[v2,bpf-next,2/2] selftests: bpf: Add a new test for bare tracepoints
diff mbox series

Message ID 20210116182133.2286884-3-qais.yousef@arm.com
State New, archived
Headers show
Series
  • Allow attaching to bare tracepoints
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Commit Message

Qais Yousef Jan. 16, 2021, 6:21 p.m. UTC
Reuse module_attach infrastructure to add a new bare tracepoint to check
we can attach to it as a raw tracepoint.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
---
 .../bpf/bpf_testmod/bpf_testmod-events.h      |  6 +++++
 .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 21 ++++++++++++++-
 .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  6 +++++
 .../selftests/bpf/prog_tests/module_attach.c  | 27 +++++++++++++++++++
 .../selftests/bpf/progs/test_module_attach.c  | 10 +++++++
 5 files changed, 69 insertions(+), 1 deletion(-)

Comments

Yonghong Song Jan. 17, 2021, 2:11 a.m. UTC | #1
On 1/16/21 10:21 AM, Qais Yousef wrote:
> Reuse module_attach infrastructure to add a new bare tracepoint to check
> we can attach to it as a raw tracepoint.
> 
> Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> ---
>   .../bpf/bpf_testmod/bpf_testmod-events.h      |  6 +++++
>   .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 21 ++++++++++++++-
>   .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  6 +++++
>   .../selftests/bpf/prog_tests/module_attach.c  | 27 +++++++++++++++++++
>   .../selftests/bpf/progs/test_module_attach.c  | 10 +++++++
>   5 files changed, 69 insertions(+), 1 deletion(-)
> 
> 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 b83ea448bc79..89c6d58e5dd6 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
>   		  __entry->pid, __entry->comm, __entry->off, __entry->len)
>   );
>   
> +/* A bare tracepoint with no event associated with it */
> +DECLARE_TRACE(bpf_testmod_test_write_bare,
> +	TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
> +	TP_ARGS(task, 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 2df19d73ca49..e900adad2276 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
>   EXPORT_SYMBOL(bpf_testmod_test_read);
>   ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
>   
> +noinline ssize_t
> +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
> +		      struct bin_attribute *bin_attr,
> +		      char *buf, loff_t off, size_t len)
> +{
> +	struct bpf_testmod_test_write_ctx ctx = {
> +		.buf = buf,
> +		.off = off,
> +		.len = len,
> +	};
> +
> +	trace_bpf_testmod_test_write_bare(current, &ctx);
> +
> +	return -EIO; /* always fail */
> +}
> +EXPORT_SYMBOL(bpf_testmod_test_write);
> +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
> +
>   static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {

Do we need to remove __ro_after_init?

> -	.attr = { .name = "bpf_testmod", .mode = 0444, },
> +	.attr = { .name = "bpf_testmod", .mode = 0666, },
>   	.read = bpf_testmod_test_read,
> +	.write = bpf_testmod_test_write,
>   };
>   
>   static int bpf_testmod_init(void)
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> index b81adfedb4f6..b3892dc40111 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
>   	size_t len;
>   };
>   
> +struct bpf_testmod_test_write_ctx {
> +	char *buf;
> +	loff_t off;
> +	size_t len;
> +};
> +
>   #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 50796b651f72..e4605c0b5af1 100644
> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
>   	return 0;
>   }
>   
> +static int trigger_module_test_write(int write_sz)
> +{
> +	int fd, err;

Init err = 0?

> +	char *buf = malloc(write_sz);
> +
> +	if (!buf)
> +		return -ENOMEM;

Looks like we already non-negative value, so return ENOMEM?

> +
> +	memset(buf, 'a', write_sz);
> +	buf[write_sz-1] = '\0';
> +
> +	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> +	err = -errno;
> +	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> +		goto out;

Change the above to
	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {
		err = -errno;
		goto out;
	}

> +
> +	write(fd, buf, write_sz);
> +	close(fd);
> +out:
> +	free(buf);
> +

No need for extra line here.

> +	return 0;

return err.

