From nobody Tue Feb 10 04:16:10 2026 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 EB47EC77B75 for ; Fri, 19 May 2023 17:22:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230356AbjESRWd (ORCPT ); Fri, 19 May 2023 13:22:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230102AbjESRVx (ORCPT ); Fri, 19 May 2023 13:21:53 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F289AE42 for ; Fri, 19 May 2023 10:21:25 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id d9443c01a7336-1ae54b623c2so31826265ad.3 for ; Fri, 19 May 2023 10:21:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1684516884; x=1687108884; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=TL6x11AHUdbqwPOBex8MH92mOu6poqhjfJN8Bz63N4s=; b=Pht+hrXlamhoKc3Sfk+JnwTbwmcG4p0AC6wXT9KK+YLT5G/A8PMg/Kgierf2mtzawr ClBv70BUaPRNqYHKjGkk7QBTOalxnZ8r6RtmZDQddTP1/P2XptlY4Z2wVzZmyx2mgkUl BcimCZ+ntm13VOGd+9TV47CPKcYCQWDP2CsA4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684516884; x=1687108884; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=TL6x11AHUdbqwPOBex8MH92mOu6poqhjfJN8Bz63N4s=; b=HiQQ7F0gKaY00EDpxBg0S183qgv9rpnku0KfJEZdF6yhMCob6MAI12NVveYmXiMZOs 1U52+VXkKIBMBiCD/wyKhRzPkswV5YHHhIqV9xNttVM0Y/YEsaA7zZht+aQzLVuL2YiX E6sRKeQCldxLIfcy0b7S+4BMGJaIIhERSomaWbIpTd4v/XwZWpUgmnZ/PaA4Vw6L2M5O yO/tlYoX0VjCAvGHzHXuiq2OXmIl8SYx1FbKozAuZqs71NnRGuPupxE9wnmrRBM7CDEq gZB3DUHLl3rJuJT5eO8Zl2eq4nhcTQyDZcskLfh6rK7xdHtYUqNlQh6jGzy/rhxusYeT C2ZQ== X-Gm-Message-State: AC+VfDwnfQfB+/K5hwRVqNN05bgyPQ5ThL7iux3qNj6ghRHGpqEc/dKT dHuXKDOHJeAf9ViE9I9eET1hxA== X-Google-Smtp-Source: ACHHUZ42iEc62iH4hoBzId667tClAxoJ0OHdYYIBvBIVMKi1bhk7AD73MYNJ7aE36NwledCLjmXG2w== X-Received: by 2002:a17:902:e80b:b0:1a1:f5dd:2dce with SMTP id u11-20020a170902e80b00b001a1f5dd2dcemr3490112plg.6.1684516883784; Fri, 19 May 2023 10:21:23 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:9b89:2dd0:d160:429d]) by smtp.gmail.com with ESMTPSA id gj19-20020a17090b109300b0024e4f169931sm1763835pjb.2.2023.05.19.10.21.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 May 2023 10:21:23 -0700 (PDT) From: Douglas Anderson To: Petr Mladek , Andrew Morton Cc: Matthias Kaehlcke , kgdb-bugreport@lists.sourceforge.net, Stephane Eranian , mpe@ellerman.id.au, Tzung-Bi Shih , Daniel Thompson , Mark Rutland , linuxppc-dev@lists.ozlabs.org, Sumit Garg , npiggin@gmail.com, davem@davemloft.net, Marc Zyngier , Stephen Boyd , sparclinux@vger.kernel.org, christophe.leroy@csgroup.eu, Catalin Marinas , ravi.v.shankar@intel.com, Randy Dunlap , Pingfan Liu , Guenter Roeck , Lecopzer Chen , Ian Rogers , ito-yuichi@fujitsu.com, ricardo.neri@intel.com, linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, Will Deacon , Chen-Yu Tsai , linux-kernel@vger.kernel.org, Masayoshi Mizuma , Andi Kleen , Douglas Anderson Subject: [PATCH v5 15/18] watchdog/perf: Add a weak function for an arch to detect if perf can use NMIs Date: Fri, 19 May 2023 10:18:39 -0700 Message-ID: <20230519101840.v5.15.Ic55cb6f90ef5967d8aaa2b503a4e67c753f64d3a@changeid> X-Mailer: git-send-email 2.40.1.698.g37aff9b760-goog In-Reply-To: <20230519101840.v5.18.Ia44852044cdcb074f387e80df6b45e892965d4a1@changeid> References: <20230519101840.v5.18.Ia44852044cdcb074f387e80df6b45e892965d4a1@changeid> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" On arm64, NMI support needs to be detected at runtime. Add a weak function to the perf hardlockup detector so that an architecture can implement it to detect whether NMIs are available. Signed-off-by: Douglas Anderson --- While I won't object to this patch landing, I consider it part of the arm64 perf hardlockup effort. I would be OK with the earlier patches in the series landing and then not landing ${SUBJECT} patch nor anything else later. I'll also note that, as an alternative to this, it would be nice if we could figure out how to make perf_event_create_kernel_counter() fail on arm64 if NMIs aren't available. Maybe we could add a "must_use_nmi" element to "struct perf_event_attr"? (no changes since v4) Changes in v4: - ("Add a weak function for an arch to detect ...") new for v4. include/linux/nmi.h | 1 + kernel/watchdog_perf.c | 12 +++++++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 47db14e7da52..eb616fc07c85 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -210,6 +210,7 @@ static inline bool trigger_single_cpu_backtrace(int cpu) =20 #ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF u64 hw_nmi_get_sample_period(int watchdog_thresh); +bool arch_perf_nmi_is_available(void); #endif =20 #if defined(CONFIG_HARDLOCKUP_CHECK_TIMESTAMP) && \ diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c index 349fcd4d2abc..8ea00c4a24b2 100644 --- a/kernel/watchdog_perf.c +++ b/kernel/watchdog_perf.c @@ -234,12 +234,22 @@ void __init hardlockup_detector_perf_restart(void) } } =20 +bool __weak __init arch_perf_nmi_is_available(void) +{ + return true; +} + /** * watchdog_hardlockup_probe - Probe whether NMI event is available at all */ int __init watchdog_hardlockup_probe(void) { - int ret =3D hardlockup_detector_event_create(); + int ret; + + if (!arch_perf_nmi_is_available()) + return -ENODEV; + + ret =3D hardlockup_detector_event_create(); =20 if (ret) { pr_info("Perf NMI watchdog permanently disabled\n"); --=20 2.40.1.698.g37aff9b760-goog