From 84e02af1ebc9988126eebe60bf19226cea835623 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Wed, 20 Apr 2022 13:52:45 -0700 Subject: elf: Move elf_dynamic_do_Rel RTLD_BOOTSTRAP branches outside elf_dynamic_do_Rel checks RTLD_BOOTSTRAP in several #ifdef branches. Create an outside RTLD_BOOTSTRAP branch to simplify reasoning about the function at the cost of a few duplicate lines. Since dl_naudit is zero in RTLD_BOOTSTRAP code, the RTLD_BOOTSTRAP branch can avoid _dl_audit_symbind calls to decrease code size. Reviewed-by: Adheemrval Zanella --- elf/do-rel.h | 49 ++++++++++++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 21 deletions(-) diff --git a/elf/do-rel.h b/elf/do-rel.h index d3e022267b..27b9b9f427 100644 --- a/elf/do-rel.h +++ b/elf/do-rel.h @@ -45,15 +45,35 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative, int lazy, int skip_ifunc) { - const ElfW(Rel) *r = (const void *) reladdr; + const ElfW(Rel) *relative = (const void *) reladdr; + const ElfW(Rel) *r = relative + nrelative; const ElfW(Rel) *end = (const void *) (reladdr + relsize); ElfW(Addr) l_addr = map->l_addr; -# if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP + const ElfW(Sym) *const symtab + = (const void *) D_PTR (map, l_info[DT_SYMTAB]); + +#ifdef RTLD_BOOTSTRAP + for (; relative < r; ++relative) + DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative); + + const ElfW (Half) *const version + = (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]); + for (; r < end; ++r) + { + ElfW (Half) ndx = version[ELFW (R_SYM) (r->r_info)] & 0x7fff; + const ElfW (Sym) *sym = &symtab[ELFW (R_SYM) (r->r_info)]; + void *const r_addr_arg = (void *) (l_addr + r->r_offset); + const struct r_found_version *rversion = &map->l_versions[ndx]; + + elf_machine_rel (map, scope, r, sym, rversion, r_addr_arg, skip_ifunc); + } +#else /* !RTLD_BOOTSTRAP */ +# if defined ELF_MACHINE_IRELATIVE const ElfW(Rel) *r2 = NULL; const ElfW(Rel) *end2 = NULL; # endif -#if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP +#if !defined DO_RELA || !defined ELF_MACHINE_PLT_REL /* We never bind lazily during ld.so bootstrap. Unfortunately gcc is not clever enough to see through all the function calls to realize that. */ @@ -82,12 +102,6 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], else #endif { - const ElfW(Sym) *const symtab = - (const void *) D_PTR (map, l_info[DT_SYMTAB]); - const ElfW(Rel) *relative = r; - r += nrelative; - -#ifndef RTLD_BOOTSTRAP /* This is defined in rtld.c, but nowhere in the static libc.a; make the reference weak so static programs can still link. This declaration cannot be done when compiling rtld.c (i.e. #ifdef @@ -106,16 +120,10 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], memory_loc += l_addr... */ if (l_addr != 0) # endif -#endif for (; relative < r; ++relative) DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative); -#ifdef RTLD_BOOTSTRAP - /* The dynamic linker always uses versioning. */ - assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL); -#else if (map->l_info[VERSYMIDX (DT_VERSYM)]) -#endif { const ElfW(Half) *const version = (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]); @@ -126,7 +134,7 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (r->r_info)]; void *const r_addr_arg = (void *) (l_addr + r->r_offset); const struct r_found_version *rversion = &map->l_versions[ndx]; -#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP +#if defined ELF_MACHINE_IRELATIVE if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE) { if (r2 == NULL) @@ -138,7 +146,7 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], elf_machine_rel (map, scope, r, sym, rversion, r_addr_arg, skip_ifunc); -#if defined SHARED && !defined RTLD_BOOTSTRAP +#if defined SHARED if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT && GLRO(dl_naudit) > 0) { @@ -151,7 +159,7 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], #endif } -#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP +#if defined ELF_MACHINE_IRELATIVE if (r2 != NULL) for (; r2 <= end2; ++r2) if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE) @@ -166,7 +174,6 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], } #endif } -#ifndef RTLD_BOOTSTRAP else { for (; r < end; ++r) @@ -184,7 +191,7 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], # endif elf_machine_rel (map, scope, r, sym, NULL, r_addr_arg, skip_ifunc); -# if defined SHARED && !defined RTLD_BOOTSTRAP +# if defined SHARED if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT && GLRO(dl_naudit) > 0) { @@ -207,8 +214,8 @@ elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], skip_ifunc); # endif } -#endif } +#endif /* !RTLD_BOOTSTRAP */ } #undef elf_dynamic_do_Rel -- cgit v1.2.3