| /* Find debugging and symbol information for a module in libdwfl. |
| Copyright (C) 2005-2011 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" |
| #include <fcntl.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include "../libdw/libdwP.h" /* DWARF_E_* values are here. */ |
| |
| |
| /* Open libelf FILE->fd and compute the load base of ELF as loaded in MOD. |
| When we return success, FILE->elf and FILE->vaddr are set up. */ |
| static inline Dwfl_Error |
| open_elf (Dwfl_Module *mod, struct dwfl_file *file) |
| { |
| if (file->elf == NULL) |
| { |
| /* CBFAIL uses errno if it's set, so clear it first in case we don't |
| set it with an open failure below. */ |
| errno = 0; |
| |
| /* If there was a pre-primed file name left that the callback left |
| behind, try to open that file name. */ |
| if (file->fd < 0 && file->name != NULL) |
| file->fd = TEMP_FAILURE_RETRY (open64 (file->name, O_RDONLY)); |
| |
| if (file->fd < 0) |
| return CBFAIL; |
| |
| Dwfl_Error error = __libdw_open_file (&file->fd, &file->elf, true, false); |
| if (error != DWFL_E_NOERROR) |
| return error; |
| } |
| else if (unlikely (elf_kind (file->elf) != ELF_K_ELF)) |
| { |
| elf_end (file->elf); |
| file->elf = NULL; |
| close (file->fd); |
| file->fd = -1; |
| return DWFL_E_BADELF; |
| } |
| |
| GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (file->elf, &ehdr_mem); |
| if (ehdr == NULL) |
| { |
| elf_error: |
| elf_end (file->elf); |
| file->elf = NULL; |
| close (file->fd); |
| file->fd = -1; |
| return DWFL_E (LIBELF, elf_errno ()); |
| } |
| |
| if (mod->e_type != ET_REL) |
| { |
| /* In any non-ET_REL file, we compute the "synchronization address". |
| |
| We start with the address at the end of the first PT_LOAD |
| segment. When prelink converts REL to RELA in an ET_DYN |
| file, it expands the space between the beginning of the |
| segment and the actual code/data addresses. Since that |
| change wasn't made in the debug file, the distance from |
| p_vaddr to an address of interest (in an st_value or DWARF |
| data) now differs between the main and debug files. The |
| distance from address_sync to an address of interest remains |
| consistent. |
| |
| If there are no section headers at all (full stripping), then |
| the end of the first segment is a valid synchronization address. |
| This cannot happen in a prelinked file, since prelink itself |
| relies on section headers for prelinking and for undoing it. |
| (If you do full stripping on a prelinked file, then you get what |
| you deserve--you can neither undo the prelinking, nor expect to |
| line it up with a debug file separated before prelinking.) |
| |
| However, when prelink processes an ET_EXEC file, it can do |
| something different. There it juggles the "special" sections |
| (SHT_DYNSYM et al) to make space for the additional prelink |
| special sections. Sometimes it will do this by moving a special |
| section like .dynstr after the real program sections in the first |
| PT_LOAD segment--i.e. to the end. That changes the end address of |
| the segment, so it no longer lines up correctly and is not a valid |
| synchronization address to use. Because of this, we need to apply |
| a different prelink-savvy means to discover the synchronization |
| address when there is a separate debug file and a prelinked main |
| file. That is done in find_debuginfo, below. */ |
| |
| size_t phnum; |
| if (unlikely (elf_getphdrnum (file->elf, &phnum) != 0)) |
| goto elf_error; |
| |
| file->vaddr = file->address_sync = 0; |
| for (size_t i = 0; i < phnum; ++i) |
| { |
| GElf_Phdr ph_mem; |
| GElf_Phdr *ph = gelf_getphdr (file->elf, i, &ph_mem); |
