linux-kernel - [tip: perf/core] perf/x86/amd: Add branch-brs helper event for Fam19h BRS

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Date:   Tue, 05 Apr 2022 08:36:41 -0000
From:   "tip-bot2 for Stephane Eranian" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Stephane Eranian <eranian@...gle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf/x86/amd: Add branch-brs helper event for Fam19h BRS

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     44175993efbae04e8b2d7f7795ff512c3a726db0
Gitweb:        https://git.kernel.org/tip/44175993efbae04e8b2d7f7795ff512c3a726db0
Author:        Stephane Eranian <eranian@...gle.com>
AuthorDate:    Tue, 22 Mar 2022 15:15:08 -07:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 05 Apr 2022 10:24:37 +02:00

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@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-5-eranian@google.com
---
 arch/x86/events/amd/core.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index c7ac70d..f7bce83 100644
--- 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,
 };