From a49ac9f83b31e41c8311d64bd2b3f97a23dcb38d Mon Sep 17 00:00:00 2001 From: Huang Rui Date: Fri, 25 Mar 2016 11:18:25 +0800 Subject: perf/x86: Move events_sysfs_show() outside CPU_SUP_INTEL randconfig builds can sometimes disable CONFIG_CPU_SUP_INTEL while enabling the AMD power reporting PMU driver, resulting in this build failure: arch/x86/kernel/cpu/perf_event.h:663:31: error: 'events_sysfs_show' undeclared here (not in a function) To fix it, move events_sysfs_show() outside of #ifdef CONFIG_CPU_SUP_INTEL. Reported-by: Randy Dunlap Reported-by: build test robot Signed-off-by: Huang Rui Cc: Borislav Petkov Cc: Borislav Petkov Cc: Fengguang Wu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sherry Hurwitz Cc: Stephen Rothwell Cc: Thomas Gleixner Cc: acme@kernel.org Cc: kbuild-all@01.org Cc: linux-next@vger.kernel.org Cc: spg_linux_kernel@amd.com Link: http://lkml.kernel.org/r/1458875905-4278-1-git-send-email-ray.huang@amd.com Signed-off-by: Ingo Molnar --- arch/x86/events/perf_event.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index ba6ef18528c9..a6771e2303d2 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -795,6 +795,9 @@ ssize_t intel_event_sysfs_show(char *page, u64 config); struct attribute **merge_attr(struct attribute **a, struct attribute **b); +ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, + char *page); + #ifdef CONFIG_CPU_SUP_AMD int amd_pmu_init(void); @@ -925,9 +928,6 @@ int p6_pmu_init(void); int knc_pmu_init(void); -ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, - char *page); - static inline int is_ht_workaround_enabled(void) { return !!(x86_pmu.flags & PMU_FL_EXCL_ENABLED); -- cgit v1.2.3 From 85dc600263c2291cea33bffa90038808ee64198b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 21 Mar 2016 11:47:52 +0100 Subject: perf/x86/amd/ibs: Fix pmu::stop() nesting Patch 5a50f5291701 ("perf/x86/ibs: Fix race with IBS_STARTING state") closed a big hole while opening another, smaller hole. Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: 5a50f5291701 ("perf/x86/ibs: Fix race with IBS_STARTING state") Signed-off-by: Ingo Molnar --- arch/x86/events/amd/ibs.c | 52 ++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 45 insertions(+), 7 deletions(-) (limited to 'arch') diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index 3ea25c3917c0..feb90f6730e8 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -28,10 +28,46 @@ static u32 ibs_caps; #define IBS_FETCH_CONFIG_MASK (IBS_FETCH_RAND_EN | IBS_FETCH_MAX_CNT) #define IBS_OP_CONFIG_MASK IBS_OP_MAX_CNT + +/* + * IBS states: + * + * ENABLED; tracks the pmu::add(), pmu::del() state, when set the counter is taken + * and any further add()s must fail. + * + * STARTED/STOPPING/STOPPED; deal with pmu::start(), pmu::stop() state but are + * complicated by the fact that the IBS hardware can send late NMIs (ie. after + * we've cleared the EN bit). + * + * In order to consume these late NMIs we have the STOPPED state, any NMI that + * happens after we've cleared the EN state will clear this bit and report the + * NMI handled (this is fundamentally racy in the face or multiple NMI sources, + * someone else can consume our BIT and our NMI will go unhandled). + * + * And since we cannot set/clear this separate bit together with the EN bit, + * there are races; if we cleared STARTED early, an NMI could land in + * between clearing STARTED and clearing the EN bit (in fact multiple NMIs + * could happen if the period is small enough), and consume our STOPPED bit + * and trigger streams of unhandled NMIs. + * + * If, however, we clear STARTED late, an NMI can hit between clearing the + * EN bit and clearing STARTED, still see STARTED set and process the event. + * If this event will have the VALID bit clear, we bail properly, but this + * is not a given. With VALID set we can end up calling pmu::stop() again + * (the throttle logic) and trigger the WARNs in there. + * + * So what we do is set STOPPING before clearing EN to avoid the pmu::stop() + * nesting, and clear STARTED late, so that we have a well defined state over + * the clearing of the EN bit. + * + * XXX: we could probably be using !atomic bitops for all this. + */ + enum ibs_states { IBS_ENABLED = 0, IBS_STARTED = 1, IBS_STOPPING = 2, + IBS_STOPPED = 3, IBS_MAX_STATES, }; @@ -377,11 +413,10 @@ static void perf_ibs_start(struct perf_event *event, int flags) perf_ibs_set_period(perf_ibs, hwc, &period); /* - * Set STARTED before enabling the hardware, such that - * a subsequent NMI must observe it. Then clear STOPPING - * such that we don't consume NMIs by accident. + * Set STARTED before enabling the hardware, such that a subsequent NMI + * must observe it. */ - set_bit(IBS_STARTED, pcpu->state); + set_bit(IBS_STARTED, pcpu->state); clear_bit(IBS_STOPPING, pcpu->state); perf_ibs_enable_event(perf_ibs, hwc, period >> 4); @@ -396,6 +431,9 @@ static void perf_ibs_stop(struct perf_event *event, int flags) u64 config; int stopping; + if (test_and_set_bit(IBS_STOPPING, pcpu->state)) + return; + stopping = test_bit(IBS_STARTED, pcpu->state); if (!stopping && (hwc->state & PERF_HES_UPTODATE)) @@ -405,12 +443,12 @@ static void perf_ibs_stop(struct perf_event *event, int flags) if (stopping) { /* - * Set STOPPING before disabling the hardware, such that it + * Set STOPPED before disabling the hardware, such that it * must be visible to NMIs the moment we clear the EN bit, * at which point we can generate an !VALID sample which * we need to consume. */ - set_bit(IBS_STOPPING, pcpu->state); + set_bit(IBS_STOPPED, pcpu->state); perf_ibs_disable_event(perf_ibs, hwc, config); /* * Clear STARTED after disabling the hardware; if it were @@ -556,7 +594,7 @@ fail: * with samples that even have the valid bit cleared. * Mark all this NMIs as handled. */ - if (test_and_clear_bit(IBS_STOPPING, pcpu->state)) + if (test_and_clear_bit(IBS_STOPPED, pcpu->state)) return 1; return 0; -- cgit v1.2.3