| if (unlikely (ph == NULL)) |
| goto elf_error; |
| if (ph->p_type == PT_LOAD) |
| { |
| file->vaddr = ph->p_vaddr & -ph->p_align; |
| file->address_sync = ph->p_vaddr + ph->p_memsz; |
| break; |
| } |
| } |
| } |
| |
| mod->e_type = ehdr->e_type; |
| |
| /* Relocatable Linux kernels are ET_EXEC but act like ET_DYN. */ |
| if (mod->e_type == ET_EXEC && file->vaddr != mod->low_addr) |
| mod->e_type = ET_DYN; |
| |
| return DWFL_E_NOERROR; |
| } |
| |
| /* Find the main ELF file for this module and open libelf on it. |
| When we return success, MOD->main.elf and MOD->main.bias are set up. */ |
| void |
| internal_function |
| __libdwfl_getelf (Dwfl_Module *mod) |
| { |
| if (mod->main.elf != NULL /* Already done. */ |
| || mod->elferr != DWFL_E_NOERROR) /* Cached failure. */ |
| return; |
| |
| mod->main.fd = (*mod->dwfl->callbacks->find_elf) (MODCB_ARGS (mod), |
| &mod->main.name, |
| &mod->main.elf); |
| const bool fallback = mod->main.elf == NULL && mod->main.fd < 0; |
| mod->elferr = open_elf (mod, &mod->main); |
| if (mod->elferr != DWFL_E_NOERROR) |
| return; |
| |
| if (!mod->main.valid) |
| { |
| /* Clear any explicitly reported build ID, just in case it was wrong. |
| We'll fetch it from the file when asked. */ |
| free (mod->build_id_bits); |
| mod->build_id_bits = NULL; |
| mod->build_id_len = 0; |
| } |
| else if (fallback) |
| { |
| /* We have an authoritative build ID for this module, so |
| don't use a file by name that doesn't match that ID. */ |
| |
| assert (mod->build_id_len > 0); |
| |
| switch (__builtin_expect (__libdwfl_find_build_id (mod, false, |
| mod->main.elf), 2)) |
| { |
| case 2: |
| /* Build ID matches as it should. */ |
| return; |
| |
| case -1: /* ELF error. */ |
| mod->elferr = INTUSE(dwfl_errno) (); |
| break; |
| |
| case 0: /* File has no build ID note. */ |
| case 1: /* FIle has a build ID that does not match. */ |
| mod->elferr = DWFL_E_WRONG_ID_ELF; |
| break; |
| |
| default: |
| abort (); |
| } |
| |
| /* We get here when it was the right ELF file. Clear it out. */ |
| elf_end (mod->main.elf); |
| mod->main.elf = NULL; |
| if (mod->main.fd >= 0) |
| { |
| close (mod->main.fd); |
| mod->main.fd = -1; |
| } |
| } |
| |
| mod->main_bias = mod->e_type == ET_REL ? 0 : mod->low_addr - mod->main.vaddr; |
| } |
| |
| /* Search an ELF file for a ".gnu_debuglink" section. */ |
| static const char * |
| find_debuglink (Elf *elf, GElf_Word *crc) |
| { |
| size_t shstrndx; |
| if (elf_getshdrstrndx (elf, &shstrndx) < 0) |
| return NULL; |
| |
| Elf_Scn *scn = NULL; |
| while ((scn = elf_nextscn (elf, scn)) != NULL) |
| { |
| GElf_Shdr shdr_mem; |
| GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| if (shdr == NULL) |
| return NULL; |
| |
| const char *name = elf_strptr (elf, shstrndx, shdr->sh_name); |
| if (name == NULL) |
| return NULL; |
| |
| if (!strcmp (name, ".gnu_debuglink")) |
| break; |
| } |
| |
| if (scn == NULL) |
| return NULL; |
| |
| /* Found the .gnu_debuglink section. Extract its contents. */ |
| Elf_Data *rawdata = elf_rawdata (scn, NULL); |
| if (rawdata == NULL) |
| return NULL; |
| |
| Elf_Data crcdata = |
| { |
| .d_type = ELF_T_WORD, |
| .d_buf = crc, |
| .d_size = sizeof *crc, |
| .d_version = EV_CURRENT, |
| }; |
| Elf_Data conv = |
| { |
| .d_type = ELF_T_WORD, |
| .d_buf = rawdata->d_buf + rawdata->d_size - sizeof *crc, |
| .d_size = sizeof *crc, |
| .d_version = EV_CURRENT, |
| }; |
| |
| GElf_Ehdr ehdr_mem; |
| GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem); |
| if (ehdr == NULL) |
| return NULL; |
| |
| Elf_Data *d = gelf_xlatetom (elf, &crcdata, &conv, ehdr->e_ident[EI_DATA]); |
| if (d == NULL) |
| return NULL; |
