perf: Disable sampled events if no PMU interrupt

Add common code to generate -ENOTSUPP at event creation time if an
architecture attempts to create a sampled event and
PERF_PMU_NO_INTERRUPT is set.

This adds a new pmu->capabilities flag.  Initially we only support
PERF_PMU_NO_INTERRUPT (to indicate a PMU has no support for generating
hardware interrupts) but there are other capabilities that can be
added later.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: Will Deacon <will.deacon@arm.com>
[peterz: rename to PERF_PMU_CAP_* and moved the pmu::capabilities word into a hole]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1405161708060.11099@vincent-weaver-1.umelst.maine.edu
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index af6dcf1..267c8f3 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -167,6 +167,11 @@ struct perf_event;
 #define PERF_EVENT_TXN 0x1
 
 /**
+ * pmu::capabilities flags
+ */
+#define PERF_PMU_CAP_NO_INTERRUPT              0x01
+
+/**
  * struct pmu - generic performance monitoring unit
  */
 struct pmu {
@@ -178,6 +183,11 @@ struct pmu {
        const char                      *name;
        int                             type;
 
+       /*
+        * various common per-pmu feature flags
+        */
+       int                             capabilities;
+
        int * __percpu                  pmu_disable_count;
        struct perf_cpu_context * __percpu pmu_cpu_context;
        int                             task_ctx_nr;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index a62d142..e9ef0c6 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7120,6 +7120,13 @@ SYSCALL_DEFINE5(perf_event_open,
                }
        }
 
+       if (is_sampling_event(event)) {
+               if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
+                       err = -ENOTSUPP;
+                       goto err_alloc;
+               }
+       }
+
        account_event(event);
 
        /*