Re: [PATCH v2 0/7] objtool/klp: sympos/module/alternative/etc fixes

[Joe Lawrence]

On 8/5/26 10:29 AM, Josh Poimboeuf wrote:
> v2: 
> - rebased on tip/master (first 6 patches were merged)
> - dropped original patches 7-8 (will post followup)
> - added .klp.symid fix
> 
> v1: https://lore.kernel.org/cover.1785727106.git.jpoimboe@xxxxxxxxxx
> 
> This consolidates fixes for the klp-build issues reported by Joe over
> the last several weeks, plus some more things I found while
> testing/reviewing.
> 
> Fun stuff like symbol resolution, module dependencies, alternatives.
> 
> Joe Lawrence (1):
>   objtool/klp: Allow new references to module exports
> 
> Josh Poimboeuf (6):
>   objtool/klp: Fix vmlinux .klp.symid link error for .no_trim_symbol
>     symbols
>   objtool/klp: Fix size of empty special section entries
>   objtool/klp: Ignore replacement offset of empty x86 alternatives
>   objtool/klp: Explicitly disallow patching or referencing init
>     code/data
>   objtool/klp: Fix cross-module klp relocation section naming
>   objtool/klp: Don't match local symbols against exports
> 
>  tools/objtool/arch/x86/special.c        | 27 ++++++++++
>  tools/objtool/include/objtool/klp.h     | 10 ++--
>  tools/objtool/include/objtool/special.h |  7 +++
>  tools/objtool/klp-diff.c                | 65 ++++++++++++++++++++++---
>  tools/objtool/klp-post-link.c           | 53 +++++++++++---------
>  tools/objtool/klp-symid.c               |  1 +
>  tools/objtool/klp-sympos.c              | 10 ++++
>  7 files changed, 141 insertions(+), 32 deletions(-)
> 

These changes (and follow-up comments) look pretty good (lightly
tested).  Could "objtool/klp: Fix vmlinux .klp.symid link error for
.no_trim_symbol symbols" peel off and merge sooner since it fixes a
commit just recently merged?

Though I think there is a still gap for EXPORT_SYMBOL_FOR_MODULES
symbols: those exported that way from vmlinux would presumably need a
klp-relocation, but klp_reloc_needed() always returns false for all
vmlinux exports.  Maybe we need to parse the namespace column from
Module.symvers to special case those?  (At least, that is how I read the
code, I don't have full repro test cases handy.)

This wouldn't block any of these patches, but if you are spinning a v3,
we could consider tacking that on while we're here.

-- 
Joe