| assert (d == &crcdata); |
| |
| return rawdata->d_buf; |
| } |
| |
| /* If the main file might have been prelinked, then we need to |
| discover the correct synchronization address between the main and |
| debug files. Because of prelink's section juggling, we cannot rely |
| on the address_sync computed from PT_LOAD segments (see open_elf). |
| |
| We will attempt to discover a synchronization address based on the |
| section headers instead. But finding a section address that is |
| safe to use requires identifying which sections are SHT_PROGBITS. |
| We can do that in the main file, but in the debug file all the |
| allocated sections have been transformed into SHT_NOBITS so we have |
| lost the means to match them up correctly. |
| |
| The only method left to us is to decode the .gnu.prelink_undo |
| section in the prelinked main file. This shows what the sections |
| looked like before prelink juggled them--when they still had a |
| direct correspondence to the debug file. */ |
| static Dwfl_Error |
| find_prelink_address_sync (Dwfl_Module *mod) |
| { |
| /* The magic section is only identified by name. */ |
| size_t shstrndx; |
| if (elf_getshdrstrndx (mod->main.elf, &shstrndx) < 0) |
| return DWFL_E_LIBELF; |
| |
| Elf_Scn *scn = NULL; |
| while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL) |
| { |
| GElf_Shdr shdr_mem; |
| GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| if (unlikely (shdr == NULL)) |
| return DWFL_E_LIBELF; |
| if (shdr->sh_type == SHT_PROGBITS |
| && !(shdr->sh_flags & SHF_ALLOC) |
| && shdr->sh_name != 0) |
| { |
| const char *secname = elf_strptr (mod->main.elf, shstrndx, |
| shdr->sh_name); |
| if (unlikely (secname == NULL)) |
| return DWFL_E_LIBELF; |
| if (!strcmp (secname, ".gnu.prelink_undo")) |
| break; |
| } |
| } |
| |
| if (scn == NULL) |
| /* There was no .gnu.prelink_undo section. */ |
| return DWFL_E_NOERROR; |
| |
| Elf_Data *undodata = elf_rawdata (scn, NULL); |
| if (unlikely (undodata == NULL)) |
| return DWFL_E_LIBELF; |
| |
| /* Decode the section. It consists of the original ehdr, phdrs, |
| and shdrs (but omits section 0). */ |
| |
| union |
| { |
| Elf32_Ehdr e32; |
| Elf64_Ehdr e64; |
| } ehdr; |
| Elf_Data dst = |
| { |
| .d_buf = &ehdr, |
| .d_size = sizeof ehdr, |
| .d_type = ELF_T_EHDR, |
| .d_version = EV_CURRENT |
| }; |
| Elf_Data src = *undodata; |
| src.d_size = gelf_fsize (mod->main.elf, ELF_T_EHDR, 1, EV_CURRENT); |
| src.d_type = ELF_T_EHDR; |
| if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src, |
| elf_getident (mod->main.elf, NULL)[EI_DATA]) |
| == NULL)) |
| return DWFL_E_LIBELF; |
| |
| size_t shentsize = gelf_fsize (mod->main.elf, ELF_T_SHDR, 1, EV_CURRENT); |
| size_t phentsize = gelf_fsize (mod->main.elf, ELF_T_PHDR, 1, EV_CURRENT); |
| |
| uint_fast16_t phnum; |
| uint_fast16_t shnum; |
| if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32) |
| { |
| if (ehdr.e32.e_shentsize != shentsize |
| || ehdr.e32.e_phentsize != phentsize) |
| return DWFL_E_BAD_PRELINK; |
| phnum = ehdr.e32.e_phnum; |
| shnum = ehdr.e32.e_shnum; |
| } |
| else |
| { |
| if (ehdr.e64.e_shentsize != shentsize |
| || ehdr.e64.e_phentsize != phentsize) |
| return DWFL_E_BAD_PRELINK; |
| phnum = ehdr.e64.e_phnum; |
| shnum = ehdr.e64.e_shnum; |
| } |
| |
| /* Since prelink does not store the zeroth section header in the undo |
| section, it cannot support SHN_XINDEX encoding. */ |
| if (unlikely (shnum >= SHN_LORESERVE) |
| || unlikely (undodata->d_size != (src.d_size |
| + phnum * phentsize |
| + (shnum - 1) * shentsize))) |
| return DWFL_E_BAD_PRELINK; |
| |
| /* We look at the allocated SHT_PROGBITS (or SHT_NOBITS) sections. (Most |
