[PATCH v2 03/11] perf tests: Exercise the flexible array member path

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

No test covered find_flex_array() and get_flex_array_member().  Add one
that keeps a struct with a trailing data[] behind a global pointer and
checks that accesses past the struct size are resolved and named after
the flexible array member.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 .../perf/tests/shell/data_type_flex_array.sh  | 104 ++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100755 tools/perf/tests/shell/data_type_flex_array.sh

diff --git a/tools/perf/tests/shell/data_type_flex_array.sh b/tools/perf/tests/shell/data_type_flex_array.sh
new file mode 100755
index 0000000000000000..983cde2b3c7d2b29
--- /dev/null
+++ b/tools/perf/tests/shell/data_type_flex_array.sh
@@ -0,0 +1,104 @@
+#!/bin/bash
+# perf data type profiling tests for flexible array members
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+perfout=$(mktemp /tmp/__perf_test.perf.out.XXXXX)
+prog=$(mktemp /tmp/__perf_test.flex.XXXXX)
+src="${prog}.c"
+
+cleanup()
+{
+	rm -f "$perfdata" "$perfout" "$prog" "$src"
+	trap - EXIT TERM INT
+}
+
+trap_cleanup()
+{
+	echo "Unexpected signal in ${FUNCNAME[1]}"
+	cleanup
+	exit 1
+}
+trap trap_cleanup EXIT TERM INT
+
+# No point in recording if the PMU cannot do memory events.
+if perf mem record -o /dev/null -- true 2>&1 | \
+		grep -q "failed: no PMU supports the memory events"; then
+	cleanup
+	exit 2
+fi
+if ! perf mem record -o /dev/null -- true 2>/dev/null; then
+	echo "Skip: cannot record memory events on this PMU"
+	cleanup
+	exit 2
+fi
+
+cat > "$src" <<'EOF'
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+struct flex {
+	int len;
+	char data[];
+};
+
+static struct flex *gp;
+static volatile sig_atomic_t done;
+
+static void stop(int sig)
+{
+	done = 1;
+}
+
+int main(void)
+{
+	unsigned long sum = 0;
+
+	gp = calloc(1, sizeof(*gp) + 4096);
+	if (gp == NULL)
+		return 1;
+	gp->len = 4096;
+
+	signal(SIGALRM, stop);
+	alarm(1);
+
+	while (!done) {
+		sum += gp->data[3];
+		gp->data[5] = 1;
+	}
+	return sum != 0;
+}
+EOF
+
+# -fPIE keeps the global pointer load PC-relative on x86_64, so the
+# resolver can tell the register holds a struct flex pointer.
+if ! cc -O0 -g -fPIE -pie -o "$prog" "$src" 2>/dev/null; then
+	echo "Skip: cannot build the workload"
+	cleanup
+	exit 2
+fi
+
+if ! perf mem record -o "$perfdata" -- "$prog" > /dev/null 2>&1; then
+	echo "FAIL: perf mem record"
+	cleanup
+	exit 1
+fi
+
+if ! perf annotate --code-with-type -i "$perfdata" --stdio \
+		--percent-limit 1 > "$perfout" 2>/dev/null; then
+	echo "FAIL: perf annotate"
+	cleanup
+	exit 1
+fi
+
+if ! grep -Fq "# data-type: struct flex +0x4 (data)" "$perfout"; then
+	echo "FAIL: flexible array member not resolved"
+	cleanup
+	exit 1
+fi
+
+echo "flexible array member resolved"
+cleanup
-- 
2.56.0