[PATCH v1 1/5] perf/core: Define the common branch type classification

Jin Yao
2017-03-31T07:20:46Z

It is often useful to know the branch types while analyzing branch
data. For example, a call is very different from a conditional branch.

Currently we have to look it up in binary while the binary may later
not be available and even the binary is available but user has to take
some time. It is very useful for user to check it directly in perf
report.

Perf already has support for disassembling the branch instruction
to get the branch type. The branch type is defined in lbr.c.

To keep consistent on kernel and userspace and make the classification
more common, the patch adds the common branch type classification
in perf_event.h.

Since the disassembling of branch instruction needs some overhead,
a new PERF_SAMPLE_BRANCH_TYPE_SAVE is introduced to indicate if it
needs to disassemble the branch instruction and record the branch
type.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
include/uapi/linux/perf_event.h | 24 +++++++++++++++++++++++-
tools/include/uapi/linux/perf_event.h | 24 +++++++++++++++++++++++-
2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d09a9cd..4d731fd 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT = 14, /* no flags */
PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT = 15, /* no cycles */

+ PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT = 16, /* save branch type */
+
PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
};

@@ -198,9 +200,27 @@ enum perf_branch_sample_type {
PERF_SAMPLE_BRANCH_NO_FLAGS = 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
PERF_SAMPLE_BRANCH_NO_CYCLES = 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,

+ PERF_SAMPLE_BRANCH_TYPE_SAVE =
+ 1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
+
PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
};

+/*
+ * Common flow change classification
+ */
+enum {
+ PERF_BR_NONE = 0, /* unknown */
+ PERF_BR_JCC_FWD = 1 << 1, /* conditional forward jump */
+ PERF_BR_JCC_BWD = 1 << 2, /* conditional backward jump */
+ PERF_BR_JMP = 1 << 3, /* jump */
+ PERF_BR_IND_JMP = 1 << 4, /* indirect jump */
+ PERF_BR_CALL = 1 << 5, /* call */
+ PERF_BR_IND_CALL = 1 << 6, /* indirect call */
+ PERF_BR_RET = 1 << 7, /* return */
+ PERF_BR_FAR_BRANCH = 1 << 8, /* SYSCALL,SYSRET,IRQ,... */
+};
+
#define PERF_SAMPLE_BRANCH_PLM_ALL \
(PERF_SAMPLE_BRANCH_USER|\
PERF_SAMPLE_BRANCH_KERNEL|\
@@ -999,6 +1019,7 @@ union perf_mem_data_src {
* in_tx: running in a hardware transaction
* abort: aborting a hardware transaction
* cycles: cycles from last branch (or 0 if not supported)
+ * type: branch type
*/
struct perf_branch_entry {
__u64 from;
@@ -1008,7 +1029,8 @@ struct perf_branch_entry {
in_tx:1, /* in transaction */
abort:1, /* transaction abort */
cycles:16, /* cycle count to last branch */
- reserved:44;
+ type:9, /* branch type */
+ reserved:35;
};

#endif /* _UAPI_LINUX_PERF_EVENT_H */
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index d09a9cd..4d731fd 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT = 14, /* no flags */
PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT = 15, /* no cycles */

+ PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT = 16, /* save branch type */
+
PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
};

@@ -198,9 +200,27 @@ enum perf_branch_sample_type {
PERF_SAMPLE_BRANCH_NO_FLAGS = 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
PERF_SAMPLE_BRANCH_NO_CYCLES = 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,

+ PERF_SAMPLE_BRANCH_TYPE_SAVE =
+ 1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
+
PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
};

+/*
+ * Common flow change classification
+ */
+enum {
+ PERF_BR_NONE = 0, /* unknown */
+ PERF_BR_JCC_FWD = 1 << 1, /* conditional forward jump */
+ PERF_BR_JCC_BWD = 1 << 2, /* conditional backward jump */
+ PERF_BR_JMP = 1 << 3, /* jump */
+ PERF_BR_IND_JMP = 1 << 4, /* indirect jump */
+ PERF_BR_CALL = 1 << 5, /* call */
+ PERF_BR_IND_CALL = 1 << 6, /* indirect call */
+ PERF_BR_RET = 1 << 7, /* return */
+ PERF_BR_FAR_BRANCH = 1 << 8, /* SYSCALL,SYSRET,IRQ,... */
+};
+
#define PERF_SAMPLE_BRANCH_PLM_ALL \
(PERF_SAMPLE_BRANCH_USER|\
PERF_SAMPLE_BRANCH_KERNEL|\
@@ -999,6 +1019,7 @@ union perf_mem_data_src {
* in_tx: running in a hardware transaction
* abort: aborting a hardware transaction
* cycles: cycles from last branch (or 0 if not supported)
+ * type: branch type
*/
struct perf_branch_entry {
__u64 from;
@@ -1008,7 +1029,8 @@ struct perf_branch_entry {
in_tx:1, /* in transaction */
abort:1, /* transaction abort */
cycles:16, /* cycle count to last branch */
- reserved:44;
+ type:9, /* branch type */
+ reserved:35;
};

#endif /* _UAPI_LINUX_PERF_EVENT_H */
--
2.7.4