| every file will have some SHT_PROGBITS sections, but it's possible to |
| have one with nothing but .bss, i.e. SHT_NOBITS.) The special sections |
| that can be moved around have different sh_type values--except for |
| .interp, the section that became the PT_INTERP segment. So we exclude |
| the SHT_PROGBITS section whose address matches the PT_INTERP p_vaddr. |
| For this reason, we must examine the phdrs first to find PT_INTERP. */ |
| |
| GElf_Addr main_interp = 0; |
| { |
| size_t main_phnum; |
| if (unlikely (elf_getphdrnum (mod->main.elf, &main_phnum))) |
| return DWFL_E_LIBELF; |
| for (size_t i = 0; i < main_phnum; ++i) |
| { |
| GElf_Phdr phdr; |
| if (unlikely (gelf_getphdr (mod->main.elf, i, &phdr) == NULL)) |
| return DWFL_E_LIBELF; |
| if (phdr.p_type == PT_INTERP) |
| { |
| main_interp = phdr.p_vaddr; |
| break; |
| } |
| } |
| } |
| |
| src.d_buf += src.d_size; |
| src.d_type = ELF_T_PHDR; |
| src.d_size = phnum * phentsize; |
| |
| GElf_Addr undo_interp = 0; |
| { |
| union |
| { |
| Elf32_Phdr p32[phnum]; |
| Elf64_Phdr p64[phnum]; |
| } phdr; |
| dst.d_buf = &phdr; |
| dst.d_size = sizeof phdr; |
| if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src, |
| ehdr.e32.e_ident[EI_DATA]) == NULL)) |
| return DWFL_E_LIBELF; |
| if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32) |
| { |
| for (uint_fast16_t i = 0; i < phnum; ++i) |
| if (phdr.p32[i].p_type == PT_INTERP) |
| { |
| undo_interp = phdr.p32[i].p_vaddr; |
| break; |
| } |
| } |
| else |
| { |
| for (uint_fast16_t i = 0; i < phnum; ++i) |
| if (phdr.p64[i].p_type == PT_INTERP) |
| { |
| undo_interp = phdr.p64[i].p_vaddr; |
| break; |
| } |
| } |
| } |
| |
| if (unlikely ((main_interp == 0) != (undo_interp == 0))) |
| return DWFL_E_BAD_PRELINK; |
| |
| src.d_buf += src.d_size; |
| src.d_type = ELF_T_SHDR; |
| src.d_size = gelf_fsize (mod->main.elf, ELF_T_SHDR, shnum - 1, EV_CURRENT); |
| |
| union |
| { |
| Elf32_Shdr s32[shnum - 1]; |
| Elf64_Shdr s64[shnum - 1]; |
| } shdr; |
| dst.d_buf = &shdr; |
| dst.d_size = sizeof shdr; |
| if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src, |
| ehdr.e32.e_ident[EI_DATA]) == NULL)) |
| return DWFL_E_LIBELF; |
| |
| /* Now we can look at the original section headers of the main file |
| before it was prelinked. First we'll apply our method to the main |
| file sections as they are after prelinking, to calculate the |
| synchronization address of the main file. Then we'll apply that |
| same method to the saved section headers, to calculate the matching |
| synchronization address of the debug file. |
| |
| The method is to consider SHF_ALLOC sections that are either |
| SHT_PROGBITS or SHT_NOBITS, excluding the section whose sh_addr |
| matches the PT_INTERP p_vaddr. The special sections that can be |
| moved by prelink have other types, except for .interp (which |
| becomes PT_INTERP). The "real" sections cannot move as such, but |
| .bss can be split into .dynbss and .bss, with the total memory |
| image remaining the same but being spread across the two sections. |
| So we consider the highest section end, which still matches up. */ |
| |
| GElf_Addr highest; |
| |
| inline void consider_shdr (GElf_Addr interp, |
| GElf_Word sh_type, |
| GElf_Xword sh_flags, |
| GElf_Addr sh_addr, |
| GElf_Xword sh_size) |
| { |
| if ((sh_flags & SHF_ALLOC) |
| && ((sh_type == SHT_PROGBITS && sh_addr != interp) |
| || sh_type == SHT_NOBITS)) |
| { |
| const GElf_Addr sh_end = sh_addr + sh_size; |
| if (sh_end > highest) |
| highest = sh_end; |
| } |
| } |
| |
| highest = 0; |
| scn = NULL; |
| while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL) |
| { |
| GElf_Shdr sh_mem; |
