/* Machine-dependent ELF dynamic relocation inline functions. ARM version. Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005, 2006, 2009, 2010 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #ifndef dl_machine_h #define dl_machine_h #define ELF_MACHINE_NAME "ARM" #include #include #define CLEAR_CACHE(BEG,END) \ INTERNAL_SYSCALL_ARM (cacheflush, , 3, (BEG), (END), 0) /* Return nonzero iff ELF header is compatible with the running host. */ static inline int __attribute__ ((unused)) elf_machine_matches_host (const Elf32_Ehdr *ehdr) { return ehdr->e_machine == EM_ARM; } /* Return the link-time address of _DYNAMIC. Conveniently, this is the first element of the GOT. We used to use the PIC register to do this without a constant pool reference, but GCC 4.2 will use a pseudo-register for the PIC base, so it may not be in r10. */ static inline Elf32_Addr __attribute__ ((unused)) elf_machine_dynamic (void) { Elf32_Addr dynamic; #ifdef __thumb2__ long tmp; asm ("ldr\t%0, 1f\n\t" "adr\t%1, 1f\n\t" "ldr\t%0, [%0, %1]\n\t" "b 2f\n" ".align 2\n" "1: .word _GLOBAL_OFFSET_TABLE_ - 1b\n" "2:" : "=r" (dynamic), "=r"(tmp)); #else asm ("ldr %0, 2f\n" "1: ldr %0, [pc, %0]\n" "b 3f\n" "2: .word _GLOBAL_OFFSET_TABLE_ - (1b+8)\n" "3:" : "=r" (dynamic)); #endif return dynamic; } /* Return the run-time load address of the shared object. */ static inline Elf32_Addr __attribute__ ((unused)) elf_machine_load_address (void) { extern void __dl_start asm ("_dl_start"); Elf32_Addr got_addr = (Elf32_Addr) &__dl_start; Elf32_Addr pcrel_addr; #ifdef __thumb__ /* Clear the low bit of the funciton address. */ got_addr &= ~(Elf32_Addr) 1; #endif asm ("adr %0, _dl_start" : "=r" (pcrel_addr)); return pcrel_addr - got_addr; } /* Set up the loaded object described by L so its unrelocated PLT entries will jump to the on-demand fixup code in dl-runtime.c. */ static inline int __attribute__ ((unused)) elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) { Elf32_Addr *got; extern void _dl_runtime_resolve (Elf32_Word); extern void _dl_runtime_profile (Elf32_Word); if (l->l_info[DT_JMPREL] && lazy) { /* patb: this is different than i386 */ /* The GOT entries for functions in the PLT have not yet been filled in. Their initial contents will arrange when called to push an index into the .got section, load ip with &_GLOBAL_OFFSET_TABLE_[3], and then jump to _GLOBAL_OFFSET_TABLE[2]. */ got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]); /* If a library is prelinked but we have to relocate anyway, we have to be able to undo the prelinking of .got.plt. The prelinker saved us here address of .plt. */ if (got[1]) l->l_mach.plt = got[1] + l->l_addr; got[1] = (Elf32_Addr) l; /* Identify this shared object. */ /* The got[2] entry contains the address of a function which gets called to get the address of a so far unresolved function and jump to it. The profiling extension of the dynamic linker allows to intercept the calls to collect information. In this case we don't store the address in the GOT so that all future calls also end in this function. */ if (profile) { got[2] = (Elf32_Addr) &_dl_runtime_profile; if (GLRO(dl_profile) != NULL && _dl_name_match_p (GLRO(dl_profile), l)) /* Say that we really want profiling and the timers are started. */ GL(dl_profile_map) = l; } else /* This function will get called to fix up the GOT entry indicated by the offset on the stack, and then jump to the resolved address. */ got[2] = (Elf32_Addr) &_dl_runtime_resolve; } return lazy; } #if defined(__USE_BX__) #define BX(x) "bx\t" #x #else #define BX(x) "mov\tpc, " #x #endif /* Mask identifying addresses reserved for the user program, where the dynamic linker should not map anything. */ #define ELF_MACHINE_USER_ADDRESS_MASK 0xf8000000UL /* Initial entry point code for the dynamic linker. The C function `_dl_start' is the real entry point; its return value is the user program's entry point. */ #define RTLD_START asm ("\ .text\n\ .globl _start\n\ .type _start, %function\n\ .globl _dl_start_user\n\ .type _dl_start_user, %function\n\ _start:\n\ @ we are PIC code, so get global offset table\n\ ldr sl, .L_GET_GOT\n\ @ See if we were run as a command with the executable file\n\ @ name as an extra leading argument.