[PATCH V2 6/6] perf tools: Add branch event knob
From: kan . liang
Date: Mon May 22 2023 - 07:31:45 EST
From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Add a new branch filter, "event", for the branch event option. It is
used to mark the events which should be logged in the branch. If it is
applied with the -j option, all the events should be logged in the
branch. If the legacy kernel doesn't support the new branch sample type,
switching off the branch event filter.
The new extension space of each branch is dumped right after the regular
branch stack information via perf report -D.
Usage examples:
perf record -e "{branch-instructions,branch-misses}:S" -j any,event
Only the first event, branch-instructions, collect the LBR. Both
branch-instructions and branch-misses are marked as logged events.
The occurrences information of them can be found in the branch stack
extension space of each branch.
perf record -e "{cpu/branch-instructions,branch_type=any/,
cpu/branch-misses,branch_type=event/}"
Only the first event, branch-instructions, collect the LBR. Only the
branch-misses event is marked as a logged event.
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
Notes: Since the new interfaces are still under review and may be
changed later, the perf tool patch only provides minimum support for the
current version. Once the interfaces are finalized, a more complete perf
tool patch can be expected.
Changes since V1:
- Drop the support of the event ID sample type
- Support the new branch stack extension
tools/perf/Documentation/perf-record.txt | 4 +++
tools/perf/util/branch.h | 8 ++++-
tools/perf/util/evsel.c | 39 ++++++++++++++++++++---
tools/perf/util/evsel.h | 6 ++++
tools/perf/util/parse-branch-options.c | 1 +
tools/perf/util/perf_event_attr_fprintf.c | 1 +
tools/perf/util/sample.h | 1 +
tools/perf/util/session.c | 8 +++++
8 files changed, 62 insertions(+), 6 deletions(-)
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index ff815c2f67e8..9183d9c414de 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -402,6 +402,10 @@ following filters are defined:
4th-Gen Xeon+ server), the save branch type is unconditionally enabled
when the taken branch stack sampling is enabled.
- priv: save privilege state during sampling in case binary is not available later
+ - event: save occurrences of the event since the last branch entry. Currently, the
+ feature is only supported by a newer CPU, e.g., Intel Sierra Forest and
+ later platforms. An error out is expected if it's used on the unsupported
+ kernel or CPUs.
+
The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
diff --git a/tools/perf/util/branch.h b/tools/perf/util/branch.h
index e41bfffe2217..f765b05bbe5f 100644
--- a/tools/perf/util/branch.h
+++ b/tools/perf/util/branch.h
@@ -25,7 +25,8 @@ struct branch_flags {
u64 spec:2;
u64 new_type:4;
u64 priv:3;
- u64 reserved:31;
+ u64 ext:1;
+ u64 reserved:30;
};
};
};
@@ -50,6 +51,11 @@ struct branch_stack {
struct branch_entry entries[];
};
+struct branch_stack_ext {
+ u64 nr;
+ u64 data[];
+};
+
/*
* The hw_idx is only available when PERF_SAMPLE_BRANCH_HW_INDEX is applied.
* Otherwise, the output format of a sample with branch stack is
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 51e8ce6edddc..19cc9272b669 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1850,6 +1850,8 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
static void evsel__disable_missing_features(struct evsel *evsel)
{
+ if (perf_missing_features.branch_event)
+ evsel->core.attr.branch_sample_type &= ~PERF_SAMPLE_BRANCH_EVT_CNTRS;
if (perf_missing_features.read_lost)
evsel->core.attr.read_format &= ~PERF_FORMAT_LOST;
if (perf_missing_features.weight_struct) {
@@ -1903,7 +1905,12 @@ bool evsel__detect_missing_features(struct evsel *evsel)
* Must probe features in the order they were added to the
* perf_event_attr interface.
