| /* Relocate debug information. |
| Copyright (C) 2005-2009 Red Hat, Inc. |
| This file is part of Red Hat elfutils. |
| |
| Red Hat elfutils is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by the |
| Free Software Foundation; version 2 of the License. |
| |
| Red Hat elfutils 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 |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License along |
| with Red Hat elfutils; if not, write to the Free Software Foundation, |
| Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. |
| |
| In addition, as a special exception, Red Hat, Inc. gives You the |
| additional right to link the code of Red Hat elfutils with code licensed |
| under any Open Source Initiative certified open source license |
| (http://www.opensource.org/licenses/index.php) which requires the |
| distribution of source code with any binary distribution and to |
| distribute linked combinations of the two. Non-GPL Code permitted under |
| this exception must only link to the code of Red Hat elfutils through |
| those well defined interfaces identified in the file named EXCEPTION |
| found in the source code files (the "Approved Interfaces"). The files |
| of Non-GPL Code may instantiate templates or use macros or inline |
| functions from the Approved Interfaces without causing the resulting |
| work to be covered by the GNU General Public License. Only Red Hat, |
| Inc. may make changes or additions to the list of Approved Interfaces. |
| Red Hat's grant of this exception is conditioned upon your not adding |
| any new exceptions. If you wish to add a new Approved Interface or |
| exception, please contact Red Hat. You must obey the GNU General Public |
| License in all respects for all of the Red Hat elfutils code and other |
| code used in conjunction with Red Hat elfutils except the Non-GPL Code |
| covered by this exception. If you modify this file, you may extend this |
| exception to your version of the file, but you are not obligated to do |
| so. If you do not wish to provide this exception without modification, |
| you must delete this exception statement from your version and license |
| this file solely under the GPL without exception. |
| |
| Red Hat elfutils is an included package of the Open Invention Network. |
| An included package of the Open Invention Network is a package for which |
| Open Invention Network licensees cross-license their patents. No patent |
| license is granted, either expressly or impliedly, by designation as an |
| included package. Should you wish to participate in the Open Invention |
| Network licensing program, please visit www.openinventionnetwork.com |
| <http://www.openinventionnetwork.com>. */ |
| |
| #include "libdwflP.h" |
| |
| typedef uint8_t GElf_Byte; |
| |
| /* Adjust *VALUE to add the load address of the SHNDX section. |
| We update the section header in place to cache the result. */ |
| |
| Dwfl_Error |
| internal_function |
| __libdwfl_relocate_value (Dwfl_Module *mod, Elf *elf, size_t *shstrndx, |
| Elf32_Word shndx, GElf_Addr *value) |
| { |
| Elf_Scn *refscn = elf_getscn (elf, shndx); |
| GElf_Shdr refshdr_mem, *refshdr = gelf_getshdr (refscn, &refshdr_mem); |
| if (refshdr == NULL) |
| return DWFL_E_LIBELF; |
| |
| if (refshdr->sh_addr == 0 && (refshdr->sh_flags & SHF_ALLOC)) |
