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Subject[PATCH 5/5] arch: x86: use sign_extend64() for sign extension
Date
Signed-off-by: Martin Kepplinger <martin.kepplinger@theobroma-systems.com>
---
arch/x86/kernel/cpu/perf_event_msr.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_msr.c b/arch/x86/kernel/cpu/perf_event_msr.c
index f32ac13..ec863b9 100644
--- a/arch/x86/kernel/cpu/perf_event_msr.c
+++ b/arch/x86/kernel/cpu/perf_event_msr.c
@@ -163,10 +163,9 @@ again:
goto again;

delta = now - prev;
- if (unlikely(event->hw.event_base == MSR_SMI_COUNT)) {
- delta <<= 32;
- delta >>= 32; /* sign extend */
- }
+ if (unlikely(event->hw.event_base == MSR_SMI_COUNT))
+ delta = sign_extend64(delta, 31);
+
local64_add(now - prev, &event->count);
}

--
2.1.4


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