[Bug ld/21464] relocation truncated to fit: R_OR1K_GOT16 on OpenRISC, when linking libQtGui.so.4.8.7

[giulio.benetti at micronovasrl dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=21464

--- Comment #8 from Giulio Benetti <giulio.benetti at micronovasrl dot com> ---
Hi Stafford,

Il 21/03/2021 04:00, shorne at gmail dot com ha scritto:
> https://sourceware.org/bugzilla/show_bug.cgi?id=21464
> 
> --- Comment #7 from Stafford Horne <shorne at gmail dot com> ---
> On Wed, Mar 17, 2021 at 10:10:13PM +0000, shorne at gmail dot com wrote:
>> https://sourceware.org/bugzilla/show_bug.cgi?id=21464
>>
>> --- Comment #6 from Stafford Horne <shorne at gmail dot com> ---
>> On Wed, Mar 17, 2021 at 09:31:59PM +0000, giulio.benetti at micronovasrl dot
>> com wrote:
>>> https://sourceware.org/bugzilla/show_bug.cgi?id=21464
>>>
>>> --- Comment #5 from Giulio Benetti <giulio.benetti at micronovasrl dot com> 
>>> ---
>>> Hi Nick,
>>>
>>> this bug still shows up with binutils 2.36.1 like:
>>> /home/giuliobenetti/git/upstream/or1k-binutils-2.36.1/host/lib/gcc/or1k-buildroot-linux-uclibc/9.3.0/../../../../or1k-buildroot-linux-uclibc/bin/ld:
>>> BFD (GNU Binutils) 2.36.1 assertion fail elf32-or1k.c:2377
>>> /home/giuliobenetti/git/upstream/or1k-binutils-2.36.1/host/lib/gcc/or1k-buildroot-linux-uclibc/9.3.0/../../../../or1k-buildroot-linux-uclibc/bin/ld:
>>> BFD (GNU Binutils) 2.36.1 assertion fail elf32-or1k.c:2377
>>> /home/giuliobenetti/git/upstream/or1k-binutils-2.36.1/host/lib/gcc/or1k-buildroot-linux-uclibc/9.3.0/../../../../or1k-buildroot-linux-uclibc/bin/ld:
>>> BFD (GNU Binutils) 2.36.1 assertion fail elf32-or1k.c:2377
>>> collect2: error: ld returned 1 exit status
>>>
> 
> Hello,
> 
> I was able to reproduce the "assertion fail elf32-or1k.c:2377" issue with my
> latest glibc toolchain versions, and I also did some debugging of LD to try to
> get an idea of what is going on.
> 
> Reproduced with:
>    - Just building protobuf on its own, not using buildroot, that was giving 
> me
>      some exceptions about not being able to find a thread librarty.
> 
> Notes
> 
> 1. The "relocation truncated to fit: R_OR1K_GOT16" error seems not be 
> outputted
>     in the latest LD.  I maybe have removed it incorrectly with some recent
> changes?  The
>     issue is not fixed.  The R_OR1K_GOT16 relocation limit means OpenRISC 
> fails
> to
>     run some PLT entries at run time when there are too many symbols.  I am
> planning
>     to fix this.

It seems to be the same bug since it fails on assert(), but maybe I'm wrong.

>     I have two ideas:
>      1. When we get to big plt entries over the limit will use 2 relocations 
> to
>         compose the GOT offset
>      2. Use an extra PLT trampoline entry to add the extra offset i.e. 16k
>         When we go over 32k we have another trampoline, that adds 16k and 
> jumps
> to
>        the previous trampoline.
> 
> 2. The "assertion fail elf32-or1k.c:2377" seems to be something different to
> me,
>     and not related to the count of GOT entries, maybe it should be a 
> different
> bug issue?

Yes, it seems since...

> 3. When debugging the "assertion fail elf32-or1k.c:2377" I see, the line we 
> are
> failing on is:
> 
>         Breakpoint 1, or1k_elf_finish_dynamic_symbol (output_bfd=0x568460,
> info=0x543320 <link_info>, h=0x81c0f8, sym=0x7fffffffb260) at
> /home/shorne/work/gnu-toolchain/binutils-gdb/bfd/elf32-or1k.c:2377
>         2377          BFD_ASSERT (h->dynindx != -1);
> 
>     So, it's asserting that the dynindx is defined, in
> or1k_elf_finish_dynamic_symbol before
>     we write out the PLT entry.
> 
>     In the failure cases we see:
> 
>         h->root.type bfd_link_hash_defweak AND h->forced_local
> 
>     These failing symbols have been forced_local but we are still trying to
> write the PLT entry.
>     That doesn't seem to make much sense.
> 
>     The forced_local has been set in _bfd_elf_link_hash_hide_symbol(), the
> generic
>     elflink code:
> 
>        #0  _bfd_elf_link_hash_hide_symbol (info=0x543320 <link_info>,
> h=0x2bcbeb8, force_local=1) at
> /home/shorne/work/gnu-toolchain/binutils-gdb/bfd/elflink.c:7756
>        #1  0x000000000045e61e in _bfd_elf_link_assign_sym_version 
> (h=0x2bcbeb8,
> data=0x7fffffffb2f0) at
> /home/shorne/work/gnu-toolchain/binutils-gdb/bfd/elflink.c:2483
>        #2  0x000000000043055d in bfd_link_hash_traverse (htab=0x56a790,
> func=func@entry=0x45e33d <_bfd_elf_link_assign_sym_version>,
> info=info@entry=0x7fffffffb2f0)
> 
>     I tried to look at other architectures and I see that most do the same
> assert, so
>     so would they also fail?
> 
>     In riscv (a relatively modern implementation) they seem to just detect 
> this
> case and return FALSE.
>     I will try to do that and send a patch, but it will be hard to test.

I've tried to imitate what riscv does:
'''
diff --git a/bfd/elf32-or1k.c b/bfd/elf32-or1k.c
index 65938e5137..74cff4bf01 100644
--- a/bfd/elf32-or1k.c
+++ b/bfd/elf32-or1k.c
@@ -2372,15 +2372,22 @@ or1k_elf_finish_dynamic_symbol (bfd *output_bfd,
        bfd_vma got_addr;
        Elf_Internal_Rela rela;

-      /* This symbol has an entry in the procedure linkage table.  Set
-        it up.  */
-      BFD_ASSERT (h->dynindx != -1);
-
        splt = htab->root.splt;
        sgot = htab->root.sgotplt;
        srela = htab->root.srelplt;
        BFD_ASSERT (splt != NULL && sgot != NULL && srela != NULL);

+      /* This symbol has an entry in the procedure linkage table.  Set
+        it up.  */
+      if ((h->dynindx == -1
+           && !((h->forced_local || bfd_link_executable (info))
+                && h->def_regular
+                && h->type == STT_GNU_IFUNC))
+          || splt == NULL
+          || sgot == NULL
+          || srela == NULL)
+        return FALSE;
+
        plt_base_addr = splt->output_section->vma + splt->output_offset;
        got_base_addr = sgot->output_section->vma + sgot->output_offset;

--
'''

but it still fails and without emitting anything, only:
collect2: error: ld returned 1 exit status

>     Any suggestion for a test case for this?
> 
> -Stafford
> 

Another package that has the same problem is libtheora

I don't know how to help you more.
Tell me if you need something else

Kind regards

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