commit: bad9ac2d7f878a31cf1ae8c1ee3768077d222bcb
From: Robert Richter <[email protected]>
Date: Wed, 25 Jul 2012 19:12:45 +0200
Subject: 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: <[email protected]> v3.5..
Signed-off-by: Robert Richter <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/kernel/cpu/perf_event_amd_ibs.c |   12 ++++++++++++
 include/linux/perf_event.h               |    2 ++
 2 files changed, 14 insertions(+), 0 deletions(-)

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
--- 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
--- 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:
  */
-- 
1.7.3.4
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