perf/x86/amd/core: Refactor branch attributes

AMD processors that are capable of recording branches support either Branch
Sampling (BRS) or Last Branch Record (LBR). In preparation for adding Last
Branch Record Extension Version 2 (LbrExtV2) support, reuse the "branches"
capability to advertise information about both BRS and LBR but make the
"branch-brs" event exclusive to Family 19h processors that support BRS.

Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/ba4a4cde6db79b1c65c49834027bbdb8a915546b.1660211399.git.sandipan.das@amd.com

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index e32a27899e1159a43b34ff357ee096cc4647f343..2f524cf845281e3cf03ab405dcf408fafa927b42 100644 (file)
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1247,23 +1247,25 @@ static ssize_t branches_show(struct device *cdev,
 
 static DEVICE_ATTR_RO(branches);
 
-static struct attribute *amd_pmu_brs_attrs[] = {
+static struct attribute *amd_pmu_branches_attrs[] = {
        &dev_attr_branches.attr,
        NULL,
 };
 
 static umode_t
-amd_brs_is_visible(struct kobject *kobj, struct attribute *attr, int i)
+amd_branches_is_visible(struct kobject *kobj, struct attribute *attr, int i)
 {
        return x86_pmu.lbr_nr ? attr->mode : 0;
 }
 
-static struct attribute_group group_caps_amd_brs = {
+static struct attribute_group group_caps_amd_branches = {
        .name  = "caps",
-       .attrs = amd_pmu_brs_attrs,
-       .is_visible = amd_brs_is_visible,
+       .attrs = amd_pmu_branches_attrs,
+       .is_visible = amd_branches_is_visible,
 };
 
+#ifdef CONFIG_PERF_EVENTS_AMD_BRS
+
 EVENT_ATTR_STR(branch-brs, amd_branch_brs,
               "event=" __stringify(AMD_FAM19H_BRS_EVENT)"\n");
 
@@ -1272,15 +1274,26 @@ static struct attribute *amd_brs_events_attrs[] = {
        NULL,
 };
 
+static umode_t
+amd_brs_is_visible(struct kobject *kobj, struct attribute *attr, int i)
+{
+       return static_cpu_has(X86_FEATURE_BRS) && x86_pmu.lbr_nr ?
+              attr->mode : 0;
+}
+
 static struct attribute_group group_events_amd_brs = {
        .name       = "events",
        .attrs      = amd_brs_events_attrs,
        .is_visible = amd_brs_is_visible,
 };
 
+#endif /* CONFIG_PERF_EVENTS_AMD_BRS */
+
 static const struct attribute_group *amd_attr_update[] = {
-       &group_caps_amd_brs,
+       &group_caps_amd_branches,
+#ifdef CONFIG_PERF_EVENTS_AMD_BRS
        &group_events_amd_brs,
+#endif
        NULL,
 };