From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76877C43334 for ; Sat, 2 Jul 2022 16:08:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232391AbiGBQIl (ORCPT ); Sat, 2 Jul 2022 12:08:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232372AbiGBQIi (ORCPT ); Sat, 2 Jul 2022 12:08:38 -0400 Received: from polaris.svanheule.net (polaris.svanheule.net [IPv6:2a00:c98:2060:a004:1::200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 699A4E09F for ; Sat, 2 Jul 2022 09:08:35 -0700 (PDT) Received: from terra.. (unknown [IPv6:2a02:a03f:eaf9:8401:aa9f:5d01:1b2a:e3cd]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sander@svanheule.net) by polaris.svanheule.net (Postfix) with ESMTPSA id DD6A42F29D8; Sat, 2 Jul 2022 18:08:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=svanheule.net; s=mail1707; t=1656778113; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=0NSjE24cwDwpcjmOlgtK2wImoG/eC1FOZtbmxQjPBj0=; b=B/25Dg7VzGoSeprNq4hnAvyFQlp+MyafaWPMZYeUlOwHgMhmoALv9MXd6v/TTNC/72GF2n vdoMfB1cnNXmXF75MyS/V8nNeY6C1JvAyr3MI7mt9kquSedc54aGzUN0lbNjhXIPQaSV7n GnE+PwVEDt4SffPsoVzLMsFdeyC8V/aKlZyeUri+HnOo+Qx9Wwk9QbK9BSqFVGOPwEp0LD iyaSBCmT1uJ1hcMk3D0IHAPAwrwWRvTvcm0jmRnvOq/HiCBSQ1LeK9q/XoZvik9foa/Cti ztxZkW0nz7JJ+RXuCFKKv615TSp3/JicN1YrUArV+yAfCY8O6VZohw2WBE1Ljw== From: Sander Vanheule To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Andy Shevchenko , elver@google.com, gregkh@linuxfoundation.org, Peter Zijlstra , Thomas Gleixner , vschneid@redhat.com, Yury Norov , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Sander Vanheule Subject: [PATCH v4 0/5] cpumask: Fix invalid uniprocessor assumptions Date: Sat, 2 Jul 2022 18:08:23 +0200 Message-Id: X-Mailer: git-send-email 2.36.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On uniprocessor builds, it is currently assumed that any cpumask will contain the single CPU: cpu0. This assumption is used to provide optimised implementations. The current assumption also appears to be wrong, by ignoring the fact that users can provide empty cpumask-s. This can result in bugs as explained in [1]. This series introduces some basic tests, and updates the optimisations for uniprocessor builds. The x86 patch was written after the kernel test robot [2] ran into a failed build. I have tried to list the files potentially affected by the changes to cpumask.h, in an attempt to find any other cases that fail on !SMP. I've gone through some of the files manually, and ran a few cross builds, but nothing else popped up. I (build) checked about half of the potientally affected files, but I do not have the resources to do them all. I hope we can fix other issues if/when they pop up later. [1] https://lore.kernel.org/all/20220530082552.46113-1-sander@svanheule.net/ [2] https://lore.kernel.org/all/202206060858.wA0FOzRy-lkp@intel.com/ Changes since v3: Link: https://lore.kernel.org/all/cover.1654410109.git.sander@svanheule.net/ - Guard againts CPU hotpluggin while testing cpu online/present masks - Add fix for cpu_llc_shared_map on x86 Changes since v2: Link: https://lore.kernel.org/all/cover.1654362935.git.sander@svanheule.net/ - Put new tests after patch fixes - Update for_each_* macros Changes since v1: Link: https://lore.kernel.org/all/cover.1654201862.git.sander@svanheule.net/ - Place tests in lib/test_cpumask.c - Drop the modified UP code in favor of the generic SMP implementation - Update declaration of cpumask_next_wrap() Sander Vanheule (5): x86/cacheinfo: move shared cache map definitions cpumask: Fix invalid uniprocessor mask assumption lib/test: Introduce cpumask KUnit test suite cpumask: Add UP optimised for_each_*_cpu versions cpumask: Update cpumask_next_wrap() signature arch/x86/kernel/cpu/cacheinfo.c | 6 ++ arch/x86/kernel/smpboot.c | 4 - include/linux/cpumask.h | 108 +++++++------------------ lib/Kconfig.debug | 9 +++ lib/Makefile | 4 +- lib/cpumask.c | 2 + lib/test_cpumask.c | 138 ++++++++++++++++++++++++++++++++ 7 files changed, 184 insertions(+), 87 deletions(-) create mode 100644 lib/test_cpumask.c -- 2.36.1