[PATCH] D36279: [Object] Fix ELFObjectFile<ELFT>::getRelocationOffset

[Rafael Avila de Espindola via llvm-commits]

The specification says

r_offset
This member gives the location at which to apply the relocation action. For a relocatable file, the value is the byte offset from the beginning of the section to the storage unit affected by the relocation. For an executable file or a shared object, the value is the virtual address of the storage unit affected by the relocation.

So there is no offset in a ET_DYN. In a ET_DYN r_offset, despite the
name, gives an address.

Cheers,
Rafael

Alexander Shaposhnikov via Phabricator via llvm-commits
<llvm-commits at lists.llvm.org> writes:

> alexshap created this revision.
>
> The assert in ELFObjectFile<ELFT>::getRelocationOffset appears to be incorrect.
> For example, dynamic libraries have e_type set to ET_DYN and contain relocations at the same time.
> The same issue might arise for some executables (e_type set to ET_EXEC).
>
>
> Repository:
>   rL LLVM
>
> https://reviews.llvm.org/D36279
>
> Files:
>   ELFObjectFile.h
>
>
> Index: ELFObjectFile.h
> ===================================================================
> --- ELFObjectFile.h
> +++ ELFObjectFile.h
> @@ -781,12 +781,9 @@
>  
>  template <class ELFT>
>  uint64_t ELFObjectFile<ELFT>::getRelocationOffset(DataRefImpl Rel) const {
> -  assert(EF.getHeader()->e_type == ELF::ET_REL &&
> -         "Only relocatable object files have relocation offsets");
>    const Elf_Shdr *sec = getRelSection(Rel);
>    if (sec->sh_type == ELF::SHT_REL)
>      return getRel(Rel)->r_offset;
> -
>    return getRela(Rel)->r_offset;
>  }
>  
>
>
> Index: ELFObjectFile.h
> ===================================================================
> --- ELFObjectFile.h
> +++ ELFObjectFile.h
> @@ -781,12 +781,9 @@
>  
>  template <class ELFT>
>  uint64_t ELFObjectFile<ELFT>::getRelocationOffset(DataRefImpl Rel) const {
> -  assert(EF.getHeader()->e_type == ELF::ET_REL &&
> -         "Only relocatable object files have relocation offsets");
>    const Elf_Shdr *sec = getRelSection(Rel);
>    if (sec->sh_type == ELF::SHT_REL)
>      return getRel(Rel)->r_offset;
> -
>    return getRela(Rel)->r_offset;
>  }
>  
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