[Bug ld/31795] ld.bfd makes ELFs of type ET_EXEC for static PIEs when load address is non-0

[mintsuki at protonmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31795

--- Comment #7 from mintsuki <mintsuki at protonmail dot com> ---
(In reply to H.J. Lu from comment #5)
> (In reply to mintsuki from comment #3)
> > Also, when generating a shared object with -shared, without -pie, having a
> > non-0 base address does not affect the ELF file type, which is always
> 
> You can't load the multiple shared libraries at the overlapping address
> range.
> 
> > ET_DYN. If what you just said is true, then why is this the behaviour here
> > and not when making a static PIE?
> 
> A testcase?

Download and unpack
https://github.com/limine-bootloader/limine-c-template/archive/d90875580fb74c3cf075b659c995e4070d265c24.tar.gz

In the extracted directory, run "make -C kernel clean all KCC=gcc KLD=ld.bfd".
The output kernel is found at "kernel/bin/kernel".

The linker script is found at "kernel/linker.ld".

So, building this with ld.bfd, the output ELF file type is ET_EXEC, as in the
subject of this bug report. Replacing ld.bfd with ld.gold or ld.lld in the
command above will generated a static PIE kernel with type ET_DYN and a non-0
base (0xffffffff80000000). ld.bfd is the outlier here.

Replacing -pie with -shared at line 73 of "kernel/GNUmakefile" and then
rebuilding, as mentioned above, will cause all 3 linkers to (correctly)
generate an ET_DYN shared object with the specified non-0 base.

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