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bh=FCGum1rTAVPaw3kfR73YNYjOCQm2+TowdZAQ4naswfQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=KM8LyCZXFoj2SvWeg4FGMfVfyTECIs2/JVcKP3TzZ0xStyDKLjYaZ0cR3odPlKCOW R89GcnDMSAgmVu93FnpXq8LTI0wIc11PuL9ccaEFetP2FTKbixbLItiNQx18OmKuYC ZCRu1Xf/noLdgQMlvM5rFelQT89YHjYdnkE4JLMY= From: Kevin Brodsky Date: Tue, 18 Aug 2026 15:08:51 +0100 Subject: [PATCH RFC v9 09/25] arm64: Enable kpkeys MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260818-kpkeys-v9-9-743ad31b2c8f@arm.com> References: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> In-Reply-To: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> To: linux-hardening@vger.kernel.org Cc: Kevin Brodsky , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linu Cherian , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , =?utf-8?q?Pierre-Cl=C3=A9ment_Tosi?= , Quentin Perret , Rick Edgecombe , Ryan Roberts , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Ira Weiny , Lorenzo Stoakes , Thomas Gleixner X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787062276; l=1824; i=kevin.brodsky@arm.com; s=20260427; h=from:subject:message-id; bh=FCGum1rTAVPaw3kfR73YNYjOCQm2+TowdZAQ4naswfQ=; b=cWs9/HhYQLlTOWcxsFeqRjaQ1YfUuLMxMTT+5dNmHs0vj2L1unepwEAB2wJrTYv+tdehkAoM/ zD6D9oE2xVzBMNqlw/+Y7ieQRDluBuS3dfwZyC+BdW4UgNNENLR2FpS X-Developer-Key: i=kevin.brodsky@arm.com; a=ed25519; pk=N2QG+eJKrvkNovwhhwJhnJ4+ScVfsGCHldmqLfcMTFs= X-Stat-Signature: dx8i9cabpxaprozzw97dkohk3opxzdj5 X-Rspamd-Queue-Id: C16FB10000E X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1787062327-276301 X-HE-Meta: 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 ilzU1Awh 0WjP7Tux3agK7quMKYnCmJA5ice3LsgDRuxNB0haDVaSlGN1GhGRqTkk5epSkGBQPXuLZe8JIZJ4hRHAOC8tdhxNE3EqLr5d8+ie1wm4z0XaPhDtqqHyixVoO30J9lQHOOSGOqlgIc2gR+fl+7pUpF9Nqb+5Qw8qYjprYgIup6RsHJz0t/1/mayciNrAnwc/0Ez+6ZEeVMVCcCZCSP1BdgO8zmExh2m9qZs52iJdPLJrGenchGKJPoVwV+Cs6V8HlNPwoJh8ie1eCAlGq2hJknzSno1QTR7ag14F6 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is the final step to enable kpkeys on arm64. We enable POE at EL1 by setting TCR2_EL1.POE, and initialise POR_EL1 to the default value, enabling access to the default pkey/POIndex (0). An ISB is added so that POE restrictions are enforced immediately. Having done this, we can now select ARCH_HAS_KPKEYS if ARM64_POE is enabled. Signed-off-by: Kevin Brodsky --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/cpufeature.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b3afe0688919..0afa085c66be 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2202,6 +2202,7 @@ config ARM64_POE def_bool y select ARCH_USES_HIGH_VMA_FLAGS select ARCH_HAS_PKEYS + select ARCH_HAS_KPKEYS help The Permission Overlay Extension is used to implement Memory Protection Keys. Memory Protection Keys provides a mechanism for diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9a22df0c5120..4f2f54007ed6 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -76,6 +76,7 @@ #include #include #include +#include #include #include @@ -2463,8 +2464,10 @@ static void cpu_enable_mops(const struct arm64_cpu_capabilities *__unused) #ifdef CONFIG_ARM64_POE static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused) { - sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE); + write_sysreg_s(POR_EL1_INIT, SYS_POR_EL1); + sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE | TCR2_EL1_POE); sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_E0POE); + isb(); } #endif -- 2.51.2