> +}
> +
>   void test_module_attach(void)
>   {
>   	const int READ_SZ = 456;
> +	const int WRITE_SZ = 457;
>   	struct test_module_attach* skel;
>   	struct test_module_attach__bss *bss;
>   	int err;
> @@ -48,8 +73,10 @@ void test_module_attach(void)
>   
>   	/* trigger tracepoint */
>   	ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read");
> +	ASSERT_OK(trigger_module_test_write(WRITE_SZ), "trigger_write");
>   
>   	ASSERT_EQ(bss->raw_tp_read_sz, READ_SZ, "raw_tp");
> +	ASSERT_EQ(bss->raw_tp_bare_write_sz, WRITE_SZ, "raw_tp_bare");
>   	ASSERT_EQ(bss->tp_btf_read_sz, READ_SZ, "tp_btf");
>   	ASSERT_EQ(bss->fentry_read_sz, READ_SZ, "fentry");
>   	ASSERT_EQ(bss->fentry_manual_read_sz, READ_SZ, "fentry_manual");
> diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
> index efd1e287ac17..bd37ceec5587 100644
> --- a/tools/testing/selftests/bpf/progs/test_module_attach.c
> +++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
> @@ -17,6 +17,16 @@ int BPF_PROG(handle_raw_tp,
>   	return 0;
>   }
>   
> +__u32 raw_tp_bare_write_sz = 0;
> +
> +SEC("raw_tp/bpf_testmod_test_write_bare")
> +int BPF_PROG(handle_raw_tp_bare,
> +	     struct task_struct *task, struct bpf_testmod_test_write_ctx *write_ctx)
> +{
> +	raw_tp_bare_write_sz = BPF_CORE_READ(write_ctx, len);
> +	return 0;
> +}
> +
>   __u32 tp_btf_read_sz = 0;
>   
>   SEC("tp_btf/bpf_testmod_test_read")
>
Qais Yousef Jan. 18, 2021, 12:18 p.m. UTC | #2
On 01/16/21 18:11, Yonghong Song wrote:
> 
> 
> On 1/16/21 10:21 AM, Qais Yousef wrote:
> > Reuse module_attach infrastructure to add a new bare tracepoint to check
> > we can attach to it as a raw tracepoint.
> > 
> > Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> > ---
> >   .../bpf/bpf_testmod/bpf_testmod-events.h      |  6 +++++
> >   .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 21 ++++++++++++++-
> >   .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  6 +++++
> >   .../selftests/bpf/prog_tests/module_attach.c  | 27 +++++++++++++++++++
> >   .../selftests/bpf/progs/test_module_attach.c  | 10 +++++++
> >   5 files changed, 69 insertions(+), 1 deletion(-)
> > 
> > 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 b83ea448bc79..89c6d58e5dd6 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> > @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
> >   		  __entry->pid, __entry->comm, __entry->off, __entry->len)
> >   );
> > +/* A bare tracepoint with no event associated with it */
> > +DECLARE_TRACE(bpf_testmod_test_write_bare,
> > +	TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
> > +	TP_ARGS(task, 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 2df19d73ca49..e900adad2276 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> > @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
> >   EXPORT_SYMBOL(bpf_testmod_test_read);
> >   ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
> > +noinline ssize_t
> > +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
> > +		      struct bin_attribute *bin_attr,
> > +		      char *buf, loff_t off, size_t len)
> > +{
> > +	struct bpf_testmod_test_write_ctx ctx = {
> > +		.buf = buf,
> > +		.off = off,
> > +		.len = len,
> > +	};
> > +
> > +	trace_bpf_testmod_test_write_bare(current, &ctx);
> > +
> > +	return -EIO; /* always fail */
> > +}
> > +EXPORT_SYMBOL(bpf_testmod_test_write);
> > +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
> > +
> >   static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
> 
> Do we need to remove __ro_after_init?

I don't think so. The structure should still remain RO AFAIU.

