[PATCH] binutils: partially revert 17c6c3b99156fe82c1e637e1a5fd9f163ac788c8

[H.J. Lu]

On Thu, Nov 17, 2022 at 10:28 AM 徐持恒 Xu Chiheng <chiheng.xu@gmail.com> wrote:
>
> No. not using NASM.
>
> using x86_64-elf-g++ -m32 to generate 32 bit code(elf32).
> using x86_64-elf-objcopy to convert it to elf64.
> then link the 32 bit code(elf64) with 64 bit code.
>

This is an unsupported operation.

H.J.
>
>
> ________________________________
> From: H.J. Lu <hjl.tools@gmail.com>
> Sent: Friday, November 18, 2022 02:06
> To: 徐持恒 Xu Chiheng <chiheng.xu@gmail.com>
> Cc: binutils@sourceware.org <binutils@sourceware.org>
> Subject: Re: [PATCH] binutils: partially revert 17c6c3b99156fe82c1e637e1a5fd9f163ac788c8
>
> On Thu, Nov 17, 2022 at 9:44 AM 徐持恒 Xu Chiheng via Binutils
> <binutils@sourceware.org> wrote:
> >
> > Phenomenal:  In 32 bit and 64 bit mixed code,  ld can't do relocation
> > for 32 bit code.
> > It is caused by commit 17c6c3b99156fe82c1e637e1a5fd9f163ac788c8.
> >
> >
> >
> >
> >   /* src_mask selects the part of the instruction (or data) to be used
> >      in the relocation sum.  If the target relocations don't have an
> >      addend in the reloc, eg. ELF USE_REL, src_mask will normally equal
> >      dst_mask to extract the addend from the section contents.  If
> >      relocations do have an addend in the reloc, eg. ELF USE_RELA, this
> >      field should normally be zero.  Non-zero values for ELF USE_RELA
> >      targets should be viewed with suspicion as normally the value in
> >      the dst_mask part of the section contents should be ignored.  */
> >   bfd_vma src_mask;
> >
> >
> >
> > Author: Jan Beulich <jbeulich@suse.com>  2021-05-07 18:05:12
> > Committer: Jan Beulich <jbeulich@suse.com>  2021-05-07 18:05:12
> > Parent: 98da05bf2698b55b73453480a3fbb92f163d2c7b (x86: don't mix disp
> > and imm processing)
> > Child:  4cf88725da1cb503be04d3237354105ec170bc86 ([gdb/symtab] Fix
> > infinite recursion in dwarf2_cu::get_builder())
> > Branches: master, test0558-01 and many more (41)
> > Follows: gdb-10-branchpoint
> > Precedes: binutils-2_37, gdb-11-branchpoint
> >
> >     x86-64/ELF: clear src_mask for all reloc types
> >
> >     x86-64 uses rela relocations. The comment next to the field's declaration
> >     says "Non-zero values for ELF USE_RELA targets should be viewed with
> >     suspicion ..." And indeed the fields being non-zero causes section
> >     contents to be accumulated into the final relocated values in addition to
> >     the relocations' addends, which is contrary to the ELF spec.
>
> Are you using NASM?
>
> --
> H.J.



-- 
H.J.