From 79d102cbfd2e9d94257fcc7c82807ef1cdf80322 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Mon, 5 Sep 2016 17:30:07 +0200 Subject: perf/x86/intel/cqm: Check cqm/mbm enabled state in event init Yanqiu Zhang reported kernel panic when using mbm event on system where CQM is detected but without mbm event support, like with perf: # perf stat -e 'intel_cqm/event=3/' -a BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 IP: [] update_sample+0xbc/0xe0 ... [] __intel_mbm_event_init+0x18/0x20 [] flush_smp_call_function_queue+0x7b/0x160 [] generic_smp_call_function_single_interrupt+0x13/0x60 [] smp_call_function_interrupt+0x27/0x40 [] call_function_interrupt+0x8c/0xa0 ... The reason is that we currently allow to init mbm event even if mbm support is not detected. Adding checks for both cqm and mbm events and support into cqm's event_init. Fixes: 33c3cc7acfd9 ("perf/x86/mbm: Add Intel Memory B/W Monitoring enumeration and init") Reported-by: Yanqiu Zhang Signed-off-by: Jiri Olsa Acked-by: Peter Zijlstra Cc: Vikas Shivappa Cc: Tony Luck Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1473089407-21857-1-git-send-email-jolsa@kernel.org Signed-off-by: Thomas Gleixner --- arch/x86/events/intel/cqm.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/x86/events/intel') diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c index 783c49ddef29..8f82b02934fa 100644 --- a/arch/x86/events/intel/cqm.c +++ b/arch/x86/events/intel/cqm.c @@ -458,6 +458,11 @@ static void __intel_cqm_event_count(void *info); static void init_mbm_sample(u32 rmid, u32 evt_type); static void __intel_mbm_event_count(void *info); +static bool is_cqm_event(int e) +{ + return (e == QOS_L3_OCCUP_EVENT_ID); +} + static bool is_mbm_event(int e) { return (e >= QOS_MBM_TOTAL_EVENT_ID && e <= QOS_MBM_LOCAL_EVENT_ID); @@ -1366,6 +1371,10 @@ static int intel_cqm_event_init(struct perf_event *event) (event->attr.config > QOS_MBM_LOCAL_EVENT_ID)) return -EINVAL; + if ((is_cqm_event(event->attr.config) && !cqm_enabled) || + (is_mbm_event(event->attr.config) && !mbm_enabled)) + return -EINVAL; + /* unsupported modes and filters */ if (event->attr.exclude_user || event->attr.exclude_kernel || -- cgit v1.2.3 From a9a94401c2b5805c71e39427b1af1bf1b9f67cd0 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Tue, 6 Sep 2016 16:23:51 +0300 Subject: perf/x86/intel/bts: Fix confused ordering of PMU callbacks The intel_bts driver is using a CPU-local 'started' variable to order callbacks and PMIs and make sure that AUX transactions don't get messed up. However, the ordering rules in regard to this variable is a complete mess, which recently resulted in perf_fuzzer-triggered warnings and panics. The general ordering rule that is patch is enforcing is that this cpu-local variable be set only when the cpu-local AUX transaction is active; consequently, this variable is to be checked before the AUX related bits can be touched. Reported-by: Vince Weaver Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: vince@deater.net Link: http://lkml.kernel.org/r/20160906132353.19887-4-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/events/intel/bts.c | 104 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 80 insertions(+), 24 deletions(-) (limited to 'arch/x86/events/intel') diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index 0a6e393a2e62..61e1d713b114 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -31,7 +31,17 @@ struct bts_ctx { struct perf_output_handle handle; struct debug_store ds_back; - int started; + int state; +}; + +/* BTS context states: */ +enum { + /* no ongoing AUX transactions */ + BTS_STATE_STOPPED = 0, + /* AUX transaction is on, BTS tracing is disabled */ + BTS_STATE_INACTIVE, + /* AUX transaction is on, BTS tracing is running */ + BTS_STATE_ACTIVE, }; static DEFINE_PER_CPU(struct bts_ctx, bts_ctx); @@ -204,6 +214,15 @@ static void bts_update(struct bts_ctx *bts) static int bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle); +/* + * Ordering PMU callbacks wrt themselves and the PMI is done by means + * of bts::state, which: + * - is set when bts::handle::event is valid, that is, between + * perf_aux_output_begin() and perf_aux_output_end(); + * - is zero otherwise; + * - is ordered against bts::handle::event with a compiler barrier. + */ + static void __bts_event_start(struct perf_event *event) { struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); @@ -221,10 +240,13 @@ static void __bts_event_start(struct perf_event *event) /* * local barrier to make sure that ds configuration made it - * before we enable BTS + * before we enable BTS and bts::state goes ACTIVE */ wmb(); + /* INACTIVE/STOPPED -> ACTIVE */ + WRITE_ONCE(bts->state, BTS_STATE_ACTIVE); + intel_pmu_enable_bts(config); } @@ -251,9 +273,6 @@ static void bts_event_start(struct perf_event *event, int flags) __bts_event_start(event); - /* PMI handler: this counter is running and likely generating PMIs */ - ACCESS_ONCE(bts->started) = 1; - return; fail_end_stop: @@ -263,30 +282,34 @@ fail_stop: event->hw.state = PERF_HES_STOPPED; } -static void __bts_event_stop(struct perf_event *event) +static void __bts_event_stop(struct perf_event *event, int state) { + struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); + + /* ACTIVE -> INACTIVE(PMI)/STOPPED(->stop()) */ + WRITE_ONCE(bts->state, state); + /* * No extra synchronization is mandated by the documentation to have * BTS data stores globally visible. */ intel_pmu_disable_bts(); - - if (event->hw.state & PERF_HES_STOPPED) - return; - - ACCESS_ONCE(event->hw.state) |= PERF_HES_STOPPED; } static void bts_event_stop(struct perf_event *event, int flags) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); - struct bts_buffer *buf = perf_get_aux(&bts->handle); + struct bts_buffer *buf = NULL; + int state = READ_ONCE(bts->state); + + if (state == BTS_STATE_ACTIVE) + __bts_event_stop(event, BTS_STATE_STOPPED); - /* PMI handler: don't restart this counter */ - ACCESS_ONCE(bts->started) = 0; + if (state != BTS_STATE_STOPPED) + buf = perf_get_aux(&bts->handle); - __bts_event_stop(event); + event->hw.state |= PERF_HES_STOPPED; if (flags & PERF_EF_UPDATE) { bts_update(bts); @@ -296,6 +319,7 @@ static void bts_event_stop(struct perf_event *event, int flags) bts->handle.head = local_xchg(&buf->data_size, buf->nr_pages << PAGE_SHIFT); + perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0), !!local_xchg(&buf->lost, 0)); } @@ -310,8 +334,20 @@ static void bts_event_stop(struct perf_event *event, int flags) void intel_bts_enable_local(void) { struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); + int state = READ_ONCE(bts->state); + + /* + * Here we transition from INACTIVE to ACTIVE; + * if we instead are STOPPED from the interrupt handler, + * stay that way. Can't be ACTIVE here though. + */ + if (WARN_ON_ONCE(state == BTS_STATE_ACTIVE)) + return; + + if (state == BTS_STATE_STOPPED) + return; - if (bts->handle.event && bts->started) + if (bts->handle.event) __bts_event_start(bts->handle.event); } @@ -319,8 +355,15 @@ void intel_bts_disable_local(void) { struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); + /* + * Here we transition from ACTIVE to INACTIVE; + * do nothing for STOPPED or INACTIVE. + */ + if (READ_ONCE(bts->state) != BTS_STATE_ACTIVE) + return; + if (bts->handle.event) - __bts_event_stop(bts->handle.event); + __bts_event_stop(bts->handle.event, BTS_STATE_INACTIVE); } static int @@ -407,9 +450,13 @@ int intel_bts_interrupt(void) struct perf_event *event = bts->handle.event; struct bts_buffer *buf; s64 old_head; - int err; + int err = -ENOSPC; - if (!event || !bts->started) + /* + * this is wrapped in intel_bts_enable_local/intel_bts_disable_local, + * so we can only be INACTIVE or STOPPED + */ + if (READ_ONCE(bts->state) == BTS_STATE_STOPPED) return 0; buf = perf_get_aux(&bts->handle); @@ -432,12 +479,21 @@ int intel_bts_interrupt(void) !!local_xchg(&buf->lost, 0)); buf = perf_aux_output_begin(&bts->handle, event); - if (!buf) - return 1; + if (buf) + err = bts_buffer_reset(buf, &bts->handle); - err = bts_buffer_reset(buf, &bts->handle); - if (err) - perf_aux_output_end(&bts->handle, 0, false); + if (err) { + WRITE_ONCE(bts->state, BTS_STATE_STOPPED); + + if (buf) { + /* + * BTS_STATE_STOPPED should be visible before + * cleared handle::event + */ + barrier(); + perf_aux_output_end(&bts->handle, 0, false); + } + } return 1; } -- cgit v1.2.3 From 4d4c474124649198d9b0a065c06f9362cf18e14e Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Tue, 6 Sep 2016 16:23:52 +0300 Subject: perf/x86/intel/bts: Fix BTS PMI detection Since BTS doesn't have a dedicated PMI status bit, the driver needs to take extra care to check for the condition that triggers it to avoid spurious NMI warnings. Regardless of the local BTS context state, the only way of knowing that the NMI is ours is to compare the write pointer against the interrupt threshold. Reported-by: Vince Weaver Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: vince@deater.net Link: http://lkml.kernel.org/r/20160906132353.19887-5-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/events/intel/bts.