From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BC21C441627 for ; Tue, 18 Aug 2026 14:11:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787062304; cv=none; b=W45+qNERH/ubApvU27S9vXO4hmnrnXMluoBnv0DXslF6czNS4VFL8+Aw0s+6bbMH6G7MK4MMmP6c2UQSETdvt+4fdfZ+DBX1Jey5nosuCZBoFiILI0Ab0p8Lm7lxrodBoXgjRNvY0jxJiVqgdUcd1W/zQ8z/L88JUxXvv4cCam8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787062304; c=relaxed/simple; bh=BkjNRdlehpq/qqZwQhBLzY19lD555G+nB+rRbzspEEE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=tVVWh0DtubKloOPGWgJNBpZ/tVH/dLVmtoRBf/KGFOH3VxtdaCO+3SMxuFCKFKGBe8JsA1LwJlANKHtmUcLwHPEr9vihbPQMrird2KEBNTbuH6NOhhGDveN5DXFYJDHWaK89tQQs5LPT54P/JZKr2nLGtHIhYD3pIwcdt+TpLBg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=WXekD//F; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="WXekD//F" 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 1D35219F6; Tue, 18 Aug 2026 07:11:38 -0700 (PDT) Received: from localhost.localdomain (e123572-lin.cambridge.arm.com [10.2.208.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5D6083F85F; Tue, 18 Aug 2026 07:11:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787062302; bh=BkjNRdlehpq/qqZwQhBLzY19lD555G+nB+rRbzspEEE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=WXekD//Fmvb8C1WyhB1190zPRpkkuswNYtmwwoMeNS+olFxji+e80KDeIztBkSSqE 1N8MXkQ+SkSeSh4MWEyuEkArYRfTujxs6s7NTROKtDpdvnWDviu8lnOK7SFAEZjvZa +iqm+CakJdybHTz5fi65HVUhf1uIj56pfWjDYRoA= From: Kevin Brodsky Date: Tue, 18 Aug 2026 15:08:46 +0100 Subject: [PATCH RFC v9 04/25] arm64: Introduce por_elx_set_pkey_perms() helper Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260818-kpkeys-v9-4-743ad31b2c8f@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=2582; i=kevin.brodsky@arm.com; s=20260427; h=from:subject:message-id; bh=BkjNRdlehpq/qqZwQhBLzY19lD555G+nB+rRbzspEEE=; b=4ZTyW5TcfHxhyckVVjluqnadzTDAbx78zgNQa3gNuWY+CA+irOo4uc0URWKL6zTzAj8ERPxz5 gARLFho9C3ZB33hSphiUVjYeAThs20KMb6VCEKJUc25+Dwhztu0cOIg X-Developer-Key: i=kevin.brodsky@arm.com; a=ed25519; pk=N2QG+eJKrvkNovwhhwJhnJ4+ScVfsGCHldmqLfcMTFs= Introduce a helper that sets the permissions of a given pkey (POIndex) in the POR_ELx format, and make use of it in arch_set_user_pkey_access(). new_por now represents the permissions of a single pkey, so rename it to new_perms and change its type accordingly. Reviewed-by: David Hildenbrand (Arm) Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/por.h | 7 +++++++ arch/arm64/mm/mmu.c | 26 ++++++++++---------------- 2 files changed, 17 insertions(+), 16 deletions(-) diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h index d913d5b529e4..19b3dd1d43a0 100644 --- a/arch/arm64/include/asm/por.h +++ b/arch/arm64/include/asm/por.h @@ -31,4 +31,11 @@ static inline bool por_elx_allows_exec(u64 por, u8 pkey) return perm & POE_X; } +static inline u64 por_elx_set_pkey_perms(u64 por, u8 pkey, u8 perms) +{ + u64 shift = POR_ELx_PERM_SHIFT(pkey); + + return (por & ~(POE_MASK << shift)) | ((u64)perms << shift); +} + #endif /* _ASM_ARM64_POR_H */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index d4de88770ecf..767478d9e84b 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -2305,8 +2305,8 @@ void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp) #ifdef CONFIG_ARCH_HAS_PKEYS int arch_set_user_pkey_access(int pkey, unsigned long init_val) { - u64 new_por; - u64 old_por; + u8 new_perms; + u64 por; if (!system_supports_poe()) return -ENOSPC; @@ -2320,25 +2320,19 @@ int arch_set_user_pkey_access(int pkey, unsigned long init_val) return -EINVAL; /* Set the bits we need in POR: */ - new_por = POE_RWX; + new_perms = POE_RWX; if (init_val & PKEY_DISABLE_WRITE) - new_por &= ~POE_W; + new_perms &= ~POE_W; if (init_val & PKEY_DISABLE_ACCESS) - new_por &= ~POE_RW; + new_perms &= ~POE_RW; if (init_val & PKEY_DISABLE_READ) - new_por &= ~POE_R; + new_perms &= ~POE_R; if (init_val & PKEY_DISABLE_EXECUTE) - new_por &= ~POE_X; + new_perms &= ~POE_X; - /* Shift the bits in to the correct place in POR for pkey: */ - new_por = POR_ELx_PERM_PREP(pkey, new_por); - - /* Get old POR and mask off any old bits in place: */ - old_por = read_sysreg_s(SYS_POR_EL0); - old_por &= ~(POE_MASK << POR_ELx_PERM_SHIFT(pkey)); - - /* Write old part along with new part: */ - write_sysreg_s(old_por | new_por, SYS_POR_EL0); + por = read_sysreg_s(SYS_POR_EL0); + por = por_elx_set_pkey_perms(por, pkey, new_perms); + write_sysreg_s(por, SYS_POR_EL0); return 0; } -- 2.51.2