| { |
| /* This is a loaded section. Find its actual |
| address and update the section header. */ |
| |
| if (*shstrndx == SHN_UNDEF |
| && unlikely (elf_getshstrndx (elf, shstrndx) < 0)) |
| return DWFL_E_LIBELF; |
| |
| const char *name = elf_strptr (elf, *shstrndx, refshdr->sh_name); |
| if (unlikely (name == NULL)) |
| return DWFL_E_LIBELF; |
| |
| if ((*mod->dwfl->callbacks->section_address) (MODCB_ARGS (mod), |
| name, shndx, refshdr, |
| &refshdr->sh_addr)) |
| return CBFAIL; |
| |
| if (refshdr->sh_addr == (Dwarf_Addr) -1l) |
| /* The callback indicated this section wasn't really loaded but we |
| don't really care. */ |
| refshdr->sh_addr = 0; /* Make no adjustment below. */ |
| |
| /* Update the in-core file's section header to show the final |
| load address (or unloadedness). This serves as a cache, |
| so we won't get here again for the same section. */ |
| if (likely (refshdr->sh_addr != 0) |
| && unlikely (! gelf_update_shdr (refscn, refshdr))) |
| return DWFL_E_LIBELF; |
| } |
| |
| /* Apply the adjustment. */ |
| *value += refshdr->sh_addr + mod->main.bias; |
| return DWFL_E_NOERROR; |
| } |
| |
| |
| /* Cache used by relocate_getsym. */ |
| struct reloc_symtab_cache |
| { |
| Elf *symelf; |
| Elf_Data *symdata; |
| Elf_Data *symxndxdata; |
| Elf_Data *symstrdata; |
| size_t symshstrndx; |
| size_t strtabndx; |
| }; |
| #define RELOC_SYMTAB_CACHE(cache) \ |
| struct reloc_symtab_cache cache = \ |
| { NULL, NULL, NULL, NULL, SHN_UNDEF, SHN_UNDEF } |
| |
| /* This is just doing dwfl_module_getsym, except that we must always use |
| the symbol table in RELOCATED itself when it has one, not MOD->symfile. */ |
| static Dwfl_Error |
| relocate_getsym (Dwfl_Module *mod, |
| Elf *relocated, struct reloc_symtab_cache *cache, |
| int symndx, GElf_Sym *sym, GElf_Word *shndx) |
| { |
| if (cache->symdata == NULL) |
| { |
| if (mod->symfile == NULL || mod->symfile->elf != relocated) |
| { |
| /* We have to look up the symbol table in the file we are |
| relocating, if it has its own. These reloc sections refer to |
| the symbol table in this file, and a symbol table in the main |
| file might not match. However, some tools did produce ET_REL |
| .debug files with relocs but no symtab of their own. */ |
| Elf_Scn *scn = NULL; |
| while ((scn = elf_nextscn (relocated, scn)) != NULL) |
| { |
| GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem); |
| if (shdr != NULL) |
| switch (shdr->sh_type) |
| { |
| default: |
| continue; |
| case SHT_SYMTAB: |
| cache->symelf = relocated; |
| cache->symdata = elf_getdata (scn, NULL); |
| cache->strtabndx = shdr->sh_link; |
| if (unlikely (cache->symdata == NULL)) |
| return DWFL_E_LIBELF; |
| break; |
| case SHT_SYMTAB_SHNDX: |
| cache->symxndxdata = elf_getdata (scn, NULL); |
| if (unlikely (cache->symxndxdata == NULL)) |
| return DWFL_E_LIBELF; |
| break; |
| } |
| if (cache->symdata != NULL && cache->symxndxdata != NULL) |
| break; |
| } |
| } |
| if (cache->symdata == NULL) |
| { |
| /* We might not have looked for a symbol table file yet, |
| when coming from __libdwfl_relocate_section. */ |
| if (unlikely (mod->symfile == NULL) |
| && unlikely (INTUSE(dwfl_module_getsymtab) (mod) < 0)) |
| return dwfl_errno (); |
| |
| /* The symbol table we have already cached is the one from |
