From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A44C4A35; Sat, 12 Sep 2026 19:49:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789242593; cv=none; b=t7odh5VG/hshPEbFEShVIMNXOWUZoVoVeNZ9RlE5D4W+RGpbeK1Wrkh7CKQvjLHd366RGE8S2971AkYvwBYYeU52Nlh5w3BzgL/plLXeyegI+Zg5Rt59B/ow7XDg3MWRqhHMhCB55PFR6FbC/u+wgQHSwRqQeA0oqjGncZssn/A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789242593; c=relaxed/simple; bh=q5yjQPmZSB6oxGU1RKNTaR29+bZswR4L9eOjyBcAkLk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=d+3oqH05gY0juvj9ZwlXBsD4N8o1XanbahD9y+VWkcoZE0rpYDPqJw+i6BAlHSX39qth0l6nZ3OygPCj+7EV5lpNxfJjTrlyu7muepJD855MBqI8mzIsDjFpgs5KBRl7N7UJaxBpXRIv+qwZaqiJqUaSnUvkXRp4+5t9VVYnR8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jhCWI947; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jhCWI947" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A500D1F000FF; Sat, 12 Sep 2026 19:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789242592; bh=cjI7JtgIFuV388QvKT8zFR3xm9E6yN+EauQBbKLmm2s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jhCWI9470avHdUp+BGxWCyKCvyJVc8y5++GzUSAE1E7cEnSROSZEHvbZw/GCXgMkC beVkX5/XGD9GHnWGZR7LH2fwWZadQXZ8hHCwwGsaB38BVh0S9NGr/JSlomeRkujXLO iKu3Kjr9gbbCzdQ0XexKk60ExscaRF6x04YRj3uQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Arnd Bergmann , Sasha Levin Subject: [PATCH 5.10 457/798] tty: hvc: restrict HVC_DCC to ARMv6+ and ARM64 Date: Sat, 12 Sep 2026 09:01:25 +0200 Message-ID: <20260912065527.620786772@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065516.948645775@linuxfoundation.org> References: <20260912065516.948645775@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Karl Mehltretter [ Upstream commit 782f4dbd1794b4f30dc116a7ca42c5962c409be8 ] hvc_dcc drives the JTAG DCC via the ARMv6/v7 CP14 debug registers (mrc/mcr p14, 0, rX, c0, c1/c5, 0 in asm/dcc.h). That encoding is undefined on older ARM cores, and also on ARMv7-M, but HVC_DCC only depends on ARM, so it can be enabled on e.g. ARM926 (ARCH_MULTI_V5), where hvc_dcc_console_init() runs __dcc_putchar() at boot and takes an undefined-instruction trap before the console is up: Internal error: Oops - undefined instruction: 0 [#1] ARM PC is at hvc_dcc_check+0x50/0x8c hvc_dcc_check from hvc_dcc_console_init+0x18/0x48 hvc_dcc_console_init from console_init+0x58/0x170 Kernel panic - not syncing: Fatal exception Restrict HVC_DCC to the CPUs where that encoding is valid: the CPU_V6 || CPU_V6K || CPU_V7 set that arch/arm/include/debug/icedcc.S guards it with, plus ARM64. Fixes: 16c63f8ea49c ("drivers: char: hvc: add arm JTAG DCC console support") Signed-off-by: Karl Mehltretter Reviewed-by: Arnd Bergmann Link: https://patch.msgid.link/20260717071616.91423-1-kmehltretter@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/hvc/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig index 8d60e0ff67b4d..85259a4b6700f 100644 --- a/drivers/tty/hvc/Kconfig +++ b/drivers/tty/hvc/Kconfig @@ -79,7 +79,7 @@ config HVC_UDBG config HVC_DCC bool "ARM JTAG DCC console" - depends on ARM || ARM64 + depends on (ARM && (CPU_V6 || CPU_V6K || CPU_V7)) || ARM64 select HVC_DRIVER select SERIAL_CORE_CONSOLE help -- 2.53.0