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Diffstat (limited to 'src/libdwfl/link_map.c')
| -rw-r--r-- | src/libdwfl/link_map.c | 888 |
1 files changed, 888 insertions, 0 deletions
diff --git a/src/libdwfl/link_map.c b/src/libdwfl/link_map.c new file mode 100644 index 00000000..05839b3a --- /dev/null +++ b/src/libdwfl/link_map.c @@ -0,0 +1,888 @@ +/* Report modules by examining dynamic linker data structures. + Copyright (C) 2008-2010 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 <config.h> +#include "libdwflP.h" + +#include <byteswap.h> +#include <endian.h> + +/* This element is always provided and always has a constant value. + This makes it an easy thing to scan for to discern the format. */ +#define PROBE_TYPE AT_PHENT +#define PROBE_VAL32 sizeof (Elf32_Phdr) +#define PROBE_VAL64 sizeof (Elf64_Phdr) + +#if BYTE_ORDER == BIG_ENDIAN +# define BE32(x) (x) +# define BE64(x) (x) +# define LE32(x) bswap_32 (x) +# define LE64(x) bswap_64 (x) +#else +# define LE32(x) (x) +# define LE64(x) (x) +# define BE32(x) bswap_32 (x) +# define BE64(x) bswap_64 (x) +#endif + + +/* Examine an auxv data block and determine its format. + Return true iff we figured it out. */ +static bool +auxv_format_probe (const void *auxv, size_t size, + uint_fast8_t *elfclass, uint_fast8_t *elfdata) +{ + const union + { + char buf[size]; + Elf32_auxv_t a32[size / sizeof (Elf32_auxv_t)]; + Elf64_auxv_t a64[size / sizeof (Elf64_auxv_t)]; + } *u = auxv; + + inline bool check64 (size_t i) + { + if (u->a64[i].a_type == BE64 (PROBE_TYPE) + && u->a64[i].a_un.a_val == BE64 (PROBE_VAL64)) + { + *elfdata = ELFDATA2MSB; + return true; + } + + if (u->a64[i].a_type == LE64 (PROBE_TYPE) + && u->a64[i].a_un.a_val == LE64 (PROBE_VAL64)) + { + *elfdata = ELFDATA2LSB; + return true; + } + + return false; + } + + inline bool check32 (size_t i) + { + if (u->a32[i].a_type == BE32 (PROBE_TYPE) + && u->a32[i].a_un.a_val == BE32 (PROBE_VAL32)) + { + *elfdata = ELFDATA2MSB; + return true; + } + + if (u->a32[i].a_type == LE32 (PROBE_TYPE) + && u->a32[i].a_un.a_val == LE32 (PROBE_VAL32)) + { + *elfdata = ELFDATA2LSB; + return true; + } + + return false; + } + + for (size_t i = 0; i < size / sizeof (Elf64_auxv_t); ++i) + { + if (check64 (i)) + { + *elfclass = ELFCLASS64; + return true; + } + + if (check32 (i * 2) || check32 (i * 2 + 1)) + { + *elfclass = ELFCLASS32; + return true; + } + } + + return false; +} + +/* This is a Dwfl_Memory_Callback that wraps another memory callback. + If the underlying callback cannot fill the data, then this will + fall back to fetching data from module files. */ + +struct integrated_memory_callback +{ + Dwfl_Memory_Callback *memory_callback; + void *memory_callback_arg; + void *buffer; +}; + +static bool +integrated_memory_callback (Dwfl *dwfl, int ndx, + void **buffer, size_t *buffer_available, + GElf_Addr vaddr, + size_t minread, + void *arg) +{ + struct integrated_memory_callback *info = arg; + + if (ndx == -1) + { + /* Called for cleanup. */ + if (info->buffer != NULL) + { + /* The last probe buffer came from the underlying callback. + Let it do its cleanup. */ + assert (*buffer == info->buffer); /* XXX */ + *buffer = info->buffer; + info->buffer = NULL; + return (*info->memory_callback) (dwfl, ndx, buffer, buffer_available, + vaddr, minread, + info->memory_callback_arg); + } + *buffer = NULL; + *buffer_available = 0; + return false; + } + + if (*buffer != NULL) + /* For a final-read request, we only use the underlying callback. */ + return (*info->memory_callback) (dwfl, ndx, buffer, buffer_available, + vaddr, minread, info->memory_callback_arg); + + /* Let the underlying callback try to fill this request. */ + if ((*info->memory_callback) (dwfl, ndx, &info->buffer, buffer_available, + vaddr, minread, info->memory_callback_arg)) + { + *buffer = info->buffer; + return