From: Alexei Starovoitov <ast@kernel.org>
Date: Fri, 2 Aug 2019 16:23:40 -0700
Subject: selftests/bpf: add loop test 5
Patch-mainline: v5.4-rc1
Git-commit: 8c30396074c131765b19eb3cb7ff764a4f2f2913
References: bsc#1177028

Add a test with multiple exit conditions.
It's not an infinite loop only when the verifier can properly track
all math on variable 'i' through all possible ways of executing this loop.

barrier()s are needed to disable llvm optimization that combines multiple
branches into fewer branches.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Gary Lin <glin@suse.com>
---
 tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c |    1 
 tools/testing/selftests/bpf/progs/loop5.c                |   32 +++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/loop5.c

--- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
@@ -72,6 +72,7 @@ void test_bpf_verif_scale(void)
 		{ "loop1.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 		{ "loop2.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 		{ "loop4.o", BPF_PROG_TYPE_SCHED_CLS },
+		{ "loop5.o", BPF_PROG_TYPE_SCHED_CLS },
 
 		/* partial unroll. 19k insn in a loop.
 		 * Total program size 20.8k insn.
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/loop5.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+char _license[] SEC("license") = "GPL";
+
+SEC("socket")
+int while_true(volatile struct __sk_buff* skb)
+{
+	int i = 0;
+
+	while (1) {
+		if (skb->len)
+			i += 3;
+		else
+			i += 7;
+		if (i == 9)
+			break;
+		barrier();
+		if (i == 10)
+			break;
+		barrier();
+		if (i == 13)
+			break;
+		barrier();
+		if (i == 14)
+			break;
+	}
+	return i;
+}