Re: The trouble with __weak and objtool got worse

[Josh Poimboeuf <jpoimboe@redhat.com>]

On Fri, Apr 15, 2022 at 08:10:18AM -0700, Josh Poimboeuf wrote:
> On Fri, Apr 15, 2022 at 01:19:04PM +0200, Peter Zijlstra wrote:
> > Now, if we do IBT/LTO builds, and run objtool on linked objects only,
> > this obvious doesn't happen, because the weak stuff has been resolved by
> > then. But ideally we'd not force that since it has a build time
> > penalty..
> > 
> > The other option seems to be to have objtool add section symbols it
> > needs, however due to ELF being a total PITA and requiring all LOCAL
> > symbols to be before GLOBAL symbols, this would mean re-ordering the
> > whole symbol table (I have the code somewhere :-/).
> > 
> > Alternatively:
> > 
> >   https://sourceware.org/pipermail/binutils/2020-December/114671.html
> > 
> > seems to suggest: -Wa,--generate-unused-section-symbols=yes, ought to
> > work, except I'm getting:
> > 
> > $ gcc -O2 -fcf-protection=none -fno-asynchronous-unwind-tables -Wa,--generate-unused-section-symbols=yes -c foo*.c
> > as: unrecognized option '--generate-unused-section-symbols=yes'
> > as: unrecognized option '--generate-unused-section-symbols=yes'
> > 
> > $ as --version
> > GNU assembler (GNU Binutils for Debian) 2.38
> 
> Can we trick the assembler into creating function symbols for all the

I meant s/function symbols/section symbols/ obviously.

> static call sites by having some inline asm (or _THIS_IP_) in the static
> call macro with a dummy reference to a code location in the function?

-- 
Josh