> 
> > -	.attr = { .name = "bpf_testmod", .mode = 0444, },
> > +	.attr = { .name = "bpf_testmod", .mode = 0666, },
> >   	.read = bpf_testmod_test_read,
> > +	.write = bpf_testmod_test_write,
> >   };
> >   static int bpf_testmod_init(void)
> > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > index b81adfedb4f6..b3892dc40111 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
> >   	size_t len;
> >   };
> > +struct bpf_testmod_test_write_ctx {
> > +	char *buf;
> > +	loff_t off;
> > +	size_t len;
> > +};
> > +
> >   #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 50796b651f72..e4605c0b5af1 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> > @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
> >   	return 0;
> >   }
> > +static int trigger_module_test_write(int write_sz)
> > +{
> > +	int fd, err;
> 
> Init err = 0?

I don't see what difference this makes.

> 
> > +	char *buf = malloc(write_sz);
> > +
> > +	if (!buf)
> > +		return -ENOMEM;
> 
> Looks like we already non-negative value, so return ENOMEM?

We already set err=-errno. So shouldn't we return negative too?

> 
> > +
> > +	memset(buf, 'a', write_sz);
> > +	buf[write_sz-1] = '\0';
> > +
> > +	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> > +	err = -errno;
> > +	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> > +		goto out;
> 
> Change the above to
> 	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> 	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {
> 		err = -errno;
> 		goto out;
> 	}

I kept the code consistent with the definition of trigger_module_test_read().

I'll leave it up to the maintainer to pick up the style changes if they prefer
it this way.

Thanks for the ack and for the review.

Cheers

--
Qais Yousef
Yonghong Song Jan. 18, 2021, 5:48 p.m. UTC | #3
On 1/18/21 4:18 AM, Qais Yousef wrote:
> On 01/16/21 18:11, Yonghong Song wrote:
>>
>>
>> On 1/16/21 10:21 AM, Qais Yousef wrote:
>>> Reuse module_attach infrastructure to add a new bare tracepoint to check
>>> we can attach to it as a raw tracepoint.
>>>
>>> Signed-off-by: Qais Yousef <qais.yousef@arm.com>
>>> ---
>>>    .../bpf/bpf_testmod/bpf_testmod-events.h      |  6 +++++
>>>    .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 21 ++++++++++++++-
>>>    .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  6 +++++
>>>    .../selftests/bpf/prog_tests/module_attach.c  | 27 +++++++++++++++++++
>>>    .../selftests/bpf/progs/test_module_attach.c  | 10 +++++++
>>>    5 files changed, 69 insertions(+), 1 deletion(-)
>>>
>>> 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 b83ea448bc79..89c6d58e5dd6 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>>> @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
>>>    		  __entry->pid, __entry->comm, __entry->off, __entry->len)
>>>    );
>>> +/* A bare tracepoint with no event associated with it */
>>> +DECLARE_TRACE(bpf_testmod_test_write_bare,
>>> +	TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
>>> +	TP_ARGS(task, 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 2df19d73ca49..e900adad2276 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>>> @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
>>>    EXPORT_SYMBOL(bpf_testmod_test_read);
>>>    ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
>>> +noinline ssize_t
>>> +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
>>> +		      struct bin_attribute *bin_attr,
>>> +		      char *buf, loff_t off, size_t len)
>>> +{
>>> +	struct bpf_testmod_test_write_ctx ctx = {
>>> +		.buf = buf,
>>> +		.off = off,
>>> +		.len = len,
>>> +	};
>>> +
>>> +	trace_bpf_testmod_test_write_bare(current, &ctx);
>>> +
>>> +	return -EIO; /* always fail */
>>> +}
>>> +EXPORT_SYMBOL(bpf_testmod_test_write);
>>> +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
>>> +
>>>    static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
>>
>> Do we need to remove __ro_after_init?
> 
> I don't think so. The structure should still remain RO AFAIU.

okay.

