From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3183F364B7; Fri, 24 Nov 2023 19:16:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1hZa0CKj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89FA0C433C8; Fri, 24 Nov 2023 19:16:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700853411; bh=gRt8z8fXPn57vPiz5t50/Mt7ET4xnTV86bbzNwVT5+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1hZa0CKjUzqK90Tt9mCqeY1gOgwsWw2+SOhxbiO2BHAfULLoCgw8Y2p8UWbYyuFku TM0JCVcnQN3liLLtlw3+KZCzgK3t7GcjVZBpgQkAjgGymFrFaET7bCEXXiF+9wSwzP YTWp0t1aIT76XIDRN7PgedgAZ2hlnXKXh9wrdTpg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Chancellor , Mark Rutland , Catalin Marinas Subject: [PATCH 5.15 177/297] arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM IAS 15.x or newer Date: Fri, 24 Nov 2023 17:53:39 +0000 Message-ID: <20231124172006.447886468@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172000.087816911@linuxfoundation.org> References: <20231124172000.087816911@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nathan Chancellor commit 146a15b873353f8ac28dc281c139ff611a3c4848 upstream. Prior to LLVM 15.0.0, LLVM's integrated assembler would incorrectly byte-swap NOP when compiling for big-endian, and the resulting series of bytes happened to match the encoding of FNMADD S21, S30, S0, S0. This went unnoticed until commit: 34f66c4c4d5518c1 ("arm64: Use a positive cpucap for FP/SIMD") Prior to that commit, the kernel would always enable the use of FPSIMD early in boot when __cpu_setup() initialized CPACR_EL1, and so usage of FNMADD within the kernel was not detected, but could result in the corruption of user or kernel FPSIMD state. After that commit, the instructions happen to trap during boot prior to FPSIMD being detected and enabled, e.g. | Unhandled 64-bit el1h sync exception on CPU0, ESR 0x000000001fe00000 -- ASIMD | CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Hardware name: linux,dummy-virt (DT) | pstate: 400000c9 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : __pi_strcmp+0x1c/0x150 | lr : populate_properties+0xe4/0x254 | sp : ffffd014173d3ad0 | x29: ffffd014173d3af0 x28: fffffbfffddffcb8 x27: 0000000000000000 | x26: 0000000000000058 x25: fffffbfffddfe054 x24: 0000000000000008 | x23: fffffbfffddfe000 x22: fffffbfffddfe000 x21: fffffbfffddfe044 | x20: ffffd014173d3b70 x19: 0000000000000001 x18: 0000000000000005 | x17: 0000000000000010 x16: 0000000000000000 x15: 00000000413e7000 | x14: 0000000000000000 x13: 0000000000001bcc x12: 0000000000000000 | x11: 00000000d00dfeed x10: ffffd414193f2cd0 x9 : 0000000000000000 | x8 : 0101010101010101 x7 : ffffffffffffffc0 x6 : 0000000000000000 | x5 : 0000000000000000 x4 : 0101010101010101 x3 : 000000000000002a | x2 : 0000000000000001 x1 : ffffd014171f2988 x0 : fffffbfffddffcb8 | Kernel panic - not syncing: Unhandled exception | CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0xec/0x108 | show_stack+0x18/0x2c | dump_stack_lvl+0x50/0x68 | dump_stack+0x18/0x24 | panic+0x13c/0x340 | el1t_64_irq_handler+0x0/0x1c | el1_abort+0x0/0x5c | el1h_64_sync+0x64/0x68 | __pi_strcmp+0x1c/0x150 | unflatten_dt_nodes+0x1e8/0x2d8 | __unflatten_device_tree+0x5c/0x15c | unflatten_device_tree+0x38/0x50 | setup_arch+0x164/0x1e0 | start_kernel+0x64/0x38c | __primary_switched+0xbc/0xc4 Restrict CONFIG_CPU_BIG_ENDIAN to a known good assembler, which is either GNU as or LLVM's IAS 15.0.0 and newer, which contains the linked commit. Closes: https://github.com/ClangBuiltLinux/linux/issues/1948 Link: https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c Signed-off-by: Nathan Chancellor Cc: stable@vger.kernel.org Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20231025-disable-arm64-be-ias-b4-llvm-15-v1-1-b25263ed8b23@kernel.org Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/Kconfig | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1153,6 +1153,8 @@ choice config CPU_BIG_ENDIAN bool "Build big-endian kernel" depends on !LD_IS_LLD || LLD_VERSION >= 130000 + # https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c + depends on AS_IS_GNU || AS_VERSION >= 150000 help Say Y if you plan on running a kernel with a big-endian userspace.