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 8D36332B126; Sat, 12 Sep 2026 18:50:36 +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=1789239037; cv=none; b=RdMzcpdkTyTWzKm2xlX72Sln5qreEEBN99Ktt19inuJ33i2MjsZ3KuImnQ7xubVAFZwdXLvkV2zZr6Hu3mE9W3b2Q9fxXejoEH0GO/4RASIRDCFJtuxAQxz9r+jVnQmX2FSpAyp2cHw3AL8OGxndnf3AqYB7E/inUwKQwc/kBY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789239037; c=relaxed/simple; bh=QAca1+aLG/qhPB1GkGZE1jtip0b1yE/2NZOxip0zhXI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BJmx7NDg0M5QryY89GFPW6R+3M53w8QRXPjgnq9Wslcyzj5ViOpH1Fn29eL4qj4kazlNUnuNq7zUS4isZZgrEzWZuBI0x3aiMa2D3q7B8YDG3uAtcBrxvsQelu5D8Mc1GCJVOTE+IeXHWcF6FYnHPBx0ZGTm6lTyhIelZoEk+ek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1HWPGEMG; 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="1HWPGEMG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 605321F000FF; Sat, 12 Sep 2026 18:50:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789239036; bh=rtE5yY7mTLCKwxVVWNt8iro1TUroqRqNJBA1MN9zI9g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1HWPGEMGW+/Zy8qDo+xdttCeKApdFN4GiXCgl252Xy27otquJYGv5aXTW5gs3AMpk hwY1/TombKE4VVznL69ps+pou4kPc94gkflgYDEBKsgyEkoWZKOvXKE/x6tKtT9uZu eD5pCYG5NclbmoDKvotF3vMWX8aIPVwmz36wl97U= 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 5.15 540/935] tty: hvc: restrict HVC_DCC to ARMv6+ and ARM64 Date: Sat, 12 Sep 2026 08:59:30 +0200 Message-ID: <20260912065539.209644695@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-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