perf/x86/amd: Add branch-brs helper event for Fam19h BRS

Add a pseudo event called branch-brs to help use the FAM Fam19h
Branch Sampling feature (BRS). BRS samples taken branches, so it is best used
when sampling on a retired taken branch event (0xc4) which is what BRS
captures.  Instead of trying to remember the event code or actual event name,
users can simply do:

$ perf record -b -e cpu/branch-brs/ -c 1000037 .....

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-5-eranian@google.com

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index c7ac70d..f7bce83 100644 (file)
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1145,8 +1145,23 @@ static struct attribute_group group_caps_amd_brs = {
        .is_visible = amd_brs_is_visible,
 };
 
+EVENT_ATTR_STR(branch-brs, amd_branch_brs,
+              "event=" __stringify(AMD_FAM19H_BRS_EVENT)"\n");
+
+static struct attribute *amd_brs_events_attrs[] = {
+       EVENT_PTR(amd_branch_brs),
+       NULL,
+};
+
+static struct attribute_group group_events_amd_brs = {
+       .name       = "events",
+       .attrs      = amd_brs_events_attrs,
+       .is_visible = amd_brs_is_visible,
+};
+
 static const struct attribute_group *amd_attr_update[] = {
        &group_caps_amd_brs,
+       &group_events_amd_brs,
        NULL,
 };