghui@...wei.com>; linux-
> kernel@...r.kernel.org; cocci@...ia.fr; linux-arm-kernel@...ts.infradead.org;
> kvmarm@...ts.linux.dev; andrew@...n.ch; quic_kkumarcs@...cinc.com;
> quic_linchen@...cinc.com; quic_leiwei@...cinc.com;
> quic_suruchia@...cinc.com; quic_pavir@...cinc.com
> Subject: Re: [cocci] [PATCH v3 3/6] arm64: tlb: Convert the opencoded field
> modify
> 
> On Thu, Apr 17, 2025 at 06:47:10PM +0800, Luo Jie wrote:
> > Replaced below code with the wrapper FIELD_MODIFY(MASK, &reg, val)
> > - reg &= ~MASK;
> > - reg |= FIELD_PREP(MASK, val);
> > The semantic patch that makes this change is available
> > in scripts/coccinelle/misc/field_modify.cocci.
> >
> > More information about semantic patching is available at
> > https://coccinelle.gitlabpages.inria.fr/website
> >
> > Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
> > ---
> >  arch/arm64/include/asm/tlbflush.h | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/tlbflush.h
> b/arch/arm64/include/asm/tlbflush.h
> > index eba1a98657f1..0d250ef4161c 100644
> > --- a/arch/arm64/include/asm/tlbflush.h
> > +++ b/arch/arm64/include/asm/tlbflush.h
> > @@ -112,8 +112,7 @@ static inline unsigned long get_trans_granule(void)
> >  	    level >= 0 && level <= 3) {					\
> >  		u64 ttl = level & 3;					\
> >  		ttl |= get_trans_granule() << 2;			\
> > -		arg &= ~TLBI_TTL_MASK;					\
> > -		arg |= FIELD_PREP(TLBI_TTL_MASK, ttl);			\
> > +		FIELD_MODIFY(TLBI_TTL_MASK, &arg, ttl);			\
> 
> This could equally be:
> 		arg = u64_replace_bits(arg, ttl, TLBI_TTL_MASK);
> 
> which already exists, so doesn't require a new macro to be introduced.
> 

I had been looking for something like this the other day but was grepping for "FIELD_REPLACE" and similar which didn't find things.. Neat to know it exists already :D

> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!