[RFC V1 11/11] perf: Capture branch privilege information
From: Anshuman Khandual
Date: Sun Jan 23 2022 - 23:33:08 EST
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 flag PERF_SAMPLE_BRANCH_PRIV_SAVE. While
here, update the BRBE driver as required.
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-perf-users@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
drivers/perf/arm_pmu_brbe.c | 28 ++++++++++++++++++++++++
include/linux/perf_event.h | 5 +++++
include/uapi/linux/perf_event.h | 13 ++++++++++-
tools/include/uapi/linux/perf_event.h | 13 ++++++++++-
tools/perf/Documentation/perf-record.txt | 1 +
tools/perf/util/parse-branch-options.c | 1 +
6 files changed, 59 insertions(+), 2 deletions(-)
diff --git a/drivers/perf/arm_pmu_brbe.c b/drivers/perf/arm_pmu_brbe.c
index 7cd1208c6c58..d4cbea74c148 100644
--- a/drivers/perf/arm_pmu_brbe.c
+++ b/drivers/perf/arm_pmu_brbe.c
@@ -270,6 +270,25 @@ static int brbe_fetch_perf_type(u64 brbinf)
}
}
+static int brbe_fetch_perf_priv(u64 brbinf)
+{
+ int brbe_el = brbe_fetch_el(brbinf);
+
+ switch (brbe_el) {
+ case BRBINF_EL_EL0:
+ return PERF_BR_USER;
+ case BRBINF_EL_EL1:
+ return PERF_BR_KERNEL;
+ case BRBINF_EL_EL2:
+ if (is_kernel_in_hyp_mode())
+ return PERF_BR_KERNEL;
+ return PERF_BR_HV;
+ default:
+ pr_warn("unknown branch privilege captured\n");
+ return -1;
+ }
+}
+
static void capture_brbe_flags(struct pmu_hw_events *cpuc, struct perf_event *event,
u64 brbinf, int idx)
{
@@ -302,6 +321,15 @@ static void capture_brbe_flags(struct pmu_hw_events *cpuc, struct perf_event *ev
cpuc->brbe_entries[idx].in_tx = brbinf & BRBINF_TX;
}
}
+
+ if (branch_sample_priv(event)) {
+ /*
+ * All these information (i.e branch privilege level) are not
+ * available for source only branch records.
+ */
+ if (type != BRBINF_VALID_SOURCE)
+ cpuc->brbe_entries[idx].priv = brbe_fetch_perf_priv(brbinf);
+ }
}
/*
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 916ce5102b33..8021b6a30d86 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1688,4 +1688,9 @@ static inline bool branch_sample_hw_index(const struct perf_event *event)
{
return event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX;
}
+
+static inline bool branch_sample_priv(const struct perf_event *event)
+{
+ return event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_PRIV_SAVE;
+}
#endif /* _LINUX_PERF_EVENT_H */
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 361fdc6b87a0..4d77710f7a4e 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 privillege 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,
};
@@ -265,6 +269,12 @@ enum {
PERF_BR_MAX,
};
+enum {
+ PERF_BR_USER = 0,
+ PERF_BR_KERNEL = 1,
+ PERF_BR_HV = 2,
+};
+
#define PERF_SAMPLE_BRANCH_PLM_ALL \
(PERF_SAMPLE_BRANCH_USER|\
PERF_SAMPLE_BRANCH_KERNEL|\
@@ -1377,7 +1387,8 @@ struct perf_branch_entry {
abort:1, /* transaction abort */
cycles:16, /* cycle count to last branch */
type:6, /* branch type */
- reserved:38;
+ priv:2, /* privilege level */
+ reserved:36;
};
union perf_sample_weight {
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 9a82b8aaed93..a2208400b0b9 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/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 privillege 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,
};
@@ -265,6 +269,12 @@ enum {
PERF_BR_MAX,
};
+enum {
+ PERF_BR_USER = 0,
+ PERF_BR_KERNEL = 1,
+ PERF_BR_HV = 2,
+};
+
#define PERF_SAMPLE_BRANCH_PLM_ALL \
(PERF_SAMPLE_BRANCH_USER|\
PERF_SAMPLE_BRANCH_KERNEL|\
@@ -1377,7 +1387,8 @@ struct perf_branch_entry {
abort:1, /* transaction abort */
cycles:16, /* cycle count to last branch */
type:6, /* branch type */
- reserved:38;
+ priv:2, /* privilege level */
+ reserved:36;
};
union perf_sample_weight {
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 9ccc75935bc5..3e33686977a1 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -387,6 +387,7 @@ following filters are defined:
- abort_tx: only when the target is a hardware transaction abort
- cond: conditional branches
- save_type: save branch type during sampling in case binary is not available later
+ - priv: save privilege state during sampling in case binary is not available later
+
The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
diff --git a/tools/perf/util/parse-branch-options.c b/tools/perf/util/parse-branch-options.c
index bb4aa88c50a8..00588b9db474 100644
--- a/tools/perf/util/parse-branch-options.c
+++ b/tools/perf/util/parse-branch-options.c
@@ -32,6 +32,7 @@ static const struct branch_mode branch_modes[] = {
BRANCH_OPT("call", PERF_SAMPLE_BRANCH_CALL),
BRANCH_OPT("save_type", PERF_SAMPLE_BRANCH_TYPE_SAVE),
BRANCH_OPT("stack", PERF_SAMPLE_BRANCH_CALL_STACK),
+ BRANCH_OPT("priv", PERF_SAMPLE_BRANCH_PRIV_SAVE),
BRANCH_END
};
--
2.25.1