Re: Add eu-strip --reloc-debug-sections-only option

[Mark Wielaard <mark at klomp dot org>]

On Fri, 2018-10-26 at 23:50 +0200, Mark Wielaard wrote:
> eu-strip already supports --reloc-debug-sections to resolve all
> relocations between .debug_ sections while creating a separate
> .debug file with -f. It is sometimes useful to do the same without
> doing any other stripping.
> 
>   --reloc-debug-sections-only
>                          Similar to --reloc-debug-sections, but resolve all
>                          trivial relocations between debug sections in
>                          place.  No other stripping is performed (operation
>                          is not reversable, incompatible with -f, -g,
>                          --remove-comment and --remove-section)
> 
> For example to ease debugging, tracing and profiling some distributions
> ship an uncompressed vmlinux ELF file which includes DWARF debuginfo.
> Since the vmlinux ELF kernel is relocatable, the relocations between the
> .debug sections are also still left in. On Fedora this file is 662M.
> eu-strip --reloc-debug-sections-only will remove more than 250MB of
> (unneeded) relocations between the .debug sections.
> 
> To reuse as much code as possible this patch series first refactors
> some of the code. It also makes it so that the type of ELF file doesn't
> matter for doing relocations (normally it only makes sense for ET_REL
> files, but the vmlinux ELF image is an ET_EXEC with SHT_RELA sections).
> 
> It also adds a new testcase to run-strip-reloc.sh to make sure that the
> result of creating a separate debug file using --reloc-debug-sections
> is identical to creating a separate debug file and then running eu-strip
> with --reloc-debug-sections-only.
> 
> [PATCH 1/4] strip: Always copy over any phdrs if there are any
> [PATCH 2/4] strip: Split out debug section relocation into separate helper
> [PATCH 3/4] strip: Extract code to update shdrstrndx into new common function
> [PATCH 4/4] strip: Add --reloc-debug-sections-only option

I pushed these 4 patches to master.

Cheers,

Mark