From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f228.google.com (mail-pl1-f228.google.com [209.85.214.228]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 154972673B0 for ; Mon, 25 May 2026 18:15:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.228 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779732929; cv=none; b=Kbgjg+woFnt0wrJTIULz0wz1iLdQWadfsIZamuTrREiJCo5ZjWqleEH4GSZDNkUodqOBUr8JfXxhoEUQqmLWi9x6z1k9AkGdokcQ/pl2sN/J2F7hcjNmbm0FIK0wiKkjsbTfT2GiCI6e3AohJ2pNZacPyOuPLNDtRRSe1JDnsgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779732929; c=relaxed/simple; bh=ojgaLqoyWLyyLbT7+5c3O1Lr3mB3c/f12bJW2gQ+ALQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CcTJfGm0WP3JR3vvk72iQBKGXJoLCa38xUsN+MXyR/2Q8mzxkWdvzVlMGfRzdW+tF2EVyubovMiV7+TGqvkDrErsD96HDM8Wp8EFduRqpRN2Bf8EGMOi6C+DGoieiBbrGunmqUFWTOJfG8HE3hw/91/hjgdafrJg0JoylEO8vxY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=broadcom.com; spf=fail smtp.mailfrom=broadcom.com; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b=cSBM9tlI; arc=none smtp.client-ip=209.85.214.228 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=broadcom.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=broadcom.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="cSBM9tlI" Received: by mail-pl1-f228.google.com with SMTP id d9443c01a7336-2ba4efedbeaso74270175ad.1 for ; Mon, 25 May 2026 11:15:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779732927; x=1780337727; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:dkim-signature:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=yjbdeHMBEOSMPFX+Z3uePz1MMNxDwCdB8xF7r1cvcC4=; b=qmc4tpaZ3aT+CwzDeQcahLX8tJhAJIuxCn/iBUHIZUpC05KftnW6CJJJofE7kdAllm sHc5MhB4YdLvI6L1SR8YSHwtgimK1NpUDIRZVtOs9sh9l4fu5SfS6JCKAvEmK/FWXwVQ JbrxKYkTqd2drKenRjcCKHn205WCboh82TR91DIoFtEv5664Us0iYhSoB13tCb9q4L1N ybjUiJDprRK8Uw5Z1S+/+rcO4Q7rk7AnPKCQjOx1ALbNvfTUiCXKCt7vb1oWRXNQ9RHV 1J58p3s8aV0e4UCZJHLB1VSgSvVEy+QgcPt/tdiS7W/1+mnmOK/RzVZ8ttP2yGrUZE6t 8URQ== X-Forwarded-Encrypted: i=1; AFNElJ+1exTxMzbYNOYfzifgmOOLVT7+7B06+e3dGbP6uPCBy7knDNfw0VWZF69EensOrfrQpRkv5zcYJNGpZNE=@vger.kernel.org X-Gm-Message-State: AOJu0YwC9lwCjPvI0RoemIwjpAtz0W0wUHswhFXdrNzWBb8/R+7BoUNF rF6TzS9QtfSFEYayMRp++OVZxnZ7bP5Gw5xd6LE4D00NeMuW/sAFsJfZYuEc6fPdmvl4LLK1+Qk lmovLQMAu30PeYkZRQ1yR0hA4dLfM+IfVujpTR/l8+pZpvVVmN6hTxiuCFrb1YiLLAGG+aIsNu1 l8cdywDjH3AkQO7IdGtIRzTkO4npmG23c6kseDX0fHqDAQNoqJX9j9NpnXHj+7moiyeNZREhH1u 0iYywKv1WmurL6kFDCQX2GE X-Gm-Gg: Acq92OHL7FN1onig4JPweIHo6G19rnT0mnRZHtAWGqzQfC+3JIGqobVfCaoJVIXRB1Q eurwBD10sSObERN+AO8Rbr8txA2gtWCYjfzT1Pn28mhAfDN+HiZqs8apOslu7I4azCpIZ0HnAM7 jjnLs+qFqsPGRWRpy9JTHJEbPKaa7WF7/qx8w04lhc3+v0jR+48eoaQvGf3y6VkUdKbF6vN913G uPuibS92O3JDkA8RzXSVcAMYOYTOSD1bulOz09SEJ/4JZzZMAfRo+g2vDJt2S9qDF2KKK5KBo2u 6g9d/4iIPf+XzJZtGBbRzGeRs0HsknsVxxI8CEVhPcbzW6fwvG190Ok+IaaJKDODkzvkhHOHiNz Osf+s++xbPlnipUMyDna9XR2Tf8i4slf+0Yg5iC7cK3V1yqHEWZT9F2T7Zbs+KlnnyBa69Jrem5 8xO96utlPynK+8PPhLJGoHlvV8P/XbX8HO5EwOZT9zx9BUieZ3XNQ3ciTfndej856B X-Received: by 2002:a17:903:1cc:b0:2b0:a980:3687 with SMTP id d9443c01a7336-2beb038f559mr171126195ad.3.1779732927308; Mon, 25 May 2026 11:15:27 -0700 (PDT) Received: from smtp-us-east1-p01-i01-si01.dlp.protect.broadcom.com (address-144-49-247-117.dlp.protect.broadcom.com. [144.49.247.117]) by smtp-relay.gmail.com with ESMTPS id d9443c01a7336-2beb55946f1sm8964065ad.7.2026.05.25.11.15.26 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 May 2026 11:15:27 -0700 (PDT) X-Relaying-Domain: broadcom.com X-CFilter-Loop: Reflected Received: by mail-dy1-f200.google.com with SMTP id 5a478bee46e88-304627c66ddso2002938eec.0 for ; Mon, 25 May 2026 11:15:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1779732925; x=1780337725; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=yjbdeHMBEOSMPFX+Z3uePz1MMNxDwCdB8xF7r1cvcC4=; b=cSBM9tlILronNx1b6JrRXF2B1u8YClp6qUvORAZ2WK7MN5VJJNxCiw4T27eEsYPWO6 K43ImbXjnEeMV6kvn+gFKNETHCAcKFgXdqlh9Km8+v4wPhFOJXK3QxQKLzrbIEZ1sCCI yjVZUnjsr1lXymKDNO3zxSHdSWoxGN+OPv+V8= X-Forwarded-Encrypted: i=1; AFNElJ/mcDQD3ZLuYsLiwyGQdXXorUdeE7zPcON3wOnxhzmbrdqA60EHv66a8mPBfLmhYbCugeEG3AYP7phrkEg=@vger.kernel.org X-Received: by 2002:a05:693c:68cc:b0:304:5a9c:6452 with SMTP id 5a478bee46e88-3045a9c6cd5mr4157851eec.17.1779732924958; Mon, 25 May 2026 11:15:24 -0700 (PDT) X-Received: by 2002:a05:693c:68cc:b0:304:5a9c:6452 with SMTP id 5a478bee46e88-3045a9c6cd5mr4157826eec.17.1779732924127; Mon, 25 May 2026 11:15:24 -0700 (PDT) Received: from [192.168.1.3] (ip68-4-215-93.oc.oc.cox.net. [68.4.215.93]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30451f3feadsm10921365eec.13.2026.05.25.11.15.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 May 2026 11:15:23 -0700 (PDT) Message-ID: <724e103e-ebc2-403c-887e-d91e403754d9@broadcom.com> Date: Mon, 25 May 2026 11:15:20 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ARM: mm: fix kexec and hibernation with CONFIG_CPU_TTBR0_PAN To: Linus Walleij Cc: linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, Catalin Marinas , Linus Walleij , Russell King , "Russell King (Oracle)" , Kees Cook , open list References: <20260523000839.430550-1-florian.fainelli@broadcom.com> Content-Language: en-US From: Florian Fainelli Autocrypt: addr=florian.fainelli@broadcom.com; keydata= xsBNBFPAG8ABCAC3EO02urEwipgbUNJ1r6oI2Vr/+uE389lSEShN2PmL3MVnzhViSAtrYxeT M0Txqn1tOWoIc4QUl6Ggqf5KP6FoRkCrgMMTnUAINsINYXK+3OLe7HjP10h2jDRX4Ajs4Ghs JrZOBru6rH0YrgAhr6O5gG7NE1jhly+EsOa2MpwOiXO4DE/YKZGuVe6Bh87WqmILs9KvnNrQ PcycQnYKTVpqE95d4M824M5cuRB6D1GrYovCsjA9uxo22kPdOoQRAu5gBBn3AdtALFyQj9DQ KQuc39/i/Kt6XLZ/RsBc6qLs+p+JnEuPJngTSfWvzGjpx0nkwCMi4yBb+xk7Hki4kEslABEB AAHNMEZsb3JpYW4gRmFpbmVsbGkgPGZsb3JpYW4uZmFpbmVsbGlAYnJvYWRjb20uY29tPsLB IQQQAQgAywUCZWl41AUJI+Jo+hcKAAG/SMv+fS3xUQWa0NryPuoRGjsA3SAUAAAAAAAWAAFr ZXktdXNhZ2UtbWFza0BwZ3AuY29tjDAUgAAAAAAgAAdwcmVmZXJyZWQtZW1haWwtZW5jb2Rp bmdAcGdwLmNvbXBncG1pbWUICwkIBwMCAQoFF4AAAAAZGGxkYXA6Ly9rZXlzLmJyb2FkY29t Lm5ldAUbAwAAAAMWAgEFHgEAAAAEFQgJChYhBNXZKpfnkVze1+R8aIExtcQpvGagAAoJEIEx tcQpvGagWPEH/2l0DNr9QkTwJUxOoP9wgHfmVhqc0ZlDsBFv91I3BbhGKI5UATbipKNqG13Z TsBrJHcrnCqnTRS+8n9/myOF0ng2A4YT0EJnayzHugXm+hrkO5O9UEPJ8a+0553VqyoFhHqA zjxj8fUu1px5cbb4R9G4UAySqyeLLeqnYLCKb4+GklGSBGsLMYvLmIDNYlkhMdnnzsSUAS61 WJYW6jjnzMwuKJ0ZHv7xZvSHyhIsFRiYiEs44kiYjbUUMcXor/uLEuTIazGrE3MahuGdjpT2 IOjoMiTsbMc0yfhHp6G/2E769oDXMVxCCbMVpA+LUtVIQEA+8Zr6mX0Yk4nDS7OiBlvOwE0E