linux-kernel - Re: [PATCH] arch/powerpc: Remove .interp section in vmlinux

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Message-ID: <aGPjibUcPDubyFY1@gate>
Date: Tue, 1 Jul 2025 08:32:57 -0500
From: Segher Boessenkool <segher@...nel.crashing.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
        Naveen N Rao <naveen@...nel.org>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] arch/powerpc: Remove .interp section in vmlinux

Hi!

On Tue, Jul 01, 2025 at 12:49:29PM +0200, Christophe Leroy wrote:
> When building with CONFIG_RELOCATABLE, there is a .interp section
> which contains the name of the expected ELF interpreter:
> 
> Contents of section .interp:
>  c0000000021c1bac 2f757372 2f6c6962 2f6c642e 736f2e31  /usr/lib/ld.so.1
>  c0000000021c1bbc 00                                   .
> 
> That information is useless and even likely wrong. Remove it.

s/ likely//

You cannot run the kernel as some dynamic object (under control of some
interpreter that will load DSOs for you), hehe.

The various bfd/elf*.c (in binutils/ld) have code like

  if (htab->elf.dynamic_sections_created)
    {
      /* Set the contents of the .interp section to the interpreter.  */
      if (bfd_link_executable (info) && !info->nointerp)
        {
          s = bfd_get_linker_section (dynobj, ".interp");
          if (s == NULL)
            abort ();
          s->size = sizeof ELF_DYNAMIC_INTERPRETER;
          s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
        }
    }

(yes there are about a hundred copies of this code, that could be
improved :-) )

whenever producing dynamic objects, so this code just sets that text and
that's all, no side effect to be worried of.

Acked-by: Segher Boessenkool <segher@...nel.crashing.org>

(Maybe this could or should be in generic code though, not architecture
code?)


Segher