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 5BA8347B437; Sat, 12 Sep 2026 12:20:50 +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=1789215652; cv=none; b=goIjSXdQN21EZCNDI0oBloxSWLKaFbwQUenAjBEhNMPU469mv9d7s6zanqk70ih72vzWUybliPp4poCU/BrUdhwxeVF8XUgntijUq2Q4eTAkuJAamr055sVhSQ5eLWen1hFvLLwHAmbj0Mypd45BV0N32Rgu8z1nNoVFmrzxyas= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789215652; c=relaxed/simple; bh=Ab2t4j01oDBkMTzWwTjW+L3vsAW9+NmW0gjFDCh3kJM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TqVO3tiG9d9i+jz/NwoVkTn9sjcxtIK4ewFarK/ay/H3VQq/4BysCZnKKCmbysYX9j6aXHDCzTefnuU/aINwed4b16kpsFrAsng0AGP1N6+SEyNNmFl7GELQuV21zWRriytkyUy4MjYVnQTuFii6H/ggOP2gKsaSpk2ZnG11Wag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oPKHOXv2; 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="oPKHOXv2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B45631F000FF; Sat, 12 Sep 2026 12:20:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789215649; bh=X1WAkt6r0E3dHH+sY3L0bAjHhLvE2yUnqlQQtmHZENM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oPKHOXv2weCDdODgGDMAZ1W3673n1oLIa6qGYbOks5UalSH7jEqba/G4OVf9KY9VO UuRV7dqeRJtjrS66rk3kqNq0AfgsOqzmowAZViC6FtwPNwECCz3jh4sKIlJ6mgtuVV pwlJQeh8QIY8ao1ag82mZNVMYvWfb0IJ6QWwoxY4= 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 6.12 0576/1376] tty: hvc: restrict HVC_DCC to ARMv6+ and ARM64 Date: Sat, 12 Sep 2026 08:50:02 +0200 Message-ID: <20260912065620.368291134@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-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 c2a4e88b328f3..5866195de26a6 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