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b=u2/EyyMbkNoksqyFV6DhyMLgjgwjvgYI+oEXVsEeJHbk1ckE8Z09qoH0k6nFGQFm9 cY75hCwPK09VXs+Xm520/ICdasDxYK+68y0wlLNPceDO8WaB2iNuZu5lBnyugyK8mH FtC7u0OpIzmBSwpTZQYHkrrhJLkHKDaQ/uH3RpDJYHzA/vrhG/xwVSk7i4jOMnmtx+ kfIciHnRXI8LXvxbZUpxFSrLKOnTtcOJi+GpcJPKkJzPjyI29rI5qjq57rjoiI3FSj 56GoJa6eh3WUF9kwy5eyLXswYoVwGrq+EKOl7BDlJQuKsL7Catq5Czvt+C9MJ72ICR qXUGtyz6RjjMQ== Message-ID: Date: Fri, 17 Apr 2026 19:38:55 +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: mdo7sy4mecampmfcohe3s3efq9zq85py X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C35CF40007 X-HE-Tag: 1776447546-585006 X-HE-Meta: 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 d9QyIcCN f2ukX8k39fypQYxW49Nmn5jhrhWSmtlNSpDqDJqd7z1JiXomS2r7ezUUz2WgyD0ShxQ3WpEn6aW/vBzS2WgT2kBjw0L2ofKTcEgWOteJMuguaxqKobyqVFNqBLGJbyEqd6+H71tmpSPpxGraJYHe9XQYSCzMckVDF+srJqp4g/dNnm1AM/Z/fvX2cwXx0zPHwa3tWz3J/10A7E52RHBZn319N4EqMPr9IDakuFDGchhZXUPkCtZBx4kFmXIpUkdZPd5AJsMZnuzWWAbCUADc+T7FTHCxB5I3N8sbC Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/17/26 17:59, Kevin Brodsky wrote: > On 17/04/2026 16:37, David Hildenbrand (Arm) wrote: >> On 2/27/26 18:54, Kevin Brodsky wrote: >>> kpkeys is a simple framework to enable the use of protection keys >>> (pkeys) to harden the kernel itself. This patch introduces the basic >>> API in : a couple of functions to set and restore >>> the pkey register and macros to define guard objects. >>> >>> kpkeys introduces a new concept on top of pkeys: the kpkeys level. >>> Each level is associated to a set of permissions for the pkeys >>> managed by the kpkeys framework. kpkeys_set_level(lvl) sets those >>> permissions according to lvl, and returns the original pkey >>> register, to be later restored by kpkeys_restore_pkey_reg(). To >>> start with, only KPKEYS_LVL_DEFAULT is available, which is meant >>> to grant RW access to KPKEYS_PKEY_DEFAULT (i.e. all memory since >>> this is the only available pkey for now). >>> >>> Because each architecture implementing pkeys uses a different >>> representation for the pkey register, and may reserve certain pkeys >>> for specific uses, support for kpkeys must be explicitly indicated >>> by selecting ARCH_HAS_KPKEYS and defining the following functions in >>> , in addition to the macros provided in >>> : >>> >>> - arch_kpkeys_set_level() >>> - arch_kpkeys_restore_pkey_reg() >>> - arch_kpkeys_enabled() >> Another thing: why not simply drop the "arch_" stuff from these helpers? > > 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 -- Cheers, David