From patchwork Tue Jul 28 10:06:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: WANG Xuerui X-Patchwork-Id: 11688833 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6A50913B6 for ; Tue, 28 Jul 2020 10:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4928620829 for ; Tue, 28 Jul 2020 10:07:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=xen0n.name header.i=@xen0n.name header.b="YxSOTBQB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728509AbgG1KHG (ORCPT ); Tue, 28 Jul 2020 06:07:06 -0400 Received: from [115.28.160.31] ([115.28.160.31]:57930 "EHLO mailbox.box.xen0n.name" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1728439AbgG1KHF (ORCPT ); Tue, 28 Jul 2020 06:07:05 -0400 Received: from ld50.lan (unknown [140.207.23.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mailbox.box.xen0n.name (Postfix) with ESMTPSA id 14BE660130; Tue, 28 Jul 2020 18:06:58 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=xen0n.name; s=mail; t=1595930818; bh=+eJkWelUGZtHbJQIpbNZhwtqQn98rWLv07lIHN6A55M=; h=From:To:Cc:Subject:Date:From; b=YxSOTBQB2TpJx5lwXb4fQAp1AcpmYQl6a2o1u+ep8ro88omuYaX6u7vHJA8LzEI2G 0l/LPkpIIaQL72doMSK41ue1DWz3f7IU9Rf7cJ/PG15xp0jpv8PiLg/ETkfuy9wjCL NVb+7o0S8BofbZ/McZQ/n9pRJENHwwt8II5lgzo4= From: WANG Xuerui To: linux-mips@vger.kernel.org Cc: WANG Xuerui Subject: [PATCH v4 0/3] Refactor FTLBPar exception handling and add GSExc handler Date: Tue, 28 Jul 2020 18:06:52 +0800 Message-Id: <20200728100655.3005831-1-git@xen0n.name> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org It was found that some undocumented unprivileged instructions could crash the kernel with a "FTLB parity error" on Loongson-3A4000, but the error registers were garbage: [ 896.970419] FTLB error exception, cp0_ecc=0x00000002: [ 896.975446] cp0_errorepc == ffffffffffffffff [ 896.979755] c0_cacheerr == 00000000 [ 896.983277] Decoded c0_cacheerr: primary cache fault in insn reference. [ 896.989963] Cache error exception: [ 896.993396] cp0_errorepc == ffffffffffffffff [ 896.997707] c0_cacheerr == 00000000 [ 897.001228] Decoded c0_cacheerr: primary cache fault in insn reference. [ 897.007916] Error bits: [ 897.010467] IDX: 0x00000000 [ 897.013284] Kernel panic - not syncing: Can't handle the cache error! [ 897.019807] ---[ end Kernel panic - not syncing: Can't handle the cache error! ]--- Turns out the FTLBPar exception code is actually implementation-specific. On Loongson cores the exception is "GSExc" instead, and is non-fatal in Loongson's linux-3.10 fork. So we dynamically register the correct handler for the exception, and do not panic on the specific undocumented case. P.S. There is not much space left in the cpuinfo_mips.options flag. We should consider moving to something like x86's feature flags that is extensible. v4: - Added Reviewed-by tags from Huacai - Dropped bouncing Cc addresses from the first patch - Fixed "MFC0" -> "mfc0" in genex.S, as that CP0 register is 32-bit according to Loongson's manuals v3: - Simplified declaration of cpu_has_gsexcex, as suggested by Huacai v2: - Removed stray GSExc logic in cpu_probe_legacy, pointed out by Huacai WANG Xuerui (3): MIPS: only register FTLBPar exception handler for supported models MIPS: add definitions for Loongson-specific CP0.Diag1 register MIPS: handle Loongson-specific GSExc exception arch/mips/include/asm/cpu-features.h | 8 ++++++ arch/mips/include/asm/cpu.h | 2 ++ arch/mips/include/asm/mipsregs.h | 11 ++++++++ arch/mips/kernel/cpu-probe.c | 16 ++++++++++++ arch/mips/kernel/genex.S | 7 +++++ arch/mips/kernel/traps.c | 38 +++++++++++++++++++++++++++- 6 files changed, 81 insertions(+), 1 deletion(-)