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'arch/x86/events/intel') diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index 61e1d713b114..9233edf993e1 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -446,26 +446,37 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle) int intel_bts_interrupt(void) { + struct debug_store *ds = this_cpu_ptr(&cpu_hw_events)->ds; struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); struct perf_event *event = bts->handle.event; struct bts_buffer *buf; s64 old_head; - int err = -ENOSPC; + int err = -ENOSPC, handled = 0; + + /* + * The only surefire way of knowing if this NMI is ours is by checking + * the write ptr against the PMI threshold. + */ + if (ds->bts_index >= ds->bts_interrupt_threshold) + handled = 1; /* * this is wrapped in intel_bts_enable_local/intel_bts_disable_local, * so we can only be INACTIVE or STOPPED */ if (READ_ONCE(bts->state) == BTS_STATE_STOPPED) - return 0; + return handled; buf = perf_get_aux(&bts->handle); + if (!buf) + return handled; + /* * Skip snapshot counters: they don't use the interrupt, but * there's no other way of telling, because the pointer will * keep moving */ - if (!buf || buf->snapshot) + if (buf->snapshot) return 0; old_head = local_read(&buf->head); @@ -473,7 +484,7 @@ int intel_bts_interrupt(void) /* no new data */ if (old_head == local_read(&buf->head)) - return 0; + return handled; perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0), !!local_xchg(&buf->lost, 0)); -- cgit v1.2.3 From ef9ef3befa0d76008e988a9ed9fe439e803351b9 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Tue, 6 Sep 2016 16:23:53 +0300 Subject: perf/x86/intel/bts: Kill a silly warning At the moment, intel_bts will WARN() out if there is more than one event writing to the same ring buffer, via SET_OUTPUT, and will only send data from one event to a buffer. There is no reason to have this warning in, so kill it. Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: vince@deater.net Link: http://lkml.kernel.org/r/20160906132353.19887-6-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/events/intel/bts.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/x86/events/intel') diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index 9233edf993e1..bdcd6510992c 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -378,8 +378,6 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle) return 0; head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1); - if (WARN_ON_ONCE(head != local_read(&buf->head))) - return -EINVAL; phys = &buf->buf[buf->cur_buf]; space = phys->offset + phys->displacement + phys->size - head; -- cgit v1.2.3 From 8ef9b8455a2a3049efa9e46e8a6402b972a3eb41 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 7 Sep 2016 14:42:55 +0200 Subject: perf/x86/intel: Fix PEBSv3 record drain Alexander hit the WARN_ON_ONCE(!event) on his Skylake while running the perf fuzzer. This means the PEBSv3 record included a status bit for an inactive event, something that _should_ not happen. Move the code that filters the status bits against our known PEBS events up a spot to guarantee we only deal with events we know about. Further add "continue" statements to the WARN_ON_ONCE()s such that we'll not die nor generate silly events in case we ever do hit them again. Reported-by: Alexander Shishkin Tested-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: stable@vger.kernel.org Fixes: a3d86542de88 ("perf/x86/intel/pebs: Add PEBSv3 decoding") Signed-off-by: Ingo Molnar --- arch/x86/events/intel/ds.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) (limited to 'arch/x86/events/intel') diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index 7ce9f3f669e6..9b983a474253 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1274,18 +1274,18 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs) struct pebs_record_nhm *p = at; u64 pebs_status; - /* PEBS v3 has accurate status bits */ + pebs_status = p->status & cpuc->pebs_enabled; + pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1; + + /* PEBS v3 has more accurate status bits */ if (x86_pmu.intel_cap.pebs_format >= 3) { - for_each_set_bit(bit, (unsigned long *)&p->status, - MAX_PEBS_EVENTS) + for_each_set_bit(bit, (unsigned long *)&pebs_status, + x86_pmu.max_pebs_events) counts[bit]++; continue; } - pebs_status = p->status & cpuc->pebs_enabled; - pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1; - /* * On some CPUs the PEBS status can be zero when PEBS is * racing with clearing of GLOBAL_STATUS. @@ -1333,8 +1333,11 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs) continue; event = cpuc->events[bit]; - WARN_ON_ONCE(!event); - WARN_ON_ONCE(!event->attr.precise_ip); + if (WARN_ON_ONCE(!event)) + continue; + + if (WARN_ON_ONCE(!event->attr.precise_ip)) + continue; /* log dropped samples number */ if (error[bit]) -- cgit v1.2.3