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 6C65CC433EF for ; Wed, 8 Dec 2021 20:11:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240080AbhLHUPI (ORCPT ); Wed, 8 Dec 2021 15:15:08 -0500 Received: from mail-ot1-f53.google.com ([209.85.210.53]:38504 "EHLO mail-ot1-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236644AbhLHUPE (ORCPT ); Wed, 8 Dec 2021 15:15:04 -0500 Received: by mail-ot1-f53.google.com with SMTP id n104-20020a9d2071000000b005799790cf0bso3911228ota.5; Wed, 08 Dec 2021 12:11:31 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gs33L1/6raqSK9QUUTnv7TCH3v7KbK1ze/ld1T0DSZo=; b=B/w+6pY2y8+0kS2I6IcKc66NFyao1W38QrtxDr9SSrdUOd07fOl0wN+H3z1AGIfCmM mc6xj/G0zsU4SnjPG6hVo+2jtBC5AydB+u+QPVY3FrmiEan76cx3L0cWiDnIuTmn9loi ofr1UuNuzkvW1oIi6TfNxj2jDJ30pUKeNZwSEsQkCdWkJnFpn5idjM2QLn4hG3s0E6fz v9Cz6FqgHZh3Oo3wavQyHvKaopiGOoYFh6/Qd0pGx/fpSwOxOB/RDNyY0aqz7F+8saVL eUiSUHLTSHranVO9G/JWf+pPE43sTU3+AJ2CpkRjht2pWX5FV9OraGCLCKSiv8Ky7tSy Kr5g== X-Gm-Message-State: AOAM530H/RBbdtufQg3gG9C7Agk5cqoYet7YK1wxUuugSvqcgmMFtlf5 hePKjV6ytlzmypAVDsdNow== X-Google-Smtp-Source: ABdhPJzTkAp++P+k4YZ8yivYOkuhUUlUlVJBOscVMAisWtQ4rlwNPi6M2Nify7bCMowWee8PHJw04Q== X-Received: by 2002:a9d:750c:: with SMTP id r12mr1428810otk.273.1638994291415; Wed, 08 Dec 2021 12:11:31 -0800 (PST) Received: from xps15.herring.priv (66-90-148-213.dyn.grandenetworks.net. [66.90.148.213]) by smtp.googlemail.com with ESMTPSA id o2sm927926oik.11.2021.12.08.12.11.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Dec 2021 12:11:30 -0800 (PST) From: Rob Herring To: Will Deacon , Mark Rutland , Peter Zijlstra Cc: Vince Weaver , Jonathan Corbet , Catalin Marinas , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org Subject: [PATCH v13 3/5] arm64: perf: Add userspace counter access disable switch Date: Wed, 8 Dec 2021 14:11:22 -0600 Message-Id: <20211208201124.310740-4-robh@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211208201124.310740-1-robh@kernel.org> References: <20211208201124.310740-1-robh@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Like x86, some users may want to disable userspace PMU counter altogether. Add a sysctl 'perf_user_access' file to control userspace counter access. The default is '0' which is disabled. Writing '1' enables access. Note that x86 supports globally enabling user access by writing '2' to /sys/bus/event_source/devices/cpu/rdpmc. As there's not existing userspace support to worry about, this shouldn't be necessary for Arm. It could be added later if the need arises. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Namhyung Kim Cc: Catalin Marinas Cc: linux-perf-users@vger.kernel.org Acked-by: Will Deacon Reviewed-by: Mark Rutland Signed-off-by: Rob Herring --- v11: - Move custom handler to next patch v10: - Add documentation - Use a custom handler (needed on the next patch) v9: - Use sysctl instead of sysfs attr - Default to disabled v8: - New patch --- Documentation/admin-guide/sysctl/kernel.rst | 11 +++++++++++ arch/arm64/kernel/perf_event.c | 17 +++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 426162009ce9..346a0dba5703 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -905,6 +905,17 @@ enabled, otherwise writing to this file will return ``-EBUSY``. The default value is 8. +perf_user_access (arm64 only) +================================= + +Controls user space access for reading perf event counters. When set to 1, +user space can read performance monitor counter registers directly. + +The default value is 0 (access disabled). + +See Documentation/arm64/perf.rst for more information. + + pid_max ======= diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index b4044469527e..6ae20c4217af 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -286,6 +286,8 @@ static const struct attribute_group armv8_pmuv3_events_attr_group = { PMU_FORMAT_ATTR(event, "config:0-15"); PMU_FORMAT_ATTR(long, "config1:0"); +static int sysctl_perf_user_access __read_mostly; + static inline bool armv8pmu_event_is_64bit(struct perf_event *event) { return event->attr.config1 & 0x1; @@ -1104,6 +1106,19 @@ static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu) return probe.present ? 0 : -ENODEV; } +static struct ctl_table armv8_pmu_sysctl_table[] = { + { + .procname = "perf_user_access", + .data = &sysctl_perf_user_access, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { } +}; + static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name, int (*map_event)(struct perf_event *event), const struct attribute_group *events, @@ -1136,6 +1151,8 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name, cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_CAPS] = caps ? caps : &armv8_pmuv3_caps_attr_group; + register_sysctl("kernel", armv8_pmu_sysctl_table); + return 0; } -- 2.32.0