[PATCH v12 03/10] perf/amd/iommu: Clean up perf_iommu_read()

From: Suravee Suthikulpanit
Date: Wed Mar 22 2017 - 03:04:59 EST


Fix coding style and make use of GENMASK_ULL macro.

Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
arch/x86/events/amd/iommu.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index e112f49..d4375da 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -320,9 +320,7 @@ static void perf_iommu_start(struct perf_event *event, int flags)

static void perf_iommu_read(struct perf_event *event)
{
- u64 count = 0ULL;
- u64 prev_raw_count = 0ULL;
- u64 delta = 0ULL;
+ u64 count, prev, delta;
struct hw_perf_event *hwc = &event->hw;

amd_iommu_pc_get_set_reg_val(_GET_DEVID(event),
@@ -330,18 +328,16 @@ static void perf_iommu_read(struct perf_event *event)
IOMMU_PC_COUNTER_REG, &count, false);

/* IOMMU pc counter register is only 48 bits */
- count &= 0xFFFFFFFFFFFFULL;
+ count &= GENMASK_ULL(47, 0);

- prev_raw_count = local64_read(&hwc->prev_count);
- if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
- count) != prev_raw_count)
+ prev = local64_read(&hwc->prev_count);
+ if (local64_cmpxchg(&hwc->prev_count, prev, count) != prev)
return;

- /* Handling 48-bit counter overflowing */
- delta = (count << COUNTER_SHIFT) - (prev_raw_count << COUNTER_SHIFT);
+ /* Handle 48-bit counter overflow */
+ delta = (count << COUNTER_SHIFT) - (prev << COUNTER_SHIFT);
delta >>= COUNTER_SHIFT;
local64_add(delta, &event->count);
-
}

static void perf_iommu_stop(struct perf_event *event, int flags)
--
1.8.3.1