> 
>>
>>> -	.attr = { .name = "bpf_testmod", .mode = 0444, },
>>> +	.attr = { .name = "bpf_testmod", .mode = 0666, },
>>>    	.read = bpf_testmod_test_read,
>>> +	.write = bpf_testmod_test_write,
>>>    };
>>>    static int bpf_testmod_init(void)
>>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> index b81adfedb4f6..b3892dc40111 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
>>>    	size_t len;
>>>    };
>>> +struct bpf_testmod_test_write_ctx {
>>> +	char *buf;
>>> +	loff_t off;
>>> +	size_t len;
>>> +};
>>> +
>>>    #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 50796b651f72..e4605c0b5af1 100644
>>> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
>>> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
>>> @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
>>>    	return 0;
>>>    }
>>> +static int trigger_module_test_write(int write_sz)
>>> +{
>>> +	int fd, err;
>>
>> Init err = 0?
> 
> I don't see what difference this makes.
> 
>>
>>> +	char *buf = malloc(write_sz);
>>> +
>>> +	if (!buf)
>>> +		return -ENOMEM;
>>
>> Looks like we already non-negative value, so return ENOMEM?
> 
> We already set err=-errno. So shouldn't we return negative too?

Oh, yes, return -ENOMEM sounds right here.

> 
>>
>>> +
>>> +	memset(buf, 'a', write_sz);
>>> +	buf[write_sz-1] = '\0';
>>> +
>>> +	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
>>> +	err = -errno;
>>> +	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
>>> +		goto out;
>>
>> Change the above to
>> 	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
>> 	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {

Here it should be ... "failed: %d\n", -errno.

>> 		err = -errno;
>> 		goto out;
>> 	}
> 
> I kept the code consistent with the definition of trigger_module_test_read().

The original patch code:

+static int trigger_module_test_write(int write_sz)
+{
+	int fd, err;
+	char *buf = malloc(write_sz);
+
+	if (!buf)
+		return -ENOMEM;
+
+	memset(buf, 'a', write_sz);
+	buf[write_sz-1] = '\0';
+
+	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
+	err = -errno;
+	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
+		goto out;
+
+	write(fd, buf, write_sz);
+	close(fd);
+out:
+	free(buf);
+
+	return 0;
+}

Even for "fd < 0" case, it "goto out" and "return 0". We should return
error code here instead of 0.

Second, "err = -errno" is set before checking fd < 0. If fd >= 0, err 
might inherit an postive errno from previous failure.
In trigger_module_test_write(), it is okay since the err is only used
when fd < 0:
         err = -errno;
         if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
                 return err;

My above rewrite intends to use "err" during final "return" statement,
so I put assignment of "err = -errno" inside the CHECK branch.
But there are different ways to implement this properly.


> 
> I'll leave it up to the maintainer to pick up the style changes if they prefer
> it this way.
> 
> Thanks for the ack and for the review.

No problem.

> 
> Cheers
> 
> --
> Qais Yousef
>
Qais Yousef Jan. 19, 2021, 9:57 a.m. UTC | #4
Hi Yonghong

On 01/18/21 09:48, Yonghong Song wrote:
> The original patch code:
> 
> +static int trigger_module_test_write(int write_sz)
> +{
> +	int fd, err;
> +	char *buf = malloc(write_sz);
> +
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	memset(buf, 'a', write_sz);
> +	buf[write_sz-1] = '\0';
> +
> +	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> +	err = -errno;
> +	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> +		goto out;
> +
> +	write(fd, buf, write_sz);
> +	close(fd);
> +out:
> +	free(buf);
> +
> +	return 0;
> +}
> 
> Even for "fd < 0" case, it "goto out" and "return 0". We should return
> error code here instead of 0.
> 
> Second, "err = -errno" is set before checking fd < 0. If fd >= 0, err might
> inherit an postive errno from previous failure.
> In trigger_module_test_write(), it is okay since the err is only used
> when fd < 0:
>         err = -errno;
>         if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
>                 return err;
> 
> My above rewrite intends to use "err" during final "return" statement,
> so I put assignment of "err = -errno" inside the CHECK branch.
> But there are different ways to implement this properly.

Okay I see now. Sorry I missed your point initially. I will fix and send v3.

