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Message-ID: <c70c0a07-a337-1710-fae7-41ab77f75544@fb.com>
Date:   Thu, 16 Sep 2021 16:46:33 -0700
From:   Yonghong Song <yhs@...com>
To:     Hou Tao <houtao1@...wei.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



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.

> 
> 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?

> +	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.

> +		close(fd);
> +		return err;
> +	}

Put one blank line here and remove the following three blank lines.

> +	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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