Re: [bpf-next v3 11/12] selftests/bpf: Add tests for bpf_prog_test_run for perf events progs

[Andrii Nakryiko]

On Mon, Jul 8, 2019 at 3:42 PM Krzesimir Nowak <krzesimir@xxxxxxxxxx> wrote:
>
> The tests check if ctx and data are correctly prepared from ctx_in and
> data_in, so accessing the ctx and using the bpf_perf_prog_read_value
> work as expected.
>

These are x86_64-specific tests, aren't they? Should probably guard
them behind #ifdef's.

> Signed-off-by: Krzesimir Nowak <krzesimir@xxxxxxxxxx>
> ---
>  tools/testing/selftests/bpf/test_verifier.c   | 48 ++++++++++
>  .../selftests/bpf/verifier/perf_event_run.c   | 96 +++++++++++++++++++
>  2 files changed, 144 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/verifier/perf_event_run.c
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index 6f124cc4ee34..484ea8842b06 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -295,6 +295,54 @@ static void bpf_fill_scale(struct bpf_test *self)
>         }
>  }
>
> +static void bpf_fill_perf_event_test_run_check(struct bpf_test *self)
> +{
> +       compiletime_assert(
> +               sizeof(struct bpf_perf_event_data) <= TEST_CTX_LEN,
> +               "buffer for ctx is too short to fit struct bpf_perf_event_data");
> +       compiletime_assert(
> +               sizeof(struct bpf_perf_event_value) <= TEST_DATA_LEN,
> +               "buffer for data is too short to fit struct bpf_perf_event_value");
> +
> +       struct bpf_perf_event_data ctx = {
> +               .regs = (bpf_user_pt_regs_t) {
> +                       .r15 = 1,
> +                       .r14 = 2,
> +                       .r13 = 3,
> +                       .r12 = 4,
> +                       .rbp = 5,
> +                       .rbx = 6,
> +                       .r11 = 7,
> +                       .r10 = 8,
> +                       .r9 = 9,
> +                       .r8 = 10,
> +                       .rax = 11,
> +                       .rcx = 12,
> +                       .rdx = 13,
> +                       .rsi = 14,
> +                       .rdi = 15,
> +                       .orig_rax = 16,
> +                       .rip = 17,
> +                       .cs = 18,
> +                       .eflags = 19,
> +                       .rsp = 20,
> +                       .ss = 21,
> +               },
> +               .sample_period = 1,
> +               .addr = 2,
> +       };
> +       struct bpf_perf_event_value data = {
> +               .counter = 1,
> +               .enabled = 2,
> +               .running = 3,
> +       };
> +
> +       memcpy(self->ctx, &ctx, sizeof(ctx));
> +       memcpy(self->data, &data, sizeof(data));

Just curious, just assignment didn't work?

> +       free(self->fill_insns);
> +       self->fill_insns = NULL;
> +}
> +
>  /* BPF_SK_LOOKUP contains 13 instructions, if you need to fix up maps */
>  #define BPF_SK_LOOKUP(func)                                            \
>         /* struct bpf_sock_tuple tuple = {} */                          \
> diff --git a/tools/testing/selftests/bpf/verifier/perf_event_run.c b/tools/testing/selftests/bpf/verifier/perf_event_run.c
> new file mode 100644
> index 000000000000..3f877458a7f8
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/verifier/perf_event_run.c
> @@ -0,0 +1,96 @@
> +#define PER_LOAD_AND_CHECK_PTREG(PT_REG_FIELD, VALUE)                  \
> +       PER_LOAD_AND_CHECK_CTX(offsetof(bpf_user_pt_regs_t, PT_REG_FIELD), VALUE)
> +#define PER_LOAD_AND_CHECK_EVENT(PED_FIELD, VALUE)                     \
> +       PER_LOAD_AND_CHECK_CTX(offsetof(struct bpf_perf_event_data, PED_FIELD), VALUE)
> +#define PER_LOAD_AND_CHECK_CTX(OFFSET, VALUE)                          \
> +       PER_LOAD_AND_CHECK_64(BPF_REG_4, BPF_REG_1, OFFSET, VALUE)
> +#define PER_LOAD_AND_CHECK_VALUE(PEV_FIELD, VALUE)                     \
> +       PER_LOAD_AND_CHECK_64(BPF_REG_7, BPF_REG_6, offsetof(struct bpf_perf_event_value, PEV_FIELD), VALUE)

Wrap long lines? Try also running scripts/checkpatch.pl again these
files you are modifying.