Thanks

--
Qais Yousef

Patch
diff mbox series

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 b83ea448bc79..89c6d58e5dd6 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
@@ -28,6 +28,12 @@  TRACE_EVENT(bpf_testmod_test_read,
 		  __entry->pid, __entry->comm, __entry->off, __entry->len)
 );
 
+/* A bare tracepoint with no event associated with it */
+DECLARE_TRACE(bpf_testmod_test_write_bare,
+	TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
+	TP_ARGS(task, 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 2df19d73ca49..e900adad2276 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -28,9 +28,28 @@  bpf_testmod_test_read(struct file *file, struct kobject *kobj,
 EXPORT_SYMBOL(bpf_testmod_test_read);
 ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
 
+noinline ssize_t
+bpf_testmod_test_write(struct file *file, struct kobject *kobj,
+		      struct bin_attribute *bin_attr,
+		      char *buf, loff_t off, size_t len)
+{
+	struct bpf_testmod_test_write_ctx ctx = {
+		.buf = buf,
+		.off = off,
+		.len = len,
+	};
+
+	trace_bpf_testmod_test_write_bare(current, &ctx);
+
+	return -EIO; /* always fail */
+}
+EXPORT_SYMBOL(bpf_testmod_test_write);
+ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
+
 static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
-	.attr = { .name = "bpf_testmod", .mode = 0444, },
+	.attr = { .name = "bpf_testmod", .mode = 0666, },
 	.read = bpf_testmod_test_read,
+	.write = bpf_testmod_test_write,
 };
 
 static int bpf_testmod_init(void)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index b81adfedb4f6..b3892dc40111 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -11,4 +11,10 @@  struct bpf_testmod_test_read_ctx {
 	size_t len;
 };
 
+struct bpf_testmod_test_write_ctx {
+	char *buf;
+	loff_t off;
+	size_t len;
+};
+
 #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 50796b651f72..e4605c0b5af1 100644
--- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
@@ -21,9 +21,34 @@  static int trigger_module_test_read(int read_sz)
 	return 0;
 }
 
+static int trigger_module_test_write(int write_sz)
+{
+	int fd, err;
+	char *buf = malloc(write_sz);
+
+	if (!buf)
+		return -ENOMEM;
+
+	memset(buf, 'a', write_sz);
+	buf[write_sz-1] = '\0';
+
+	fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
+	err = -errno;
+	if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
+		goto out;
+
+	write(fd, buf, write_sz);
+	close(fd);
+out:
+	free(buf);
+
+	return 0;
+}
+
 void test_module_attach(void)
 {
 	const int READ_SZ = 456;
+	const int WRITE_SZ = 457;
 	struct test_module_attach* skel;
 	struct test_module_attach__bss *bss;
 	int err;
@@ -48,8 +73,10 @@  void test_module_attach(void)
 
 	/* trigger tracepoint */
 	ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read");
+	ASSERT_OK(trigger_module_test_write(WRITE_SZ), "trigger_write");
 
 	ASSERT_EQ(bss->raw_tp_read_sz, READ_SZ, "raw_tp");
+	ASSERT_EQ(bss->raw_tp_bare_write_sz, WRITE_SZ, "raw_tp_bare");
 	ASSERT_EQ(bss->tp_btf_read_sz, READ_SZ, "tp_btf");
 	ASSERT_EQ(bss->fentry_read_sz, READ_SZ, "fentry");
 	ASSERT_EQ(bss->fentry_manual_read_sz, READ_SZ, "fentry_manual");
diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
index efd1e287ac17..bd37ceec5587 100644
--- a/tools/testing/selftests/bpf/progs/test_module_attach.c
+++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
@@ -17,6 +17,16 @@  int BPF_PROG(handle_raw_tp,
 	return 0;
 }
 
+__u32 raw_tp_bare_write_sz = 0;
+
+SEC("raw_tp/bpf_testmod_test_write_bare")
+int BPF_PROG(handle_raw_tp_bare,
+	     struct task_struct *task, struct bpf_testmod_test_write_ctx *write_ctx)
+{
+	raw_tp_bare_write_sz = BPF_CORE_READ(write_ctx, len);
+	return 0;
+}
+
 __u32 tp_btf_read_sz = 0;
 
 SEC("tp_btf/bpf_testmod_test_read")