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Date: Fri, 17 Sep 2021 22:03:43 +0800
From: Hou Tao <houtao1@...wei.com>
To: Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...nel.org>
CC: Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, <bpf@...r.kernel.org>,
<netdev@...r.kernel.org>
Subject: Re: [PATCH 3/3] bpf/selftests: add test for writable bare tracepoint
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@...wei.com>
>> ---
>> .../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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