linux-kernel - [PATCH] Support for perf on AMD family17h processors

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Date:   Wed, 16 Nov 2016 11:01:53 -0600
From:   Janakarajan Natarajan <Janakarajan.Natarajan@....com>
To:     <linux-kernel@...r.kernel.org>
CC:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Janakarajan Natarajan <Janakarajan.Natarajan@....com>
Subject: [PATCH] Support for perf on AMD family17h processors

This patch enables perf core PMU support for AMD family17h processors.
In family17h, there is no PMC-event constraint. All events, irrespective
of the type, can be measured using any of the performance counters.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@....com>
---
 arch/x86/events/amd/core.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index f5f4b3f..849688d 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -652,7 +652,11 @@ static __initconst const struct x86_pmu amd_pmu = {
 	.amd_nb_constraints	= 1,
 };
 
-static int __init amd_core_pmu_init(void)
+/*
+ * This function initializes core PMU to enable support
+ * for AMD Core PMC Extension.
+ */
+static int __init amd_core_pmc_ext_init(void)
 {
 	if (!boot_cpu_has(X86_FEATURE_PERFCTR_CORE))
 		return 0;
@@ -662,7 +666,12 @@ static int __init amd_core_pmu_init(void)
 		pr_cont("Fam15h ");
 		x86_pmu.get_event_constraints = amd_get_event_constraints_f15h;
 		break;
-
+	case 0x17:
+		pr_cont("Fam17h ");
+		/* In family 17h, there are no event constraints in the PMC hardware.
+		 * We fallback to using default amd_get_event_constraints.
+		 */
+		break;
 	default:
 		pr_err("core perfctr but no constraints; unknown hardware!\n");
 		return -ENODEV;
@@ -696,7 +705,7 @@ __init int amd_pmu_init(void)
 
 	x86_pmu = amd_pmu;
 
-	ret = amd_core_pmu_init();
+	ret = amd_core_pmc_ext_init();
 	if (ret)
 		return ret;
 
-- 
2.7.4