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Date:   Sat, 16 Apr 2022 13:25:46 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "H.J. Lu" <hjl.tools@gmail.com>
Cc:     the arch/x86 maintainers <x86@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Miroslav Benes <mbenes@suse.cz>, rostedt@goodmis.org,
        linux-toolchains@vger.kernel.org
Subject: Re: The trouble with __weak and objtool got worse
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On Fri, Apr 15, 2022 at 02:04:32PM -0700, H.J. Lu wrote:
> On Fri, Apr 15, 2022 at 4:19 AM Peter Zijlstra <peterz@infradead.org> wrote:

> > *HOWEVER*, sometimes it generates things like this (using new enough
> > binutils):
> >
> > foo-weak.o:
> >
> > Relocation section '.rela.static_call_sites' at offset 0x2c8 contains 1 entry:
> >     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
> > 0000000000000000  0000000200000002 R_X86_64_PC32          0000000000000000 foo + 0
> > 0000000000000004  0000000d00000002 R_X86_64_PC32          0000000000000000 __SCT__foo + 1
> >
> > foo.o:
> >
> > Relocation section '.rela.static_call_sites' at offset 0x310 contains 2 entries:
> >     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
> > 0000000000000000  0000000200000002 R_X86_64_PC32          0000000000000000 foo + d
> > 0000000000000004  0000000d00000002 R_X86_64_PC32          0000000000000000 __SCT__foo + 1
> >
> > foos.o:
> >
> > Relocation section '.rela.static_call_sites' at offset 0x430 contains 4 entries:
> >     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
> > 0000000000000000  0000000100000002 R_X86_64_PC32          0000000000000000 foo + 0
> > 0000000000000004  0000000d00000002 R_X86_64_PC32          0000000000000000 __SCT__foo + 1
> > 0000000000000008  0000000100000002 R_X86_64_PC32          0000000000000000 foo + d
> > 000000000000000c  0000000d00000002 R_X86_64_PC32          0000000000000000 __SCT__foo + 1
> >
> > And now we can see how that foos.o .static_call_sites goes side-ways, we
> > now have _two_ patch sites in foo. One for the weak symbol at foo+0
> > (which is no longer a static_call site!) and one at foo+d which is in
> > fact the right location.
> 
> This can't be right.  "foo" must point to the non-weak function.
> Please file a linker bug report.

It does point to the non-weak symbol; they both do, even the relocs that
started out as pointing to the weak symbol.

Are you saying the linker *should* have removed the relocs that were
based on the weak symbol?