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Subject: Re: [PATCH] livepatch: introduce klp_func called interface
From: zhang warden <zhangwarden@gmail.com>
In-Reply-To: <Zloh/TbRFIX6UtA+@redhat.com>
Date: Tue, 4 Jun 2024 16:14:51 +0800
Cc: Miroslav Benes <mbenes@suse.cz>,
 Josh Poimboeuf <jpoimboe@kernel.org>,
 Jiri Kosina <jikos@kernel.org>,
 Petr Mladek <pmladek@suse.com>,
 live-patching@vger.kernel.org,
 linux-kernel@vger.kernel.org
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References: <20240520005826.17281-1-zhangwarden@gmail.com>
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 <alpine.LSU.2.21.2405210823590.4805@pobox.suse.cz>
 <Zloh/TbRFIX6UtA+@redhat.com>
To: Joe Lawrence <joe.lawrence@redhat.com>


> On Jun 1, 2024, at 03:16, Joe Lawrence <joe.lawrence@redhat.com> =
wrote:
>=20
> Adding these attributes to livepatch sysfs would be expedient and
> probably easier for us to use, but imposes a recurring burden on us to
> maintain and test (where is the documentation and kselftest for this =
new
> interface?).  Or, we could let the other tools handle all of that for
> us.
How this attribute imposes a recurring burden to maintain and test?

> Perhaps if someone already has an off-the-shelf script that is using
> ftrace to monitor livepatched code, it could be donated to
> Documentation/livepatch/?  I can ask our QE folks if they have =
something
> like this.

My intention to introduce this attitude to sysfs is that user who what =
to see if this function is called can just need to show this function =
attribute in the livepatch sysfs interface.

User who have no experience of using ftrace will have problems to get =
the calling state of the patched function. After all, ftrace is a =
professional kernel tracing tools.

Adding this attribute will be more easier for us to show if this patched =
function is called. Actually, I have never try to use ftrace to trace a =
patched function. Is it OK of using ftrace for a livepatched function?

Regards,
Wardenjohn