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 A5BE8FF8867 for ; Wed, 29 Apr 2026 13:51:55 +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=zqk/vbnimW0wuDYnJIfvubH6gxgbLhYzeZKE1huaELw=; b=oWSW3TFlvLspZamOS/P8/45PP/ Zx0yep2z1WIWs7pSGR2lEqDAcmq5MxfBygQ+84rssEhWdTCOfvGhbV6iasVdT5C/CJoRDFox/Ylh2 1MOvu5sSiTWtQYkS/iDTMUodVnqh9XauzOIjDp5lABCekD9LLFUQG2PM7O2kJm8Wk/BglVYG7YKwJ ZOo3Qrieo+CgF4kOU0v4sZA2Nz855Faxtobtup3eWXWB16ddP0eXyHxwI9Ypk6Qfn+dQBcIEChuF3 fMZQXnlJ4zjacf+spYOACVurIGrvL3jjnYW4ynGZwxReeiT2R0EoDGwEMRAvE73SRbL/KPVp+jgp8 SmMymxeA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wI5KO-00000003hee-2doe; Wed, 29 Apr 2026 13:51:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wI5KM-00000003he8-3qD6 for linux-arm-kernel@lists.infradead.org; Wed, 29 Apr 2026 13:51:48 +0000 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 45D0E2574; Wed, 29 Apr 2026 06:51:39 -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 88EC53F62B; Wed, 29 Apr 2026 06:51:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1777470704; bh=9ELD/DjcFqzDnlav/KpHjVLh1+VYuwo61V/4bESQjnU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gX6jMWWvzRfAvmOAyHfw3oN8bG5OkDuYdKN3FuWWM6nhaa2QUnNyeU/dyUa3NlDBi VXs6MpNaq7hopQBIK1wh64NZPzPhrdUFDqsIC1BKYJuqTwtkmHUbCfAApjLUnpBUHb gwlcI8mEEm00HYzB+UqwukBUQ6gsicOZH89qCdnE= Message-ID: <8a315ca2-3754-4a66-990e-55b85191aa6e@arm.com> Date: Wed, 29 Apr 2026 12:54:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 11/15] arm64: mm: Don't abuse memblock NOMAP to check for overlaps 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> <20260427153416.2103979-28-ardb+git@google.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20260427153416.2103979-28-ardb+git@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260429_065147_099057_30E411FF X-CRM114-Status: GOOD ( 22.08 ) 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 27/04/2026 17:34, Ard Biesheuvel wrote: > From: Ard Biesheuvel > > Now that the DRAM mapping routines respect existing table mappings and > contiguous block and page mappings, it is no longer needed to fiddle > with the memblock tables to set and clear the NOMAP attribute in order > to omit text and rodata when creating the linear map. > > Instead, map the kernel text and rodata alias first with the desired > attributes, so that they will not be remapped later with different > attributes when mapping the memblocks. > > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/mm/mmu.c | 24 +++++++------------- > 1 file changed, 8 insertions(+), 16 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 5e2348b15783..1a4b4337d29a 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1148,12 +1148,15 @@ static void __init map_mem(void) > flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; > > /* > - * Take care not to create a writable alias for the > - * read-only text and rodata sections of the kernel image. > - * So temporarily mark them as NOMAP to skip mappings in > - * the following for-loop > + * Map the linear alias of the [_text, __init_begin) interval > + * as non-executable now, and remove the write permission in > + * mark_linear_text_alias_ro() above (which will be called after > + * alternative patching has completed). This makes the contents > + * of the region accessible to subsystems such as hibernate, > + * but protects it from inadvertent modification or execution. > */ > - memblock_mark_nomap(kernel_start, kernel_end - kernel_start); > + __map_memblock(kernel_start, kernel_end, pgprot_tagged(PAGE_KERNEL), Is it now necessary for that mapping to be tagged? If so, it should probably be called out in the commit message. - Kevin > + flags); > > /* map all the memory banks */ > for_each_mem_range(i, &start, &end) { > @@ -1165,17 +1168,6 @@ static void __init map_mem(void) > __map_memblock(start, end, pgprot_tagged(PAGE_KERNEL), > flags); > } > - > - /* > - * Map the linear alias of the [_text, __init_begin) interval > - * as non-executable now, and remove the write permission in > - * mark_linear_text_alias_ro() below (which will be called after > - * alternative patching has completed). This makes the contents > - * of the region accessible to subsystems such as hibernate, > - * but protects it from inadvertent modification or execution. > - */ > - __map_memblock(kernel_start, kernel_end, PAGE_KERNEL, 0); > - memblock_clear_nomap(kernel_start, kernel_end - kernel_start); > } > > void mark_rodata_ro(void)