perf/x86/ibs: Check syscall attribute flags

commit bad9ac2d7f878a31cf1ae8c1ee3768077d222bcb upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
index da9bcdcd9856666daf006c06ae6e14af4c77bca9..4018f6e0869186af1cd7d20e4bcc79f9ba4b9c61 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -207,6 +207,15 @@ 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;
@@ -227,6 +236,9 @@ 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 b541bdf7ff3ccadd0ce644c480b42fa33ef6a1c6..c3c98a6d1c915b081dcd9eee9b852c906081b4fe 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:
  */