From 10a446ddcc1100d6d76c6aa0c6d4775209388152 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Wed, 4 Apr 2018 23:09:37 +0100 Subject: elf: Unify symbol address run-time calculation [BZ #19818] Wrap symbol address run-time calculation into a macro and use it throughout, replacing inline calculations. There are a couple of variants, most of them different in a functionally insignificant way. Most calculations are right following RESOLVE_MAP, at which point either the map or the symbol returned can be checked for validity as the macro sets either both or neither. In some places both the symbol and the map has to be checked however. My initial implementation therefore always checked both, however that resulted in code larger by as much as 0.3%, as many places know from elsewhere that no check is needed. I have decided the size growth was unacceptable. Having looked closer I realized that it's the map that is the culprit. Therefore I have modified LOOKUP_VALUE_ADDRESS to accept an additional boolean argument telling it to access the map without checking it for validity. This in turn has brought quite nice results, with new code actually being smaller for i686, and MIPS o32, n32 and little-endian n64 targets, unchanged in size for x86-64 and, unusually, marginally larger for big-endian MIPS n64, as follows: i686: text data bss dec hex filename 152255 4052 192 156499 26353 ld-2.27.9000-base.so 152159 4052 192 156403 262f3 ld-2.27.9000-elf-symbol-value.so MIPS/o32/el: text data bss dec hex filename 142906 4396 260 147562 2406a ld-2.27.9000-base.so 142890 4396 260 147546 2405a ld-2.27.9000-elf-symbol-value.so MIPS/n32/el: text data bss dec hex filename 142267 4404 260 146931 23df3 ld-2.27.9000-base.so 142171 4404 260 146835 23d93 ld-2.27.9000-elf-symbol-value.so MIPS/n64/el: text data bss dec hex filename 149835 7376 408 157619 267b3 ld-2.27.9000-base.so 149787 7376 408 157571 26783 ld-2.27.9000-elf-symbol-value.so MIPS/o32/eb: text data bss dec hex filename 142870 4396 260 147526 24046 ld-2.27.9000-base.so 142854 4396 260 147510 24036 ld-2.27.9000-elf-symbol-value.so MIPS/n32/eb: text data bss dec hex filename 142019 4404 260 146683 23cfb ld-2.27.9000-base.so 141923 4404 260 146587 23c9b ld-2.27.9000-elf-symbol-value.so MIPS/n64/eb: text data bss dec hex filename 149763 7376 408 157547 2676b ld-2.27.9000-base.so 149779 7376 408 157563 2677b ld-2.27.9000-elf-symbol-value.so x86-64: text data bss dec hex filename 148462 6452 400 155314 25eb2 ld-2.27.9000-base.so 148462 6452 400 155314 25eb2 ld-2.27.9000-elf-symbol-value.so [BZ #19818] * sysdeps/generic/ldsodefs.h (LOOKUP_VALUE_ADDRESS): Add `set' parameter. (SYMBOL_ADDRESS): New macro. [!ELF_FUNCTION_PTR_IS_SPECIAL] (DL_SYMBOL_ADDRESS): Use SYMBOL_ADDRESS for symbol address calculation. * elf/dl-runtime.c (_dl_fixup): Likewise. (_dl_profile_fixup): Likewise. * elf/dl-symaddr.c (_dl_symbol_address): Likewise. * elf/rtld.c (dl_main): Likewise. * sysdeps/aarch64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/alpha/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/arm/dl-machine.h (elf_machine_rel): Likewise. (elf_machine_rela): Likewise. * sysdeps/hppa/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/hppa/dl-symaddr.c (_dl_symbol_address): Likewise. * sysdeps/i386/dl-machine.h (elf_machine_rel): Likewise. (elf_machine_rela): Likewise. * sysdeps/ia64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/m68k/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/microblaze/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/mips/dl-machine.h (ELF_MACHINE_BEFORE_RTLD_RELOC): Likewise. (elf_machine_reloc): Likewise. (elf_machine_got_rel): Likewise. * sysdeps/mips/dl-trampoline.c (__dl_runtime_resolve): Likewise. * sysdeps/nios2/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/powerpc/powerpc32/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/powerpc/powerpc64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/riscv/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/s390/s390-32/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/s390/s390-64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/sh/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/sparc/sparc32/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/sparc/sparc64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/tile/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise. Reviewed-by: Adhemerval Zanella --- elf/dl-runtime.c | 11 ++++------- elf/dl-symaddr.c | 2 +- elf/rtld.c | 2 +- 3 files changed, 6 insertions(+), 9 deletions(-) (limited to 'elf') diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c index 61ef6d61ca..63bbc89776 100644 --- a/elf/dl-runtime.c +++ b/elf/dl-runtime.c @@ -124,14 +124,13 @@ _dl_fixup ( of the object that defines sym. Now add in the symbol offset. */ value = DL_FIXUP_MAKE_VALUE (result, - sym ? (LOOKUP_VALUE_ADDRESS (result) - + sym->st_value) : 0); + SYMBOL_ADDRESS (result, sym, false)); } else { /* We already found the symbol. The module (and therefore its load address) is also known. */ - value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value); + value = DL_FIXUP_MAKE_VALUE (l, SYMBOL_ADDRESS (l, sym, true)); result = l; } @@ -241,9 +240,7 @@ _dl_profile_fixup ( of the object that defines sym. Now add in the symbol offset. */ value = DL_FIXUP_MAKE_VALUE (result, - defsym != NULL - ? LOOKUP_VALUE_ADDRESS (result) - + defsym->st_value : 0); + SYMBOL_ADDRESS (result, defsym, false)); if (defsym != NULL && __builtin_expect (ELFW(ST_TYPE) (defsym->st_info) @@ -254,7 +251,7 @@ _dl_profile_fixup ( { /* We already found the symbol. The module (and therefore its load address) is also known. */ - value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value); + value = DL_FIXUP_MAKE_VALUE (l, SYMBOL_ADDRESS (l, refsym, true)); if (__builtin_expect (ELFW(ST_TYPE) (refsym->st_info) == STT_GNU_IFUNC, 0)) diff --git a/elf/dl-symaddr.c b/elf/dl-symaddr.c index 0f16ab74e6..7f1ccc2516 100644 --- a/elf/dl-symaddr.c +++ b/elf/dl-symaddr.c @@ -22,7 +22,7 @@ void * _dl_symbol_address (struct link_map *map, const ElfW(Sym) *ref) { - ElfW(Addr) value = (map ? map->l_addr : 0) + ref->st_value; + ElfW(Addr) value = SYMBOL_ADDRESS (map, ref, false); /* Return the pointer to function descriptor. */ if (ELFW(ST_TYPE) (ref->st_info) == STT_FUNC) diff --git a/elf/rtld.c b/elf/rtld.c index f8d9597cdd..e7681ebb1f 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1916,7 +1916,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n", NULL, ELF_RTYPE_CLASS_PLT, DL_LOOKUP_ADD_DEPENDENCY, NULL); - loadbase = LOOKUP_VALUE_ADDRESS (result); + loadbase = LOOKUP_VALUE_ADDRESS (result, false); _dl_printf ("%s found at 0x%0*Zd in object at 0x%0*Zd\n", _dl_argv[i], -- cgit v1.2.3