linux-kernel - Re: [PATCH v10 0/5] Extended MODVERSIONS Support

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Message-ID: <Z0UHZQErgTDpie0y@bombadil.infradead.org>
Date: Mon, 25 Nov 2024 15:25:25 -0800
From: Luis Chamberlain <mcgrof@...nel.org>
To: Matthew Maurer <mmaurer@...gle.com>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nicolas@...sle.eu>, Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Jonathan Corbet <corbet@....net>, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
	linux-kbuild@...r.kernel.org, rust-for-linux@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v10 0/5] Extended MODVERSIONS Support

On Sat, Nov 23, 2024 at 02:42:14AM +0000, Matthew Maurer wrote:
> This patch series is intended for use alongside the Implement DWARF
> modversions series [1] to enable RUST and MODVERSIONS at the same
> time.
> 
> Elsewhere, we've seen a desire for long symbol name support for LTO
> symbol names [2], and the previous series came up [3] as a possible
> solution rather than hashing, which some have objected [4] to.
> 
> This series adds a MODVERSIONS format which uses a section per column.
> This avoids userspace tools breaking if we need to make a similar change
> to the format in the future - we would do so by adding a new section,
> rather than editing the struct definition. In the new format, the name
> section is formatted as a concatenated sequence of NUL-terminated
> strings, which allows for arbitrary length names.
> 
> Emitting the extended format is guarded by CONFIG_EXTENDED_MODVERSIONS,
> but the kernel always knows how to validate both the original and
> extended formats.
> 
> Emitting the existing format is now guarded by CONFIG_BASIC_MODVERSIONS,
> but it is enabled by default when MODVERSIONS is enabled and must be
> explicitly disabled by the user.
> 
> Disabling CONFIG_BASIC_MODVERSIONS may cause some userspace tools to be
> unable to retrieve CRCs until they are patched to understand the new
> location. Even with CONFIG_BASIC_MODVERSIONS enabled, those tools will
> be unable to read the CRCs for long symbols until they are updated to
> read the new format. This is not expected to interfere with normal
> operation, as the primary use for CRCs embedded in the module is
> load-time verification by the kernel. Recording and monitoring of CRCs
> is typically done through Module.symvers.
> 
> Selecting RUST and MODVERSIONS is now possible if GENDWARFKSYMS is
> selected, and will implicitly select EXTENDED_MODVERSIONS.
> 
> This series depends upon the module verification refactor patches [5]
> that were split off of v5 (now in modules-next)
> and DWARF-based versions [1].

Thanks for doing all this.

Acked-by: Luis Chamberlain <mcgrof@...nel.org>

 Luis