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 AD98B282F1B; Sat, 12 Sep 2026 07:42:43 +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=1789198964; cv=none; b=pSoNjZ1FdRhKKIAEu+6sboR35Nokd0dhgY77cudVDXrfl9AUTVaalWY1NfG6vZcUYH/uF/6u+q2zAWEG3ryhUSzz/Hlk3lUe7QTlVssWeakbZ06fceS8hLtQRFD3IGc1CXf0l4LGFJp39+T/QCx7QWPZa+sisfQeWl1rYPg712E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789198964; c=relaxed/simple; bh=muOewpgMgt0LCUXv0YwUn8235Hv0I2idAlqEIEYOQT4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iXd8KizELLQhV+DTTGFsR0LriRL2IOtueSfsDGnfhgldrpKj4nf0qnrJvpaOWojJEjvP7PRZm2ZGIzuk4pGThvyPkviIB73Bl4va5cNf+8iGixDhvEMLsO1PxIgSra7yxNJohB5xJWQkC4qEy85h02HX9HMfMTHRx2wws4RVr9c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VcRhXR+C; 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="VcRhXR+C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 250E61F000FF; Sat, 12 Sep 2026 07:42:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789198963; bh=cWAbbvCCMZ+HWKOKz9labPqsl3R6ymzpp+pinEhKJn8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VcRhXR+CkWNqjrq7RKw1Qxos6XwegRuLWtnC0DIstX/LiUUN8kLTfM9ylyL1FtxU/ 96sK5Bx1bNCjNoPanmAAAy0FOG+8OBH9aWxdIXLcYzydrHd6g1aA7MnslN5dbei+De dwHxbzWRKYFsrlYs3lmwbsNTWP6GImucFoE7t1Cg= 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 7.2 0487/1815] tty: hvc: restrict HVC_DCC to ARMv6+ and ARM64 Date: Sat, 12 Sep 2026 08:37:17 +0200 Message-ID: <20260912065700.325481856@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065648.999753832@linuxfoundation.org> References: <20260912065648.999753832@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 7.2-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