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

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index fed60e6..1a258d4 100644 (file)
--- 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 {