Re: Overlapping program headers/segments

[Jan Beulich <jbeulich@suse.com>]

On 24.09.2023 20:32, Max Larsson via Binutils wrote:
> What I have done so far, is to put the .rodata section in its own segment via defining a target
> specific method for 'elf_backend_modify_segment'. How to do it, I copied/looked/adapted from
> elfxx-mips.c:_bfd_mips_elf_modify_segment_map That works as expected.
>  
> But The result is that the program headers overlap. Like this:
>  
> Program Headers:
>   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
>   LOAD           0x000000 0x10000000 0x10000000 0x02034 0x02034 R E 0x10000
>   LOAD           0x020000 0x10010000 0x10010000 0x000f0 0x000f0 RW  0x10000
>   DYNAMIC        0x020028 0x10010028 0x10010028 0x000b8 0x000b8 RW  0x4
>   LOAD           0x012000 0x10002000 0x10002000 0x00031 0x00031 R   0x10000
>  Section to Segment mapping:
>   Segment Sections...
>    00     .hash .dynsym .dynstr .rela.dyn .rela.got2 .rela.plt .text .plt
>    01     .init_array .fini_array .got2 .dynamic .got
>    02     .dynamic
>    03     .rodata
>  
> You see, if you take the Virt-/PhysAddr and add the MemSize from the first
> program header the result is 0x10002034, which is greater than the Virt-/PhysAddr
> of the last program header   0x10002000.
> 
> So my question why do I get such a result, and how can I avoid it?

You didn't provide the linker script, which may have the observed effect together
with your code change: If it puts .text and .rodata together, then the overlap is
to be expected (as would frequently happen for NOTE segments and .note sections),
I think.

Jan