1 files changed, 225 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/bpf_loop.c b/tools/testing/selftests/bpf/progs/bpf_loop.c
new file mode 100644
index 000000000000..1d194455b109
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_loop.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct callback_ctx {
+	int output;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 32);
+	__type(key, int);
+	__type(value, int);
+} map1 SEC(".maps");
+
+/* These should be set by the user program */
+u32 nested_callback_nr_loops;
+u32 stop_index = -1;
+u32 nr_loops;
+int pid;
+int callback_selector;
+
+/* Making these global variables so that the userspace program
+ * can verify the output through the skeleton
+ */
+int nr_loops_returned;
+int g_output;
+int err;
+
+static int callback(__u32 index, void *data)
+{
+	struct callback_ctx *ctx = data;
+
+	if (index >= stop_index)
+		return 1;
+
+	ctx->output += index;
+
+	return 0;
+}
+
+static int empty_callback(__u32 index, void *data)
+{
+	return 0;
+}
+
+static int nested_callback2(__u32 index, void *data)
+{
+	nr_loops_returned += bpf_loop(nested_callback_nr_loops, callback, data, 0);
+
+	return 0;
+}
+
+static int nested_callback1(__u32 index, void *data)
+{
+	bpf_loop(nested_callback_nr_loops, nested_callback2, data, 0);
+	return 0;
+}
+
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int test_prog(void *ctx)
+{
+	struct callback_ctx data = {};
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	nr_loops_returned = bpf_loop(nr_loops, callback, &data, 0);
+
+	if (nr_loops_returned < 0)
+		err = nr_loops_returned;
+	else
+		g_output = data.output;
+
+	return 0;
+}
+
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int prog_null_ctx(void *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	nr_loops_returned = bpf_loop(nr_loops, empty_callback, NULL, 0);
+
+	return 0;
+}
+
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int prog_invalid_flags(void *ctx)
+{
+	struct callback_ctx data = {};
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	err = bpf_loop(nr_loops, callback, &data, 1);
+
+	return 0;
+}
+
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int prog_nested_calls(void *ctx)
+{
+	struct callback_ctx data = {};
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	nr_loops_returned = 0;
+	bpf_loop(nr_loops, nested_callback1, &data, 0);
+
+	g_output = data.output;
+
+	return 0;
+}
+
+static int callback_set_f0(int i, void *ctx)
+{
+	g_output = 0xF0;
+	return 0;
+}
+
+static int callback_set_0f(int i, void *ctx)
+{
+	g_output = 0x0F;
+	return 0;
+}
+
+/*
+ * non-constant callback is a corner case for bpf_loop inline logic
+ */
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int prog_non_constant_callback(void *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	int (*callback)(int i, void *ctx);
+
+	g_output = 0;
+
+	if (callback_selector == 0x0F)
+		callback = callback_set_0f;
+	else
+		callback = callback_set_f0;
+
+	bpf_loop(1, callback, NULL, 0);
+
+	return 0;
+}
+
+static int stack_check_inner_callback(void *ctx)
+{
+	return 0;
+}
+
+static int map1_lookup_elem(int key)
+{
+	int *val = bpf_map_lookup_elem(&map1, &key);
+
+	return val ? *val : -1;
+}
+
+static void map1_update_elem(int key, int val)
+{
+	bpf_map_update_elem(&map1, &key, &val, BPF_ANY);
+}
+
+static int stack_check_outer_callback(void *ctx)
+{
+	int a = map1_lookup_elem(1);
+	int b = map1_lookup_elem(2);
+	int c = map1_lookup_elem(3);
+	int d = map1_lookup_elem(4);
+	int e = map1_lookup_elem(5);
+	int f = map1_lookup_elem(6);
+
+	bpf_loop(1, stack_check_inner_callback, NULL, 0);
+
+	map1_update_elem(1, a + 1);
+	map1_update_elem(2, b + 1);
+	map1_update_elem(3, c + 1);
+	map1_update_elem(4, d + 1);
+	map1_update_elem(5, e + 1);
+	map1_update_elem(6, f + 1);
+
+	return 0;
+}
+
+/* Some of the local variables in stack_check and
+ * stack_check_outer_callback would be allocated on stack by
+ * compiler. This test should verify that stack content for these
+ * variables is preserved between calls to bpf_loop (might be an issue
+ * if loop inlining allocates stack slots incorrectly).
+ */
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int stack_check(void *ctx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	int a = map1_lookup_elem(7);
+	int b = map1_lookup_elem(8);
+	int c = map1_lookup_elem(9);
+	int d = map1_lookup_elem(10);
+	int e = map1_lookup_elem(11);
+	int f = map1_lookup_elem(12);
+
+	bpf_loop(1, stack_check_outer_callback, NULL, 0);
+
+	map1_update_elem(7,  a + 1);
+	map1_update_elem(8, b + 1);
+	map1_update_elem(9, c + 1);
+	map1_update_elem(10, d + 1);
+	map1_update_elem(11, e + 1);
+	map1_update_elem(12, f + 1);
+
+	return 0;
+}