On Tue, Jun 30, 2020 at 11:46 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Add two tests for PTR_TO_BTF_ID vs. null ptr comparison,
> one for PTR_TO_BTF_ID in the ctx structure and the
> other for PTR_TO_BTF_ID after one level pointer chasing.
> In both cases, the test ensures condition is not
> removed.
>
> For example, for this test
> struct bpf_fentry_test_t {
> struct bpf_fentry_test_t *a;
> };
> int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> {
> if (arg == 0)
> test7_result = 1;
> return 0;
> }
> Before the previous verifier change, we have xlated codes:
> int test7(long long unsigned int * ctx):
> ; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> 0: (79) r1 = *(u64 *)(r1 +0)
> ; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> 1: (b4) w0 = 0
> 2: (95) exit
> After the previous verifier change, we have:
> int test7(long long unsigned int * ctx):
> ; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> 0: (79) r1 = *(u64 *)(r1 +0)
> ; if (arg == 0)
> 1: (55) if r1 != 0x0 goto pc+4
> ; test7_result = 1;
> 2: (18) r1 = map[id:6][0]+48
> 4: (b7) r2 = 1
> 5: (7b) *(u64 *)(r1 +0) = r2
> ; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> 6: (b4) w0 = 0
> 7: (95) exit
>
> Cc: Andrii Nakryiko <andriin@xxxxxx>
> Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> Cc: Wenbo Zhang <ethercflow@xxxxxxxxx>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
LGTM, two nits below.
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> net/bpf/test_run.c | 19 +++++++++++++++-
> .../selftests/bpf/prog_tests/fentry_fexit.c | 2 +-
> .../testing/selftests/bpf/progs/fentry_test.c | 22 +++++++++++++++++++
> .../testing/selftests/bpf/progs/fexit_test.c | 22 +++++++++++++++++++
> 4 files changed, 63 insertions(+), 2 deletions(-)
>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/fentry_test.c b/tools/testing/selftests/bpf/progs/fentry_test.c
> index 9365b686f84b..5f645fdaba6f 100644
> --- a/tools/testing/selftests/bpf/progs/fentry_test.c
> +++ b/tools/testing/selftests/bpf/progs/fentry_test.c
> @@ -55,3 +55,25 @@ int BPF_PROG(test6, __u64 a, void *b, short c, int d, void * e, __u64 f)
> e == (void *)20 && f == 21;
> return 0;
> }
> +
> +struct bpf_fentry_test_t {
> + struct bpf_fentry_test_t *a;
> +};
nit: __attribute__((preserve_access_index)) ?
> +
> +__u64 test7_result = 0;
> +SEC("fentry/bpf_fentry_test7")
> +int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> +{
> + if (arg == 0)
> + test7_result = 1;
> + return 0;
> +}
> +
> +__u64 test8_result = 0;
> +SEC("fentry/bpf_fentry_test8")
> +int BPF_PROG(test8, struct bpf_fentry_test_t *arg)
> +{
> + if (arg->a == 0)
> + test8_result = 1;
> + return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/progs/fexit_test.c b/tools/testing/selftests/bpf/progs/fexit_test.c
> index bd1e17d8024c..0952affb22a6 100644
> --- a/tools/testing/selftests/bpf/progs/fexit_test.c
> +++ b/tools/testing/selftests/bpf/progs/fexit_test.c
> @@ -56,3 +56,25 @@ int BPF_PROG(test6, __u64 a, void *b, short c, int d, void *e, __u64 f, int ret)
> e == (void *)20 && f == 21 && ret == 111;
> return 0;
> }
> +
> +struct bpf_fentry_test_t {
> + struct bpf_fentry_test *a;
> +};
same nit
> +
> +__u64 test7_result = 0;
> +SEC("fexit/bpf_fentry_test7")
> +int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
> +{
> + if (arg == 0)
> + test7_result = 1;
> + return 0;
> +}
> +
> +__u64 test8_result = 0;
> +SEC("fexit/bpf_fentry_test8")
> +int BPF_PROG(test8, struct bpf_fentry_test_t *arg)
> +{
> + if (arg->a == 0)
> + test8_result = 1;
> + return 0;
> +}
> --
> 2.24.1
>