\n\ ldr r4, .L_SKIP_ARGS\n\ @ at start time, all the args are on the stack\n\ mov r0, sp\n\ bl _dl_start\n\ @ returns user entry point in r0\n\ _dl_start_user:\n\ adr r6, .L_GET_GOT\n\ add sl, sl, r6\n\ ldr r4, [sl, r4]\n\ @ save the entry point in another register\n\ mov r6, r0\n\ @ get the original arg count\n\ ldr r1, [sp]\n\ @ get the argv address\n\ add r2, sp, #4\n\ @ Fix up the stack if necessary.\n\ cmp r4, #0\n\ bne .L_fixup_stack\n\ .L_done_fixup:\n\ @ compute envp\n\ add r3, r2, r1, lsl #2\n\ add r3, r3, #4\n\ @ now we call _dl_init\n\ ldr r0, .L_LOADED\n\ ldr r0, [sl, r0]\n\ @ call _dl_init\n\ bl _dl_init_internal(PLT)\n\ @ load the finalizer function\n\ ldr r0, .L_FINI_PROC\n\ add r0, sl, r0\n\ @ jump to the user_s entry point\n\ " BX(r6) "\n\ \n\ @ iWMMXt and EABI targets require the stack to be eight byte\n\ @ aligned - shuffle arguments etc.\n\ .L_fixup_stack:\n\ @ subtract _dl_skip_args from original arg count\n\ sub r1, r1, r4\n\ @ store the new argc in the new stack location\n\ str r1, [sp]\n\ @ find the first unskipped argument\n\ mov r3, r2\n\ add r4, r2, r4, lsl #2\n\ @ shuffle argv down\n\ 1: ldr r5, [r4], #4\n\ str r5, [r3], #4\n\ cmp r5, #0\n\ bne 1b\n\ @ shuffle envp down\n\ 1: ldr r5, [r4], #4\n\ str r5, [r3], #4\n\ cmp r5, #0\n\ bne 1b\n\ @ shuffle auxv down\n\ 1: ldmia r4!, {r0, r5}\n\ stmia r3!, {r0, r5}\n\ cmp r0, #0\n\ bne 1b\n\ @ Update _dl_argv\n\ ldr r3, .L_ARGV\n\ str r2, [sl, r3]\n\ b .L_done_fixup\n\ \n\ .L_GET_GOT:\n\ .word _GLOBAL_OFFSET_TABLE_ - .L_GET_GOT\n\ .L_SKIP_ARGS:\n\ .word _dl_skip_args(GOTOFF)\n\ .L_FINI_PROC:\n\ .word _dl_fini(GOTOFF)\n\ .L_ARGV:\n\ .word _dl_argv(GOTOFF)\n\ .L_LOADED:\n\ .word _rtld_local(GOTOFF)\n\ .previous\n\ "); /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or TLS variable, so undefined references should not be allowed to define the value. ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one of the main executable's symbols, as for a COPY reloc. */ #if defined USE_TLS && (!defined RTLD_BOOTSTRAP || USE___THREAD) # define elf_machine_type_class(type) \ ((((type) == R_ARM_JUMP_SLOT || (type) == R_ARM_TLS_DTPMOD32 \ || (type) == R_ARM_TLS_DTPOFF32 || (type) == R_ARM_TLS_TPOFF32) \ * ELF_RTYPE_CLASS_PLT) \ | (((type) == R_ARM_COPY) * ELF_RTYPE_CLASS_COPY)) #else #define elf_machine_type_class(type) \ ((((type) == R_ARM_JUMP_SLOT) * ELF_RTYPE_CLASS_PLT) \ | (((type) == R_ARM_COPY) * ELF_RTYPE_CLASS_COPY)) #endif /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */ #define ELF_MACHINE_JMP_SLOT R_ARM_JUMP_SLOT /* ARM never uses Elf32_Rela relocations for the dynamic linker. Prelinked libraries may use Elf32_Rela though. */ #define ELF_MACHINE_PLT_REL 1 /* We define an initialization functions. This is called very early in _dl_sysdep_start. */ #define DL_PLATFORM_INIT dl_platform_init () static inline void __attribute__ ((unused)) dl_platform_init (void) { if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') /* Avoid an empty string which would disturb us. */ GLRO(dl_platform) = NULL; } static inline Elf32_Addr elf_machine_fixup_plt (struct link_map *map, lookup_t t, const Elf32_Rel *reloc, Elf32_Addr *reloc_addr, Elf32_Addr value) { return *reloc_addr = value; } /* Return the final value of a plt relocation. */ static inline Elf32_Addr elf_machine_plt_value (struct link_map *map, const Elf32_Rel *reloc, Elf32_Addr value) { return value; } #endif /* !dl_machine_h */ /* ARM never uses Elf32_Rela relocations for the dynamic linker. Prelinked libraries may use Elf32_Rela though. */ #define ELF_MACHINE_NO_RELA defined RTLD_BOOTSTRAP /* Names of the architecture-specific auditing callback functions. */ #define ARCH_LA_PLTENTER arm_gnu_pltenter #define ARCH_LA_PLTEXIT arm_gnu_pltexit #ifdef