linux-kernel - [PATCH V6 01/14] perf/x86: Use event_base_rdpmc for the RDPMC userspace support

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Date:   Fri, 17 Jul 2020 07:05:41 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, acme@...hat.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     jolsa@...nel.org, eranian@...gle.com,
        alexander.shishkin@...ux.intel.com, ak@...ux.intel.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V6 01/14] perf/x86: Use event_base_rdpmc for the RDPMC userspace support

From: Kan Liang <kan.liang@...ux.intel.com>

The RDPMC index is always re-calculated for the RDPMC userspace support,
which is unnecessary.

The RDPMC index value is stored in the variable event_base_rdpmc for
the kernel usage, which can be used for RDPMC userspace support as well.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/core.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 1cbf57dc2ac8..8e108ea378e3 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2208,17 +2208,12 @@ static void x86_pmu_event_unmapped(struct perf_event *event, struct mm_struct *m
 
 static int x86_pmu_event_idx(struct perf_event *event)
 {
-	int idx = event->hw.idx;
+	struct hw_perf_event *hwc = &event->hw;
 
-	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
+	if (!(hwc->flags & PERF_X86_EVENT_RDPMC_ALLOWED))
 		return 0;
 
-	if (x86_pmu.num_counters_fixed && idx >= INTEL_PMC_IDX_FIXED) {
-		idx -= INTEL_PMC_IDX_FIXED;
-		idx |= 1 << 30;
-	}
-
-	return idx + 1;
+	return hwc->event_base_rdpmc + 1;
 }
 
 static ssize_t get_attr_rdpmc(struct device *cdev,
-- 
2.17.1