| GElf_Shdr *sh = gelf_getshdr (scn, &sh_mem); |
| if (unlikely (sh == NULL)) |
| return DWFL_E_LIBELF; |
| consider_shdr (main_interp, sh->sh_type, sh->sh_flags, |
| sh->sh_addr, sh->sh_size); |
| } |
| if (highest > mod->main.vaddr) |
| { |
| mod->main.address_sync = highest; |
| |
| highest = 0; |
| if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32) |
| for (size_t i = 0; i < shnum - 1; ++i) |
| consider_shdr (undo_interp, shdr.s32[i].sh_type, shdr.s32[i].sh_flags, |
| shdr.s32[i].sh_addr, shdr.s32[i].sh_size); |
| else |
| for (size_t i = 0; i < shnum - 1; ++i) |
| consider_shdr (undo_interp, shdr.s64[i].sh_type, shdr.s64[i].sh_flags, |
| shdr.s64[i].sh_addr, shdr.s64[i].sh_size); |
| |
| if (highest > mod->debug.vaddr) |
| mod->debug.address_sync = highest; |
| else |
| return DWFL_E_BAD_PRELINK; |
| } |
| |
| return DWFL_E_NOERROR; |
| } |
| |
| /* Find the separate debuginfo file for this module and open libelf on it. |
| When we return success, MOD->debug is set up. */ |
| static Dwfl_Error |
| find_debuginfo (Dwfl_Module *mod) |
| { |
| if (mod->debug.elf != NULL) |
| return DWFL_E_NOERROR; |
| |
| GElf_Word debuglink_crc = 0; |
| const char *debuglink_file = find_debuglink (mod->main.elf, &debuglink_crc); |
| |
| mod->debug.fd = (*mod->dwfl->callbacks->find_debuginfo) (MODCB_ARGS (mod), |
| mod->main.name, |
| debuglink_file, |
| debuglink_crc, |
| &mod->debug.name); |
| Dwfl_Error result = open_elf (mod, &mod->debug); |
| if (result == DWFL_E_NOERROR && mod->debug.address_sync != 0) |
| result = find_prelink_address_sync (mod); |
| return result; |
| } |
| |
| |
| /* Try to find a symbol table in FILE. |
| Returns DWFL_E_NOERROR if a proper one is found. |
| Returns DWFL_E_NO_SYMTAB if not, but still sets results for SHT_DYNSYM. */ |
| static Dwfl_Error |
| load_symtab (struct dwfl_file *file, struct dwfl_file **symfile, |
| Elf_Scn **symscn, Elf_Scn **xndxscn, |
| size_t *syments, GElf_Word *strshndx) |
| { |
| bool symtab = false; |
| Elf_Scn *scn = NULL; |
| while ((scn = elf_nextscn (file->elf, scn)) != NULL) |
| { |
| GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem); |
| if (shdr != NULL) |
| switch (shdr->sh_type) |
| { |
| case SHT_SYMTAB: |
| symtab = true; |
| *symscn = scn; |
| *symfile = file; |
| *strshndx = shdr->sh_link; |
| *syments = shdr->sh_size / shdr->sh_entsize; |
| if (*xndxscn != NULL) |
| return DWFL_E_NOERROR; |
| break; |
| |
| case SHT_DYNSYM: |
| if (symtab) |
| break; |
| /* Use this if need be, but keep looking for SHT_SYMTAB. */ |
| *symscn = scn; |
| *symfile = file; |
| *strshndx = shdr->sh_link; |
| *syments = shdr->sh_size / shdr->sh_entsize; |
| break; |
| |
| case SHT_SYMTAB_SHNDX: |
| *xndxscn = scn; |
| if (symtab) |
| return DWFL_E_NOERROR; |
| break; |
| |
| default: |
| break; |
| } |
| } |
| |
| if (symtab) |
| /* We found one, though no SHT_SYMTAB_SHNDX to go with it. */ |
| return DWFL_E_NOERROR; |
| |
| /* We found no SHT_SYMTAB, so any SHT_SYMTAB_SHNDX was bogus. |
| We might have found an SHT_DYNSYM and set *SYMSCN et al though. */ |
| *xndxscn = NULL; |
| return DWFL_E_NO_SYMTAB; |
| } |
| |
| |
| /* Translate addresses into file offsets. |
| OFFS[*] start out zero and remain zero if unresolved. */ |
| static void |
| find_offsets (Elf *elf, size_t phnum, size_t n, |
| GElf_Addr addrs[n], GElf_Off offs[n]) |
| { |
| size_t unsolved = n; |
| for (size_t i = 0; i < phnum; ++i) |
| { |
| GElf_Phdr phdr_mem; |
| GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem); |
| if (phdr != NULL && phdr->p_type == PT_LOAD && phdr->p_memsz > 0) |
| for (size_t j = 0; j < n; ++j) |
| if (offs[j] == 0 |
| && addrs[j] >= phdr->p_vaddr |