U8AbwQEIAKxr71oqe+0+MYCc7WafWEcpQHFUwvYLcdBoOnmJPxDwDRpvU5LhqSPvk/yJdh9k 4xUDQu3rm1qIW2I9Puk5n/Jz/lZsqGw8T13DKyu8eMcvaA/irm9lX9El27DPHy/0qsxmxVmU pu9y9S+BmaMb2CM9IuyxMWEl9ruWFS2jAWh/R8CrdnL6+zLk60R7XGzmSJqF09vYNlJ6Bdbs MWDXkYWWP5Ub1ZJGNJQ4qT7g8IN0qXxzLQsmz6tbgLMEHYBGx80bBF8AkdThd6SLhreCN7Uh IR/5NXGqotAZao2xlDpJLuOMQtoH9WVNuuxQQZHVd8if+yp6yRJ5DAmIUt5CCPcAEQEAAcLB gQQYAQIBKwUCU8AbwgUbDAAAAMBdIAQZAQgABgUCU8AbwQAKCRCTYAaomC8PVQ0VCACWk3n+ obFABEp5Rg6Qvspi9kWXcwCcfZV41OIYWhXMoc57ssjCand5noZi8bKg0bxw4qsg+9cNgZ3P N/DFWcNKcAT3Z2/4fTnJqdJS//YcEhlr8uGs+ZWFcqAPbteFCM4dGDRruo69IrHfyyQGx16s CcFlrN8vD066RKevFepb/ml7eYEdN5SRALyEdQMKeCSf3mectdoECEqdF/MWpfWIYQ1hEfdm C2Kztm+h3Nkt9ZQLqc3wsPJZmbD9T0c9Rphfypgw/SfTf2/CHoYVkKqwUIzI59itl5Lze+R5 wDByhWHx2Ud2R7SudmT9XK1e0x7W7a5z11Q6vrzuED5nQvkhAAoJEIExtcQpvGagugcIAJd5 EYe6KM6Y6RvI6TvHp+QgbU5dxvjqSiSvam0Ms3QrLidCtantcGT2Wz/2PlbZqkoJxMQc40rb fXa4xQSvJYj0GWpadrDJUvUu3LEsunDCxdWrmbmwGRKqZraV2oG7YEddmDqOe0Xm/NxeSobc MIlnaE6V0U8f5zNHB7Y46yJjjYT/Ds1TJo3pvwevDWPvv6rdBeV07D9s43frUS6xYd1uFxHC 7dZYWJjZmyUf5evr1W1gCgwLXG0PEi9n3qmz1lelQ8lSocmvxBKtMbX/OKhAfuP/iIwnTsww 95A2SaPiQZA51NywV8OFgsN0ITl2PlZ4Tp9hHERDe6nQCsNI/Us= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e On 5/25/2026 6:35 AM, Linus Walleij wrote: > Hi Florian, > > thanks for digging in and finding this! > > On Sat, May 23, 2026 at 2:08 AM Florian Fainelli > wrote: > >> Commit 7af5b901e847 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 >> page table walks disablement") implemented PAN for LPAE kernels by >> setting TTBCR.EPD0 on every kernel entry, disabling TTBR0 page-table >> walks while running in kernel mode. The commit correctly updated >> cpu_suspend() in arch/arm/kernel/suspend.c, but missed two other code >> paths that switch the CPU to the identity mapping before jumping to >> low-PA (TTBR0-range) physical addresses: >> >> 1. setup_mm_for_reboot() in arch/arm/mm/idmap.c, used by the kexec >> reboot path. With TTBCR.EPD0 still set, the subsequent branch to >> the identity-mapped cpu_v7_reset causes a PrefetchAbort because the >> TTBR0 page-table walk needed to resolve the identity-mapped address >> is disabled. This manifests as a hard hang or "bad PC value" panic >> on LPAE kernels booted on CPUs that strictly enforce EPD0 for >> instruction fetch (e.g. Cortex-A53 in AArch32 mode) while the same >> image may accidentally work on Cortex-A15 due to microarchitectural >> differences in EPD0 enforcement. >> >> 2. arch_restore_image() in arch/arm/kernel/hibernate.c, which calls >> cpu_switch_mm(idmap_pgd, &init_mm) directly without going through >> setup_mm_for_reboot(), leaving TTBCR.EPD0 set while the identity >> mapping is active. >> >> Fix both sites by calling uaccess_save_and_enable() before switching >> to the identity mapping, mirroring what the original commit did for >> cpu_suspend(). >> >> Fixes: 7af5b901e847 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") >> Cc: Catalin Marinas >> Cc: Linus Walleij >> Assisted-by: Cursor:claude-sonnet-4.6 >> Signed-off-by: Florian Fainelli > > Reviewed-by: Linus Walleij > > Please put this patch into Russell's patch tracker. Thank you, now done: https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9476/1 -- Florian