Re: [PATCH 3/3] bpf/selftests: add test for writable bare tracepoint

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Hi,

On 9/17/2021 7:46 AM, Yonghong Song wrote:
>
>
> On 9/16/21 6:55 AM, Hou Tao wrote:
>> Add a writable bare tracepoint in bpf_testmod module, and
>> trigger its calling when reading /sys/kernel/bpf_testmod
>> with a specific buffer length.
>
> The patch cannot be applied cleanly with bpf-next tree.
> Please rebase and resubmit.
Will do
>
>>
>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
>> ---
>>   .../bpf/bpf_testmod/bpf_testmod-events.h      | 15 +++++++
>>   .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 10 +++++
>>   .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  5 +++
>>   .../selftests/bpf/prog_tests/module_attach.c  | 40 ++++++++++++++++++-
>>   .../selftests/bpf/progs/test_module_attach.c  | 14 +++++++
>>   5 files changed, 82 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>> b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>> index 89c6d58e5dd6..11ee801e75e7 100644
>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>> @@ -34,6 +34,21 @@ DECLARE_TRACE(bpf_testmod_test_write_bare,
>>       TP_ARGS(task, ctx)
>>   );
>>   +#undef BPF_TESTMOD_DECLARE_TRACE
>> +#ifdef DECLARE_TRACE_WRITABLE
>> +#define BPF_TESTMOD_DECLARE_TRACE(call, proto, args, size) \
>> +    DECLARE_TRACE_WRITABLE(call, PARAMS(proto), PARAMS(args), size)
>> +#else
>> +#define BPF_TESTMOD_DECLARE_TRACE(call, proto, args, size) \
>> +    DECLARE_TRACE(call, PARAMS(proto), PARAMS(args))
>> +#endif
>> +
>> +BPF_TESTMOD_DECLARE_TRACE(bpf_testmod_test_writable_bare,
>> +    TP_PROTO(struct bpf_testmod_test_writable_ctx *ctx),
>> +    TP_ARGS(ctx),
>> +    sizeof(struct bpf_testmod_test_writable_ctx)
>> +);
>> +
>>   #endif /* _BPF_TESTMOD_EVENTS_H */
>>     #undef TRACE_INCLUDE_PATH
>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> index 141d8da687d2..3d3fb16eaf8c 100644
>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> @@ -26,6 +26,16 @@ bpf_testmod_test_read(struct file *file, struct kobject
>> *kobj,
>>         trace_bpf_testmod_test_read(current, &ctx);
>>   +    /* Magic number to enable writable tp */
>> +    if (len == 1024) {
>> +        struct bpf_testmod_test_writable_ctx writable = {
>> +            .val = 1024,
>> +        };
>> +        trace_bpf_testmod_test_writable_bare(&writable);
>> +        if (writable.ret)
>> +            return snprintf(buf, len, "%d\n", writable.val);
>> +    }
>> +
>>       return -EIO; /* always fail */
>>   }
>>   EXPORT_SYMBOL(bpf_testmod_test_read);
>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>> b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>> index b3892dc40111..553d94214aa6 100644
>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>> @@ -17,4 +17,9 @@ struct bpf_testmod_test_write_ctx {
>>       size_t len;
>>   };
>>   +struct bpf_testmod_test_writable_ctx {
>> +    bool ret;
>> +    int val;
>> +};
>> +
>>   #endif /* _BPF_TESTMOD_H */
>> diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c
>> b/tools/testing/selftests/bpf/prog_tests/module_attach.c
>> index d85a69b7ce44..5565bcab1531 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
>> @@ -6,11 +6,39 @@
>>     static int duration;
>>   +#define BPF_TESTMOD_PATH "/sys/kernel/bpf_testmod"
>> +
>> +static int trigger_module_test_writable(int *val)
>> +{
>> +    int fd, err;
>> +    char buf[1025];
>
