Commit c21de5fc authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

selftests/bpf: extend existing map resize tests for per-cpu use case 



Add a per-cpu array resizing use case and demonstrate how
bpf_get_smp_processor_id() can be used to directly access proper data
with no extra checks.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230711232400.1658562-2-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent f42bcd16

tools/testing/selftests/bpf/prog_tests/global_map_resize.c

+11 −3
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ static void global_map_resize_bss_subtest(void) 
	struct test_global_map_resize *skel;

	struct bpf_map *map;

	const __u32 desired_sz = sizeof(skel->bss->sum) + sysconf(_SC_PAGE_SIZE) * 2;

	size_t array_len, actual_sz;

	size_t array_len, actual_sz, new_sz;



	skel = test_global_map_resize__open();

	if (!ASSERT_OK_PTR(skel, "test_global_map_resize__open"))
@@ -42,6 +42,10 @@ static void global_map_resize_bss_subtest(void) 
	if (!ASSERT_EQ(bpf_map__value_size(map), desired_sz, "resize"))

		goto teardown;



	new_sz = sizeof(skel->data_percpu_arr->percpu_arr[0]) * libbpf_num_possible_cpus();

	err = bpf_map__set_value_size(skel->maps.data_percpu_arr, new_sz);

	ASSERT_OK(err, "percpu_arr_resize");



	/* set the expected number of elements based on the resized array */

	array_len = (desired_sz - sizeof(skel->bss->sum)) / sizeof(skel->bss->array[0]);

	if (!ASSERT_GT(array_len, 1, "array_len"))
@@ -84,11 +88,11 @@ static void global_map_resize_bss_subtest(void) 


static void global_map_resize_data_subtest(void)

{

	int err;

	struct test_global_map_resize *skel;

	struct bpf_map *map;

	const __u32 desired_sz = sysconf(_SC_PAGE_SIZE) * 2;

	size_t array_len, actual_sz;

	size_t array_len, actual_sz, new_sz;

	int err;



	skel = test_global_map_resize__open();

	if (!ASSERT_OK_PTR(skel, "test_global_map_resize__open"))
@@ -108,6 +112,10 @@ static void global_map_resize_data_subtest(void) 
	if (!ASSERT_EQ(bpf_map__value_size(map), desired_sz, "resize"))

		goto teardown;



	new_sz = sizeof(skel->data_percpu_arr->percpu_arr[0]) * libbpf_num_possible_cpus();

	err = bpf_map__set_value_size(skel->maps.data_percpu_arr, new_sz);

	ASSERT_OK(err, "percpu_arr_resize");



	/* set the expected number of elements based on the resized array */

	array_len = (desired_sz - sizeof(skel->bss->sum)) / sizeof(skel->data_custom->my_array[0]);

	if (!ASSERT_GT(array_len, 1, "array_len"))

tools/testing/selftests/bpf/progs/test_global_map_resize.c

+6 −2
Original line number Diff line number Diff line
@@ -29,13 +29,16 @@ int my_int SEC(".data.non_array"); 
int my_array_first[1] SEC(".data.array_not_last");

int my_int_last SEC(".data.array_not_last");



int percpu_arr[1] SEC(".data.percpu_arr");



SEC("tp/syscalls/sys_enter_getpid")

int bss_array_sum(void *ctx)

{

	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	sum = 0;

	/* this will be zero, we just rely on verifier not rejecting this */

	sum = percpu_arr[bpf_get_smp_processor_id()];



	for (size_t i = 0; i < bss_array_len; ++i)

		sum += array[i];
@@ -49,7 +52,8 @@ int data_array_sum(void *ctx) 
	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	sum = 0;

	/* this will be zero, we just rely on verifier not rejecting this */

	sum = percpu_arr[bpf_get_smp_processor_id()];



	for (size_t i = 0; i < data_array_len; ++i)

		sum += my_array[i];