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 E569037A4B9; Wed, 29 Apr 2026 13:57:36 +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=1777471059; cv=none; b=ZMbIDc6zkMpacPnzvtNAi2MZM1dc9kNO68Fe82RW707ZpZj9lKSempl9nWSMNXdJdHkJ9NQqGkyR6UnRHW9xRPSu1a/BFv2apUEzl78sj+58SdP4nSEAZPmpbwcd/h/rIwxcs6HFtw/o8ko9e4GjTq3Qk7jpGmVLPGonO2Us4Eg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777471059; c=relaxed/simple; bh=51AOjeUHqGDov+TlvZ961wTG4/ToLBw1MVjjZ/EnINw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FAV6KFD9nl2KOZGXWJgI5kHihymi/2bR7anZtM1USWkjulGm+qZR041q2rN3JtyLemSB3LkLXMQrdwM9Wx5vWP5/U3qOeLKJAA7y0vqv4E7sMr+0Ve54Fh6uFbDpFoMYRgtmcDAQb1WSdA9Qw0wtAjYia3KChqRZo99OI6bmJaI= 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=VZYMMPru; 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="VZYMMPru" 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 7FB45337B; Wed, 29 Apr 2026 06:57:30 -0700 (PDT) Received: from [10.57.62.76] (unknown [10.57.62.76]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B54813F62B; Wed, 29 Apr 2026 06:57:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1777471056; bh=51AOjeUHqGDov+TlvZ961wTG4/ToLBw1MVjjZ/EnINw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VZYMMPruwp21m0Xl4JeKfECbeTob5+cc9VVBwFqewef4YFQpd9Inm1HT5mWQ5/6XG ItElSh4Ig+yLgjTKWv4g3SNaz5OOVx2Ve3sKphhXFiZ/dF5OXmmvFug+NBjU9oGbIA 5KSpb9He9n9hVC8WDP9z/KmEA1lJ8qPdpTJ9HzCk= Message-ID: <21a547ae-7121-4cd1-b203-4d8182eb7cc9@arm.com> Date: Wed, 29 Apr 2026 15:57:29 +0200 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 15/15] arm64: mm: Remap linear aliases of the fixmap page tables read-only To: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Ryan Roberts , Anshuman Khandual , Liz Prucka , Seth Jenkins , Kees Cook , Mike Rapoport , David Hildenbrand , Andrew Morton , linux-mm@kvack.org, linux-hardening@vger.kernel.org References: <20260427153416.2103979-17-ardb+git@google.com> <20260427153416.2103979-32-ardb+git@google.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20260427153416.2103979-32-ardb+git@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/04/2026 17:34, Ard Biesheuvel wrote: > [...] > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 84d81bae07a7..e76fe5b0c5fe 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1076,6 +1076,11 @@ void __init mark_linear_text_alias_ro(void) > (unsigned long)__init_begin - (unsigned long)_text, > pgprot_tagged(PAGE_KERNEL_RO)); > > + /* Map the fixmap PTE table at __fixmap_pgdir_start R/O in linear map too */ > + update_mapping_prot(__pa_symbol(__fixmap_pgdir_start), > + (unsigned long)lm_alias(__fixmap_pgdir_start), > + PAGE_SIZE, pgprot_tagged(PAGE_KERNEL_RO)); Is that definitely just one page? > + > remap_linear_data_alias(true); > > if (IS_ENABLED(CONFIG_HIBERNATION)) {