> Not critical, but do you need such a big stack size?
> Maybe smaller one?
65 is also fine.
>
>> +    ssize_t rd;
>> +
>> +    fd = open(BPF_TESTMOD_PATH, O_RDONLY);
>> +    err = -errno;
>> +    if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
>> +        return err;
>> +
>> +    rd = read(fd, buf, sizeof(buf) - 1);
>> +    err = rd < 0 ? -errno : -EIO;
>> +    if (CHECK(rd <= 0, "testmod_file_read", "failed: %d\n", err)) {
>
> Please use ASSERT_* macros. You can take a look at other self tests.
The reason using CHECK instead of ASSERT is we can output the errno
if read() fails.
>> +        close(fd);
>> +        return err;
>> +    }
>
> Put one blank line here and remove the following three blank lines.
Will do.
>
>> +    buf[rd] = '\0';
>> +
>> +    *val = strtol(buf, NULL, 0);
>> +
>> +    close(fd);
>> +
>> +    return 0;
>> +}
>> +
>>   static int trigger_module_test_read(int read_sz)
>>   {
>>       int fd, err;
>>   -    fd = open("/sys/kernel/bpf_testmod", O_RDONLY);
>> +    fd = open(BPF_TESTMOD_PATH, O_RDONLY);
>>       err = -errno;
>>       if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
>>           return err;
>> @@ -32,7 +60,7 @@ static int trigger_module_test_write(int write_sz)
>>       memset(buf, 'a', write_sz);
>>       buf[write_sz-1] = '\0';
>>   -    fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
>> +    fd = open(BPF_TESTMOD_PATH, O_WRONLY);
>>       err = -errno;
>>       if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err)) {
>>           free(buf);
>> @@ -58,6 +86,7 @@ void test_module_attach(void)
>>       struct test_module_attach__bss *bss;
>>       struct bpf_link *link;
>>       int err;
>> +    int writable_val;
>>         skel = test_module_attach__open();
>>       if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
>> @@ -90,6 +119,13 @@ void test_module_attach(void)
>>       ASSERT_EQ(bss->fexit_ret, -EIO, "fexit_tet");
>>       ASSERT_EQ(bss->fmod_ret_read_sz, READ_SZ, "fmod_ret");
>>   +    bss->raw_tp_writable_bare_ret = 1;
>> +    bss->raw_tp_writable_bare_val = 511;
>> +    writable_val = 0;
>> +    ASSERT_OK(trigger_module_test_writable(&writable_val), "trigger_writable");
>> +    ASSERT_EQ(bss->raw_tp_writable_bare_in_val, 1024, "writable_test");
>> +    ASSERT_EQ(bss->raw_tp_writable_bare_val, writable_val, "writable_test");
>> +
>>       test_module_attach__detach(skel);
>>         /* attach fentry/fexit and make sure it get's module reference */
>> diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c
>> b/tools/testing/selftests/bpf/progs/test_module_attach.c
>> index bd37ceec5587..4f5c780fcd21 100644
>> --- a/tools/testing/selftests/bpf/progs/test_module_attach.c
>> +++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
>> @@ -27,6 +27,20 @@ int BPF_PROG(handle_raw_tp_bare,
>>       return 0;
>>   }
>>   +int raw_tp_writable_bare_in_val = 0;
>> +int raw_tp_writable_bare_ret = 0;
>> +int raw_tp_writable_bare_val = 0;
>> +
>> +SEC("raw_tp_writable/bpf_testmod_test_writable_bare")
>> +int BPF_PROG(handle_raw_tp_writable_bare,
>> +         struct bpf_testmod_test_writable_ctx *writable)
>> +{
>> +    raw_tp_writable_bare_in_val = writable->val;
>> +    writable->ret = raw_tp_writable_bare_ret;
>> +    writable->val = raw_tp_writable_bare_val;
>> +    return 0;
>> +}
>> +
>>   __u32 tp_btf_read_sz = 0;
>>     SEC("tp_btf/bpf_testmod_test_read")
>>
> .




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