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

From: Krzesimir Nowak
Date: Fri Jul 12 2019 - 13:37:29 EST

On Fri, Jul 12, 2019 at 2:38 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> 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.

Yeah, they are x86_64 specific, because pt_regs are arch specific. I
was wondering what to do here in the cover letter. Ifdef? Ifdef and
cover also other arches (please no)? Do some weird tricks with
overriding the definition of pt_regs? Else?

>
> > 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.

Will wrap. Checkpatch was also complaining about complex macro not
being inside parens, but I can't see how to wrap it in parens and keep
it working at the same time.

>
> > +#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.

Oops. Will fix.

>
> > + 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
> >



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