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selftests/bpf: Verify bpf_iter for global percpu data

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Add a test to verify that it is OK to iter the percpu_array map used for
global percpu data.

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/bpf/20260813152324.97937-11-leon.hwang@linux.dev
This commit is contained in:
Leon Hwang 2026-08-13 23:23:23 +08:00 committed by Andrii Nakryiko
parent 1ed2294b31
commit 15945d02c6
2 changed files with 77 additions and 0 deletions
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52
tools/testing/selftests/bpf/prog_tests/global_data_init.c
View File

@ -327,6 +327,56 @@ static void test_global_percpu_data_verifier_log(void)
RUN_TESTS(test_global_percpu_data);
}
static void test_global_percpu_data_iter(void)
{
DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
struct test_global_percpu_data *skel;
union bpf_iter_link_info linfo = {};
struct bpf_link *link = NULL;
int fd, num_cpus, len, err;
char buf[16];
num_cpus = libbpf_num_possible_cpus();
if (!ASSERT_GT(num_cpus, 0, "libbpf_num_possible_cpus"))
return;
skel = test_global_percpu_data__open();
if (!ASSERT_OK_PTR(skel, "test_global_percpu_data__open"))
return;
skel->rodata->num_cpus = num_cpus;
skel->rodata->offsetof_num = offsetof(struct test_global_percpu_data__percpu, struct_data);
skel->rodata->offsetof_num += sizeof(skel->percpu->struct_data) - sizeof(int);
skel->rodata->elem_sz = roundup(sizeof(struct test_global_percpu_data__percpu), 8);
skel->percpu->struct_data.nums[6] = 0xc0de;
err = test_global_percpu_data__load(skel);
if (!ASSERT_OK(err, "test_global_percpu_data__load"))
goto out;
linfo.map.map_fd = bpf_map__fd(skel->maps.percpu);
opts.link_info = &linfo;
opts.link_info_len = sizeof(linfo);
link = bpf_program__attach_iter(skel->progs.dump_percpu_data, &opts);
if (!ASSERT_OK_PTR(link, "bpf_program__attach_iter"))
goto out;
fd = bpf_iter_create(bpf_link__fd(link));
if (!ASSERT_GE(fd, 0, "bpf_iter_create"))
goto out;
while ((len = read(fd, buf, sizeof(buf))) > 0)
do { } while (0);
ASSERT_EQ(len, 0, "read iter");
ASSERT_TRUE(skel->bss->run_iter, "run_iter");
ASSERT_EQ(skel->bss->percpu_data_sum, 0xc0de * num_cpus, "percpu_data_sum");
close(fd);
out:
bpf_link__destroy(link);
test_global_percpu_data__destroy(skel);
}
void test_global_percpu_data(void)
{
if (!feat_supported(NULL, FEAT_PERCPU_DATA)) {
@ -343,4 +393,6 @@ void test_global_percpu_data(void)
if (test__start_subtest("rdonly_direct_write"))
test_global_percpu_data_rdonly_direct_write();
test_global_percpu_data_verifier_log();
if (test__start_subtest("iter"))
test_global_percpu_data_iter();
}

25
tools/testing/selftests/bpf/progs/test_global_percpu_data.c
View File

@ -61,4 +61,29 @@ int verifier_snprintf(void *ctx)
return 0;
}
volatile const __u32 num_cpus = 0;
volatile const int offsetof_num;
volatile const int elem_sz;
__u32 percpu_data_sum = 0;
bool run_iter = false;
SEC("iter/bpf_map_elem")
__auxiliary
int dump_percpu_data(struct bpf_iter__bpf_map_elem *ctx)
{
void *pptr = ctx->value;
int i;
if (!pptr)
return 0;
run_iter = true;
for (i = 0; i < num_cpus; i++) {
percpu_data_sum += *(int *) (pptr + offsetof_num);
pptr += elem_sz;
}
return 0;
}
char _license[] SEC("license") = "GPL";