1 files changed, 60 insertions, 0 deletions
diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
new file mode 100644
index 000000000..7981c69ed
--- /dev/null
+++ b/tools/perf/tests/bpf-script-example.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bpf-script-example.c
+ * Test basic LLVM building
+ */
+#ifndef LINUX_VERSION_CODE
+# error Need LINUX_VERSION_CODE
+# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
+#endif
+#define BPF_ANY 0
+#define BPF_MAP_TYPE_ARRAY 2
+#define BPF_FUNC_map_lookup_elem 1
+#define BPF_FUNC_map_update_elem 2
+
+static void *(*bpf_map_lookup_elem)(void *map, void *key) =
+	(void *) BPF_FUNC_map_lookup_elem;
+static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
+	(void *) BPF_FUNC_map_update_elem;
+
+/*
+ * Following macros are taken from tools/lib/bpf/bpf_helpers.h,
+ * and are used to create BTF defined maps. It is easier to take
+ * 2 simple macros, than being able to include above header in
+ * runtime.
+ *
+ * __uint - defines integer attribute of BTF map definition,
+ * Such attributes are represented using a pointer to an array,
+ * in which dimensionality of array encodes specified integer
+ * value.
+ *
+ * __type - defines pointer variable with typeof(val) type for
+ * attributes like key or value, which will be defined by the
+ * size of the type.
+ */
+#define __uint(name, val) int (*name)[val]
+#define __type(name, val) typeof(val) *name
+
+#define SEC(NAME) __attribute__((section(NAME), used))
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__type(value, int);
+} flip_table SEC(".maps");
+
+SEC("func=do_epoll_wait")
+int bpf_func__SyS_epoll_pwait(void *ctx)
+{
+	int ind =0;
+	int *flag = bpf_map_lookup_elem(&flip_table, &ind);
+	int new_flag;
+	if (!flag)
+		return 0;
+	/* flip flag and store back */
+	new_flag = !*flag;
+	bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
+	return new_flag;
+}
+char _license[] SEC("license") = "GPL";
+int _version SEC("version") = LINUX_VERSION_CODE;