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b=ozVwLVWtbbv1dAM7yazhYlk9vBe+pKM2xJQmU3CiYqNJsEr7tzkK6TWdMIXiJlWlf Xi0Gr58XdKl+3sujWzhDdtlzNzkBwE5zzpUG2Ql0vQmCymqK/xC5KY3I8Riknd/8pt 8lkOHH2ydXVU5JhblmB7Rj/oOzBBE4/+qkTHM0WYQxKgAfsglgKPYf59suelKyClVR cLaIBFMEPbb8ftZykqjauwGJAPzMzHveyDuG+uT4/k8TXjSBUZRmbPtyN98cvN9rky J8QnLPwrNrYd5t51NQFAXwcftF7jzJsXozYUHNaRxaE8Wp4lrmHOUWSN0S7VgKyALv 3SQB8ubcc9iuw== Message-ID: Date: Mon, 20 Apr 2026 20:49:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 01/30] mm: Introduce kpkeys To: Kevin Brodsky , linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Lorenzo Stoakes , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , Ryan Roberts , Thomas Gleixner , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org References: <20260227175518.3728055-1-kevin.brodsky@arm.com> <20260227175518.3728055-2-kevin.brodsky@arm.com> <00b24db8-0063-48d6-8bc4-e8b670d8f0d5@kernel.org> <913002a5-e002-4001-ad19-037102d1f97d@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: bs6xxzr5dmup6obhumhj1cdq5qxpwm9n X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D043C8000C X-HE-Tag: 1776710954-639075 X-HE-Meta: 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 3bcnfnD1 TsmACjoLFn1FjaMZfOoicj+04nGagfp3uXJKhK9LmK8muqzBtaOl++kKSOwJzYzHMu0P/HYsIRgtR/O7YSnr3kxvs8mWuAOLsHij9YumWfG3uqL73CTOLJLwJywwbHEfuBWPq4VQ6Uaf7i1NNYRHWhsMSSrIzcocawKSNYNZqs7FxqpzlST0pXIGskpZBcNjbnOUXIWHT1v1KVEsVfx/TmfJXsdSZUROltoh64Gfv+S/YM29yp+k7JR1FpfGKZtU7TDYql47U8HwZDMhTpCDQUeIi9klWdq/jy6x/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/20/26 08:46, Kevin Brodsky wrote: > On 17/04/2026 19:38, David Hildenbrand (Arm) wrote: >> On 4/17/26 17:59, Kevin Brodsky wrote: >>> The first two are not meant to be directly called, they're the >>> arch-specific implementation of kpkeys_set_level() and >>> kpkeys_restore_pkey_reg(), and those generic functions handle some >>> generic logic. >>> >>> arch_kpkeys_enabled() is directly used in generic code, so I suppose it >>> could be renamed to kpkeys_enabled()? It's actually implemented in an >>> arch header so I wasn't too sure about it. >> I was skimming over patch #13 and spotted: >> >> +void·__init·kpkeys_hardened_pgtables_init(void) >> +{ >> +› if·(!arch_kpkeys_enabled()) >> +› › return; >> + >> +› static_branch_enable(&kpkeys_hardened_pgtables_key); >> +} >> >> The arch_* there can just go IMHO. >> >> I'd also do it for the two ones used by the GUARD macros. If we don't >> expect common code wrappers (arch_kpkeys_enabled() vs. kpkeys_enabled), >> then the arch_ is unnecessary information -- IMHO > > Makes sense. I could just rename arch_kpkeys_enabled() to > kpkeys_enabled(), but I'm thinking having an arch abstraction could be > clearer, after looking into protecting sparse-vmemmap page tables. The > new version would look like this: > > * : >     - arch_supports_kpkeys() >     - arch_supports_kpkeys_early() [can be called before features have > been detected] > > * defines: >     - kpkeys_enabled() -> arch_supports_kpkeys() >     - kpkeys_hardened_pgtables_enabled() -> static key >     - kpkeys_hardened_pgtables_early_enabled() -> > arch_supports_kpkeys_early() [called when setting up sparse-vmemmap, > linear map, etc.] > > There is extra #ifdef'ing going on in , but > doesn't need to worry about it. I think this might be > easier to follow, I don't like too much having an interface function > like kpkeys_enabled() defined in an arch header (not great for > kernel-doc comments either). Any thoughts? No strong opinion on the indirection as long as we don't call arch_ stuff from ordinary pkey user code :) -- Cheers, David