diff mbox series

[bpf-next,v2,6/6] bpf/selftests: Test for bpf_per_cpu_ptr() and bpf_this_cpu_ptr()

Message ID 20200903223332.881541-7-haoluo@google.com
State New
Headers show
Series bpf: BTF support for ksyms | expand

Commit Message

Hao Luo Sept. 3, 2020, 10:33 p.m. UTC
Test bpf_per_cpu_ptr() and bpf_this_cpu_ptr(). Test two paths in the
kernel. If the base pointer points to a struct, the returned reg is
of type PTR_TO_BTF_ID. Direct pointer dereference can be applied on
the returned variable. If the base pointer isn't a struct, the
returned reg is of type PTR_TO_MEM, which also supports direct pointer
dereference.

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Hao Luo <haoluo@google.com>
---
 .../selftests/bpf/prog_tests/ksyms_btf.c      | 10 +++++++
 .../selftests/bpf/progs/test_ksyms_btf.c      | 26 +++++++++++++++++++
 2 files changed, 36 insertions(+)

Comments

Andrii Nakryiko Sept. 4, 2020, 8:15 p.m. UTC | #1
On Thu, Sep 3, 2020 at 3:35 PM Hao Luo <haoluo@google.com> wrote:
>
> Test bpf_per_cpu_ptr() and bpf_this_cpu_ptr(). Test two paths in the
> kernel. If the base pointer points to a struct, the returned reg is
> of type PTR_TO_BTF_ID. Direct pointer dereference can be applied on
> the returned variable. If the base pointer isn't a struct, the
> returned reg is of type PTR_TO_MEM, which also supports direct pointer
> dereference.
>
> Acked-by: Andrii Nakryiko <andriin@fb.com>
> Signed-off-by: Hao Luo <haoluo@google.com>
> ---
>  .../selftests/bpf/prog_tests/ksyms_btf.c      | 10 +++++++
>  .../selftests/bpf/progs/test_ksyms_btf.c      | 26 +++++++++++++++++++
>  2 files changed, 36 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> index 7b6846342449..22cc642dbc0e 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> @@ -58,6 +58,16 @@ void test_ksyms_btf(void)
>         CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active",
>               "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr);
>
> +       CHECK(data->out__rq_cpu == -1, "rq_cpu",
> +             "got %u, exp != -1\n", data->out__rq_cpu);
> +       CHECK(data->out__percpu_bpf_prog_active == -1, "percpu_bpf_prog_active",
> +             "got %d, exp != -1\n", data->out__percpu_bpf_prog_active);
> +
> +       CHECK(data->out__this_rq_cpu == -1, "this_rq_cpu",
> +             "got %u, exp != -1\n", data->out__this_rq_cpu);
> +       CHECK(data->out__this_bpf_prog_active == -1, "this_bpf_prog_active",
> +             "got %d, exp != -1\n", data->out__this_bpf_prog_active);

see below for few suggestions to make these test more specific

out__this_bpf_prog_active it should always be > 0, no?

> +
>  cleanup:
>         test_ksyms_btf__destroy(skel);
>  }
> diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> index e04e31117f84..02d564349892 100644
> --- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> @@ -8,15 +8,41 @@
>  __u64 out__runqueues = -1;
>  __u64 out__bpf_prog_active = -1;
>
> +__u32 out__rq_cpu = -1; /* percpu struct fields */
> +int out__percpu_bpf_prog_active = -1; /* percpu int */
> +
> +__u32 out__this_rq_cpu = -1;
> +int out__this_bpf_prog_active = -1;
> +
>  extern const struct rq runqueues __ksym; /* struct type global var. */
>  extern const int bpf_prog_active __ksym; /* int type global var. */
>
>  SEC("raw_tp/sys_enter")
>  int handler(const void *ctx)
>  {
> +       struct rq *rq;
> +       int *active;
> +       __u32 cpu;
> +
>         out__runqueues = (__u64)&runqueues;
>         out__bpf_prog_active = (__u64)&bpf_prog_active;
>
> +       cpu = bpf_get_smp_processor_id();
> +
> +       /* test bpf_per_cpu_ptr() */
> +       rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu);
> +       if (rq)
> +               out__rq_cpu = rq->cpu;
> +       active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
> +       if (active)
> +               out__percpu_bpf_prog_active = *active;

this is equivalent to using bpf_this_cpu_ptr(), so:

1. you can compare value with out__this_xxx in user-space

2. it's interesting to also test that you can read value from some
other CPU. Can you add another variable and get value from CPU #0
always? E.g., for out__cpu_0_rq_cpu it should always be zero, right?

