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[PATCH] Set dynobj to a normal input file if possible

H.J. Lu hjl.tools@gmail.com
Fri Apr 22 12:35:00 GMT 2016 
On Fri, Apr 22, 2016 at 1:55 AM, Alan Modra <amodra@gmail.com> wrote:
> On Thu, Apr 21, 2016 at 09:49:50PM -0700, H.J. Lu wrote:
>> On Thu, Apr 21, 2016 at 8:39 PM, Hans-Peter Nilsson
>> <hans-peter.nilsson@axis.com> wrote:
>> >> Date: Wed, 20 Apr 2016 20:31:50 -0700
>> >> From: "H.J. Lu" <hongjiu.lu@intel.com>
>> >
>> >>       * elflink.c (_bfd_elf_link_create_dynstrtab): Set dynobj to a
>> >>       normal input file if possible.
>> >
>> > Looks like this caused, for a cross -m32 build to arm-unknown-eabi:
>> >
>> > Running /tmp/hpautotest-binutils/bsrc/src/ld/testsuite/ld-arm/arm-elf.exp ...
>> > FAIL: Indirect cross-library function reference
>> > FAIL: TLS dynamic application
>> > FAIL: GOT relocations in executables
>> > FAIL: Thumb and -gc-sections
>> > FAIL: Simple dynamic application
>> > FAIL: Simple dynamic application without .rel.plt in linker script
>> > FAIL: Non-pcrel function reference
>> > FAIL: Mixed ARM/Thumb dynamic application
>> > FAIL: Mixed ARM/Thumb arch5 dynamic application
>> > FAIL: Using Thumb lib by another lib
>> > FAIL: MOVW/MOVT against shared libraries
>> > FAIL: Mixed ARM/Thumb dynamic application with farcalls
>> > FAIL: Mixed ARM/Thumb arch5 dynamic application with farcalls
>> > FAIL: TLS long plt
>> > FAIL: IFUNC test 7
>> > FAIL: IFUNC test 8
>> > FAIL: IFUNC test 9
>> > FAIL: IFUNC test 10
>> > FAIL: IFUNC test 13
>> > FAIL: IFUNC test 14
>> > FAIL: IFUNC test 15
>> > FAIL: IFUNC test 16
>> > FAIL: Preempt Thumb symbol
>> > FAIL: ld-arm/unresolved-1-dyn
>
> Sounds like something should be fixed in the arm backend.  Powerpc64
> deliberately sets dynobj to the linker created "stub bfd", so there
> isn't some underlying generic problem with attaching the linker
> sections to a linker created bfd.  In fact, it's a good idea.
>
> Hmm.
> ld-new: linker stubs: file class ELFCLASSNONE incompatible with ELFCLASS32
> ld-new: final link failed: File in wrong format
>
> Yes, looks like there needs to be a small tweak.  See bfd/elf64-ppc.c
> ppc64_elf_init_stub_bfd

They need something like

elf_elfheader (fake_bfd)->e_ident[EI_CLASS]
   = (get_elf_backend_data (link_info.output_bfd)->s->arch_size == 64
       ? ELFCLASS64 : ELFCLASS32);

Currently, we hold linker created dynamic sections in an input shared
object, which has its own dynamic sections, when the first input file
from linker is a shared object.  It may lead to conflicts between
linker created dynamic sections and shared object's dynamic sections.
We can use a a fake bfd to hold linker created dynamic sections.
Unfortunately, it doesn't work due to BFD_LINKER_CREATED.  Dynamic
sections in bfd with BFD_LINKER_CREATED may be ignored.

-- 
H.J.
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