*/
- if (!perf_missing_features.read_lost &&
+ if (!perf_missing_features.branch_event &&
+ (evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_EVT_CNTRS)) {
+ perf_missing_features.branch_event = true;
+ pr_debug2("switching off branch event support\n");
+ return true;
+ } else if (!perf_missing_features.read_lost &&
(evsel->core.attr.read_format & PERF_FORMAT_LOST)) {
perf_missing_features.read_lost = true;
pr_debug2("switching off PERF_FORMAT_LOST support\n");
@@ -2339,7 +2346,8 @@ u64 evsel__bitfield_swap_branch_flags(u64 value)
new_val |= bitfield_swap(value, 24, 2);
new_val |= bitfield_swap(value, 26, 4);
new_val |= bitfield_swap(value, 30, 3);
- new_val |= bitfield_swap(value, 33, 31);
+ new_val |= bitfield_swap(value, 33, 1);
+ new_val |= bitfield_swap(value, 34, 30);
} else {
new_val = bitfield_swap(value, 63, 1);
new_val |= bitfield_swap(value, 62, 1);
@@ -2350,7 +2358,8 @@ u64 evsel__bitfield_swap_branch_flags(u64 value)
new_val |= bitfield_swap(value, 38, 2);
new_val |= bitfield_swap(value, 34, 4);
new_val |= bitfield_swap(value, 31, 3);
- new_val |= bitfield_swap(value, 0, 31);
+ new_val |= bitfield_swap(value, 30, 1);
+ new_val |= bitfield_swap(value, 0, 30);
}
return new_val;
@@ -2550,7 +2559,8 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
if (type & PERF_SAMPLE_BRANCH_STACK) {
const u64 max_branch_nr = UINT64_MAX /
sizeof(struct branch_entry);
- struct branch_entry *e;
+ struct branch_entry *e, *e0;
+ bool has_ext = false;
unsigned int i;
OVERFLOW_CHECK_u64(array);
@@ -2571,7 +2581,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
*/
e = (struct branch_entry *)&data->branch_stack->hw_idx;
}
-
+ e0 = e;
if (swapped) {
/*
* struct branch_flag does not have endian
@@ -2589,6 +2599,25 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
OVERFLOW_CHECK(array, sz, max_size);
array = (void *)array + sz;
+
+ for (i = 0, e = e0; i < data->branch_stack->nr; i++, e++) {
+ if (e->flags.ext) {
+ has_ext = true;
+ break;
+ }
+ }
+
+ if (has_ext) {
+ OVERFLOW_CHECK_u64(array);
+
+ data->branch_stack_ext = (struct branch_stack_ext *)array++;
+ if (data->branch_stack_ext->nr > max_branch_nr)
+ return -EFAULT;
+ sz = data->branch_stack_ext->nr * sizeof(u64);
+
+ OVERFLOW_CHECK(array, sz, max_size);
+ array = (void *)array + sz;
+ }
}
if (type & PERF_SAMPLE_REGS_USER) {
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 24cb807ef6ce..aa666e24f8e6 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -187,6 +187,7 @@ struct perf_missing_features {
bool code_page_size;
bool weight_struct;
bool read_lost;
+ bool branch_event;
};
extern struct perf_missing_features perf_missing_features;
@@ -473,6 +474,11 @@ static inline bool evsel__has_branch_hw_idx(const struct evsel *evsel)
return evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX;
}
+static inline bool evsel__has_branch_evt_cntrs(const struct evsel *evsel)
+{
+ return evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_EVT_CNTRS;
+}
+
static inline bool evsel__has_callchain(const struct evsel *evsel)
{
/*
diff --git a/tools/perf/util/parse-branch-options.c b/tools/perf/util/parse-branch-options.c
index fd67d204d720..ab5d6dabe659 100644
--- a/tools/perf/util/parse-branch-options.c
+++ b/tools/perf/util/parse-branch-options.c
@@ -36,6 +36,7 @@ static const struct branch_mode branch_modes[] = {
BRANCH_OPT("stack", PERF_SAMPLE_BRANCH_CALL_STACK),
BRANCH_OPT("hw_index", PERF_SAMPLE_BRANCH_HW_INDEX),
BRANCH_OPT("priv", PERF_SAMPLE_BRANCH_PRIV_SAVE),
+ BRANCH_OPT("event", PERF_SAMPLE_BRANCH_EVT_CNTRS),
BRANCH_END
};
diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
index 7e5e7b30510d..3133a4f003eb 100644
--- a/tools/perf/util/perf_event_attr_fprintf.c
+++ b/tools/perf/util/perf_event_attr_fprintf.c
@@ -53,6 +53,7 @@ static void __p_branch_sample_type(char *buf, size_t size, u64 value)
bit_name(COND), bit_name(CALL_STACK), bit_name(IND_JUMP),
bit_name(CALL), bit_name(NO_FLAGS), bit_name(NO_CYCLES),
bit_name(TYPE_SAVE), bit_name(HW_INDEX), bit_name(PRIV_SAVE),
+ bit_name(EVT_CNTRS),
{ .name = NULL, }
};
#undef bit_name
diff --git a/tools/perf/util/sample.h b/tools/perf/util/sample.h
index 33b08e0ac746..62abae1c9cd3 100644
--- a/tools/perf/util/sample.h
+++ b/tools/perf/util/sample.h
@@ -101,6 +101,7 @@ struct perf_sample {
void *raw_data;
struct ip_callchain *callchain;
struct branch_stack *branch_stack;
+ struct branch_stack_ext *branch_stack_ext;
struct regs_dump user_regs;
struct regs_dump intr_regs;
struct stack_dump user_stack;
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 749d5b5c135b..a1e303c2eaa8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1159,6 +1159,7 @@ static void callchain__printf(struct evsel *evsel,
static void branch_stack__printf(struct perf_sample *sample, bool callstack)
{
struct branch_entry *entries = perf_sample__branch_entries(sample);
+ struct branch_stack_ext *branch_stack_ext = sample->branch_stack_ext;
uint64_t i;
if (!callstack) {
@@ -1200,6 +1201,13 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack)
}
}
}
+
+ if (branch_stack_ext) {
+ printf("... branch stack ext: nr:%" PRIu64 "\n", sample->branch_stack_ext->nr);
+ for (i = 0; i < branch_stack_ext->nr; i++) {
+ printf("..... %2"PRIu64": %016" PRIx64 "\n", i, branch_stack_ext->data[i]);
+ }
+ }
}
static void regs_dump__printf(u64 mask, u64 *regs, const char *arch)
--
2.35.1