| the file being relocated, so it's what we need. Or else |
| this is an ET_REL .debug file with no .symtab of its own; |
| the symbols refer to the section indices in the main file. */ |
| cache->symelf = mod->symfile->elf; |
| cache->symdata = mod->symdata; |
| cache->symxndxdata = mod->symxndxdata; |
| cache->symstrdata = mod->symstrdata; |
| } |
| } |
| |
| if (unlikely (gelf_getsymshndx (cache->symdata, cache->symxndxdata, |
| symndx, sym, shndx) == NULL)) |
| return DWFL_E_LIBELF; |
| |
| if (sym->st_shndx != SHN_XINDEX) |
| *shndx = sym->st_shndx; |
| |
| switch (*shndx) |
| { |
| case SHN_ABS: |
| case SHN_UNDEF: |
| case SHN_COMMON: |
| return DWFL_E_NOERROR; |
| } |
| |
| return __libdwfl_relocate_value (mod, cache->symelf, &cache->symshstrndx, |
| *shndx, &sym->st_value); |
| } |
| |
| /* Handle an undefined symbol. We really only support ET_REL for Linux |
| kernel modules, and offline archives. The behavior of the Linux module |
| loader is very simple and easy to mimic. It only matches magically |
| exported symbols, and we match any defined symbols. But we get the same |
| answer except when the module's symbols are undefined and would prevent |
| it from being loaded. */ |
| static Dwfl_Error |
| resolve_symbol (Dwfl_Module *referer, struct reloc_symtab_cache *symtab, |
| GElf_Sym *sym, GElf_Word shndx) |
| { |
| /* First we need its name. */ |
| if (sym->st_name != 0) |
| { |
| if (symtab->symstrdata == NULL) |
| { |
| /* Cache the strtab for this symtab. */ |
| assert (referer->symfile == NULL |
| || referer->symfile->elf != symtab->symelf); |
| symtab->symstrdata = elf_getdata (elf_getscn (symtab->symelf, |
| symtab->strtabndx), |
| NULL); |
| if (unlikely (symtab->symstrdata == NULL)) |
| return DWFL_E_LIBELF; |
| } |
| if (unlikely (sym->st_name >= symtab->symstrdata->d_size)) |
| return DWFL_E_BADSTROFF; |
| |
| const char *name = symtab->symstrdata->d_buf; |
| name += sym->st_name; |
| |
| for (Dwfl_Module *m = referer->dwfl->modulelist; m != NULL; m = m->next) |
| if (m != referer) |
| { |
| /* Get this module's symtab. |
| If we got a fresh error reading the table, report it. |
| If we just have no symbols in this module, no harm done. */ |
| if (m->symdata == NULL |
| && m->symerr == DWFL_E_NOERROR |
| && INTUSE(dwfl_module_getsymtab) (m) < 0 |
| && m->symerr != DWFL_E_NO_SYMTAB) |
| return m->symerr; |
| |
| for (size_t ndx = 1; ndx < m->syments; ++ndx) |
| { |
| sym = gelf_getsymshndx (m->symdata, m->symxndxdata, |
| ndx, sym, &shndx); |
| if (unlikely (sym == NULL)) |
| return DWFL_E_LIBELF; |
| if (sym->st_shndx != SHN_XINDEX) |
| shndx = sym->st_shndx; |
| |
| /* We are looking for a defined global symbol with a name. */ |
| if (shndx == SHN_UNDEF || shndx == SHN_COMMON |
| || GELF_ST_BIND (sym->st_info) == STB_LOCAL |
| || sym->st_name == 0) |
| continue; |
| |
| /* Get this candidate symbol's name. */ |
| if (unlikely (sym->st_name >= m->symstrdata->d_size)) |
| return DWFL_E_BADSTROFF; |
| const char *n = m->symstrdata->d_buf; |
| n += sym->st_name; |
| |
| /* Does the name match? */ |
| if (strcmp (name, n)) |
| continue; |
| |
| /* We found it! */ |
| if (shndx == SHN_ABS) |
| return DWFL_E_NOERROR; |
| |
| /* In an ET_REL file, the symbol table values are relative |
