[PATCH 15/21] perf/x86/intel/lbr: Create kmem_cache for the LBR context data

kan.liang
2020-06-19T14:08:35Z

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@linux.intel.com>
---
arch/x86/events/intel/lbr.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index fde23e8..28f0d41 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1533,9 +1533,17 @@ 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;
@@ -1544,6 +1552,8 @@ 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);
}
@@ -1551,6 +1561,8 @@ 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.
@@ -1629,6 +1643,7 @@ void intel_pmu_lbr_init_knl(void)
void __init intel_pmu_arch_lbr_init(void)
{
unsigned int unused_edx;
+ size_t size;
u64 lbr_nr;

/* Arch LBR Capabilities */
@@ -1644,8 +1659,11 @@ void __init intel_pmu_arch_lbr_init(void)
return;

x86_pmu.lbr_nr = lbr_nr;
- x86_get_pmu()->task_ctx_size = sizeof(struct x86_perf_task_context_arch_lbr) +
- lbr_nr * sizeof(struct x86_perf_arch_lbr_entry);
+
+ size = sizeof(struct x86_perf_task_context_arch_lbr) +
+ lbr_nr * sizeof(struct x86_perf_arch_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