> +
> +       /* test bpf_this_cpu_ptr */
> +       rq = (struct rq *)bpf_this_cpu_ptr(&runqueues);
> +       out__this_rq_cpu = rq->cpu;
> +       active = (int *)bpf_this_cpu_ptr(&bpf_prog_active);
> +       out__this_bpf_prog_active = *active;
> +
>         return 0;
>  }
>
> --
> 2.28.0.526.ge36021eeef-goog
>
Hao Luo Sept. 14, 2020, 4:59 p.m. UTC | #2
Thanks for taking a look!

On Fri, Sep 4, 2020 at 1:15 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Sep 3, 2020 at 3:35 PM Hao Luo <haoluo@google.com> wrote:
> >
> > Test bpf_per_cpu_ptr() and bpf_this_cpu_ptr(). Test two paths in the
> > kernel. If the base pointer points to a struct, the returned reg is
> > of type PTR_TO_BTF_ID. Direct pointer dereference can be applied on
> > the returned variable. If the base pointer isn't a struct, the
> > returned reg is of type PTR_TO_MEM, which also supports direct pointer
> > dereference.
> >
> > Acked-by: Andrii Nakryiko <andriin@fb.com>
> > Signed-off-by: Hao Luo <haoluo@google.com>
> > ---
> >  .../selftests/bpf/prog_tests/ksyms_btf.c      | 10 +++++++
> >  .../selftests/bpf/progs/test_ksyms_btf.c      | 26 +++++++++++++++++++
> >  2 files changed, 36 insertions(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> > index 7b6846342449..22cc642dbc0e 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
> > @@ -58,6 +58,16 @@ void test_ksyms_btf(void)
> >         CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active",
> >               "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr);
> >
> > +       CHECK(data->out__rq_cpu == -1, "rq_cpu",
> > +             "got %u, exp != -1\n", data->out__rq_cpu);
> > +       CHECK(data->out__percpu_bpf_prog_active == -1, "percpu_bpf_prog_active",
> > +             "got %d, exp != -1\n", data->out__percpu_bpf_prog_active);
> > +
> > +       CHECK(data->out__this_rq_cpu == -1, "this_rq_cpu",
> > +             "got %u, exp != -1\n", data->out__this_rq_cpu);
> > +       CHECK(data->out__this_bpf_prog_active == -1, "this_bpf_prog_active",
> > +             "got %d, exp != -1\n", data->out__this_bpf_prog_active);
>
> see below for few suggestions to make these test more specific
>
> out__this_bpf_prog_active it should always be > 0, no?
>

I could be wrong, but I remember raw_trace_point is not tracked by
bpf_prog_active. So I used bpf_prog_active >= 0 to be safe.

