On 8/31/22 02:41, Arnaldo Carvalho de Melo wrote:

Em Wed, Aug 24, 2022 at 10:18:20AM +0530, Anshuman Khandual escreveu:

quoted

This updates the perf tool with generic branch type classification with new
ABI extender place holder i.e PERF_BR_EXTEND_ABI, the new 4 bit branch type
field i.e perf_branch_entry.new_type, new generic page fault related branch
types and some arch specific branch types as added earlier in the kernel.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <redacted>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <redacted>
---
 tools/include/uapi/linux/perf_event.h | 16 ++++++++-
 tools/perf/builtin-script.c           |  2 +-
 tools/perf/util/branch.c              | 52 ++++++++++++++++++++++++++-
 tools/perf/util/branch.h              |  6 +++-
 tools/perf/util/session.c             |  2 +-
 5 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 146c137ff0c1..0f7c7ce29899 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h

@@ -255,9 +255,22 @@ enum {
 	PERF_BR_IRQ		= 12,	/* irq */
 	PERF_BR_SERROR		= 13,	/* system error */
 	PERF_BR_NO_TX		= 14,	/* not in transaction */
+	PERF_BR_EXTEND_ABI	= 15,	/* extend ABI */
 	PERF_BR_MAX,
 };
 
+enum {
+	PERF_BR_NEW_FAULT_ALGN		= 0,    /* Alignment fault */
+	PERF_BR_NEW_FAULT_DATA		= 1,    /* Data fault */
+	PERF_BR_NEW_FAULT_INST		= 2,    /* Inst fault */
+	PERF_BR_NEW_ARCH_1		= 3,    /* Architecture specific */
+	PERF_BR_NEW_ARCH_2		= 4,    /* Architecture specific */
+	PERF_BR_NEW_ARCH_3		= 5,    /* Architecture specific */
+	PERF_BR_NEW_ARCH_4		= 6,    /* Architecture specific */
+	PERF_BR_NEW_ARCH_5		= 7,    /* Architecture specific */
+	PERF_BR_NEW_MAX,
+};
+
 #define PERF_SAMPLE_BRANCH_PLM_ALL \
 	(PERF_SAMPLE_BRANCH_USER|\
 	 PERF_SAMPLE_BRANCH_KERNEL|\

@@ -1375,7 +1388,8 @@ struct perf_branch_entry {
 		abort:1,    /* transaction abort */
 		cycles:16,  /* cycle count to last branch */
 		type:4,     /* branch type */
-		reserved:40;
+		new_type:4, /* additional branch type */
+		reserved:36;
 };
 
 union perf_sample_weight {

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 13580a9c50b8..585171479876 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c

@@ -877,7 +877,7 @@ static int print_bstack_flags(FILE *fp, struct branch_entry *br)
 		       br->flags.in_tx ? 'X' : '-',
 		       br->flags.abort ? 'A' : '-',
 		       br->flags.cycles,
-		       br->flags.type ? branch_type_name(br->flags.type) : "-");
+		       get_branch_type(br));
 }
 
 static int perf_sample__fprintf_brstack(struct perf_sample *sample,

diff --git a/tools/perf/util/branch.c b/tools/perf/util/branch.c
index abc673347bee..6d962b0a4532 100644
--- a/tools/perf/util/branch.c
+++ b/tools/perf/util/branch.c

@@ -21,7 +21,10 @@ void branch_type_count(struct branch_type_stat *st, struct branch_flags *flags,
 	if (flags->type == PERF_BR_UNKNOWN || from == 0)
 		return;
 
-	st->counts[flags->type]++;
+	if (flags->type == PERF_BR_EXTEND_ABI)
+		st->new_counts[flags->new_type]++;
+	else
+		st->counts[flags->type]++;
 
 	if (flags->type == PERF_BR_COND) {
 		if (to > from)

@@ -36,6 +39,25 @@ void branch_type_count(struct branch_type_stat *st, struct branch_flags *flags,
 		st->cross_4k++;
 }
 
+const char *branch_new_type_name(int new_type)
+{
+	const char *branch_new_names[PERF_BR_NEW_MAX] = {
+		"FAULT_ALGN",
+		"FAULT_DATA",
+		"FAULT_INST",
+		"ARCH_1",
+		"ARCH_2",
+		"ARCH_3",
+		"ARCH_4",
+		"ARCH_5"
+	};
+
+	if (new_type >= 0 && new_type < PERF_BR_NEW_MAX)
+		return branch_new_names[new_type];
+
+	return NULL;
+}
+
 const char *branch_type_name(int type)
 {
 	const char *branch_names[PERF_BR_MAX] = {

@@ -62,6 +84,17 @@ const char *branch_type_name(int type)
 	return NULL;
 }
 
+const char *get_branch_type(struct branch_entry *e)
+{
+	if (e->flags.type == PERF_BR_UNKNOWN)
+		return "";
+
+	if (e->flags.type == PERF_BR_EXTEND_ABI)
+		return branch_new_type_name(e->flags.new_type);
+
+	return branch_type_name(e->flags.type);
+}
+
 void branch_type_stat_display(FILE *fp, struct branch_type_stat *st)
 {
 	u64 total = 0;

@@ -108,6 +141,15 @@ void branch_type_stat_display(FILE *fp, struct branch_type_stat *st)
 				100.0 *
 				(double)st->counts[i] / (double)total);
 	}
+
+	for (i = 0; i < PERF_BR_NEW_MAX; i++) {
+		if (st->new_counts[i] > 0)
+			fprintf(fp, "\n%8s: %5.1f%%",
+				branch_new_type_name(i),
+				100.0 *
+				(double)st->new_counts[i] / (double)total);
+	}
+

Strange:

  75     8.89 ubuntu:20.04-x-powerpc64el    : FAIL gcc version 10.3.0 (Ubuntu 10.3.0-1ubuntu1~20.04)
        inlined from 'branch_type_stat_display' at util/branch.c:152:4:
    /usr/powerpc64le-linux-gnu/include/bits/stdio2.h:100:10: error: '%8s' directive argument is null [-Werror=format-overflow=]
      100 |   return __fprintf_chk (__stream, __USE_FORTIFY_LEVEL - 1, __fmt,
          |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      101 |    __va_arg_pack ());
          |    ~~~~~~~~~~~~~~~~~

Indeed. But this new code block here looks exact same like the previous and existing one
i.e with branch_new_name() and PERF_BR_NEW_MAX. The complain is that - '%8s' directive
argument is NULL. This warning might just be a false positive [1], because of a compiler
problem on powerpc64el ? But please do let me know if something needs to be changed here
to avoid this warning.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90036

- Anshuman

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