[S] Change in coreboot[main]: util/cbfstool: Deal with how lld organizes loadable segments

[Arthur Heymans (Code Review)]

Attention is currently required from: Angel Pons, Nico Huber.

Arthur Heymans has posted comments on this change by Arthur Heymans. ( https://review.coreboot.org/c/coreboot/+/84043?usp=email )

Change subject: util/cbfstool: Deal with how lld organizes loadable segments
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Patch Set 11:

(1 comment)

File util/cbfstool/cbfs-mkstage.c:

https://review.coreboot.org/c/coreboot/+/84043/comment/e4b3f9f0_95432226?usp... :
PS7, Line 301: prev = cur
> Maybe I'm confusing myself too much. What do we actually try to assert?
> That things for `_data .. _edata` are consecutive, I guess?
>
> Looking at a BFD linked romstage, I would check `vaddr` there as well:
> $ readelf --segments build/cbfs/fallback/romstage.elf 
>
> Elf file type is EXEC (Executable file)
> Entry point 0x2000031
> There are 2 program headers, starting at offset 52
>
> Program Headers:
>   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
>   LOAD           0x000080 0x02000000 0x02000000 0x0c1d0 0x0c1d0 R E 0x20
>   LOAD           0x00c250 0xff7cb0a8 0x0200c1d0 0x00018 0x00018 RW  0x4
>
>  Section to Segment mapping:
>   Segment Sections...
>    00     .text 
>    01     .data 
>
> Just not compare the executable segment.

So what we want is extract out loadable sections and make it into a XIP binary. We want them to be consecutive. We only use PT_LOAD segments anyway, but it's indeed reasonable to not update the loop variable on non PT_LOAD.