[SOL] Recalculate the size of the program header table

[LucasSte]

Problem

When linking LLD calls finalizeSections, where it assigns the size of the program header table based on the number of program headers:

llvm-project/lld/ELF/Writer.cpp

Lines 2026 to 2027 in cefd647

	ctx.out.programHeaders->size =
	sizeof(Elf_Phdr) * ctx.mainPart->phdrs.size();

But after that, it removes empty PT_LOAD headers:

llvm-project/lld/ELF/Writer.cpp

Lines 336 to 340 in cefd647

	// Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a
	// 0 sized region. This has to be done late since only after assignAddresses
	// we know the size of the sections.
	for (Partition &part : ctx.partitions)
	removeEmptyPTLoad(ctx, part.phdrs);

So effectively the number of headers changes, but the size of the table does not.

Solution

Recalculate the size of the program header table after removing empty headers.

[nagisa]

This makes sense to me, although it probably does not hurt anything if the section is allocated a little too large.

[LucasSte]

This makes sense to me, although it probably does not hurt anything if the section is allocated a little too large.

The sbpf ELF loader requires the first section to be adjacent to the program header table.