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Diffstat (limited to 'sysdeps/arm/dl-machine.h')
| -rw-r--r-- | sysdeps/arm/dl-machine.h | 662 |
1 files changed, 662 insertions, 0 deletions
diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h new file mode 100644 index 0000000..02d1a5e --- /dev/null +++ b/sysdeps/arm/dl-machine.h @@ -0,0 +1,662 @@ +/* Machine-dependent ELF dynamic relocation inline functions. ARM version. + Copyright (C) 1995-2014 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, see + <http://www.gnu.org/licenses/>. */ + +#ifndef dl_machine_h +#define dl_machine_h + +#define ELF_MACHINE_NAME "ARM" + +#include <sys/param.h> +#include <tls.h> +#include <dl-tlsdesc.h> +#include <dl-irel.h> + +#ifndef CLEAR_CACHE +# error CLEAR_CACHE definition required to handle TEXTREL +#endif + +/* 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. */ +static inline Elf32_Addr __attribute__ ((unused)) +elf_machine_dynamic (void) +{ + /* Declaring this hidden ensures that a PC-relative reference is used. */ + extern const Elf32_Addr _GLOBAL_OFFSET_TABLE_[] attribute_hidden; + return _GLOBAL_OFFSET_TABLE_[0]; +} + + +/* Return the run-time load address of the shared object. */ +static inline Elf32_Addr __attribute__ ((unused)) +elf_machine_load_address (void) +{ + extern Elf32_Addr internal_function __dl_start (void *) 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; + } + + if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy) + *(Elf32_Addr*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr) + = (Elf32_Addr) &_dl_tlsdesc_lazy_resolver; + + return lazy; +} + +#if defined(ARCH_HAS_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. */ +#ifndef RTLD_BOOTSTRAP +# 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 \ + || (type) == R_ARM_TLS_DESC) \ + * 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 +/* Handle a PC24 reloc, including the out-of-range case. */ +auto void +relocate_pc24 (struct link_map *map, Elf32_Addr value, + Elf32_Addr *const reloc_addr, Elf32_Sword addend) +{ + Elf32_Addr new_value; + + /* Set NEW_VALUE based on V, and return true iff it overflows 24 bits. */ + inline bool set_new_value (Elf32_Addr v) + { + new_value = v + addend - (Elf32_Addr) reloc_addr; + Elf32_Addr topbits = new_value & 0xfe000000; + return topbits != 0xfe000000 && topbits != 0x00000000; + } + + if (set_new_value (value)) + { + /* The PC-relative address doesn't fit in 24 bits! */ + + static void *fix_page; + static size_t fix_offset; + if (fix_page == NULL) + { + void *new_page = __mmap (NULL, GLRO(dl_pagesize), + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANON, -1, 0); + if (new_page == MAP_FAILED) + _dl_signal_error (0, map->l_name, NULL, + "could not map page for fixup"); + fix_page = new_page; + assert (fix_offset == 0); + } + + Elf32_Word *fix_address = fix_page + fix_offset; + fix_address[0] = 0xe51ff004; /* ldr pc, [pc, #-4] */ + fix_address[1] = value; + + fix_offset += sizeof fix_address[0] * 2; + if (fix_offset >= GLRO(dl_pagesize)) + { + fix_page = NULL; + fix_offset = 0; + } + + if (set_new_value ((Elf32_Addr) fix_address)) + _dl_signal_error (0, map->l_name, NULL, + "R_ARM_PC24 relocation out of range"); + } + + *reloc_addr = (*reloc_addr & 0xff000000) | ((new_value >> 2) & 0x00ffffff); +} + +/* 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, int skip_ifunc) +{ + 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; + + if (sym != NULL + && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0) + && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1) + && __builtin_expect (!skip_ifunc, 1)) + value = elf_ifunc_invoke (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: + { + struct unaligned + { + Elf32_Addr x; + } __attribute__ ((packed, may_alias)); +# 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 + /* Support relocations on mis-aligned offsets. */ + ((struct unaligned *) reloc_addr)->x += value; + break; + } + case R_ARM_TLS_DESC: + { + struct tlsdesc volatile *td = + (struct tlsdesc volatile *)reloc_addr; + +# ifndef RTLD_BOOTSTRAP + if (! sym) + td->entry = _dl_tlsdesc_undefweak; + else +# endif + { + value = sym->st_value + td->argument.value; + +# ifndef RTLD_BOOTSTRAP +# ifndef SHARED + CHECK_STATIC_TLS (map, sym_map); +# else + if (!TRY_STATIC_TLS (map, sym_map)) + { + td->argument.pointer + = _dl_make_tlsdesc_dynamic (sym_map, value); + td->entry = _dl_tlsdesc_dynamic; + } + else +# endif +# endif + { + td->argument.value = value + sym_map->l_tls_offset; + td->entry = _dl_tlsdesc_return; + } + } + } + break; + case R_ARM_PC24: + relocate_pc24 (map, value, reloc_addr, + /* Sign-extend the 24-bit addend in the + instruction (which counts instructions), and + then shift it up two so as to count bytes. */ + (((Elf32_Sword) *reloc_addr << 8) >> 8) << 2); + break; +#if !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; + case R_ARM_IRELATIVE: + value = map->l_addr + *reloc_addr; + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + *reloc_addr = value; + 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, int skip_ifunc) +{ + 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; + + if (sym != NULL + && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0) + && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1) + && __builtin_expect (!skip_ifunc, 1)) + value = elf_ifunc_invoke (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: + relocate_pc24 (map, value, reloc_addr, reloc->r_addend); + break; +#if !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; + case R_ARM_IRELATIVE: + value = map->l_addr + *reloc_addr; + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + *reloc_addr = value; + 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, + int skip_ifunc) +{ + 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 if (__builtin_expect (r_type == R_ARM_TLS_DESC, 1)) + { + struct tlsdesc volatile *td = + (struct tlsdesc volatile *)reloc_addr; + + /* The linker must have given us the parameter we need in the + first GOT entry, and left the second one empty. We fill the + last with the resolver address */ + assert (td->entry == 0); + td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)]) + + map->l_addr); + } + else + _dl_reloc_bad_type (map, r_type, 1); +} + +#endif /* RESOLVE_MAP */ |