| && addrs[j] - phdr->p_vaddr < phdr->p_filesz) |
| { |
| offs[j] = addrs[j] - phdr->p_vaddr + phdr->p_offset; |
| if (--unsolved == 0) |
| break; |
| } |
| } |
| } |
| |
| /* Try to find a dynamic symbol table via phdrs. */ |
| static void |
| find_dynsym (Dwfl_Module *mod) |
| { |
| GElf_Ehdr ehdr_mem; |
| GElf_Ehdr *ehdr = gelf_getehdr (mod->main.elf, &ehdr_mem); |
| |
| size_t phnum; |
| if (unlikely (elf_getphdrnum (mod->main.elf, &phnum) != 0)) |
| return; |
| |
| for (size_t i = 0; i < phnum; ++i) |
| { |
| GElf_Phdr phdr_mem; |
| GElf_Phdr *phdr = gelf_getphdr (mod->main.elf, i, &phdr_mem); |
| if (phdr == NULL) |
| break; |
| |
| if (phdr->p_type == PT_DYNAMIC) |
| { |
| /* Examine the dynamic section for the pointers we need. */ |
| |
| Elf_Data *data = elf_getdata_rawchunk (mod->main.elf, |
| phdr->p_offset, phdr->p_filesz, |
| ELF_T_DYN); |
| if (data == NULL) |
| continue; |
| |
| enum |
| { |
| i_symtab, |
| i_strtab, |
| i_hash, |
| i_gnu_hash, |
| i_max |
| }; |
| GElf_Addr addrs[i_max] = { 0, }; |
| GElf_Xword strsz = 0; |
| size_t n = data->d_size / gelf_fsize (mod->main.elf, |
| ELF_T_DYN, 1, EV_CURRENT); |
| for (size_t j = 0; j < n; ++j) |
| { |
| GElf_Dyn dyn_mem; |
| GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem); |
| if (dyn != NULL) |
| switch (dyn->d_tag) |
| { |
| case DT_SYMTAB: |
| addrs[i_symtab] = dyn->d_un.d_ptr; |
| continue; |
| |
| case DT_HASH: |
| addrs[i_hash] = dyn->d_un.d_ptr; |
| continue; |
| |
| case DT_GNU_HASH: |
| addrs[i_gnu_hash] = dyn->d_un.d_ptr; |
| continue; |
| |
| case DT_STRTAB: |
| addrs[i_strtab] = dyn->d_un.d_ptr; |
| continue; |
| |
| case DT_STRSZ: |
| strsz = dyn->d_un.d_val; |
| continue; |
| |
| default: |
| continue; |
| |
| case DT_NULL: |
| break; |
| } |
| break; |
| } |
| |
| /* Translate pointers into file offsets. */ |
| GElf_Off offs[i_max] = { 0, }; |
| find_offsets (mod->main.elf, phnum, i_max, addrs, offs); |
| |
| /* Figure out the size of the symbol table. */ |
| if (offs[i_hash] != 0) |
| { |
| /* In the original format, .hash says the size of .dynsym. */ |
| |
| size_t entsz = SH_ENTSIZE_HASH (ehdr); |
| data = elf_getdata_rawchunk (mod->main.elf, |
| offs[i_hash] + entsz, entsz, |
| entsz == 4 ? ELF_T_WORD |
| : ELF_T_XWORD); |
| if (data != NULL) |
| mod->syments = (entsz == 4 |
| ? *(const GElf_Word *) data->d_buf |
| : *(const GElf_Xword *) data->d_buf); |
| } |
| if (offs[i_gnu_hash] != 0 && mod->syments == 0) |
| { |
| /* In the new format, we can derive it with some work. */ |
| |
| const struct |
| { |
| Elf32_Word nbuckets; |
| Elf32_Word symndx; |
| Elf32_Word maskwords; |
| Elf32_Word shift2; |
| } *header; |
| |
| data = elf_getdata_rawchunk (mod->main.elf, offs[i_gnu_hash], |
| sizeof *header, ELF_T_WORD); |
| if (data != NULL) |
| { |
| header = data->d_buf; |
| Elf32_Word nbuckets = header->nbuckets; |
| Elf32_Word symndx = header->symndx; |
| GElf_Off buckets_at = (offs[i_gnu_hash] + sizeof *header |
| + (gelf_getclass (mod->main.elf) |
| * sizeof (Elf32_Word) |
| * header->maskwords)); |
| |
| data = elf_getdata_rawchunk (mod->main.elf, buckets_at, |
| nbuckets * sizeof (Elf32_Word), |
| ELF_T_WORD); |
| if (data != NULL && symndx < nbuckets) |
| { |
| const Elf32_Word *const buckets = data->d_buf; |
| Elf32_Word maxndx = symndx; |
| for (Elf32_Word bucket = 0; bucket < nbuckets; ++bucket) |
| if (buckets[bucket] > maxndx) |
| maxndx = buckets[bucket]; |
| |
| GElf_Off hasharr_at = (buckets_at |
| + nbuckets * sizeof (Elf32_Word)); |
| hasharr_at += (maxndx - symndx) * sizeof (Elf32_Word); |
| do |
| { |
| data = elf_getdata_rawchunk (mod->main.elf, |
| hasharr_at, |
| sizeof (Elf32_Word), |
