Re: [PATCH] kprobes: Enable tracing for mololithic kernel images

From: Christoph Hellwig <hch@lst.de>
To: Luis Chamberlain <mcgrof@kernel.org>
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Subject: Re: [PATCH] kprobes: Enable tracing for mololithic kernel images
Date: Thu, 9 Jun 2022 05:48:52 +0200	[thread overview]
Message-ID: <20220609034852.GA30873@lst.de> (raw)
In-Reply-To: <YqEF6+YKqCHsWZJW@bombadil.infradead.org>

On Wed, Jun 08, 2022 at 01:26:19PM -0700, Luis Chamberlain wrote:
> No, that was removed because it has only one user.

That is only part of the story.  The other part is that the overall
kernel simply does not have any business allocating exutable memory.
Executable memory is a very special concept for modules or module-like
code like kprobes, and should not be exposed as a general concept.

Especially as executable memory really should not also be writable
for security reasons.  In other words, we should actually never
allocate executable memory, every.  We might seal memory and then
mark it executable after having written to it, which is how modules
and kprobes are implemented on all modern Linux ports anyway.