LD: Cannot add content to ctors section

[Ben Hirschberg]

Yeah, well, if life was so easy...

The original solution was using C with attribute constructor. It it is not working in this scenario because it adds the function to the ".init_array" section and not the ".ctors".

-----Original Message-----
From: H.J. Lu <hjl.tools@gmail.com>
Sent: Wednesday, May 20, 2020 2:45 PM
To: Ben Hirschberg <bhirschb@cyberarmor.io>
Cc: binutils@sourceware.org
Subject: Re: LD: Cannot add content to ctors section

On Wed, May 20, 2020 at 2:40 AM Ben Hirschberg <bhirschb@cyberarmor.io> wrote:
>
> Hi!
>
> I have a setup (Alpine Linux with Go executables) where I cannot rely on contents of ".init_array" to be called, but ".ctors" are called by musl-libc's loader.
>
> I am trying to add my constructors (C or ASM) to the ".ctors" section, but after linking my shared object they seem to be moved to ".init_array" (however in Alpine the ".ctors" section stays in the final image but it is empty)
>
> Why is this happening? Can make my array stay in ".ctors" section?
>
> Thanks
> Ben
>
> Here is my ASM code:
>
>        .intel_syntax noprefix
>        .text
>
>        .section      .rodata
> .Message:
>        .string "Constructor called!"
>
>        .text
> Constructor:
>        lea    rdi, .Message[rip]
>        jmp    puts@PLT
>
>        .section      .ctors,"a"
> __CTOR_LIST__:
>        .quad  Constructor
>

Do it in C with constructor attribute.

--
H.J.
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