mirror of
https://github.com/clearlinux/graphene.git
synced 2026-08-19 04:07:39 +00:00
Paweł Marczewski
2cfdd510dc
After this change, LibOS will no longer perform dynamic linking. The ELF loading code executes load commands and passes control to interpreter (ld.so), which handles necessary relocations and loading additional libraries. In this way, the code resembles what Linux kernel does when executing a new program. Before, dynamic linking was necessary for making LibOS entry point (syscalldb function) available for applications. However, that meant duplicating the work already done by ld.so, and introduced a lot of unnecessary complexity. After changing LibOS entry API to use the GS register, it's possible to omit dynamic linking entirely. The main function (__load_elf_object()) still needs cleanup and possibly rewriting from scratch. However, this change prepares ground for that rewrite. Summary of changes: - Remove dynamic relocation step (DO_DYNAMIC_RELOCATE()). - Don't call __load_elf_object() again for ELFs reported via register_library(). We only need to notify GDB about these. - Remove fields related to dynamic linking from link_map (dynamic section address, hashes, etc.), and setup for these fields. - need_interp(): To check if we need an interpreter, check only if the binary requests one (PT_INTERP), instead of traversing the dynamic section (before, we ignored dynamic dependencies on LibOS itself, but now there shouldn't be any). - RELOCATE(): always adjust addresses, instead of checking if they're already inside the mapped range. I think the previous behaviour was a workaround to make repeated relocations work. - Get rid of load modes that are no longer used (OBJECT_REMAP, OBJECT_USER). - Remove the workaround for repeated relocation in glibc patches (R_X86_64_NONE). Signed-off-by: Paweł Marczewski <pawel@invisiblethingslab.com>