[PATCH] D71035: [llvm-objcopy][ELF] -O binary: use LMA instead of sh_offset to decide where to write section contents

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 232953.
MaskRay edited the summary of this revision.
MaskRay added a comment.

Fix formula: sh_offset - p_offset + p_paddr

See bfd/elf.c:1182 for a reference.

/* We used to use the same adjustment for SEC_LOAD

  	   sections, but that doesn't work if the segment
  	   is packed with code from multiple VMAs.
  	   Instead we calculate the section LMA based on
  	   the segment LMA.  It is assumed that the
  	   segment will contain sections with contiguous
  	   LMAs, even if the VMAs are not.  */

newsect->lma = (phdr->p_paddr + hdr->sh_offset - phdr->p_offset);

For sections not in a PT_LOAD, the BFD code uses a different formula.

  		newsect->lma = (phdr->p_paddr
  				+ hdr->sh_addr - phdr->p_vaddr);

We don't need care about that because -O binary does not dump non-SHF_ALLOC sections.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71035/new/

https://reviews.llvm.org/D71035

Files:
  llvm/test/tools/llvm-objcopy/ELF/binary-paddr.test
  llvm/tools/llvm-objcopy/ELF/Object.cpp

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