| to the section, not to the module's load base. */ |
| size_t symshstrndx = SHN_UNDEF; |
| return __libdwfl_relocate_value (m, m->symfile->elf, |
| &symshstrndx, |
| shndx, &sym->st_value); |
| } |
| } |
| } |
| |
| return DWFL_E_RELUNDEF; |
| } |
| |
| static Dwfl_Error |
| relocate_section (Dwfl_Module *mod, Elf *relocated, const GElf_Ehdr *ehdr, |
| size_t shstrndx, struct reloc_symtab_cache *reloc_symtab, |
| Elf_Scn *scn, GElf_Shdr *shdr, |
| Elf_Scn *tscn, bool debugscn, bool partial) |
| { |
| /* First, fetch the name of the section these relocations apply to. */ |
| GElf_Shdr tshdr_mem; |
| GElf_Shdr *tshdr = gelf_getshdr (tscn, &tshdr_mem); |
| const char *tname = elf_strptr (relocated, shstrndx, tshdr->sh_name); |
| if (tname == NULL) |
| return DWFL_E_LIBELF; |
| |
| if (debugscn && ! ebl_debugscn_p (mod->ebl, tname)) |
| /* This relocation section is not for a debugging section. |
| Nothing to do here. */ |
| return DWFL_E_NOERROR; |
| |
| /* Fetch the section data that needs the relocations applied. */ |
| Elf_Data *tdata = elf_rawdata (tscn, NULL); |
| if (tdata == NULL) |
| return DWFL_E_LIBELF; |
| |
| /* Apply one relocation. Returns true for any invalid data. */ |
| Dwfl_Error relocate (GElf_Addr offset, const GElf_Sxword *addend, |
| int rtype, int symndx) |
| { |
| /* First see if this is a reloc we can handle. |
| If we are skipping it, don't bother resolving the symbol. */ |
| Elf_Type type = ebl_reloc_simple_type (mod->ebl, rtype); |
| if (unlikely (type == ELF_T_NUM)) |
| return DWFL_E_BADRELTYPE; |
| |
| /* First, resolve the symbol to an absolute value. */ |
| GElf_Addr value; |
| |
| if (symndx == STN_UNDEF) |
| /* When strip removes a section symbol referring to a |
| section moved into the debuginfo file, it replaces |
| that symbol index in relocs with STN_UNDEF. We |
| don't actually need the symbol, because those relocs |
| are always references relative to the nonallocated |
| debugging sections, which start at zero. */ |
| value = 0; |
| else |
| { |
| GElf_Sym sym; |
| GElf_Word shndx; |
| Dwfl_Error error = relocate_getsym (mod, relocated, reloc_symtab, |
| symndx, &sym, &shndx); |
| if (unlikely (error != DWFL_E_NOERROR)) |
| return error; |
| |
| if (shndx == SHN_UNDEF || shndx == SHN_COMMON) |
| { |
| /* Maybe we can figure it out anyway. */ |
| error = resolve_symbol (mod, reloc_symtab, &sym, shndx); |
| if (error != DWFL_E_NOERROR) |
| return error; |
| } |
| |
| value = sym.st_value; |
| } |
| |
| /* These are the types we can relocate. */ |
| #define TYPES DO_TYPE (BYTE, Byte); DO_TYPE (HALF, Half); \ |
| DO_TYPE (WORD, Word); DO_TYPE (SWORD, Sword); \ |
| DO_TYPE (XWORD, Xword); DO_TYPE (SXWORD, Sxword) |
| size_t size; |
| switch (type) |
| { |
| #define DO_TYPE(NAME, Name) \ |
| case ELF_T_##NAME: \ |
| size = sizeof (GElf_##Name); \ |
| break |
| TYPES; |
| #undef DO_TYPE |
| default: |
| return DWFL_E_BADRELTYPE; |
| } |
| |
| if (offset + size > tdata->d_size) |
| return DWFL_E_BADRELOFF; |
| |
| #define DO_TYPE(NAME, Name) GElf_##Name Name; |
| union { TYPES; } tmpbuf; |
| #undef DO_TYPE |
| Elf_Data tmpdata = |
| { |
| .d_type = type, |
| .d_buf = &tmpbuf, |
| .d_size = size, |
| .d_version = EV_CURRENT, |
| }; |
| Elf_Data rdata = |
| { |
| .d_type = type, |
| .d_buf = tdata->d_buf + offset, |
