[PATCH bpf-next v1 8/8] bpf/selftests: Test for bpf_per_cpu_ptr()

[Hao Luo <haoluo@google.com>]

Test bpf_per_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.

Signed-off-by: Hao Luo <haoluo@google.com>
---
 .../testing/selftests/bpf/prog_tests/ksyms_btf.c  |  4 ++++
 .../testing/selftests/bpf/progs/test_ksyms_btf.c  | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index 1dad61ba7e99..bdedd4a76b42 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -71,6 +71,10 @@ void test_ksyms_btf(void)
 	      "got %llu, exp %llu\n", data->out__runqueues, runqueues_addr);
 	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 %u\n", data->out__rq_cpu, 1);
+	CHECK(data->out__process_counts == -1, "process_counts",
+	      "got %lu, exp != -1", data->out__process_counts);
 
 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..78cf1ebb753d 100644
--- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c
@@ -7,16 +7,29 @@
 
 __u64 out__runqueues = -1;
 __u64 out__bpf_prog_active = -1;
+__u32 out__rq_cpu = -1;
+unsigned long out__process_counts = -1;
 
-extern const struct rq runqueues __ksym; /* struct type global var. */
+extern const struct rq runqueues __ksym; /* struct type percpu var. */
 extern const int bpf_prog_active __ksym; /* int type global var. */
+extern const unsigned long process_counts __ksym; /* int type percpu var. */
 
 SEC("raw_tp/sys_enter")
 int handler(const void *ctx)
 {
+	struct rq *rq;
+	unsigned long *count;
+
 	out__runqueues = (__u64)&runqueues;
 	out__bpf_prog_active = (__u64)&bpf_prog_active;
 
+	rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1);
+	if (rq)
+		out__rq_cpu = rq->cpu;
+	count = (unsigned long *)bpf_per_cpu_ptr(&process_counts, 1);
+	if (count)
+		out__process_counts = *count;
+
 	return 0;
 }
 
-- 
2.28.0.220.ged08abb693-goog