linux-kernel - [PATCH 4/4] perf session: Show branch speculation info in raw dump

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Date:   Thu, 11 Aug 2022 18:16:49 +0530
From:   Sandipan Das <sandipan.das@....com>
To:     <linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
        <x86@...nel.org>
CC:     <peterz@...radead.org>, <bp@...en8.de>, <acme@...nel.org>,
        <namhyung@...nel.org>, <jolsa@...nel.org>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <mark.rutland@....com>,
        <alexander.shishkin@...ux.intel.com>,
        <dave.hansen@...ux.intel.com>, <like.xu.linux@...il.com>,
        <eranian@...gle.com>, <ananth.narayan@....com>,
        <ravi.bangoria@....com>, <santosh.shukla@....com>,
        <sandipan.das@....com>
Subject: [PATCH 4/4] perf session: Show branch speculation info in raw dump

Show the branch speculation info if provided by the branch recording
hardware feature. This can be useful for optimizing code further.

E.g.

  $ perf record -j any,u ./test_branch
  $ perf report --dump-raw-trace

Before:

  [...]
  8380958377610 0x40b178 [0x1b0]: PERF_RECORD_SAMPLE(IP, 0x2): 7952/7952: 0x4f851a period: 48973 addr: 0
  ... branch stack: nr:16
  .....  0: 00000000004b52fd -> 00000000004f82c0 0 cycles  P   0
  .....  1: ffffffff8220137c -> 00000000004b52f0 0 cycles M    0
  .....  2: 000000000041d1c4 -> 00000000004b52f0 0 cycles  P   0
  .....  3: 00000000004e7ead -> 000000000041d1b0 0 cycles M    0
  .....  4: 00000000004e7f91 -> 00000000004e7ead 0 cycles  P   0
  .....  5: 00000000004e7ea8 -> 00000000004e7f70 0 cycles  P   0
  .....  6: 00000000004e7e52 -> 00000000004e7e98 0 cycles M    0
  .....  7: 00000000004e7e1f -> 00000000004e7e40 0 cycles M    0
  .....  8: 00000000004e7f60 -> 00000000004e7df0 0 cycles  P   0
  .....  9: 00000000004e7f58 -> 00000000004e7f60 0 cycles M    0
  ..... 10: 000000000041d85d -> 00000000004e7f50 0 cycles  P   0
  ..... 11: 000000000043306a -> 000000000041d840 0 cycles  P   0
  ..... 12: ffffffff8220137c -> 0000000000433040 0 cycles M    0
  ..... 13: 000000000041e4a1 -> 0000000000433040 0 cycles  P   0
  ..... 14: ffffffff8220137c -> 000000000041e490 0 cycles M    0
  ..... 15: 000000000041d89b -> 000000000041e487 0 cycles  P   0
   ... thread: test_branch:7952
   ...... dso: /data/sandipan/test_branch
  [...]

After:

  [...]
  8380958377610 0x40b178 [0x1b0]: PERF_RECORD_SAMPLE(IP, 0x2): 7952/7952: 0x4f851a period: 48973 addr: 0
  ... branch stack: nr:16
  .....  0: 00000000004b52fd -> 00000000004f82c0 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  .....  1: ffffffff8220137c -> 00000000004b52f0 0 cycles M    0  NON_SPEC_CORRECT_PATH
  .....  2: 000000000041d1c4 -> 00000000004b52f0 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  .....  3: 00000000004e7ead -> 000000000041d1b0 0 cycles M    0  NON_SPEC_CORRECT_PATH
  .....  4: 00000000004e7f91 -> 00000000004e7ead 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  .....  5: 00000000004e7ea8 -> 00000000004e7f70 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  .....  6: 00000000004e7e52 -> 00000000004e7e98 0 cycles M    0  SPEC_CORRECT_PATH
  .....  7: 00000000004e7e1f -> 00000000004e7e40 0 cycles M    0  NON_SPEC_CORRECT_PATH
  .....  8: 00000000004e7f60 -> 00000000004e7df0 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  .....  9: 00000000004e7f58 -> 00000000004e7f60 0 cycles M    0  NON_SPEC_CORRECT_PATH
  ..... 10: 000000000041d85d -> 00000000004e7f50 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  ..... 11: 000000000043306a -> 000000000041d840 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  ..... 12: ffffffff8220137c -> 0000000000433040 0 cycles M    0  NON_SPEC_CORRECT_PATH
  ..... 13: 000000000041e4a1 -> 0000000000433040 0 cycles  P   0  NON_SPEC_CORRECT_PATH
  ..... 14: ffffffff8220137c -> 000000000041e490 0 cycles M    0  NON_SPEC_CORRECT_PATH
  ..... 15: 000000000041d89b -> 000000000041e487 0 cycles  P   0  NON_SPEC_CORRECT_PATH
   ... thread: test_branch:7952
   ...... dso: /data/sandipan/test_branch
  [...]

Signed-off-by: Sandipan Das <sandipan.das@....com>
---
 tools/perf/util/session.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 98e16659a149..39ba4a21aa42 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1172,7 +1172,7 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack)
 		struct branch_entry *e = &entries[i];
 
 		if (!callstack) {
-			printf("..... %2"PRIu64": %016" PRIx64 " -> %016" PRIx64 " %hu cycles %s%s%s%s %x %s\n",
+			printf("..... %2"PRIu64": %016" PRIx64 " -> %016" PRIx64 " %hu cycles %s%s%s%s %x %s %s\n",
 				i, e->from, e->to,
 				(unsigned short)e->flags.cycles,
 				e->flags.mispred ? "M" : " ",
@@ -1180,7 +1180,8 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack)
 				e->flags.abort ? "A" : " ",
 				e->flags.in_tx ? "T" : " ",
 				(unsigned)e->flags.reserved,
-				e->flags.type ? branch_type_name(e->flags.type) : "");
+				e->flags.type ? branch_type_name(e->flags.type) : "",
+				e->flags.spec ? branch_spec_desc(e->flags.spec) : "");
 		} else {
 			if (i == 0) {
 				printf("..... %2"PRIu64": %016" PRIx64 "\n"
-- 
2.34.1