On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@xxxxxxxxxx> 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 DWARF-based versions [1] and Masahiro's u32 > fixup patch [5]. > > [1] https://lore.kernel.org/lkml/20241219210736.2990838-20-samitolvanen@xxxxxxxxxx/ > [2] https://lore.kernel.org/lkml/20240605032120.3179157-1-song@xxxxxxxxxx/ > [3] https://lore.kernel.org/lkml/ZoxbEEsK40ASi1cY@xxxxxxxxxxxxxxxxxxxxxx/ > [4] https://lore.kernel.org/lkml/0b2697fd-7ab4-469f-83a6-ec9ebc701ba0@xxxxxxxx/ > [5] https://lore.kernel.org/linux-kbuild/20241228154603.2234284-1-masahiroy@xxxxxxxxxx > > Changes in v13: > - Fixed up missed s32 usage (Thanks Sami). Applied to linux-kbuild. Thanks. -- Best Regards Masahiro Yamada
