From 79d102cbfd2e9d94257fcc7c82807ef1cdf80322 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Mon, 5 Sep 2016 17:30:07 +0200 Subject: [PATCH] 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(+) 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 || -- 2.20.1