RESOLVE_MAP /* Deal with an out-of-range PC24 reloc. */ auto Elf32_Addr fix_bad_pc24 (Elf32_Addr *const reloc_addr, Elf32_Addr value) { static void *fix_page; static unsigned int fix_offset; static size_t pagesize; Elf32_Word *fix_address; if (! fix_page) { if (! pagesize) pagesize = getpagesize (); fix_page = mmap (NULL, pagesize, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (! fix_page) assert (! "could not map page for fixup"); fix_offset = 0; } fix_address = (Elf32_Word *)(fix_page + fix_offset); fix_address[0] = 0xe51ff004; /* ldr pc, [pc, #-4] */ fix_address[1] = value; fix_offset += 8; if (fix_offset >= pagesize) fix_page = NULL; return (Elf32_Addr)fix_address; } /* Perform the relocation specified by RELOC and SYM (which is fully resolved). MAP is the object containing the reloc. */ auto inline void __attribute__ ((always_inline)) elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, const Elf32_Sym *sym, const struct r_found_version *version, void *const reloc_addr_arg) { Elf32_Addr *const reloc_addr = reloc_addr_arg; const unsigned int r_type = ELF32_R_TYPE (reloc->r_info); #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC if (__builtin_expect (r_type == R_ARM_RELATIVE, 0)) { # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC /* 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 RTLD_BOOTSTRAP) because rtld.c contains the common defn for _dl_rtld_map, which is incompatible with a weak decl in the same file. */ # ifndef SHARED weak_extern (_dl_rtld_map); # endif if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */ # endif *reloc_addr += map->l_addr; } # ifndef RTLD_BOOTSTRAP else if (__builtin_expect (r_type == R_ARM_NONE, 0)) return; # endif else #endif { const Elf32_Sym *const refsym = sym; struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type); Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value; switch (r_type) { case R_ARM_COPY: if (sym == NULL) /* This can happen in trace mode if an object could not be found. */ break; if (sym->st_size > refsym->st_size || (GLRO(dl_verbose) && sym->st_size < refsym->st_size)) { const char *strtab; strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); _dl_error_printf ("\ %s: Symbol `%s' has different size in shared object, consider re-linking\n", rtld_progname ?: "", strtab + refsym->st_name); } memcpy (reloc_addr_arg, (void *) value, MIN (sym->st_size, refsym->st_size)); break; case R_ARM_GLOB_DAT: case R_ARM_JUMP_SLOT: # ifdef RTLD_BOOTSTRAP /* Fix weak undefined references. */ if (sym != NULL && sym->st_value == 0) *reloc_addr = 0; else # endif *reloc_addr = value; break; case R_ARM_ABS32: { # 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 RTLD_BOOTSTRAP) because rtld.c contains the common defn for _dl_rtld_map, which is incompatible with a weak decl in the same file. */ # ifndef SHARED weak_extern (_dl_rtld_map); # endif if (map == &GL(dl_rtld_map)) /* Undo the relocation done here during bootstrapping. Now we will relocate it anew, possibly using a binding found in the user program or a loaded library rather than the dynamic linker's built-in definitions used while loading those libraries. */ value -= map->l_addr + refsym->st_value; # endif *reloc_addr += value; break; } case R_ARM_PC24: { Elf32_Sword addend; Elf32_Addr newvalue, topbits; addend = *reloc_addr & 0x00ffffff; if (addend & 0x00800000) addend |= 0xff000000; newvalue = value - (Elf32_Addr)reloc_addr + (addend << 2); topbits = newvalue & 0xfe000000; if (topbits != 0xfe000000 && topbits != 0x00000000) { newvalue = fix_bad_pc24(reloc_addr, value) - (Elf32_Addr)reloc_addr + (addend << 2); topbits = newvalue & 0xfe000000; if (topbits != 0xfe000000 && topbits != 0x00000000) { _dl_signal_error (0, map->l_name, NULL, "R_ARM_PC24 relocation out of range"); } } newvalue >>= 2; value = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff); *reloc_addr = value; } break; #if defined USE_TLS && !defined RTLD_BOOTSTRAP case R_ARM_TLS_DTPMOD32: /* Get the