From patchwork Fri Jun 28 06:51:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adrian Hunter X-Patchwork-Id: 13715539 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C3E02C2BBCA for ; Fri, 28 Jun 2024 06:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=5OqL3QyG4zt2I/FKVDBxJULF2Kbs5R1Ssvp5xzDLqLE=; b=Byz9fkIUcMrb0nUTStYSIXHWyA v/8a+mDJw32vbZLNnWvY6JJ2n7WvgboSXQ/UTxViBBj9PHPzJnxbe+sMWXIbbNAT2j/NvgmdzNW2e e3FxX0VT23GL2YmzhNVENBaCg3cZx2LKygoFGrS8lomYXd2xAI6T38mL75sTkgFBtHhO6eXzaHspl 1vG9367TwTUhk75dNAhgYxadkQ7UiPTrrI7bgWNi0dOhP+/vYDXdczRKLepSehsCIG7ezadFhDfUr TWbulZlCn0EFdbUgX+GbHTPXpEQ6FU1/OHXu0YUy5YozpvS41EEmDhtSIpkjeXUYwpzWFyDzJtxDd IXyDmSIA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sN5Se-0000000Cnq5-30lo; Fri, 28 Jun 2024 06:51:56 +0000 Received: from mgamail.intel.com ([198.175.65.16]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sN5ST-0000000Cnij-1IU1 for linux-arm-kernel@lists.infradead.org; Fri, 28 Jun 2024 06:51:46 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1719557506; x=1751093506; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=F9h0RszHO5yWHDMqvx0EnB0TOAidG4NUutQweuY+fEg=; b=IjkC64cBO+lcDvVxgD5oX0om7y7PvNK3huBo+5TODX0ETy4eTN4W6KTc eU3UXyjmXX+Y19ysmNM3HGnUCDi2E1fcacWi+As61Ys84MB74sfd9Cuiy PMp0MiGv+uGY7XlgrfX7gDjxYOtgVOTJSqr9UKLGJJQJJ3STJZ4I4m9Iz J+N3XL/0bF1aBJOOv5C+vJVuXfnYlZ4Y8UTBj5MoRjKj8h3mWufc3xOye g/veJaUWTc6FiVx5SKEWT5QATxtLHYrgQ9hB2is57IlZP0i3yne+4Tn9u c4zppv3sk0pdJSK/tBN6uEXUpFGSD8N+qARmb3JbegJbdYrZWI+r1zPuk A==; X-CSE-ConnectionGUID: 5IfR/6SWQdaPdH0kAzMkjA== X-CSE-MsgGUID: KsK1MzrnSlO33OsGb5S65A== X-IronPort-AV: E=McAfee;i="6700,10204,11116"; a="16857135" X-IronPort-AV: E=Sophos;i="6.09,168,1716274800"; d="scan'208";a="16857135" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2024 23:51:45 -0700 X-CSE-ConnectionGUID: 1GggjTDmS9O40rr6Z5cKvA== X-CSE-MsgGUID: D62jIfFVRj6qcLr9hkGC8w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,168,1716274800"; d="scan'208";a="75386678" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO localhost.localdomain) ([10.246.49.253]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2024 23:51:39 -0700 From: Adrian Hunter To: Peter Zijlstra Cc: Ingo Molnar , Mark Rutland , Alexander Shishkin , Heiko Carstens , Thomas Richter , Hendrik Brueckner , Suzuki K Poulose , Mike Leach , James Clark , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Yicong Yang , Jonathan Cameron , Will Deacon , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Ian Rogers , Andi Kleen , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH V8 02/12] perf/x86/intel/pt: Add support for pause / resume Date: Fri, 28 Jun 2024 09:51:01 +0300 Message-Id: <20240628065111.59718-3-adrian.hunter@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240628065111.59718-1-adrian.hunter@intel.com> References: <20240628065111.59718-1-adrian.hunter@intel.com> MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240627_235145_426643_A2D19573 X-CRM114-Status: GOOD ( 19.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Prevent tracing to start if aux_paused. Implement support for PERF_EF_PAUSE / PERF_EF_RESUME. When aux_paused, stop tracing. When not aux_paused, only start tracing if it isn't currently meant to be stopped. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen --- arch/x86/events/intel/pt.c | 63 ++++++++++++++++++++++++++++++++++++-- arch/x86/events/intel/pt.h | 4 +++ 2 files changed, 64 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index 14db6d9d318b..fab54d7f7f7f 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -418,6 +418,9 @@ static void pt_config_start(struct perf_event *event) struct pt *pt = this_cpu_ptr(&pt_ctx); u64 ctl = event->hw.config; + if (READ_ONCE(event->aux_paused)) + return; + ctl |= RTIT_CTL_TRACEEN; if (READ_ONCE(pt->vmx_on)) perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_PARTIAL); @@ -534,7 +537,20 @@ static void