sparc64: Fix for perf event counts sometimes reported as negative numbers

Use an unsigned number to prevent sign extension in the calculation
to work out the difference between the previous and the current
count obtained from the perfomance instrumentation counters.

Orabug: 22607658

Signed-off-by: Dave Aldridge <david.j.aldridge@oracle.com>
(cherry picked from commit b0fb8b78a2cc452512296ce5bec1fa927ebf867e)
(cherry picked from commit da8cc212a978a1f54cadadeaabed46d9d5f839b3)
Signed-off-by: Allen Pais <allen.pais@oracle.com>

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 6be35b1310393d8fffab3e9a11d20034f035d137..d5e46143f99c805b0fe5d547a0424f86aad4b8f7 100644 (file)
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -862,8 +862,7 @@ static u64 sparc_perf_event_update(struct perf_event *event,
                                   struct hw_perf_event *hwc, int idx)
 {
        int shift = 64 - 32;
-       u64 prev_raw_count, new_raw_count;
-       s64 delta;
+       u64 prev_raw_count, new_raw_count, delta;
 
 again:
        prev_raw_count = local64_read(&hwc->prev_count);