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Commit 8c303960 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

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: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
parent a78d0dbe

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

+1 −0
Original line number Diff line number Diff line
@@ -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.

tools/testing/selftests/bpf/progs/loop5.c

0 → 100644
+32 −0
Original line number Diff line number Diff line 
// 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;

}