On 8/2/19 4:33 PM, Alexei Starovoitov wrote:
> 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.
Agreed with motivation of this test.
>
> barrier()s are needed to disable llvm optimization that combines multiple
> branches into fewer branches.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> .../bpf/prog_tests/bpf_verif_scale.c | 1 +
> tools/testing/selftests/bpf/progs/loop5.c | 37 +++++++++++++++++++
> 2 files changed, 38 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/loop5.c
>
> 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 757e39540eda..29615a4a9362 100644
> --- 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_RAW_TRACEPOINT }, > + { "loop5.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
More like a BPF_PROG_TYPE_SCHED_CLS type although probably it does not
matter as we did not attach it to anywhere?
>
> /* 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
> index 000000000000..9d9817efe208
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/loop5.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 Facebook
> +#include <linux/sched.h>
> +#include <linux/ptrace.h>
The above headers probably not needed.
> +#include <stdint.h>
> +#include <stddef.h>
> +#include <stdbool.h>
> +#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 (true) {
> + 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;
> +}
>