| .d_size = size, |
| .d_version = EV_CURRENT, |
| }; |
| |
| /* XXX check for overflow? */ |
| if (addend) |
| { |
| /* For the addend form, we have the value already. */ |
| value += *addend; |
| switch (type) |
| { |
| #define DO_TYPE(NAME, Name) \ |
| case ELF_T_##NAME: \ |
| tmpbuf.Name = value; \ |
| break |
| TYPES; |
| #undef DO_TYPE |
| default: |
| abort (); |
| } |
| } |
| else |
| { |
| /* Extract the original value and apply the reloc. */ |
| Elf_Data *d = gelf_xlatetom (relocated, &tmpdata, &rdata, |
| ehdr->e_ident[EI_DATA]); |
| if (d == NULL) |
| return DWFL_E_LIBELF; |
| assert (d == &tmpdata); |
| switch (type) |
| { |
| #define DO_TYPE(NAME, Name) \ |
| case ELF_T_##NAME: \ |
| tmpbuf.Name += (GElf_##Name) value; \ |
| break |
| TYPES; |
| #undef DO_TYPE |
| default: |
| abort (); |
| } |
| } |
| |
| /* Now convert the relocated datum back to the target |
| format. This will write into rdata.d_buf, which |
| points into the raw section data being relocated. */ |
| Elf_Data *s = gelf_xlatetof (relocated, &rdata, &tmpdata, |
| ehdr->e_ident[EI_DATA]); |
| if (s == NULL) |
| return DWFL_E_LIBELF; |
| assert (s == &rdata); |
| |
| /* We have applied this relocation! */ |
| return DWFL_E_NOERROR; |
| } |
| |
| /* Fetch the relocation section and apply each reloc in it. */ |
| Elf_Data *reldata = elf_getdata (scn, NULL); |
| if (reldata == NULL) |
| return DWFL_E_LIBELF; |
| |
| Dwfl_Error result = DWFL_E_NOERROR; |
| bool first_badreltype = true; |
| inline void check_badreltype (void) |
| { |
| if (first_badreltype) |
| { |
| first_badreltype = false; |
| if (ebl_get_elfmachine (mod->ebl) == EM_NONE) |
| /* This might be because ebl_openbackend failed to find |
| any libebl_CPU.so library. Diagnose that clearly. */ |
| result = DWFL_E_UNKNOWN_MACHINE; |
| } |
| } |
| |
| size_t nrels = shdr->sh_size / shdr->sh_entsize; |
| size_t complete = 0; |
| if (shdr->sh_type == SHT_REL) |
| for (size_t relidx = 0; !result && relidx < nrels; ++relidx) |
| { |
| GElf_Rel rel_mem, *r = gelf_getrel (reldata, relidx, &rel_mem); |
| if (r == NULL) |
| return DWFL_E_LIBELF; |
| result = relocate (r->r_offset, NULL, |
| GELF_R_TYPE (r->r_info), |
| GELF_R_SYM (r->r_info)); |
| check_badreltype (); |
| if (partial) |
| switch (result) |
| { |
| case DWFL_E_NOERROR: |
| /* We applied the relocation. Elide it. */ |
| memset (&rel_mem, 0, sizeof rel_mem); |
| gelf_update_rel (reldata, relidx, &rel_mem); |
| ++complete; |
| break; |
| case DWFL_E_BADRELTYPE: |
| case DWFL_E_RELUNDEF: |
| /* We couldn't handle this relocation. Skip it. */ |
| result = DWFL_E_NOERROR; |
| break; |
| default: |
| break; |
| } |
| } |
| else |
| for (size_t relidx = 0; !result && relidx < nrels; ++relidx) |
| { |
| GElf_Rela rela_mem, *r = gelf_getrela (reldata, relidx, |
| &rela_mem); |
| if (r == NULL) |
| return DWFL_E_LIBELF; |
| result = relocate (r->r_offset, &r->r_addend, |
| GELF_R_TYPE (r->r_info), |
| GELF_R_SYM (r->r_info)); |
| check_badreltype (); |
| if (partial) |
| switch (result) |
| { |
| case DWFL_E_NOERROR: |
| /* We applied the relocation. Elide it. */ |
| memset (&rela_mem, 0, sizeof rela_mem); |
| gelf_update_rela (reldata, relidx, &rela_mem); |
| ++complete; |
| break; |
| case DWFL_E_BADRELTYPE: |
| case DWFL_E_RELUNDEF: |
