perf/x86: Mark Intel PT and LBR/BTS as mutually exclusive

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 <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kaixu Xia <kaixu.xia@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: kan.liang@intel.com
Cc: markus.t.metzger@intel.com
Cc: mathieu.poirier@linaro.org
Link: http://lkml.kernel.org/r/1421237903-181015-12-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 87e5081f4cdc..47499661e8d4 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -408,6 +408,12 @@ 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
  */
@@ -506,6 +512,11 @@ 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;
@@ -603,6 +614,12 @@ 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);
@@ -689,6 +706,29 @@ 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 *