true; + } + + /* Now look for module text covering this address. */ + + Dwfl_Module *mod; + (void) INTUSE(dwfl_addrsegment) (dwfl, vaddr, &mod); + if (mod == NULL) + return false; + + Dwarf_Addr bias; + Elf_Scn *scn = INTUSE(dwfl_module_address_section) (mod, &vaddr, &bias); + if (unlikely (scn == NULL)) + { +#if 0 // XXX would have to handle ndx=-1 cleanup calls passed down. + /* If we have no sections we can try to fill it from the module file + based on its phdr mappings. */ + if (likely (mod->e_type != ET_REL) && mod->main.elf != NULL) + return INTUSE(dwfl_elf_phdr_memory_callback) + (dwfl, 0, buffer, buffer_available, + vaddr - mod->main.bias, minread, mod->main.elf); +#endif + return false; + } + + Elf_Data *data = elf_rawdata (scn, NULL); + if (unlikely (data == NULL)) + // XXX throw error? + return false; + + if (unlikely (data->d_size < vaddr)) + return false; + + /* Provide as much data as we have. */ + void *contents = data->d_buf + vaddr; + size_t avail = data->d_size - vaddr; + if (unlikely (avail < minread)) + return false; + + /* If probing for a string, make sure it's terminated. */ + if (minread == 0 && unlikely (memchr (contents, '\0', avail) == NULL)) + return false; + + /* We have it! */ + *buffer = contents; + *buffer_available = avail; + return true; +} + +static size_t +addrsize (uint_fast8_t elfclass) +{ + return elfclass * 4; +} + +/* Report a module for each struct link_map in the linked list at r_map + in the struct r_debug at R_DEBUG_VADDR. + + For each link_map entry, if an existing module resides at its address, + this just modifies that module's name and suggested file name. If + no such module exists, this calls dwfl_report_elf on the l_name string. + + Returns the number of modules found, or -1 for errors. */ + +static int +report_r_debug (uint_fast8_t elfclass, uint_fast8_t elfdata, + Dwfl *dwfl, GElf_Addr r_debug_vaddr, + Dwfl_Memory_Callback *memory_callback, + void *memory_callback_arg) +{ + /* Skip r_version, to aligned r_map field. */ + GElf_Addr read_vaddr = r_debug_vaddr + addrsize (elfclass); + + void *buffer = NULL; + size_t buffer_available = 0; + inline int release_buffer (int result) + { + if (buffer != NULL) + (void) (*memory_callback) (dwfl, -1, &buffer, &buffer_available, 0, 0, + memory_callback_arg); + return result; + } + + GElf_Addr addrs[4]; + inline bool read_addrs (GElf_Addr vaddr, size_t n) + { + size_t nb = n * addrsize (elfclass); /* Address words -> bytes to read. */ + + /* Read a new buffer if the old one doesn't cover these words. */ + if (buffer == NULL + || vaddr < read_vaddr + || vaddr - read_vaddr + nb > buffer_available) + { + release_buffer (0); + + read_vaddr = vaddr; + int segndx = INTUSE(dwfl_addrsegment) (dwfl, vaddr, NULL); + if (unlikely (segndx < 0) + || unlikely (! (*memory_callback) (dwfl, segndx, + &buffer, &buffer_available, + vaddr, nb, memory_callback_arg))) + return true; + } + + const union + { + Elf32_Addr a32[n]; + Elf64_Addr a64[n]; + } *in = vaddr - read_vaddr + buffer; + + if (elfclass == ELFCLASS32) + { + if (elfdata == ELFDATA2MSB) + for (size_t i = 0; i < n; ++i) + addrs[i] = BE32 (in->a32[i]); + else + for (size_t i = 0; i < n; ++i) + addrs[i] = LE32 (in->a32[i]); + } + else + { + if (elfdata == ELFDATA2MSB) + for (size_t i = 0; i < n; ++i) + addrs[i] = BE64 (in->a64[i]); + else + for (size_t i = 0; i < n; ++i) + addrs[i] = LE64 (in->a64[i]); + } + + return false; + } + + if (unlikely (read_addrs (read_vaddr, 1))) + return release_buffer (-1); + + GElf_Addr next = addrs[0]; + + Dwfl_Module **lastmodp = &dwfl->modulelist; + int result = 0; + + /* There can't be more elements in the link_map list than there are + segments. DWFL->lookup_elts is probably twice that number, so it + is certainly above the upper bound. If we iterate too many times, + there must be a loop in the pointers due to