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Date: Fri, 13 May 2022 09:49:37 +0800 From: Feng Zhou <zhoufeng.zf@...edance.com> To: Andrii Nakryiko <andrii.nakryiko@...il.com> Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, john fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...nel.org>, Dave Marchevsky <davemarchevsky@...com>, Joanne Koong <joannekoong@...com>, Geliang Tang <geliang.tang@...e.com>, Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>, duanxiongchun@...edance.com, Muchun Song <songmuchun@...edance.com>, Dongdong Wang <wangdongdong.6@...edance.com>, Cong Wang <cong.wang@...edance.com>, zhouchengming@...edance.com, yosryahmed@...gle.com Subject: Re: [External] Re: [PATCH bpf-next v2 2/2] selftests/bpf: add test case for bpf_map_lookup_percpu_elem 在 2022/5/13 上午12:43, Andrii Nakryiko 写道: > On Wed, May 11, 2022 at 8:58 PM Feng Zhou <zhoufeng.zf@...edance.com> wrote: >> 在 2022/5/12 上午11:34, Andrii Nakryiko 写道: >>> On Wed, May 11, 2022 at 2:39 AM Feng zhou <zhoufeng.zf@...edance.com> wrote: >>>> From: Feng Zhou <zhoufeng.zf@...edance.com> >>>> >>>> test_progs: >>>> Tests new ebpf helpers bpf_map_lookup_percpu_elem. >>>> >>>> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com> >>>> --- >>>> .../bpf/prog_tests/map_lookup_percpu_elem.c | 46 ++++++++++++++++ >>>> .../bpf/progs/test_map_lookup_percpu_elem.c | 54 +++++++++++++++++++ >>>> 2 files changed, 100 insertions(+) >>>> create mode 100644 tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c >>>> create mode 100644 tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >>>> >>>> diff --git a/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c >>>> new file mode 100644 >>>> index 000000000000..58b24c2112b0 >>>> --- /dev/null >>>> +++ b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c >>>> @@ -0,0 +1,46 @@ >>>> +// SPDX-License-Identifier: GPL-2.0 >>>> +// Copyright (c) 2022 Bytedance >>> /* */ instead of // >> Ok, I will do. Thanks. >> >> >>>> + >>>> +#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); >>> I think this is actually wrong and will break selftests on systems >>> with offline CPUs. Please use libbpf_num_possible_cpus() instead. >> >> Ok, I will do. Thanks. >> >> >>>> + int *buf; >>>> + >>>> + buf = (int *)malloc(nr_cpus*sizeof(int)); >>>> + if (!ASSERT_OK_PTR(buf, "malloc")) >>>> + return; >>>> + memset(buf, 0, nr_cpus*sizeof(int)); >>> this is wrong, kernel expects to have roundup(sz, 8) per each CPU, >>> while you have just 4 bytes per each element >>> >>> please also have spaces around multiplication operator here and above >> >> Ok, I will use 8 bytes for key and val. Thanks. >> >> >>>> + 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; >>> buf leaking here >> >> Yes, sorry for my negligence. >> >> >>>> + ret = test_map_lookup_percpu_elem__attach(skel); >>>> + ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach"); >>>> + >>>> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_array_map), &key, buf, 0); >>>> + ASSERT_OK(ret, "percpu_array_map update"); >>>> + >>>> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_hash_map), &key, buf, 0); >>>> + ASSERT_OK(ret, "percpu_hash_map update"); >>>> + >>>> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_lru_hash_map), &key, buf, 0); >>>> + ASSERT_OK(ret, "percpu_lru_hash_map update"); >>>> + >>>> + 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"); >>> this would be better done as three separate ASSERT_EQ(), combining >>> into opaque true/false isn't helpful if something breaks >> >> Good suggestion. >> >> >>>> + >>>> + test_map_lookup_percpu_elem__destroy(skel); >>>> +} >>>> diff --git a/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >>>> new file mode 100644 >>>> index 000000000000..5d4ef86cbf48 >>>> --- /dev/null >>>> +++ b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >>>> @@ -0,0 +1,54 @@ >>>> +// SPDX-License-Identifier: GPL-2.0 >>>> +// Copyright (c) 2022 Bytedance >>> /* */ instead of // >> >> Ok, I will do. Thanks. >> >> >>>> + >>>> +#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; >>>> + >>>> +struct { >>>> + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); >>>> + __uint(max_entries, 1); >>>> + __type(key, __u32); >>>> + __type(value, __u32); >>>> +} percpu_array_map SEC(".maps"); >>>> + >>>> +struct { >>>> + __uint(type, BPF_MAP_TYPE_PERCPU_HASH); >>>> + __uint(max_entries, 1); >>>> + __type(key, __u32); >>>> + __type(value, __u32); >>>> +} percpu_hash_map SEC(".maps"); >>>> + >>>> +struct { >>>> + __uint(type, BPF_MAP_TYPE_LRU_PERCPU_HASH); >>>> + __uint(max_entries, 1); >>>> + __type(key, __u32); >>>> + __type(value, __u32); >>>> +} percpu_lru_hash_map SEC(".maps"); >>>> + >>>> +SEC("tp/syscalls/sys_enter_getuid") >>>> +int sysenter_getuid(const void *ctx) >>>> +{ >>>> + __u32 key = 0; >>>> + __u32 cpu = 0; >>>> + __u32 *value; >>>> + >>>> + value = bpf_map_lookup_percpu_elem(&percpu_array_map, &key, cpu); >>>> + if (value) >>>> + percpu_array_elem_val = *value; >>>> + >>>> + value = bpf_map_lookup_percpu_elem(&percpu_hash_map, &key, cpu); >>>> + if (value) >>>> + percpu_hash_elem_val = *value; >>>> + >>>> + value = bpf_map_lookup_percpu_elem(&percpu_lru_hash_map, &key, cpu); >>>> + if (value) >>>> + percpu_lru_hash_elem_val = *value; >>>> + >>> if the test happens to run on CPU 0 then the test doesn't really test >>> much. It would be more interesting to have a bpf_loop() iteration that >>> would fetch values on each possible CPU instead and do something with >>> it. >> >> Good suggestion. I check the code and find no bpf helper function to get >> possible CPU nums. >> >> I think for the test function, read cpu0 elem value correctly should be >> considered to be no problem. >> >> Or is it necessary to add a new helper function to get num_possible_cpus ? >> >> > You can pass number of CPUs from user-space to BPF program through > read-only variable (search for `const volatile` under progs/ for > examples) > Ok, will do. Thanks. >>>> + return 0; >>>> +} >>>> + >>>> +char _license[] SEC("license") = "GPL"; >>>> -- >>>> 2.20.1 >>>>
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