selftests/bpf: add loop test 5

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>

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
index e9e72d8d7aaedf6639a7832ce4e42f2e679909cc..0caf8eafa9ebc9539285cfa2961baebb3850b88c 100644 (file)
--- 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.

diff --git a/tools/testing/selftests/bpf/progs/loop5.c b/tools/testing/selftests/bpf/progs/loop5.c
new file mode 100644 (file)
index 0000000..28d1d66
--- /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;
+}