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:
you can compare value with out__this_xxx in user-space
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