perf_counter: provide misc bits in the event header

Limit the size of each record to 64k (or should we count in multiples
of u64 and have a 512K limit?), this gives 16 bits or spare room in the
header, which we can use for misc bits, so as to not have to grow the
record with u64 every time we have a few bits to report.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.769271806@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 84a39081344c..4af98f943d3b 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1831,6 +1831,9 @@ static void perf_counter_output(struct perf_counter *counter,
         header.type = PERF_EVENT_COUNTER_OVERFLOW;
         header.size = sizeof(header);
 
+        header.misc = user_mode(regs) ?
+                PERF_EVENT_MISC_USER : PERF_EVENT_MISC_KERNEL;
+
         if (record_type & PERF_RECORD_IP) {
                 ip = instruction_pointer(regs);
                 header.type |= __PERF_EVENT_IP;