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

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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: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230711232400.1658562-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2023-07-11 16:24:00 -07:00 committed by Alexei Starovoitov
parent f42bcd168d
commit c21de5fc5f
2 changed files with 17 additions and 5 deletions
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14
tools/testing/selftests/bpf/prog_tests/global_map_resize.c
View File

@ -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 @@ teardown:
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"))

8
tools/testing/selftests/bpf/progs/test_global_map_resize.c
View File

@ -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];