> > +
> >  cleanup:
> >         test_ksyms_btf__destroy(skel);
> >  }
> > diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> > index e04e31117f84..02d564349892 100644
> > --- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> > +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
> > @@ -8,15 +8,41 @@
> >  __u64 out__runqueues = -1;
> >  __u64 out__bpf_prog_active = -1;
> >
> > +__u32 out__rq_cpu = -1; /* percpu struct fields */
> > +int out__percpu_bpf_prog_active = -1; /* percpu int */
> > +
> > +__u32 out__this_rq_cpu = -1;
> > +int out__this_bpf_prog_active = -1;
> > +
> >  extern const struct rq runqueues __ksym; /* struct type global var. */
> >  extern const int bpf_prog_active __ksym; /* int type global var. */
> >
> >  SEC("raw_tp/sys_enter")
> >  int handler(const void *ctx)
> >  {
> > +       struct rq *rq;
> > +       int *active;
> > +       __u32 cpu;
> > +
> >         out__runqueues = (__u64)&runqueues;
> >         out__bpf_prog_active = (__u64)&bpf_prog_active;
> >
> > +       cpu = bpf_get_smp_processor_id();
> > +
> > +       /* test bpf_per_cpu_ptr() */
> > +       rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu);
> > +       if (rq)
> > +               out__rq_cpu = rq->cpu;
> > +       active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
> > +       if (active)
> > +               out__percpu_bpf_prog_active = *active;
>
> this is equivalent to using bpf_this_cpu_ptr(), so:
>
> 1. you can compare value with out__this_xxx in user-space
>
> 2. it's interesting to also test that you can read value from some
> other CPU. Can you add another variable and get value from CPU #0
> always? E.g., for out__cpu_0_rq_cpu it should always be zero, right?
>

Ack. That makes sense. You are right, out__cpu_0_rq_cpu is always zero.

> > +
> > +       /* test bpf_this_cpu_ptr */
> > +       rq = (struct rq *)bpf_this_cpu_ptr(&runqueues);
> > +       out__this_rq_cpu = rq->cpu;
> > +       active = (int *)bpf_this_cpu_ptr(&bpf_prog_active);
> > +       out__this_bpf_prog_active = *active;
> > +
> >         return 0;
> >  }
> >
> > --
> > 2.28.0.526.ge36021eeef-goog
> >
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index 7b6846342449..22cc642dbc0e 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -58,6 +58,16 @@  void test_ksyms_btf(void)
 	CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active",
 	      "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr);
 
+	CHECK(data->out__rq_cpu == -1, "rq_cpu",
+	      "got %u, exp != -1\n", data->out__rq_cpu);
+	CHECK(data->out__percpu_bpf_prog_active == -1, "percpu_bpf_prog_active",
+	      "got %d, exp != -1\n", data->out__percpu_bpf_prog_active);
+
+	CHECK(data->out__this_rq_cpu == -1, "this_rq_cpu",
+	      "got %u, exp != -1\n", data->out__this_rq_cpu);
+	CHECK(data->out__this_bpf_prog_active == -1, "this_bpf_prog_active",
+	      "got %d, exp != -1\n", data->out__this_bpf_prog_active);
+
 cleanup:
 	test_ksyms_btf__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
index e04e31117f84..02d564349892 100644
--- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
@@ -8,15 +8,41 @@ 
 __u64 out__runqueues = -1;
 __u64 out__bpf_prog_active = -1;
 
+__u32 out__rq_cpu = -1; /* percpu struct fields */
+int out__percpu_bpf_prog_active = -1; /* percpu int */
+
+__u32 out__this_rq_cpu = -1;
+int out__this_bpf_prog_active = -1;
+
 extern const struct rq runqueues __ksym; /* struct type global var. */
 extern const int bpf_prog_active __ksym; /* int type global var. */
 
 SEC("raw_tp/sys_enter")
 int handler(const void *ctx)
 {
+	struct rq *rq;
+	int *active;
+	__u32 cpu;
+
 	out__runqueues = (__u64)&runqueues;
 	out__bpf_prog_active = (__u64)&bpf_prog_active;
 
+	cpu = bpf_get_smp_processor_id();
+
+	/* test bpf_per_cpu_ptr() */
+	rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu);
+	if (rq)
+		out__rq_cpu = rq->cpu;
+	active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
+	if (active)
+		out__percpu_bpf_prog_active = *active;
+
+	/* test bpf_this_cpu_ptr */
+	rq = (struct rq *)bpf_this_cpu_ptr(&runqueues);
+	out__this_rq_cpu = rq->cpu;
+	active = (int *)bpf_this_cpu_ptr(&bpf_prog_active);
+	out__this_bpf_prog_active = *active;
+
 	return 0;
 }