pt_config(struct perf_event *event) reg |= (event->attr.config & PT_CONFIG_MASK); event->hw.config = reg; + + /* + * Allow resume before starting so as not to overwrite a value set by a + * PMI. + */ + WRITE_ONCE(pt->resume_allowed, 1); + pt_config_start(event); + + /* + * Allow pause after starting so its pt_config_stop() doesn't race with + * pt_config_start(). + */ + WRITE_ONCE(pt->pause_allowed, 1); } static void pt_config_stop(struct perf_event *event) @@ -1511,6 +1527,7 @@ void intel_pt_interrupt(void) buf = perf_aux_output_begin(&pt->handle, event); if (!buf) { event->hw.state = PERF_HES_STOPPED; + pt->resume_allowed = 0; return; } @@ -1519,6 +1536,7 @@ void intel_pt_interrupt(void) ret = pt_buffer_reset_markers(buf, &pt->handle); if (ret) { perf_aux_output_end(&pt->handle, 0); + pt->resume_allowed = 0; return; } @@ -1573,6 +1591,26 @@ static void pt_event_start(struct perf_event *event, int mode) struct pt *pt = this_cpu_ptr(&pt_ctx); struct pt_buffer *buf; + if (mode & PERF_EF_RESUME) { + if (READ_ONCE(pt->resume_allowed)) { + u64 status; + + /* + * Only if the trace is not active and the error and + * stopped bits are clear, is it safe to start, but a + * PMI might have just cleared these, so resume_allowed + * must be checked again also. + */ + rdmsrl(MSR_IA32_RTIT_STATUS, status); + if (!(status & (RTIT_STATUS_TRIGGEREN | + RTIT_STATUS_ERROR | + RTIT_STATUS_STOPPED)) && + READ_ONCE(pt->resume_allowed)) + pt_config_start(event); + } + return; + } + buf = perf_aux_output_begin(&pt->handle, event); if (!buf) goto fail_stop; @@ -1601,6 +1639,16 @@ static void pt_event_stop(struct perf_event *event, int mode) { struct pt *pt = this_cpu_ptr(&pt_ctx); + if (mode & PERF_EF_PAUSE) { + if (READ_ONCE(pt->pause_allowed)) + pt_config_stop(event); + return; + } + + /* Protect against racing */ + WRITE_ONCE(pt->pause_allowed, 0); + WRITE_ONCE(pt->resume_allowed, 0); + /* * Protect against the PMI racing with disabling wrmsr, * see comment in intel_pt_interrupt(). @@ -1659,8 +1707,12 @@ static long pt_event_snapshot_aux(struct perf_event *event, /* * Here, handle_nmi tells us if the tracing is on */ - if (READ_ONCE(pt->handle_nmi)) + if (READ_ONCE(pt->handle_nmi)) { + /* Protect against racing */ + WRITE_ONCE(pt->pause_allowed, 0); + WRITE_ONCE(pt->resume_allowed, 0); pt_config_stop(event); + } pt_read_offset(buf); pt_update_head(pt); @@ -1677,8 +1729,11 @@ static long pt_event_snapshot_aux(struct perf_event *event, * Compiler barrier not needed as we couldn't have been * preempted by anything that touches pt->handle_nmi. */ - if (pt->handle_nmi) + if (pt->handle_nmi) { + WRITE_ONCE(pt->resume_allowed, 1); pt_config_start(event); + WRITE_ONCE(pt->pause_allowed, 1); + } return ret; } @@ -1794,7 +1849,9 @@ static __init int pt_init(void) if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) pt_pmu.pmu.capabilities = PERF_PMU_CAP_AUX_NO_SG; - pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE; + pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | + PERF_PMU_CAP_ITRACE | + PERF_PMU_CAP_AUX_PAUSE; pt_pmu.pmu.attr_groups = pt_attr_groups; pt_pmu.pmu.task_ctx_nr = perf_sw_context; pt_pmu.pmu.event_init = pt_event_init; diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h index 96906a62aacd..b9527205e028 100644 --- a/arch/x86/events/intel/pt.h +++ b/arch/x86/events/intel/pt.h @@ -117,6 +117,8 @@ struct pt_filters { * @filters: last configured filters * @handle_nmi: do handle PT PMI on this cpu, there's an active event * @vmx_on: 1 if VMX is ON on this cpu + * @pause_allowed: PERF_EF_PAUSE is allowed to stop tracing + * @resume_allowed: PERF_EF_RESUME is allowed to start tracing * @output_base: cached RTIT_OUTPUT_BASE MSR value * @output_mask: cached RTIT_OUTPUT_MASK MSR value */ @@ -125,6 +127,8 @@ struct pt { struct pt_filters filters; int handle_nmi; int vmx_on; + int pause_allowed; + int resume_allowed; u64 output_base; u64 output_mask; };