linux-kernel - [PATCH V3 17/23] perf/x86/intel/lbr: Create kmem

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Date:   Fri,  3 Jul 2020 05:49:23 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        tglx@...utronix.de, bp@...en8.de, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org, dave.hansen@...el.com,
        yu-cheng.yu@...el.com, bigeasy@...utronix.de, gorcunov@...il.com,
        hpa@...or.com, alexey.budankov@...ux.intel.com, eranian@...gle.com,
        ak@...ux.intel.com, like.xu@...ux.intel.com,
        yao.jin@...ux.intel.com, wei.w.wang@...el.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V3 17/23] perf/x86/intel/lbr: Create kmem_cache for the LBR context data

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

A new kmem_cache method is introduced to allocate the PMU specific data
task_ctx_data, which requires the PMU specific code to create a
kmem_cache.

Currently, the task_ctx_data is only used by the Intel LBR call stack
feature, which is introduced since Haswell. The kmem_cache should be
only created for Haswell and later platforms. There is no alignment
requirement for the existing platforms.

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/lbr.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index bb42e4d..4fb1be4 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1532,9 +1532,17 @@ void __init intel_pmu_lbr_init_snb(void)
 	 */
 }
 
+static inline struct kmem_cache *
+create_lbr_kmem_cache(size_t size, size_t align)
+{
+	return kmem_cache_create("x86_lbr", size, align, 0, NULL);
+}
+
 /* haswell */
 void intel_pmu_lbr_init_hsw(void)
 {
+	size_t size = sizeof(struct x86_perf_task_context);
+
 	x86_pmu.lbr_nr	 = 16;
 	x86_pmu.lbr_tos	 = MSR_LBR_TOS;
 	x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
@@ -1543,6 +1551,8 @@ void intel_pmu_lbr_init_hsw(void)
 	x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
 	x86_pmu.lbr_sel_map  = hsw_lbr_sel_map;
 
+	x86_get_pmu()->task_ctx_cache = create_lbr_kmem_cache(size, 0);
+
 	if (lbr_from_signext_quirk_needed())
 		static_branch_enable(&lbr_from_quirk_key);
 }
@@ -1550,6 +1560,8 @@ void intel_pmu_lbr_init_hsw(void)
 /* skylake */
 __init void intel_pmu_lbr_init_skl(void)
 {
+	size_t size = sizeof(struct x86_perf_task_context);
+
 	x86_pmu.lbr_nr	 = 32;
 	x86_pmu.lbr_tos	 = MSR_LBR_TOS;
 	x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
@@ -1559,6 +1571,8 @@ __init void intel_pmu_lbr_init_skl(void)
 	x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
 	x86_pmu.lbr_sel_map  = hsw_lbr_sel_map;
 
+	x86_get_pmu()->task_ctx_cache = create_lbr_kmem_cache(size, 0);
+
 	/*
 	 * SW branch filter usage:
 	 * - support syscall, sysret capture.
@@ -1632,6 +1646,7 @@ void __init intel_pmu_arch_lbr_init(void)
 	union cpuid28_ebx ebx;
 	union cpuid28_ecx ecx;
 	unsigned int unused_edx;
+	size_t size;
 	u64 lbr_nr;
 
 	/* Arch LBR Capabilities */
@@ -1656,8 +1671,10 @@ void __init intel_pmu_arch_lbr_init(void)
 	x86_pmu.lbr_br_type = ecx.split.lbr_br_type;
 	x86_pmu.lbr_nr = lbr_nr;
 
-	x86_get_pmu()->task_ctx_size = sizeof(struct x86_perf_task_context_arch_lbr) +
-				       lbr_nr * sizeof(struct lbr_entry);
+	size = sizeof(struct x86_perf_task_context_arch_lbr) +
+	       lbr_nr * sizeof(struct lbr_entry);
+	x86_get_pmu()->task_ctx_size = size;
+	x86_get_pmu()->task_ctx_cache = create_lbr_kmem_cache(size, 0);
 
 	x86_pmu.lbr_from = MSR_ARCH_LBR_FROM_0;
 	x86_pmu.lbr_to = MSR_ARCH_LBR_TO_0;
-- 
2.7.4