From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3F5F6CD98F2 for ; Mon, 22 Jun 2026 13:16:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lgvQzYjbMrpc1MMyior1P3ZPdYtIuPkBiGx7cWNFLN4=; b=L/bBT+kv8JLrwrlZi4h9d3E3+s MC070fwrTrzLm4JKCB/m1y1dX5mRbI4E2O1+UKd4qgW7nHkty/CxfvVDIzGNSswR8VkPD4LAJA7B5 PIEkpV3++OaJauk3h0cKODGW+mN5Ls0ev/1B7wOJJnlOXeNScRd9GDdZnzMO+6DoU1pnvuHYg68N3 HqjGo7PGz6oVVLSCWexuk0qsJrQYftzRt6Rp1ecouQMFa9K0UY9PSbiHZgz6Tc/xxDcqDuRn4bWEo L7rmgup7RTRPFhEVKqD3gDIsn2kt/hEZLRS6fSlArWRpVa/jGtGWlwPv9jFRGZ6cVEnSSuFg4V/hB mYF6Pjdg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wbeVh-000000050hZ-432h; Mon, 22 Jun 2026 13:16:21 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wbeVg-000000050hL-2tFZ for linux-arm-kernel@lists.infradead.org; Mon, 22 Jun 2026 13:16:20 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 75BB5601F6; Mon, 22 Jun 2026 13:16:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC02A1F00A3E; Mon, 22 Jun 2026 13:16:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782134179; bh=lgvQzYjbMrpc1MMyior1P3ZPdYtIuPkBiGx7cWNFLN4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=LVFFHQd1hVV3xyaHdbvqy1IUptTyefGIMhFmpKHheR2hHi6h8Pupkh+49sWuI7kTB PRd5VH4p0hJ8/a+656aexGPb9vnMnVEhMzYMigNWoV/vj/BFqdF/hmRFySwJJcj+ix TxzLge8swBRCE3yYyAyZ7mSR16RlNyj6gb04oPEb02rgmljsIcP3fU+hgoQLycwk7y 38rtzXCtQk/nPDAW1c+OaHFUfiOotUYFisfnzyk46xCBG3mSBC6r97s9nCD0U40zNa tQEOsfzjDo5uayhGH/KCENJxRX+DngaoamEa08AwIJ0JlqEVCOaNIE+BbmJJPHEUoj eDeFxlZqAgW/Q== Message-ID: Date: Mon, 22 Jun 2026 15:16:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v8 04/24] arm64: Introduce por_elx_set_pkey_perms() helper To: Kevin Brodsky , linux-hardening@vger.kernel.org Cc: Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , 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, Lorenzo Stoakes , Thomas Gleixner References: <20260526-kpkeys-v8-0-eaaacdacc67c@arm.com> <20260526-kpkeys-v8-4-eaaacdacc67c@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: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/26/26 13:15, Kevin Brodsky wrote: > 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(). > > 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..bffb4d2b1246 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, u64 perms) > +{ > + u64 shift = POR_ELx_PERM_SHIFT(pkey); > + > + return (por & ~(POE_MASK << shift)) | (perms << shift); > +} > + > #endif /* _ASM_ARM64_POR_H */ > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index dd85e093ffdb..493310cf0486 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -2339,8 +2339,8 @@ 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; > + u64 new_perms; You should spell out the renaming of the variable. Given that perms is 4bit per key, should we use a u8 for it instead? > + u64 por; > > if (!system_supports_poe()) > return -ENOSPC; > @@ -2354,25 +2354,19 @@ 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); Was wondering whether to move reading+writing of the register into the same helper, but you cannot reuse this exactly the same way for SYS_POR_EL1 as it seems. Reviewed-by: David Hildenbrand (Arm) -- Cheers, David