On Wed, Jun 24, 2020 at 09:16:43AM -0700, Fangrui Song wrote: > > On 2020-06-24, Arvind Sankar wrote: > >On Tue, Jun 23, 2020 at 06:49:33PM -0700, Kees Cook wrote: > >> When linking vmlinux with LLD, the synthetic sections .symtab, .strtab, > >> and .shstrtab are listed as orphaned. Add them to the STABS_DEBUG section > >> so there will be no warnings when --orphan-handling=warn is used more > >> widely. (They are added above comment as it is the more common > > > >Nit 1: is "after .comment" better than "above comment"? It's above in the > >sense of higher file offset, but it's below in readelf output. > > I mean this order:) > > .comment > .symtab > .shstrtab > .strtab > > This is the case in the absence of a linker script if at least one object file has .comment (mostly for GCC/clang version information) or the linker is LLD which adds a .comment > > >Nit 2: These aren't actually debugging sections, no? Is it better to add > >a new macro for it, and is there any plan to stop LLD from warning about > >them? > > https://reviews.llvm.org/D75149 "[ELF] --orphan-handling=: don't warn/error for unused synthesized sections" > described that .symtab .shstrtab .strtab are different in GNU ld. > Since many other GNU ld synthesized sections (.rela.dyn .plt ...) can be renamed or dropped > via output section descriptions, I don't understand why the 3 sections > can't be customized. So IIUC, lld will now warn about .rela.dyn etc only if they're non-empty? > > I created a feature request: https://sourceware.org/bugzilla/show_bug.cgi?id=26168 > (If this is supported, it is a consistent behavior to warn for orphan > .symtab/.strtab/.shstrtab > > There may be 50% chance that the maintainer decides that "LLD diverges" > I would disagree: there is no fundamental problems with .symtab/.strtab/.shstrtab which make them special in output section descriptions or orphan handling.) > .shstrtab is a little special in that it can't be discarded if the ELF file contains any sections at all. But yeah, there's no reason they can't be renamed or placed in a custom location in the file.