| ELF_T_WORD); |
| if (data != NULL |
| && (*(const Elf32_Word *) data->d_buf & 1u)) |
| { |
| mod->syments = maxndx + 1; |
| break; |
| } |
| ++maxndx; |
| hasharr_at += sizeof (Elf32_Word); |
| } while (data != NULL); |
| } |
| } |
| } |
| if (offs[i_strtab] > offs[i_symtab] && mod->syments == 0) |
| mod->syments = ((offs[i_strtab] - offs[i_symtab]) |
| / gelf_fsize (mod->main.elf, |
| ELF_T_SYM, 1, EV_CURRENT)); |
| |
| if (mod->syments > 0) |
| { |
| mod->symdata = elf_getdata_rawchunk (mod->main.elf, |
| offs[i_symtab], |
| gelf_fsize (mod->main.elf, |
| ELF_T_SYM, |
| mod->syments, |
| EV_CURRENT), |
| ELF_T_SYM); |
| if (mod->symdata != NULL) |
| { |
| mod->symstrdata = elf_getdata_rawchunk (mod->main.elf, |
| offs[i_strtab], |
| strsz, |
| ELF_T_BYTE); |
| if (mod->symstrdata == NULL) |
| mod->symdata = NULL; |
| } |
| if (mod->symdata == NULL) |
| mod->symerr = DWFL_E (LIBELF, elf_errno ()); |
| else |
| { |
| mod->symfile = &mod->main; |
| mod->symerr = DWFL_E_NOERROR; |
| } |
| return; |
| } |
| } |
| } |
| } |
| |
| /* Try to find a symbol table in either MOD->main.elf or MOD->debug.elf. */ |
| static void |
| find_symtab (Dwfl_Module *mod) |
| { |
| if (mod->symdata != NULL /* Already done. */ |
| || mod->symerr != DWFL_E_NOERROR) /* Cached previous failure. */ |
| return; |
| |
| __libdwfl_getelf (mod); |
| mod->symerr = mod->elferr; |
| if (mod->symerr != DWFL_E_NOERROR) |
| return; |
| |
| /* First see if the main ELF file has the debugging information. */ |
| Elf_Scn *symscn = NULL, *xndxscn = NULL; |
| GElf_Word strshndx; |
| mod->symerr = load_symtab (&mod->main, &mod->symfile, &symscn, |
| &xndxscn, &mod->syments, &strshndx); |
| switch (mod->symerr) |
| { |
| default: |
| return; |
| |
| case DWFL_E_NOERROR: |
| break; |
| |
| case DWFL_E_NO_SYMTAB: |
| /* Now we have to look for a separate debuginfo file. */ |
| mod->symerr = find_debuginfo (mod); |
| switch (mod->symerr) |
| { |
| default: |
| return; |
| |
| case DWFL_E_NOERROR: |
| mod->symerr = load_symtab (&mod->debug, &mod->symfile, &symscn, |
| &xndxscn, &mod->syments, &strshndx); |
| break; |
| |
| case DWFL_E_CB: /* The find_debuginfo hook failed. */ |
| mod->symerr = DWFL_E_NO_SYMTAB; |
| break; |
| } |
| |
| switch (mod->symerr) |
| { |
| default: |
| return; |
| |
| case DWFL_E_NOERROR: |
| break; |
| |
| case DWFL_E_NO_SYMTAB: |
| if (symscn != NULL) |
| { |
| /* We still have the dynamic symbol table. */ |
| mod->symerr = DWFL_E_NOERROR; |
| break; |
| } |
| |
| /* Last ditch, look for dynamic symbols without section headers. */ |
| find_dynsym (mod); |
| return; |
| } |
| break; |
| } |
| |
| /* This does some sanity checks on the string table section. */ |
| if (elf_strptr (mod->symfile->elf, strshndx, 0) == NULL) |
| { |
| elferr: |
| mod->symerr = DWFL_E (LIBELF, elf_errno ()); |
| return; |
| } |
| |
| /* Cache the data; MOD->syments was set above. */ |
| |
| mod->symstrdata = elf_getdata (elf_getscn (mod->symfile->elf, strshndx), |
| NULL); |
| if (mod->symstrdata == NULL) |
| goto elferr; |
| |
| if (xndxscn == NULL) |
| mod->symxndxdata = NULL; |
| else |
| { |
| mod->symxndxdata = elf_getdata (xndxscn, NULL); |
| if (mod->symxndxdata == NULL) |
| goto elferr; |
| } |
| |
| mod->symdata = elf_getdata (symscn, NULL); |
| if (mod->symdata == NULL) |
| goto elferr; |
| } |
| |
| |
| /* Try to open a libebl backend for MOD. */ |
| Dwfl_Error |
| internal_function |
| __libdwfl_module_getebl (Dwfl_Module *mod) |
| { |
| if (mod->ebl == NULL) |
| { |
| __libdwfl_getelf (mod); |
| if (mod->elferr != DWFL_E_NOERROR) |
| return mod->elferr; |
| |
| mod->ebl = ebl_openbackend (mod->main.elf); |
| if (mod->ebl == NULL) |
