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selftests/bpf: Fix some bugs in map_lookup_percpu_elem testcase
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comments from Andrii Nakryiko, details in here:
https://lore.kernel.org/lkml/[email protected]/T/

use /* */ instead of //
use libbpf_num_possible_cpus() instead of sysconf(_SC_NPROCESSORS_ONLN)
use 8 bytes for value size
fix memory leak
use ASSERT_EQ instead of ASSERT_OK
add bpf_loop to fetch values on each possible CPU

Fixes: ed7c137 ("selftests/bpf: add test case for bpf_map_lookup_percpu_elem")
Signed-off-by: Feng Zhou <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
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zf1575192187 authored and anakryiko committed May 20, 2022
1 parent 834650b commit 7aa424e
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Showing 2 changed files with 73 additions and 39 deletions.
48 changes: 30 additions & 18 deletions tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
Original file line number Diff line number Diff line change
@@ -1,30 +1,38 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2022 Bytedance
/* Copyright (c) 2022 Bytedance */

#include <test_progs.h>

#include "test_map_lookup_percpu_elem.skel.h"

#define TEST_VALUE 1

void test_map_lookup_percpu_elem(void)
{
struct test_map_lookup_percpu_elem *skel;
int key = 0, ret;
int nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
int *buf;
__u64 key = 0, sum;
int ret, i, nr_cpus = libbpf_num_possible_cpus();
__u64 *buf;

buf = (int *)malloc(nr_cpus*sizeof(int));
buf = malloc(nr_cpus*sizeof(__u64));
if (!ASSERT_OK_PTR(buf, "malloc"))
return;
memset(buf, 0, nr_cpus*sizeof(int));
buf[0] = TEST_VALUE;

skel = test_map_lookup_percpu_elem__open_and_load();
if (!ASSERT_OK_PTR(skel, "test_map_lookup_percpu_elem__open_and_load"))
return;
for (i = 0; i < nr_cpus; i++)
buf[i] = i;
sum = (nr_cpus - 1) * nr_cpus / 2;

skel = test_map_lookup_percpu_elem__open();
if (!ASSERT_OK_PTR(skel, "test_map_lookup_percpu_elem__open"))
goto exit;

skel->rodata->my_pid = getpid();
skel->rodata->nr_cpus = nr_cpus;

ret = test_map_lookup_percpu_elem__load(skel);
if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__load"))
goto cleanup;

ret = test_map_lookup_percpu_elem__attach(skel);
ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach");
if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach"))
goto cleanup;

ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_array_map), &key, buf, 0);
ASSERT_OK(ret, "percpu_array_map update");
Expand All @@ -37,10 +45,14 @@ void test_map_lookup_percpu_elem(void)

syscall(__NR_getuid);

ret = skel->bss->percpu_array_elem_val == TEST_VALUE &&
skel->bss->percpu_hash_elem_val == TEST_VALUE &&
skel->bss->percpu_lru_hash_elem_val == TEST_VALUE;
ASSERT_OK(!ret, "bpf_map_lookup_percpu_elem success");
test_map_lookup_percpu_elem__detach(skel);

ASSERT_EQ(skel->bss->percpu_array_elem_sum, sum, "percpu_array lookup percpu elem");
ASSERT_EQ(skel->bss->percpu_hash_elem_sum, sum, "percpu_hash lookup percpu elem");
ASSERT_EQ(skel->bss->percpu_lru_hash_elem_sum, sum, "percpu_lru_hash lookup percpu elem");

cleanup:
test_map_lookup_percpu_elem__destroy(skel);
exit:
free(buf);
}
64 changes: 43 additions & 21 deletions tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c
Original file line number Diff line number Diff line change
@@ -1,52 +1,74 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2022 Bytedance
/* Copyright (c) 2022 Bytedance */

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>

int percpu_array_elem_val = 0;
int percpu_hash_elem_val = 0;
int percpu_lru_hash_elem_val = 0;
__u64 percpu_array_elem_sum = 0;
__u64 percpu_hash_elem_sum = 0;
__u64 percpu_lru_hash_elem_sum = 0;
const volatile int nr_cpus;
const volatile int my_pid;

struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, __u32);
__type(value, __u64);
} percpu_array_map SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, __u32);
__type(key, __u64);
__type(value, __u64);
} percpu_hash_map SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_LRU_PERCPU_HASH);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, __u32);
__type(key, __u64);
__type(value, __u64);
} percpu_lru_hash_map SEC(".maps");

struct read_percpu_elem_ctx {
void *map;
__u64 sum;
};

static int read_percpu_elem_callback(__u32 index, struct read_percpu_elem_ctx *ctx)
{
__u64 key = 0;
__u64 *value;

value = bpf_map_lookup_percpu_elem(ctx->map, &key, index);
if (value)
ctx->sum += *value;
return 0;
}

SEC("tp/syscalls/sys_enter_getuid")
int sysenter_getuid(const void *ctx)
{
__u32 key = 0;
__u32 cpu = 0;
__u32 *value;
struct read_percpu_elem_ctx map_ctx;

value = bpf_map_lookup_percpu_elem(&percpu_array_map, &key, cpu);
if (value)
percpu_array_elem_val = *value;
if (my_pid != (bpf_get_current_pid_tgid() >> 32))
return 0;

value = bpf_map_lookup_percpu_elem(&percpu_hash_map, &key, cpu);
if (value)
percpu_hash_elem_val = *value;
map_ctx.map = &percpu_array_map;
map_ctx.sum = 0;
bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
percpu_array_elem_sum = map_ctx.sum;

value = bpf_map_lookup_percpu_elem(&percpu_lru_hash_map, &key, cpu);
if (value)
percpu_lru_hash_elem_val = *value;
map_ctx.map = &percpu_hash_map;
map_ctx.sum = 0;
bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
percpu_hash_elem_sum = map_ctx.sum;

map_ctx.map = &percpu_lru_hash_map;
map_ctx.sum = 0;
bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
percpu_lru_hash_elem_sum = map_ctx.sum;

return 0;
}
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