diff options
Diffstat (limited to 'REORG.TODO/elf/dl-reloc.c')
| -rw-r--r-- | REORG.TODO/elf/dl-reloc.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/REORG.TODO/elf/dl-reloc.c b/REORG.TODO/elf/dl-reloc.c new file mode 100644 index 0000000000..b3c3a9bbf9 --- /dev/null +++ b/REORG.TODO/elf/dl-reloc.c @@ -0,0 +1,363 @@ +/* Relocate a shared object and resolve its references to other loaded objects. + Copyright (C) 1995-2017 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/>. */ + +#include <errno.h> +#include <libintl.h> +#include <stdlib.h> +#include <unistd.h> +#include <ldsodefs.h> +#include <sys/mman.h> +#include <sys/param.h> +#include <sys/types.h> +#include <_itoa.h> +#include <libc-pointer-arith.h> +#include "dynamic-link.h" + +/* Statistics function. */ +#ifdef SHARED +# define bump_num_cache_relocations() ++GL(dl_num_cache_relocations) +#else +# define bump_num_cache_relocations() ((void) 0) +#endif + + +/* We are trying to perform a static TLS relocation in MAP, but it was + dynamically loaded. This can only work if there is enough surplus in + the static TLS area already allocated for each running thread. If this + object's TLS segment is too big to fit, we fail. If it fits, + we set MAP->l_tls_offset and return. + This function intentionally does not return any value but signals error + directly, as static TLS should be rare and code handling it should + not be inlined as much as possible. */ +int +internal_function +_dl_try_allocate_static_tls (struct link_map *map) +{ + /* If we've already used the variable with dynamic access, or if the + alignment requirements are too high, fail. */ + if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET + || map->l_tls_align > GL(dl_tls_static_align)) + { + fail: + return -1; + } + +#if TLS_TCB_AT_TP + size_t freebytes = GL(dl_tls_static_size) - GL(dl_tls_static_used); + if (freebytes < TLS_TCB_SIZE) + goto fail; + freebytes -= TLS_TCB_SIZE; + + size_t blsize = map->l_tls_blocksize + map->l_tls_firstbyte_offset; + if (freebytes < blsize) + goto fail; + + size_t n = (freebytes - blsize) / map->l_tls_align; + + size_t offset = GL(dl_tls_static_used) + (freebytes - n * map->l_tls_align + - map->l_tls_firstbyte_offset); + + map->l_tls_offset = GL(dl_tls_static_used) = offset; +#elif TLS_DTV_AT_TP + /* dl_tls_static_used includes the TCB at the beginning. */ + size_t offset = (ALIGN_UP(GL(dl_tls_static_used) + - map->l_tls_firstbyte_offset, + map->l_tls_align) + + map->l_tls_firstbyte_offset); + size_t used = offset + map->l_tls_blocksize; + + if (used > GL(dl_tls_static_size)) + goto fail; + + map->l_tls_offset = offset; + map->l_tls_firstbyte_offset = GL(dl_tls_static_used); + GL(dl_tls_static_used) = used; +#else +# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" +#endif + + /* If the object is not yet relocated we cannot initialize the + static TLS region. Delay it. */ + if (map->l_real->l_relocated) + { +#ifdef SHARED + if (__builtin_expect (THREAD_DTV()[0].counter != GL(dl_tls_generation), + 0)) + /* Update the slot information data for at least the generation of + the DSO we are allocating data for. */ + (void) _dl_update_slotinfo (map->l_tls_modid); +#endif + + GL(dl_init_static_tls) (map); + } + else + map->l_need_tls_init = 1; + + return 0; +} + +void +internal_function __attribute_noinline__ +_dl_allocate_static_tls (struct link_map *map) +{ + if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET + || _dl_try_allocate_static_tls (map)) + { + _dl_signal_error (0, map->l_name, NULL, N_("\ +cannot allocate memory in static TLS