information from the link map returned by the resolv function. */ if (sym_map != NULL) *reloc_addr = sym_map->l_tls_modid; break; case R_ARM_TLS_DTPOFF32: if (sym != NULL) *reloc_addr += sym->st_value; break; case R_ARM_TLS_TPOFF32: if (sym != NULL) { CHECK_STATIC_TLS (map, sym_map); *reloc_addr += sym->st_value + sym_map->l_tls_offset; } break; #endif default: _dl_reloc_bad_type (map, r_type, 0); break; } } } # ifndef RTLD_BOOTSTRAP auto inline void __attribute__ ((always_inline)) elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, const Elf32_Sym *sym, const struct r_found_version *version, void *const reloc_addr_arg) { Elf32_Addr *const reloc_addr = reloc_addr_arg; const unsigned int r_type = ELF32_R_TYPE (reloc->r_info); if (__builtin_expect (r_type == R_ARM_RELATIVE, 0)) *reloc_addr = map->l_addr + reloc->r_addend; else if (__builtin_expect (r_type == R_ARM_NONE, 0)) return; else { # ifndef RESOLVE_CONFLICT_FIND_MAP const Elf32_Sym *const refsym = sym; # endif struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type); Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value; switch (r_type) { # ifndef RESOLVE_CONFLICT_FIND_MAP /* Not needed for dl-conflict.c. */ case R_ARM_COPY: if (sym == NULL) /* This can happen in trace mode if an object could not be found. */ break; if (sym->st_size > refsym->st_size || (GLRO(dl_verbose) && sym->st_size < refsym->st_size)) { const char *strtab; strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); _dl_error_printf ("\ %s: Symbol `%s' has different size in shared object, consider re-linking\n", rtld_progname ?: "", strtab + refsym->st_name); } memcpy (reloc_addr_arg, (void *) value, MIN (sym->st_size, refsym->st_size)); break; # endif /* !RESOLVE_CONFLICT_FIND_MAP */ case R_ARM_GLOB_DAT: case R_ARM_JUMP_SLOT: case R_ARM_ABS32: *reloc_addr = value + reloc->r_addend; break; case R_ARM_PC24: { Elf32_Addr newvalue, topbits; newvalue = value + reloc->r_addend - (Elf32_Addr)reloc_addr; topbits = newvalue & 0xfe000000; if (topbits != 0xfe000000 && topbits != 0x00000000) { newvalue = fix_bad_pc24(reloc_addr, value) - (Elf32_Addr)reloc_addr + (reloc->r_addend << 2); topbits = newvalue & 0xfe000000; if (topbits != 0xfe000000 && topbits != 0x00000000) { _dl_signal_error (0, map->l_name, NULL, "R_ARM_PC24 relocation out of range"); } } newvalue >>= 2; value = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff); *reloc_addr = value; } break; #if defined USE_TLS && !defined RTLD_BOOTSTRAP case R_ARM_TLS_DTPMOD32: /* Get the information from the link map returned by the resolv function. */ if (sym_map != NULL) *reloc_addr = sym_map->l_tls_modid; break; case R_ARM_TLS_DTPOFF32: *reloc_addr = (sym == NULL ? 0 : sym->st_value) + reloc->r_addend; break; case R_ARM_TLS_TPOFF32: if (sym != NULL) { CHECK_STATIC_TLS (map, sym_map); *reloc_addr = (sym->st_value + sym_map->l_tls_offset + reloc->r_addend); } break; #endif default: _dl_reloc_bad_type (map, r_type, 0); break; } } } # endif auto inline void __attribute__ ((always_inline)) elf_machine_rel_relative (Elf32_Addr l_addr, const Elf32_Rel *reloc, void *const reloc_addr_arg) { Elf32_Addr *const reloc_addr = reloc_addr_arg; *reloc_addr += l_addr; } # ifndef RTLD_BOOTSTRAP auto inline void __attribute__ ((always_inline)) elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc, void *const reloc_addr_arg) { Elf32_Addr *const reloc_addr = reloc_addr_arg; *reloc_addr = l_addr + reloc->r_addend; } # endif auto inline void __attribute__ ((always_inline)) elf_machine_lazy_rel (struct link_map *map, Elf32_Addr l_addr, const Elf32_Rel *reloc) { Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset); const unsigned int r_type = ELF32_R_TYPE (reloc->r_info); /* Check for unexpected PLT reloc type. */ if (__builtin_expect (r_type == R_ARM_JUMP_SLOT, 1)) { if (__builtin_expect (map->l_mach.plt, 0) == 0) *reloc_addr += l_addr; else *reloc_addr = map->l_mach.plt; } else _dl_reloc_bad_type (map, r_type, 1); } #endif /* RESOLVE_MAP */