linux-kernel - Re: [PATCH v5 21/25] arm64/mm: Implement new [get_and_]clear_full

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: <ZcuebesH1pvx4sxl@FVFF77S0Q05N.cambridge.arm.com>
Date: Tue, 13 Feb 2024 16:53:01 +0000
From: Mark Rutland <mark.rutland@....com>
To: Ryan Roberts <ryan.roberts@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
	Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Wilcox <willy@...radead.org>,
	David Hildenbrand <david@...hat.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	John Hubbard <jhubbard@...dia.com>, Zi Yan <ziy@...dia.com>,
	Barry Song <21cnbao@...il.com>,
	Alistair Popple <apopple@...dia.com>,
	Yang Shi <shy828301@...il.com>, Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 21/25] arm64/mm: Implement new
 [get_and_]clear_full_ptes() batch APIs

On Tue, Feb 13, 2024 at 04:48:50PM +0000, Ryan Roberts wrote:
> On 13/02/2024 16:43, Mark Rutland wrote:
> > On Fri, Feb 02, 2024 at 08:07:52AM +0000, Ryan Roberts wrote:

> >> +static inline void __clear_full_ptes(struct mm_struct *mm, unsigned long addr,
> >> +				pte_t *ptep, unsigned int nr, int full)
> >> +{
> >> +	for (;;) {
> >> +		__ptep_get_and_clear(mm, addr, ptep);
> >> +		if (--nr == 0)
> >> +			break;
> >> +		ptep++;
> >> +		addr += PAGE_SIZE;
> >> +	}
> >> +}
> > 
> > The loop construct is a bit odd; can't this be:
> 
> I found it a little odd at first, but its avoiding the ptep and addr increments
> the last time through the loop. Its the preferred pattern for these functions in
> core-mm. See default set_ptes(), wrprotect_ptes(), clear_full_ptes() in
> include/linux/pgtable.h.
> 
> So I'd prefer to leave it as is so that we match them. What do you think?

That's fair enough; it I'm happy with it as-is.

Mark.