Re: [RFC] DT_X86_64_PLT* dependency

[Florian Weimer <fweimer@redhat.com>]

* H. J. Lu:

> When these tags are generated, the r_addend field of the R_X86_64_JUMP_SLOT
> relocation stores the offset of the indirect branch instruction.  However, glibc
> versions which don't have this commit in glibc 2.36:
>
> commit f8587a61892cbafd98ce599131bf4f103466f084
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Fri May 20 19:21:48 2022 -0700
>
>     x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT
>
>     According to x86-64 psABI, r_addend should be ignored for R_X86_64_GLOB_DAT
>     and R_X86_64_JUMP_SLOT.  Since linkers always set their r_addends to 0, we
>     can ignore their r_addends.
>
>     Reviewed-by: Fangrui Song <maskray@google.com>
>
> won't ignore the r_addend value in the R_X86_64_JUMP_SLOT relocation.   Such
> binaries will fail to run with these versions of glibc.  I am working
> on a linker patch
> to add a glibc version dependency similar to GLIBC_ABI_DT_RELR for DT_RELR.
> Although this commit has been backported to glibc 2.33/2.34/2.35
> release branches,
> there may be 2.33/2.34/2.35 glibc binaries without the fix. 

Can we reuse the GLIBC_ABI_DT_RELR marker?

> Should binaries with DT_X86_64_PLT tags depend on glibc 2.36 or 2.33?

I don't understand this question.  The binaries will  run on any system
that has the marker symbol.  Or do you suggest to use an existing glibc
symbol version?

Thanks,
Florian