netdev - Re: [PATCH bpf-next] selftests/bpf: ensure core_reloc_kernel is reading test

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Date:   Thu, 21 Nov 2019 23:26:59 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next] selftests/bpf: ensure core_reloc_kernel is
 reading test_progs's data only

On Thu, Nov 21, 2019 at 9:59 AM Andrii Nakryiko <andriin@...com> wrote:
>
> test_core_reloc_kernel.c selftest is the only CO-RE test that reads and
> returns for validation calling thread's information (pid, tgid, comm). Thus it
> has to make sure that only test_prog's invocations are honored.
>
> Fixes: df36e621418b ("selftests/bpf: add CO-RE relocs testing setup")
> Reported-by: Alexei Starovoitov <ast@...nel.org>
> Signed-off-by: Andrii Nakryiko <andriin@...com>
> ---
>  .../selftests/bpf/prog_tests/core_reloc.c        | 16 +++++++++++-----
>  .../selftests/bpf/progs/test_core_reloc_kernel.c |  4 ++++
>  2 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> index ec9e2fdd6b89..05fe85281ff7 100644
> --- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> +++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> @@ -2,6 +2,7 @@
>  #include <test_progs.h>
>  #include "progs/core_reloc_types.h"
>  #include <sys/mman.h>
> +#include <sys/syscall.h>
>
>  #define STRUCT_TO_CHAR_PTR(struct_name) (const char *)&(struct struct_name)
>
> @@ -452,6 +453,7 @@ static struct core_reloc_test_case test_cases[] = {
>  struct data {
>         char in[256];
>         char out[256];
> +       uint64_t my_pid_tgid;
>  };
>
>  static size_t roundup_page(size_t sz)
> @@ -471,9 +473,12 @@ void test_core_reloc(void)
>         struct bpf_map *data_map;
>         struct bpf_program *prog;
>         struct bpf_object *obj;
> +       uint64_t my_pid_tgid;
>         struct data *data;
>         void *mmap_data = NULL;
>
> +       my_pid_tgid = getpid() | ((uint64_t)syscall(SYS_gettid) << 32);
> +
>         for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
>                 test_case = &test_cases[i];
>                 if (!test__start_subtest(test_case->case_name))
> @@ -517,11 +522,6 @@ void test_core_reloc(void)
>                                 goto cleanup;
>                 }
>
> -               link = bpf_program__attach_raw_tracepoint(prog, tp_name);
> -               if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
> -                         PTR_ERR(link)))
> -                       goto cleanup;
> -
>                 data_map = bpf_object__find_map_by_name(obj, "test_cor.bss");
>                 if (CHECK(!data_map, "find_data_map", "data map not found\n"))
>                         goto cleanup;
> @@ -537,6 +537,12 @@ void test_core_reloc(void)
>
>                 memset(mmap_data, 0, sizeof(*data));
>                 memcpy(data->in, test_case->input, test_case->input_len);
> +               data->my_pid_tgid = my_pid_tgid;
> +
> +               link = bpf_program__attach_raw_tracepoint(prog, tp_name);
> +               if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
> +                         PTR_ERR(link)))
> +                       goto cleanup;
>
>                 /* trigger test run */
>                 usleep(1);
> diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> index a4b5e0562ed5..d2fe8f337846 100644
> --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> @@ -11,6 +11,7 @@ char _license[] SEC("license") = "GPL";
>  static volatile struct data {
>         char in[256];
>         char out[256];
> +       uint64_t my_pid_tgid;
>  } data;

There was a conflict here, since global data support patchset was
already applied.
I resolved it and applied to bpf-next.
Thanks