Re: [tip: core/urgent] compiler.h: Avoid the usage of __typeof_unqual__() when __GENKSYMS__ is defined

[Ingo Molnar <mingo@kernel.org>]

* Borislav Petkov <bp@alien8.de> wrote:

> On Thu, Apr 10, 2025 at 10:58:46AM -0000, tip-bot2 for Uros Bizjak wrote:
> > The following commit has been merged into the core/urgent branch of tip:
> > 
> > Commit-ID:     e696e5a114b59035f5a889d5484fedec4f40c1f3
> > Gitweb:        https://git.kernel.org/tip/e696e5a114b59035f5a889d5484fedec4f40c1f3
> > Author:        Uros Bizjak <ubizjak@gmail.com>
> > AuthorDate:    Fri, 04 Apr 2025 12:24:37 +02:00
> > Committer:     Borislav Petkov (AMD) <bp@alien8.de>
> > CommitterDate: Thu, 10 Apr 2025 12:44:27 +02:00
> > 
> > compiler.h: Avoid the usage of __typeof_unqual__() when __GENKSYMS__ is defined
> > 
> > Current version of genksyms doesn't know anything about __typeof_unqual__()
> > operator.  Avoid the usage of __typeof_unqual__() with genksyms to prevent
> > errors when symbols are versioned.
> > 
> > There were no problems with gendwarfksyms.
> > 
> > Fixes: ac053946f5c40 ("compiler.h: introduce TYPEOF_UNQUAL() macro")
> > Closes: https://lore.kernel.org/lkml/81a25a60-de78-43fb-b56a-131151e1c035@molgen.mpg.de/
> > Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
> > Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> > Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> > Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
> > Link: https://lore.kernel.org/r/20250404102535.705090-1-ubizjak@gmail.com
> > ---
> >  include/linux/compiler.h | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> > index 27725f1..98057f9 100644
> > --- a/include/linux/compiler.h
> > +++ b/include/linux/compiler.h
> > @@ -229,10 +229,10 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
> >  /*
> >   * Use __typeof_unqual__() when available.
> >   *
> > - * XXX: Remove test for __CHECKER__ once
> > - * sparse learns about __typeof_unqual__().
> > + * XXX: Remove test for __GENKSYMS__ once "genksyms" handles
> > + * __typeof_unqual__(), and test for __CHECKER__ once "sparse" handles it.
> >   */
> > -#if CC_HAS_TYPEOF_UNQUAL && !defined(__CHECKER__)
> > +#if CC_HAS_TYPEOF_UNQUAL && !defined(__GENKSYMS__) && !defined(__CHECKER__)
> >  # define USE_TYPEOF_UNQUAL 1
> >  #endif
> 
> So mingo is right - this is not really a fix but a brown-paper bag of
> sorts.

Yeah, agreed, I've removed this workaround from tip:core/urgent for the 
time being - it's not like genksyms is some magic external entity we 
have to work around, it's an in-kernel tool that can be fixed/enhanced 
in scripts/genksyms/.

Maybe akpm can merge this or some other fix and sort it out? AFAICS the 
bug came in via the -mm tree in January, via:

  ac053946f5c4 ("compiler.h: introduce TYPEOF_UNQUAL() macro")

Thanks,

	Ingo