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Subject[tip: perf/core] perf/x86/amd/core: Refactor branch attributes
The following commit has been merged into the perf/core branch of tip:

Commit-ID: 9603aa79e851c652f6da873205c92213af36b24f
Gitweb: https://git.kernel.org/tip/9603aa79e851c652f6da873205c92213af36b24f
Author: Sandipan Das <sandipan.das@amd.com>
AuthorDate: Thu, 11 Aug 2022 17:59:50 +05:30
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 27 Aug 2022 00:05:42 +02:00

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
---
arch/x86/events/amd/core.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index e32a278..2f524cf 100644
--- 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,
};

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