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Subject[tip: perf/core] perf: Capture branch privilege information
The following commit has been merged into the perf/core branch of tip:

Commit-ID: 7203d4a5c19fc13c5229c4c1a08a5f9222207230
Gitweb: https://git.kernel.org/tip/7203d4a5c19fc13c5229c4c1a08a5f9222207230
Author: Anshuman Khandual <anshuman.khandual@arm.com>
AuthorDate: Wed, 24 Aug 2022 10:18:17 +05:30
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 27 Aug 2022 00:05:47 +02:00

perf: Capture branch privilege information

Platforms like arm64 could capture privilege level information for all the
branch records. Hence this adds a new element in the struct branch_entry to
record the privilege level information, which could be requested through a
new event.attr.branch_sample_type based flag PERF_SAMPLE_BRANCH_PRIV_SAVE.
This flag helps user choose whether privilege information is captured.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: James Clark <james.clark@arm.com>
Link: https://lkml.kernel.org/r/20220824044822.70230-4-anshuman.khandual@arm.com
---
include/uapi/linux/perf_event.h | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index fed60e6..1a258d4 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -204,6 +204,8 @@ enum perf_branch_sample_type_shift {

PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT = 17, /* save low level index of raw branch records */

+ PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT = 18, /* save privilege mode */
+
PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
};

@@ -233,6 +235,8 @@ enum perf_branch_sample_type {

PERF_SAMPLE_BRANCH_HW_INDEX = 1U << PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT,

+ PERF_SAMPLE_BRANCH_PRIV_SAVE = 1U << PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT,
+
PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
};

@@ -282,6 +286,13 @@ enum {
PERF_BR_NEW_MAX,
};

+enum {
+ PERF_BR_PRIV_UNKNOWN = 0,
+ PERF_BR_PRIV_USER = 1,
+ PERF_BR_PRIV_KERNEL = 2,
+ PERF_BR_PRIV_HV = 3,
+};
+
#define PERF_SAMPLE_BRANCH_PLM_ALL \
(PERF_SAMPLE_BRANCH_USER|\
PERF_SAMPLE_BRANCH_KERNEL|\
@@ -1402,7 +1413,8 @@ struct perf_branch_entry {
type:4, /* branch type */
spec:2, /* branch speculation info */
new_type:4, /* additional branch type */
- reserved:34;
+ priv:3, /* privilege level */
+ reserved:31;
};

union perf_sample_weight {
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