From c2ba078eb5f54ea941f099b02c118f8aa7b04204 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Thu, 19 Dec 2013 16:11:19 +0100 Subject: [PATCH] backends: aarch64 always has _GLOBAL_OFFSET_TABLE_ point to .got[0]. Like some other architectures aarch64 has a special rule for the _GLOBAL_OFFSET_TABLE_ symbol. Even if there is a .plt.got section the symbol value still points to the start of the .got section. This is also what the dynamic linker expects. See https://sourceware.org/ml/libc-ports/2013-06/msg00057.html Signed-off-by: Mark Wielaard --- backends/ChangeLog | 5 +++++ backends/aarch64_init.c | 1 + backends/aarch64_symbol.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 34 insertions(+) diff --git a/backends/ChangeLog b/backends/ChangeLog index d5f6b53..24cc63d 100644 --- a/backends/ChangeLog +++ b/backends/ChangeLog @@ -1,3 +1,8 @@ +2013-12-19 Mark Wielaard + + * aarch64_init.c (aarch64_init): Hook check_special_symbol. + * aarch64_symbol.c (aarch64_check_special_symbol): New function. + 2013-12-18 Mark Wielaard * Makefile.am (ppc64_SRCS): Add ppc64_resolve_sym.c. diff --git a/backends/aarch64_init.c b/backends/aarch64_init.c index 749af2a..d663d40 100644 --- a/backends/aarch64_init.c +++ b/backends/aarch64_init.c @@ -56,6 +56,7 @@ aarch64_init (elf, machine, eh, ehlen) HOOK (eh, core_note); HOOK (eh, reloc_simple_type); HOOK (eh, return_value_location); + HOOK (eh, check_special_symbol); return MODVERSION; } diff --git a/backends/aarch64_symbol.c b/backends/aarch64_symbol.c index b0f3377..e41a7a7 100644 --- a/backends/aarch64_symbol.c +++ b/backends/aarch64_symbol.c @@ -32,6 +32,7 @@ #include #include +#include #define BACKEND aarch64_ #include "libebl_CPU.h" @@ -54,3 +55,30 @@ aarch64_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type) return ELF_T_NUM; } } + +/* If this is the _GLOBAL_OFFSET_TABLE_ symbol, then it should point to + .got[0] even if there is a .got.plt section. */ +bool +aarch64_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym, + const char *name, const GElf_Shdr *destshdr) +{ + if (name != NULL + && strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0) + { + const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name); + if (sname != NULL && strcmp (sname, ".got.plt") == 0) + { + Elf_Scn *scn = NULL; + while ((scn = elf_nextscn (elf, scn)) != NULL) + { + GElf_Shdr shdr_mem; + GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); + sname = elf_strptr (elf, ehdr->e_shstrndx, shdr->sh_name); + if (sname != NULL && strcmp (sname, ".got") == 0) + return sym->st_value == shdr->sh_addr; + } + } + } + + return false; +} -- 2.7.4