From f64f4ce069300f33e26b025ebb0233d5ca3957a5 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Fri, 29 Oct 2021 10:29:54 -0300 Subject: elf: Assume disjointed .rela.dyn and .rela.plt for loader The patch removes the the ELF_DURING_STARTUP optimization and assume both .rel.dyn and .rel.plt might not be subsequent. This allows some code simplification since relocation will be handled independently where it is done on bootstrap. At least on x86_64_64, I can not measure any performance implications. Running 10000 time the command LD_DEBUG=statistics ./elf/ld.so ./libc.so And filtering the "total startup time in dynamic loader" result, the geometric mean is: patched master Ryzen 7 5900x 24140 24952 i7-4510U 45957 45982 (The results do show some variation, I did not make any statistical analysis). It also allows build arm with lld, since it inserts ".ARM.exidx" between ".rel.dyn" and ".rel.plt" for the loader. Checked on x86_64-linux-gnu and arm-linux-gnueabihf. Reviewed-by: H.J. Lu --- elf/dynamic-link.h | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) (limited to 'elf') diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index ac4cc70..f619615 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -65,12 +65,6 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], #ifdef RESOLVE_MAP -# if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP -# define ELF_DURING_STARTUP (1) -# else -# define ELF_DURING_STARTUP (0) -# endif - /* Get the definitions of `elf_dynamic_do_rel' and `elf_dynamic_do_rela'. These functions are almost identical, so we use cpp magic to avoid duplicating their code. It cannot be done in a more general function @@ -106,9 +100,8 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], \ if (ranges[0].start + ranges[0].size == (start + size)) \ ranges[0].size -= size; \ - if (ELF_DURING_STARTUP \ - || (!(do_lazy) \ - && (ranges[0].start + ranges[0].size) == start)) \ + if (!(do_lazy) \ + && (ranges[0].start + ranges[0].size) == start) \ { \ /* Combine processing the sections. */ \ ranges[0].size += size; \ @@ -121,20 +114,13 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], } \ } \ \ - if (ELF_DURING_STARTUP) \ - elf_dynamic_do_##reloc ((map), scope, ranges[0].start, ranges[0].size, \ - ranges[0].nrelative, 0, skip_ifunc); \ - else \ - { \ - int ranges_index; \ - for (ranges_index = 0; ranges_index < 2; ++ranges_index) \ - elf_dynamic_do_##reloc ((map), scope, \ - ranges[ranges_index].start, \ - ranges[ranges_index].size, \ - ranges[ranges_index].nrelative, \ - ranges[ranges_index].lazy, \ - skip_ifunc); \ - } \ + for (int ranges_index = 0; ranges_index < 2; ++ranges_index) \ + elf_dynamic_do_##reloc ((map), scope, \ + ranges[ranges_index].start, \ + ranges[ranges_index].size, \ + ranges[ranges_index].nrelative, \ + ranges[ranges_index].lazy, \ + skip_ifunc); \ } while (0) # if ELF_MACHINE_NO_REL || ELF_MACHINE_NO_RELA -- cgit v1.1