perf/x86/ibs: Check syscall attribute flags

Current implementation simply ignores attribute flags. Thus, there is
no notification to userland of unsupported features. Check syscall's
attribute flags to let userland know if a feature is supported by the
kernel. This is also needed to distinguish between future kernels what
might support a feature.

Cc: <stable@vger.kernel.org> v3.5..
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120910093018.GO8285@erda.amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
index 7bfb5be..eebd5ff 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -209,6 +209,15 @@ static int perf_ibs_precise_event(struct perf_event *event, u64 *config)
        return -EOPNOTSUPP;
 }
 
+static const struct perf_event_attr ibs_notsupp = {
+       .exclude_user   = 1,
+       .exclude_kernel = 1,
+       .exclude_hv     = 1,
+       .exclude_idle   = 1,
+       .exclude_host   = 1,
+       .exclude_guest  = 1,
+};
+
 static int perf_ibs_init(struct perf_event *event)
 {
        struct hw_perf_event *hwc = &event->hw;
@@ -229,6 +238,9 @@ static int perf_ibs_init(struct perf_event *event)
        if (event->pmu != &perf_ibs->pmu)
                return -ENOENT;
 
+       if (perf_flags(&event->attr) & perf_flags(&ibs_notsupp))
+               return -EINVAL;
+
        if (config & ~perf_ibs->config_mask)
                return -EINVAL;
 

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 33ed9d6..bdb4161 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -274,6 +274,8 @@ struct perf_event_attr {
        __u64   branch_sample_type; /* enum branch_sample_type */
 };
 
+#define perf_flags(attr)       (*(&(attr)->read_format + 1))
+
 /*
  * Ioctls that can be done on a perf event fd:
  */