| /* We couldn't handle this relocation. Skip it. */ |
| result = DWFL_E_NOERROR; |
| break; |
| default: |
| break; |
| } |
| } |
| |
| if (likely (result == DWFL_E_NOERROR)) |
| { |
| if (!partial || complete == nrels) |
| /* Mark this relocation section as being empty now that we have |
| done its work. This affects unstrip -R, so e.g. it emits an |
| empty .rela.debug_info along with a .debug_info that has |
| already been fully relocated. */ |
| nrels = 0; |
| else if (complete != 0) |
| { |
| /* We handled some of the relocations but not all. |
| We've zeroed out the ones we processed. |
| Now remove them from the section. */ |
| |
| size_t next = 0; |
| if (shdr->sh_type == SHT_REL) |
| for (size_t relidx = 0; relidx < nrels; ++relidx) |
| { |
| GElf_Rel rel_mem; |
| GElf_Rel *r = gelf_getrel (reldata, relidx, &rel_mem); |
| if (r->r_info != 0 || r->r_offset != 0) |
| { |
| if (next != relidx) |
| gelf_update_rel (reldata, next, r); |
| ++next; |
| } |
| } |
| else |
| for (size_t relidx = 0; relidx < nrels; ++relidx) |
| { |
| GElf_Rela rela_mem; |
| GElf_Rela *r = gelf_getrela (reldata, relidx, &rela_mem); |
| if (r->r_info != 0 || r->r_offset != 0 || r->r_addend != 0) |
| { |
| if (next != relidx) |
| gelf_update_rela (reldata, next, r); |
| ++next; |
| } |
| } |
| nrels = next; |
| } |
| |
| shdr->sh_size = reldata->d_size = nrels * shdr->sh_entsize; |
| gelf_update_shdr (scn, shdr); |
| } |
| |
| return result; |
| } |
| |
| Dwfl_Error |
| internal_function |
| __libdwfl_relocate (Dwfl_Module *mod, Elf *debugfile, bool debug) |
| { |
| assert (mod->e_type == ET_REL); |
| |
| GElf_Ehdr ehdr_mem; |
| const GElf_Ehdr *ehdr = gelf_getehdr (debugfile, &ehdr_mem); |
| if (ehdr == NULL) |
| return DWFL_E_LIBELF; |
| |
| size_t d_shstrndx; |
| if (elf_getshstrndx (debugfile, &d_shstrndx) < 0) |
| return DWFL_E_LIBELF; |
| |
| RELOC_SYMTAB_CACHE (reloc_symtab); |
| |
| /* Look at each section in the debuginfo file, and process the |
| relocation sections for debugging sections. */ |
| Dwfl_Error result = DWFL_E_NOERROR; |
| Elf_Scn *scn = NULL; |
| while (result == DWFL_E_NOERROR |
| && (scn = elf_nextscn (debugfile, scn)) != NULL) |
| { |
| GElf_Shdr shdr_mem; |
| GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| |
| if ((shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA) |
| && shdr->sh_size != 0) |
| { |
| /* It's a relocation section. */ |
| |
| Elf_Scn *tscn = elf_getscn (debugfile, shdr->sh_info); |
| if (unlikely (tscn == NULL)) |
| result = DWFL_E_LIBELF; |
| else |
| result = relocate_section (mod, debugfile, ehdr, d_shstrndx, |
| &reloc_symtab, scn, shdr, tscn, |
| debug, !debug); |
| } |
| } |
| |
| return result; |
| } |
| |
| Dwfl_Error |
| internal_function |
| __libdwfl_relocate_section (Dwfl_Module *mod, Elf *relocated, |
| Elf_Scn *relocscn, Elf_Scn *tscn, bool partial) |
| { |
| GElf_Ehdr ehdr_mem; |
| GElf_Shdr shdr_mem; |
| |
| RELOC_SYMTAB_CACHE (reloc_symtab); |
| |
| size_t shstrndx; |
| if (elf_getshstrndx (relocated, &shstrndx) < 0) |
| return DWFL_E_LIBELF; |
| |
| return (__libdwfl_module_getebl (mod) |
| ?: relocate_section (mod, relocated, |
| gelf_getehdr (relocated, &ehdr_mem), shstrndx, |
| &reloc_symtab, |
| relocscn, gelf_getshdr (relocscn, &shdr_mem), |
| tscn, false, partial)); |
| } |