Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161095AbaKNNpI (ORCPT ); Fri, 14 Nov 2014 08:45:08 -0500 Received: from mga14.intel.com ([192.55.52.115]:5892 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934667AbaKNNpE (ORCPT ); Fri, 14 Nov 2014 08:45:04 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="416495557" From: Alexander Shishkin To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Robert Richter , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Stephane Eranian , Andi Kleen , kan.liang@intel.com, adrian.hunter@intel.com, markus.t.metzger@intel.com, mathieu.poirier@linaro.org, acme@infradead.org, Alexander Shishkin Subject: [PATCH v8 11/14] x86: perf: Intel PT and LBR/BTS are mutually exclusive Date: Fri, 14 Nov 2014 15:43:44 +0200 Message-Id: <1415972627-37514-12-git-send-email-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1415972627-37514-1-git-send-email-alexander.shishkin@linux.intel.com> References: <1415972627-37514-1-git-send-email-alexander.shishkin@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Intel PT cannot be used at the same time as LBR or BTS and will cause a general protection fault if they are used together. In order to avoid fixing up GPs in the fast path, instead we disallow creating LBR/BTS events when PT events are present and vice versa. Signed-off-by: Alexander Shishkin --- arch/x86/kernel/cpu/perf_event.c | 43 ++++++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/perf_event.h | 40 +++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/perf_event_intel.c | 26 ++++++++++---------- 3 files changed, 95 insertions(+), 14 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 143e5f5dc8..1cca1ac9b6 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -259,6 +259,14 @@ static void hw_perf_event_destroy(struct perf_event *event) } } +void hw_perf_lbr_event_destroy(struct perf_event *event) +{ + hw_perf_event_destroy(event); + + /* undo the lbr/bts event accounting */ + x86_del_exclusive(x86_lbr_exclusive_lbr); +} + static inline int x86_pmu_initialized(void) { return x86_pmu.handle_irq != NULL; @@ -298,6 +306,35 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event) return x86_pmu_extra_regs(val, event); } +/* + * Check if we can create event of a certain type (that no conflicting events + * are present). + */ +int x86_add_exclusive(unsigned int what) +{ + int ret = -EBUSY, i; + + if (atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what])) + return 0; + + mutex_lock(&pmc_reserve_mutex); + for (i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++) + if (i != what && atomic_read(&x86_pmu.lbr_exclusive[i])) + goto out; + + atomic_inc(&x86_pmu.lbr_exclusive[what]); + ret = 0; + +out: + mutex_unlock(&pmc_reserve_mutex); + return ret; +} + +void x86_del_exclusive(unsigned int what) +{ + atomic_dec(&x86_pmu.lbr_exclusive[what]); +} + int x86_setup_perfctr(struct perf_event *event) { struct perf_event_attr *attr = &event->attr; @@ -342,6 +379,12 @@ int x86_setup_perfctr(struct perf_event *event) /* BTS is currently only allowed for user-mode. */ if (!attr->exclude_kernel) return -EOPNOTSUPP; + + /* disallow bts if conflicting events are present */ + if (x86_add_exclusive(x86_lbr_exclusive_lbr)) + return -EBUSY; + + event->destroy = hw_perf_lbr_event_destroy; } hwc->config |= config; diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index fc5eb390b3..620612d311 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -402,6 +402,12 @@ union x86_pmu_config { #define X86_CONFIG(args...) ((union x86_pmu_config){.bits = {args}}).value +enum { + x86_lbr_exclusive_lbr, + x86_lbr_exclusive_pt, + x86_lbr_exclusive_max, +}; + /* * struct x86_pmu - generic x86 pmu */ @@ -498,6 +504,11 @@ struct x86_pmu { bool lbr_double_abort; /* duplicated lbr aborts */ /* + * Intel PT/LBR/BTS are exclusive + */ + atomic_t lbr_exclusive[x86_lbr_exclusive_max]; + + /* * Extra registers for events */ struct extra_reg *extra_regs; @@ -582,6 +593,12 @@ static inline int x86_pmu_rdpmc_index(int index) return x86_pmu.rdpmc_index ? x86_pmu.rdpmc_index(index) : index; } +int x86_add_exclusive(unsigned int what); + +void x86_del_exclusive(unsigned int what); + +void hw_perf_lbr_event_destroy(struct perf_event *event); + int x86_setup_perfctr(struct perf_event *event); int x86_pmu_hw_config(struct perf_event *event); @@ -668,6 +685,29 @@ static inline int amd_pmu_init(void) #ifdef CONFIG_CPU_SUP_INTEL +static inline bool intel_pmu_needs_lbr_smpl(struct perf_event *event) +{ + /* user explicitly requested branch sampling */ + if (has_branch_stack(event)) + return true; + + /* implicit branch sampling to correct PEBS skid */ + if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1 && + x86_pmu.intel_cap.pebs_format < 2) + return true; + + return false; +} + +static inline bool intel_pmu_has_bts(struct perf_event *event) +{ + if (event->attr.config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS && + !event->attr.freq && event->hw.sample_period == 1) + return true; + + return false; +} + int intel_pmu_save_and_restart(struct perf_event *event); struct event_constraint * diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 944bf019b7..c64e97a1cb 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1029,20 +1029,6 @@ static __initconst const u64 slm_hw_cache_event_ids }, }; -static inline bool intel_pmu_needs_lbr_smpl(struct perf_event *event) -{ - /* user explicitly requested branch sampling */ - if (has_branch_stack(event)) - return true; - - /* implicit branch sampling to correct PEBS skid */ - if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1 && - x86_pmu.intel_cap.pebs_format < 2) - return true; - - return false; -} - static void intel_pmu_disable_all(void) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); @@ -1751,6 +1737,18 @@ static int intel_pmu_hw_config(struct perf_event *event) ret = intel_pmu_setup_lbr_filter(event); if (ret) return ret; + + /* + * bts is set up earlier in this path, so don't account + * twice + */ + if (!intel_pmu_has_bts(event)) { + /* disallow lbr if conflicting events are present */ + if (x86_add_exclusive(x86_lbr_exclusive_lbr)) + return -EBUSY; + + event->destroy = hw_perf_lbr_event_destroy; + } } if (event->attr.type != PERF_TYPE_RAW) -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/