> +#define PER_LOAD_AND_CHECK_64(DST, SRC, OFFSET, VALUE)                 \
> +       BPF_LDX_MEM(BPF_DW, DST, SRC, OFFSET),                          \
> +       BPF_JMP_IMM(BPF_JEQ, DST, VALUE, 2),                            \
> +       BPF_MOV64_IMM(BPF_REG_0, VALUE),                                \
> +       BPF_EXIT_INSN()
> +
> +{
> +       "check if regs contain expected values",
> +       .insns = {
> +       PER_LOAD_AND_CHECK_PTREG(r15, 1),
> +       PER_LOAD_AND_CHECK_PTREG(r14, 2),
> +       PER_LOAD_AND_CHECK_PTREG(r13, 3),
> +       PER_LOAD_AND_CHECK_PTREG(r12, 4),
> +       PER_LOAD_AND_CHECK_PTREG(rbp, 5),
> +       PER_LOAD_AND_CHECK_PTREG(rbx, 6),
> +       PER_LOAD_AND_CHECK_PTREG(r11, 7),
> +       PER_LOAD_AND_CHECK_PTREG(r10, 8),
> +       PER_LOAD_AND_CHECK_PTREG(r9, 9),
> +       PER_LOAD_AND_CHECK_PTREG(r8, 10),
> +       PER_LOAD_AND_CHECK_PTREG(rax, 11),
> +       PER_LOAD_AND_CHECK_PTREG(rcx, 12),
> +       PER_LOAD_AND_CHECK_PTREG(rdx, 13),
> +       PER_LOAD_AND_CHECK_PTREG(rsi, 14),
> +       PER_LOAD_AND_CHECK_PTREG(rdi, 15),
> +       PER_LOAD_AND_CHECK_PTREG(orig_rax, 16),
> +       PER_LOAD_AND_CHECK_PTREG(rip, 17),
> +       PER_LOAD_AND_CHECK_PTREG(cs, 18),
> +       PER_LOAD_AND_CHECK_PTREG(eflags, 19),
> +       PER_LOAD_AND_CHECK_PTREG(rsp, 20),
> +       PER_LOAD_AND_CHECK_PTREG(ss, 21),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .result = ACCEPT,
> +       .prog_type = BPF_PROG_TYPE_PERF_EVENT,
> +       .ctx_len = sizeof(struct bpf_perf_event_data),
> +       .data_len = sizeof(struct bpf_perf_event_value),
> +       .fill_helper = bpf_fill_perf_event_test_run_check,
> +       .override_data_out_len = true,
> +},
> +{
> +       "check if sample period and addr contain expected values",
> +       .insns = {
> +       PER_LOAD_AND_CHECK_EVENT(sample_period, 1),
> +       PER_LOAD_AND_CHECK_EVENT(addr, 2),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .result = ACCEPT,
> +       .prog_type = BPF_PROG_TYPE_PERF_EVENT,
> +       .ctx_len = sizeof(struct bpf_perf_event_data),
> +       .data_len = sizeof(struct bpf_perf_event_value),
> +       .fill_helper = bpf_fill_perf_event_test_run_check,
> +       .override_data_out_len = true,
> +},
> +{
> +       "check if bpf_perf_prog_read_value returns expected data",
> +       .insns = {
> +       // allocate space for a struct bpf_perf_event_value
> +       BPF_MOV64_REG(BPF_REG_6, BPF_REG_10),
> +       BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -(int)sizeof(struct bpf_perf_event_value)),
> +       // prepare parameters for bpf_perf_prog_read_value(ctx, struct bpf_perf_event_value*, u32)
> +       // BPF_REG_1 already contains the context
> +       BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
> +       BPF_MOV64_IMM(BPF_REG_3, sizeof(struct bpf_perf_event_value)),
> +       BPF_EMIT_CALL(BPF_FUNC_perf_prog_read_value),
> +       // check the return value
> +       BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
> +       BPF_EXIT_INSN(),
> +       // check if the fields match the expected values

Use /* */ comments.

> +       PER_LOAD_AND_CHECK_VALUE(counter, 1),
> +       PER_LOAD_AND_CHECK_VALUE(enabled, 2),
> +       PER_LOAD_AND_CHECK_VALUE(running, 3),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .result = ACCEPT,
> +       .prog_type = BPF_PROG_TYPE_PERF_EVENT,
> +       .ctx_len = sizeof(struct bpf_perf_event_data),
> +       .data_len = sizeof(struct bpf_perf_event_value),
> +       .fill_helper = bpf_fill_perf_event_test_run_check,
> +       .override_data_out_len = true,
> +},
> +#undef PER_LOAD_AND_CHECK_64
> +#undef PER_LOAD_AND_CHECK_VALUE
> +#undef PER_LOAD_AND_CHECK_CTX
> +#undef PER_LOAD_AND_CHECK_EVENT
> +#undef PER_LOAD_AND_CHECK_PTREG
> --
> 2.20.1
>