block")); + } +} + +/* Initialize static TLS area and DTV for current (only) thread. + libpthread implementations should provide their own hook + to handle all threads. */ +void +_dl_nothread_init_static_tls (struct link_map *map) +{ +#if TLS_TCB_AT_TP + void *dest = (char *) THREAD_SELF - map->l_tls_offset; +#elif TLS_DTV_AT_TP + void *dest = (char *) THREAD_SELF + map->l_tls_offset + TLS_PRE_TCB_SIZE; +#else +# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" +#endif + + /* Initialize the memory. */ + memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size), + '\0', map->l_tls_blocksize - map->l_tls_initimage_size); +} + + +void +_dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[], + int reloc_mode, int consider_profiling) +{ + struct textrels + { + caddr_t start; + size_t len; + int prot; + struct textrels *next; + } *textrels = NULL; + /* Initialize it to make the compiler happy. */ + const char *errstring = NULL; + int lazy = reloc_mode & RTLD_LAZY; + int skip_ifunc = reloc_mode & __RTLD_NOIFUNC; + +#ifdef SHARED + /* If we are auditing, install the same handlers we need for profiling. */ + if ((reloc_mode & __RTLD_AUDIT) == 0) + consider_profiling |= GLRO(dl_audit) != NULL; +#elif defined PROF + /* Never use dynamic linker profiling for gprof profiling code. */ +# define consider_profiling 0 +#endif + + if (l->l_relocated) + return; + + /* If DT_BIND_NOW is set relocate all references in this object. We + do not do this if we are profiling, of course. */ + // XXX Correct for auditing? + if (!consider_profiling + && __builtin_expect (l->l_info[DT_BIND_NOW] != NULL, 0)) + lazy = 0; + + if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_RELOC)) + _dl_debug_printf ("\nrelocation processing: %s%s\n", + DSO_FILENAME (l->l_name), lazy ? " (lazy)" : ""); + + /* DT_TEXTREL is now in level 2 and might phase out at some time. + But we rewrite the DT_FLAGS entry to a DT_TEXTREL entry to make + testing easier and therefore it will be available at all time. */ + if (__glibc_unlikely (l->l_info[DT_TEXTREL] != NULL)) + { + /* Bletch. We must make read-only segments writable + long enough to relocate them. */ + const ElfW(Phdr) *ph; + for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph) + if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0) + { + struct textrels *newp; + + newp = (struct textrels *) alloca (sizeof (*newp)); + newp->len = ALIGN_UP (ph->p_vaddr + ph->p_memsz, GLRO(dl_pagesize)) + - ALIGN_DOWN (ph->p_vaddr, GLRO(dl_pagesize)); + newp->start = PTR_ALIGN_DOWN (ph->p_vaddr, GLRO(dl_pagesize)) + + (caddr_t) l->l_addr; + + if (__mprotect (newp->start, newp->len, PROT_READ|PROT_WRITE) < 0) + { + errstring = N_("cannot make segment writable for relocation"); + call_error: + _dl_signal_error (errno, l->l_name, NULL, errstring); + } + +#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7 + newp->prot = (PF_TO_PROT + >> ((ph->p_flags & (PF_R | PF_W | PF_X)) * 4)) & 0xf; +#else + newp->prot = 0; + if (ph->p_flags & PF_R) + newp->prot |= PROT_READ; + if (ph->p_flags & PF_W) + newp->prot |= PROT_WRITE; + if (ph->p_flags & PF_X) + newp->prot |= PROT_EXEC; +#endif + newp->next = textrels; + textrels = newp; + } + } + + { + /* Do the actual relocation of the object's GOT and other data. */ + + /* String table object symbols. */ + const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]); + + /* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */ +#define RESOLVE_MAP(ref, version, r_type) \ + ((ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL \ + && __glibc_likely (!dl_symbol_visibility_binds_local_p (*ref))) \ + ? ((__builtin_expect ((*ref) == l->l_lookup_cache.sym, 0) \ + && elf_machine_type_class (r_type) == l->l_lookup_cache.type_class) \ + ? (bump_num_cache_relocations (), \ + (*ref) = l->l_lookup_cache.ret, \ + l->l_lookup_cache.value) \ + : ({ lookup_t _lr; \ + int _tc = elf_machine_type_class (r_type); \ + l->l_lookup_cache.type_class = _tc; \ + l->l_lookup_cache.sym = (*ref); \ + const struct r_found_version *v = NULL; \ + if ((version) != NULL && (version)->hash != 0) \ + v = (version); \ + _lr = _dl_lookup_symbol_x (strtab + (*ref)->st_name, l, (ref), \ + scope, v, _tc, \ + DL_LOOKUP_ADD_DEPENDENCY, NULL); \ + l->l_lookup_cache.ret = (*ref); \ + l->l_lookup_cache.value = _lr; })) \ + : l) + +#include "dynamic-link.h" + + ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling, skip_ifunc); + +#ifndef PROF + if (__glibc_unlikely (consider_profiling) + && l->l_info[DT_PLTRELSZ] != NULL) + { + /* Allocate the array which will contain the already found + relocations. If the shared object lacks a PLT (for example + if it only contains lead function) the l_info[DT_PLTRELSZ] + will be NULL. */ + size_t sizeofrel = l->l_info[DT_PLTREL]->d_un.d_val == DT_RELA + ? sizeof (ElfW(Rela)) + : sizeof (ElfW(Rel)); + size_t relcount = l->l_info[DT_PLTRELSZ]->d_un.d_val / sizeofrel; + l->l_reloc_result = calloc (sizeof (l->l_reloc_result[0]), relcount); + + if (l->l_reloc_result == NULL) + { + errstring = N_("\ +%s: out of memory to store relocation results for %s\n"); + _dl_fatal_printf (errstring, RTLD_PROGNAME, l->l_name); + } + } +#endif + } + + /* Mark the object so we know this work has been done. */ + l->l_relocated = 1; + + /* Undo the segment protection changes. */ + while (__builtin_expect (textrels != NULL, 0)) + { + if (__mprotect (textrels->start, textrels->len, textrels->prot) < 0) + { + errstring = N_("cannot restore segment prot after reloc"); + goto call_error; + } + +#ifdef CLEAR_CACHE + CLEAR_CACHE (textrels->start, textrels->start + textrels->len); +#endif + + textrels = textrels->next; + } + + /* In case we can protect the data now that the relocations are + done, do it. */ + if (l->l_relro_size != 0) + _dl_protect_relro (l); +} + + +void internal_function +_dl_protect_relro (struct link_map *l) +{ + ElfW(Addr) start = ALIGN_DOWN((l->l_addr + + l->l_relro_addr), + GLRO(dl_pagesize)); + ElfW(Addr) end = ALIGN_DOWN((l->l_addr + + l->l_relro_addr + + l->l_relro_size), + GLRO(dl_pagesize)); + if (start != end + && __mprotect ((void *) start, end - start, PROT_READ) < 0) + { + static const char errstring[] = N_("\ +cannot apply additional memory protection after relocation"); + _dl_signal_error (errno, l->l_name, NULL, errstring); + } +} + +void +internal_function __attribute_noinline__ +_dl_reloc_bad_type (struct link_map *map, unsigned int type, int plt) +{ +#define DIGIT(b) _itoa_lower_digits[(b) & 0xf]; + + /* XXX We cannot translate these messages. */ + static const char msg[2][32 +#if __ELF_NATIVE_CLASS == 64 + + 6 +#endif + ] = { "unexpected reloc type 0x", + "unexpected PLT reloc type 0x" }; + char msgbuf[sizeof (msg[0])]; + char *cp; + + cp = __stpcpy (msgbuf, msg[plt]); +#if __ELF_NATIVE_CLASS == 64 + if (__builtin_expect(type > 0xff, 0)) + { + *cp++ = DIGIT (type >> 28); + *cp++ = DIGIT (type >> 24); + *cp++ = DIGIT (type >> 20); + *cp++ = DIGIT (type >> 16); + *cp++ = DIGIT (type >> 12); + *cp++ = DIGIT (type >> 8); + } +#endif + *cp++ = DIGIT (type >> 4); + *cp++ = DIGIT (type); + *cp = '\0'; + + _dl_signal_error (0, map->l_name, NULL, msgbuf); +} |