From patchwork Mon Dec 7 16:30:14 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 57805 Delivered-To: patch@linaro.org Received: by 10.112.147.194 with SMTP id tm2csp1256216lbb; Mon, 7 Dec 2015 08:32:24 -0800 (PST) X-Received: by 10.98.42.148 with SMTP id q142mr45577782pfq.0.1449505944013; Mon, 07 Dec 2015 08:32:24 -0800 (PST) Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id tm10si2932461pac.203.2015.12.07.08.32.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Dec 2015 08:32:23 -0800 (PST) Received-SPF: pass (google.com: domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) client-ip=2001:1868:205::9; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) smtp.mailfrom=linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a5ygc-0004BD-Sb; Mon, 07 Dec 2015 16:30:50 +0000 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a5ygY-0003sw-DD for linux-arm-kernel@lists.infradead.org; Mon, 07 Dec 2015 16:30:48 +0000 Received: from edgewater-inn.cambridge.arm.com (edgewater-inn.cambridge.arm.com [10.1.203.29]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id tB7GUNWr016745; Mon, 7 Dec 2015 16:30:23 GMT Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 9B5251AE48B6; Mon, 7 Dec 2015 16:30:29 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH] arm64: Documentation: add list of software workarounds for errata Date: Mon, 7 Dec 2015 16:30:14 +0000 Message-Id: <1449505814-30096-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151207_083046_887446_8E5D9AC1 X-CRM114-Status: GOOD ( 13.89 ) X-Spam-Score: -6.9 (------) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-6.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [217.140.96.50 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: catalin.marinas@arm.com, Will Deacon MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org It's not immediately obvious which hardware errata are worked around in the Linux kernel for an arbitrary kernel tree, so add a file to keep track of what we're working around. Signed-off-by: Will Deacon --- Documentation/arm64/silicon-errata.txt | 58 ++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 Documentation/arm64/silicon-errata.txt -- 2.1.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel Acked-by: Catalin Marinas diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt new file mode 100644 index 000000000000..58b71ddf9b60 --- /dev/null +++ b/Documentation/arm64/silicon-errata.txt @@ -0,0 +1,58 @@ + Silicon Errata and Software Workarounds + ======================================= + +Author: Will Deacon +Date : 27 November 2015 + +It is an unfortunate fact of life that hardware is often produced with +so-called "errata", which can cause it to deviate from the architecture +under specific circumstances. For hardware produced by ARM, these +errata are broadly classified into the following categories: + + Category A: A critical error without a viable workaround. + Category B: A significant or critical error with an acceptable + workaround. + Category C: A minor error that is not expected to occur under normal + operation. + +For more information, consult one of the "Software Developers Errata +Notice" documents available on infocenter.arm.com (registration +required). + +As far as Linux is concerned, Category B errata may require some special +treatment in the operating system. For example, avoiding a particular +sequence of code, or configuring the processor in a particular way. A +less common situation may require similar actions in order to declassify +a Category A erratum into a Category C erratum. These are collectively +known as "software workarounds" and are only required in the minority of +cases (e.g. those cases that both require a non-secure workaround *and* +can be triggered by Linux). + +For software workarounds that may adversely impact systems unaffected by +the erratum in question, a Kconfig entry is added under "Kernel +Features" -> "ARM errata workarounds via the alternatives framework". +These are enabled by default and patched in at runtime when an affected +CPU is detected. For less-intrusive workarounds, a Kconfig option is not +available and the code is structured (preferably with a comment) in such +a way that the erratum will not be hit. + +This approach can make it slightly onerous to determine exactly which +errata are worked around in an arbitrary kernel source tree, so this +file acts as a registry of software workarounds in the Linux Kernel and +will be updated when new workarounds are committed and backported to +stable kernels. + +| Implementor | Component | Erratum ID | Kconfig | ++----------------+-----------------+-----------------+-------------------------+ +| ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 | +| ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 | +| ARM | Cortex-A53 | #824069 | ARM64_ERRATUM_824069 | +| ARM | Cortex-A53 | #819472 | ARM64_ERRATUM_819472 | +| ARM | Cortex-A53 | #845719 | ARM64_ERRATUM_845719 | +| ARM | Cortex-A53 | #843419 | ARM64_ERRATUM_843419 | +| ARM | Cortex-A57 | #832075 | ARM64_ERRATUM_832075 | +| ARM | Cortex-A57 | #852523 | N/A | +| ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 | +| | | | | +| Cavium | ThunderX ITS | #22375, #24313 | CAVIUM_ERRATUM_22375 | +| Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |