From patchwork Thu Jan 9 16:54:17 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Fainelli X-Patchwork-Id: 13932986 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 24EFAE77199 for ; Thu, 9 Jan 2025 16:55:59 +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: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=q8mSLMBktMbzDleBxc69wxcwOxXrMut2APraWinG8Yc=; b=UkeKiYyKEA5UFsrBq50j2mHwUH UpPKvWwTxY24W5IL/wk//udWFfEvkhiuCmS1ybTxmMlmexGKtD2W4qv4P8kf+UKPYfXVdK9kjhRM3 zL3K6KZ1M42YB9ExoS77yhjK5DbyjYfJ5ytzqrRY+nSFQlvEOCejSNqDRamUfY4VqT6RiD9Y8Q9mG w8IUjBNcKIJPe3ShB/V1JAScO2nfziz3u5n9d43qrF9jFwCr1ac4oOzEGWSl0N0CVQuxZ+vh76aum NP23os/1eqlxPCVWRFbF25FzzgxZ5oQtvk2pcWOnLMPbUps6GFCbrQs5ztDB0h2NSXX7QLvQk9w/9 M3DHdtqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVvos-0000000Cl3l-35Re; Thu, 09 Jan 2025 16:55:42 +0000 Received: from relay.smtp-ext.broadcom.com ([192.19.144.207]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVvne-0000000Ckqb-21yI for linux-arm-kernel@lists.infradead.org; Thu, 09 Jan 2025 16:54:28 +0000 Received: from mail-lvn-it-01.lvn.broadcom.net (mail-lvn-it-01.lvn.broadcom.net [10.36.132.253]) by relay.smtp-ext.broadcom.com (Postfix) with ESMTP id A74E0C003ACE; Thu, 9 Jan 2025 08:54:23 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 relay.smtp-ext.broadcom.com A74E0C003ACE DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=broadcom.com; s=dkimrelay; t=1736441663; bh=gDEC6eC+hE/3rES1P+/GSapucTV+adxfwsIx2MfNOTE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GafJDr1M7LLL8Re1WOBG//t/CK5O5LXkj23wghl1l1b2R3G0f2PhuavAuM1HotAKR nEgGHP2iSD8mzeWz7oP7acYTGpe3VPk3voOV6b/h3DgwjQbZ+JvXYu+bJmEuAVazrj ud2oKTCWavkpWEmmikeDeoyTHRAWFohBeAmh1Xuc= Received: from fainelli-desktop.igp.broadcom.net (fainelli-desktop.dhcp.broadcom.net [10.67.48.245]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail-lvn-it-01.lvn.broadcom.net (Postfix) with ESMTPSA id 3F51018041CAC6; Thu, 9 Jan 2025 08:54:23 -0800 (PST) From: Florian Fainelli To: stable@vger.kernel.org Cc: Ard Biesheuvel , Anshuman Khandual , Will Deacon , Steven Price , Robin Murphy , Catalin Marinas , Florian Fainelli , Baruch Siach , Petr Tesarik , Mark Rutland , Joey Gouly , "Mike Rapoport (IBM)" , Yang Shi , linux-arm-kernel@lists.infradead.org (moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] arm64: mm: account for hotplug memory when randomizing the linear region Date: Thu, 9 Jan 2025 08:54:17 -0800 Message-ID: <20250109165419.1623683-2-florian.fainelli@broadcom.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250109165419.1623683-1-florian.fainelli@broadcom.com> References: <20250109165419.1623683-1-florian.fainelli@broadcom.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250109_085426_799703_F85F1C6D X-CRM114-Status: GOOD ( 18.18 ) 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 From: Ard Biesheuvel commit 97d6786e0669daa5c2f2d07a057f574e849dfd3e upstream As a hardening measure, we currently randomize the placement of physical memory inside the linear region when KASLR is in effect. Since the random offset at which to place the available physical memory inside the linear region is chosen early at boot, it is based on the memblock description of memory, which does not cover hotplug memory. The consequence of this is that the randomization offset may be chosen such that any hotplugged memory located above memblock_end_of_DRAM() that appears later is pushed off the end of the linear region, where it cannot be accessed. So let's limit this randomization of the linear region to ensure that this can no longer happen, by using the CPU's addressable PA range instead. As it is guaranteed that no hotpluggable memory will appear that falls outside of that range, we can safely put this PA range sized window anywhere in the linear region. Signed-off-by: Ard Biesheuvel Cc: Anshuman Khandual Cc: Will Deacon Cc: Steven Price Cc: Robin Murphy Link: https://lore.kernel.org/r/20201014081857.3288-1-ardb@kernel.org Signed-off-by: Catalin Marinas Signed-off-by: Florian Fainelli --- arch/arm64/mm/init.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 80cc79760e8e..09c219aa9d78 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -401,15 +401,18 @@ void __init arm64_memblock_init(void) if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { extern u16 memstart_offset_seed; - u64 range = linear_region_size - - (memblock_end_of_DRAM() - memblock_start_of_DRAM()); + u64 mmfr0 = read_cpuid(ID_AA64MMFR0_EL1); + int parange = cpuid_feature_extract_unsigned_field( + mmfr0, ID_AA64MMFR0_PARANGE_SHIFT); + s64 range = linear_region_size - + BIT(id_aa64mmfr0_parange_to_phys_shift(parange)); /* * If the size of the linear region exceeds, by a sufficient - * margin, the size of the region that the available physical - * memory spans, randomize the linear region as well. + * margin, the size of the region that the physical memory can + * span, randomize the linear region as well. */ - if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) { + if (memstart_offset_seed > 0 && range >= (s64)ARM64_MEMSTART_ALIGN) { range /= ARM64_MEMSTART_ALIGN; memstart_addr -= ARM64_MEMSTART_ALIGN * ((range * memstart_offset_seed) >> 16);