| return DWFL_E_LIBEBL; |
| } |
| return DWFL_E_NOERROR; |
| } |
| |
| /* Try to start up libdw on DEBUGFILE. */ |
| static Dwfl_Error |
| load_dw (Dwfl_Module *mod, struct dwfl_file *debugfile) |
| { |
| if (mod->e_type == ET_REL && !debugfile->relocated) |
| { |
| const Dwfl_Callbacks *const cb = mod->dwfl->callbacks; |
| |
| /* The debugging sections have to be relocated. */ |
| if (cb->section_address == NULL) |
| return DWFL_E_NOREL; |
| |
| Dwfl_Error error = __libdwfl_module_getebl (mod); |
| if (error != DWFL_E_NOERROR) |
| return error; |
| |
| find_symtab (mod); |
| Dwfl_Error result = mod->symerr; |
| if (result == DWFL_E_NOERROR) |
| result = __libdwfl_relocate (mod, debugfile->elf, true); |
| if (result != DWFL_E_NOERROR) |
| return result; |
| |
| /* Don't keep the file descriptors around. */ |
| if (mod->main.fd != -1 && elf_cntl (mod->main.elf, ELF_C_FDREAD) == 0) |
| { |
| close (mod->main.fd); |
| mod->main.fd = -1; |
| } |
| if (debugfile->fd != -1 && elf_cntl (debugfile->elf, ELF_C_FDREAD) == 0) |
| { |
| close (debugfile->fd); |
| debugfile->fd = -1; |
| } |
| } |
| |
| mod->dw = INTUSE(dwarf_begin_elf) (debugfile->elf, DWARF_C_READ, NULL); |
| if (mod->dw == NULL) |
| { |
| int err = INTUSE(dwarf_errno) (); |
| return err == DWARF_E_NO_DWARF ? DWFL_E_NO_DWARF : DWFL_E (LIBDW, err); |
| } |
| |
| /* Until we have iterated through all CU's, we might do lazy lookups. */ |
| mod->lazycu = 1; |
| |
| return DWFL_E_NOERROR; |
| } |
| |
| /* Try to start up libdw on either the main file or the debuginfo file. */ |
| static void |
| find_dw (Dwfl_Module *mod) |
| { |
| if (mod->dw != NULL /* Already done. */ |
| || mod->dwerr != DWFL_E_NOERROR) /* Cached previous failure. */ |
| return; |
| |
| __libdwfl_getelf (mod); |
| mod->dwerr = mod->elferr; |
| if (mod->dwerr != DWFL_E_NOERROR) |
| return; |
| |
| /* First see if the main ELF file has the debugging information. */ |
| mod->dwerr = load_dw (mod, &mod->main); |
| switch (mod->dwerr) |
| { |
| case DWFL_E_NOERROR: |
| mod->debug.elf = mod->main.elf; |
| mod->debug.address_sync = mod->main.address_sync; |
| return; |
| |
| case DWFL_E_NO_DWARF: |
| break; |
| |
| default: |
| goto canonicalize; |
| } |
| |
| /* Now we have to look for a separate debuginfo file. */ |
| mod->dwerr = find_debuginfo (mod); |
| switch (mod->dwerr) |
| { |
| case DWFL_E_NOERROR: |
| mod->dwerr = load_dw (mod, &mod->debug); |
| break; |
| |
| case DWFL_E_CB: /* The find_debuginfo hook failed. */ |
| mod->dwerr = DWFL_E_NO_DWARF; |
| return; |
| |
| default: |
| break; |
| } |
| |
| canonicalize: |
| mod->dwerr = __libdwfl_canon_error (mod->dwerr); |
| } |
| |
| Dwarf * |
| dwfl_module_getdwarf (Dwfl_Module *mod, Dwarf_Addr *bias) |
| { |
| if (mod == NULL) |
| return NULL; |
| |
| find_dw (mod); |
| if (mod->dwerr == DWFL_E_NOERROR) |
| { |
| /* If dwfl_module_getelf was used previously, then partial apply |
| relocation to miscellaneous sections in the debug file too. */ |
| if (mod->e_type == ET_REL |
| && mod->main.relocated && ! mod->debug.relocated) |
| { |
| mod->debug.relocated = true; |
| if (mod->debug.elf != mod->main.elf) |
| (void) __libdwfl_relocate (mod, mod->debug.elf, false); |
| } |
| |
| *bias = dwfl_adjusted_dwarf_addr (mod, 0); |
| return mod->dw; |
| } |
| |
| __libdwfl_seterrno (mod->dwerr); |
| return NULL; |
| } |
| INTDEF (dwfl_module_getdwarf) |
| |
| int |
| dwfl_module_getsymtab (Dwfl_Module *mod) |
| { |
| if (mod == NULL) |
| return -1; |
| |
| find_symtab (mod); |
| if (mod->symerr == DWFL_E_NOERROR) |
| return mod->syments; |
| |
| __libdwfl_seterrno (mod->symerr); |
| return -1; |
| } |
| INTDEF (dwfl_module_getsymtab) |