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s=arc-20220608; d=hostedemail.com; t=1772215052; a=rsa-sha256; cv=none; b=eg+YkXZKotIhDdo1NzO+V7GsJatzfjYCUoL3M9y0BwsFYvXSKT1CsJOFMj94FrMdEYlS7b Ll/xnGkZu3S+6uy76MIr6aftSFXmkUHb3I+CBxorcMLGpDtVScYjRRlvs6O0eDLfD5Qq96 T2nC0NRz0pbBfh6r85TtXzKTd/4+KD4= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=none; spf=pass (imf01.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com; dmarc=pass (policy=none) header.from=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 239D714BF; Fri, 27 Feb 2026 09:57:25 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 112383F73B; Fri, 27 Feb 2026 09:57:26 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , David Hildenbrand , 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 Subject: [PATCH v6 23/30] arm64: kpkeys: Ensure the linear map can be modified Date: Fri, 27 Feb 2026 17:55:11 +0000 Message-ID: <20260227175518.3728055-24-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20260227175518.3728055-1-kevin.brodsky@arm.com> References: <20260227175518.3728055-1-kevin.brodsky@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: ukoq3mibaorc3pajegi4ijew8p76mkq1 X-Rspamd-Queue-Id: 4051F4000E X-Rspamd-Server: rspam03 X-HE-Tag: 1772215052-379879 X-HE-Meta: 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 Dd8lcnM5 HgSfY6s6JUDISWgimjCABbYDA8YB/nPU9pIkCxPCO9boYA/1G13PjpLGHSk3FKvhMrIbB8Y9rM+SS0+7jTeLLLrqw2U2A1px3awpl5cFTJLrb2ZRVqSf8NGyQE+1+caTc7H8GpXf+MJm5C0rdrBvsKdq7SA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When the kpkeys_hardened_pgtables feature is enabled, we need to be able to modify attributes (specifically the pkey/POIndex) in the linear map at page granularity. Add the appropriate check to can_set_direct_map() and force_pte_mapping(), on the same principle as rodata_full and other features. These functions can be called very early, before POE is actually detected. Introduce a helper that returns whether the hardening feature is/will be enabled, by checking whether POE is supported by the CPU if it hasn't been detected yet. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/kpkeys.h | 18 ++++++++++++++++++ arch/arm64/mm/mmu.c | 3 ++- arch/arm64/mm/pageattr.c | 3 ++- 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h index 64d6e22740ec..eeebbdfe239a 100644 --- a/arch/arm64/include/asm/kpkeys.h +++ b/arch/arm64/include/asm/kpkeys.h @@ -57,6 +57,24 @@ static __always_inline void arch_kpkeys_restore_pkey_reg(u64 pkey_reg) #endif /* CONFIG_ARM64_POE */ +#ifdef CONFIG_KPKEYS_HARDENED_PGTABLES + +static inline bool arm64_supports_kpkeys_hardened_pgtables(void) +{ + /* POE is a boot feature */ + return boot_capabilities_finalized() ? + system_supports_poe() : cpu_has_poe(); +} + +#else /* CONFIG_KPKEYS_HARDENED_PGTABLES */ + +static inline bool arm64_supports_kpkeys_hardened_pgtables(void) +{ + return false; +} + +#endif /* CONFIG_KPKEYS_HARDENED_PGTABLES */ + #endif /* __ASSEMBLY__ */ #endif /* __ASM_KPKEYS_H */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index a8e982ac5079..ea1cb1875257 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -764,7 +764,8 @@ static inline bool force_pte_mapping(void) return true; if (bbml2) return false; - return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world(); + return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world() || + arm64_supports_kpkeys_hardened_pgtables(); } static DEFINE_MUTEX(pgtable_split_lock); diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index d2a7e104a5c2..05e57387c0b5 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -96,7 +96,8 @@ bool can_set_direct_map(void) * Realms need to make pages shared/protected at page granularity. */ return rodata_full || debug_pagealloc_enabled() || - arm64_kfence_can_set_direct_map() || is_realm_world(); + arm64_kfence_can_set_direct_map() || is_realm_world() || + arm64_supports_kpkeys_hardened_pgtables(); } static int update_range_prot(unsigned long start, unsigned long size, -- 2.51.2