link_map clobberation. */ + size_t iterations = 0; + while (next != 0 && ++iterations < dwfl->lookup_elts) + { + if (read_addrs (next, 4)) + return release_buffer (-1); + + GElf_Addr l_addr = addrs[0]; + GElf_Addr l_name = addrs[1]; + GElf_Addr l_ld = addrs[2]; + next = addrs[3]; + + /* If a clobbered or truncated memory image has no useful pointer, + just skip this element. */ + if (l_ld == 0) + continue; + + /* Fetch the string at the l_name address. */ + const char *name = NULL; + if (buffer != NULL + && read_vaddr <= l_name + && l_name + 1 - read_vaddr < buffer_available + && memchr (l_name - read_vaddr + buffer, '\0', + buffer_available - (l_name - read_vaddr)) != NULL) + name = l_name - read_vaddr + buffer; + else + { + release_buffer (0); + read_vaddr = l_name; + int segndx = INTUSE(dwfl_addrsegment) (dwfl, l_name, NULL); + if (likely (segndx >= 0) + && (*memory_callback) (dwfl, segndx, + &buffer, &buffer_available, + l_name, 0, memory_callback_arg)) + name = buffer; + } + + if (name != NULL && name[0] == '\0') + name = NULL; + + /* If content-sniffing already reported a module covering + the same area, find that existing module to adjust. + The l_ld address is the only one we know for sure + to be within the module's own segments (its .dynamic). */ + Dwfl_Module *mod = INTUSE(dwfl_addrmodule) (dwfl, l_ld); + if (mod != NULL) + { + /* We have a module. We can give it a better name from l_name. */ + if (name != NULL && mod->name[0] == '[') + { + char *newname = strdup (basename (name)); + if (newname != NULL) + { + free (mod->name); + mod->name = newname; + } + } + + if (name == NULL && mod->name[0] == '/') + name = mod->name; + + /* If we don't have a file for it already, we can pre-install + the full file name from l_name. Opening the file by this + name will be the fallback when no build ID match is found. + XXX hook for sysroot */ + if (name != NULL && mod->main.name == NULL) + mod->main.name = strdup (name); + } + else if (name != NULL) + { + /* We have to find the file's phdrs to compute along with l_addr + what its runtime address boundaries are. */ + + // XXX hook for sysroot + mod = INTUSE(dwfl_report_elf) (dwfl, basename (name), + name, -1, l_addr); + } + + if (mod != NULL) + { + ++result; + + /* Move this module to the end of the list, so that we end + up with a list in the same order as the link_map chain. */ + if (mod->next != NULL) + { + if (*lastmodp != mod) + { + lastmodp = &dwfl->modulelist; + while (*lastmodp != mod) + lastmodp = &(*lastmodp)->next; + } + *lastmodp = mod->next; + mod->next = NULL; + while (*lastmodp != NULL) + lastmodp = &(*lastmodp)->next; + *lastmodp = mod; + } + + lastmodp = &mod->next; + } + } + + return release_buffer (result); +} + +static GElf_Addr +consider_executable (Dwfl_Module *mod, GElf_Addr at_phdr, GElf_Addr at_entry, + uint_fast8_t *elfclass, uint_fast8_t *elfdata, + Dwfl_Memory_Callback *memory_callback, + void *memory_callback_arg) +{ + GElf_Ehdr ehdr; + if (unlikely (gelf_getehdr (mod->main.elf, &ehdr) == NULL)) + return 0; + + if (at_entry != 0) + { + /* If we have an AT_ENTRY value, reject this executable if + its entry point address could not have supplied that. */ + + if (ehdr.e_entry == 0) + return 0; + + if (mod->e_type == ET_EXEC) + { + if (ehdr.e_entry != at_entry) + return 0; + } + else + { + /* It could be a PIE. */ + } + } + + // XXX this could be saved in the file cache: phdr vaddr, DT_DEBUG d_val vaddr + /* Find the vaddr of the DT_DEBUG's d_ptr. This is the memory + address where &r_debug was written at runtime. */ + GElf_Xword align = mod->dwfl->segment_align; + GElf_Addr d_val_vaddr = 0; + for (uint_fast16_t i = 0; i < ehdr.e_phnum; ++i) + { + GElf_Phdr phdr_mem; + GElf_Phdr *phdr = gelf_getphdr (mod->main.elf, i, &phdr_mem); + if (phdr == NULL) + break; + + if (phdr->p_align > 1 && (align == 0 || phdr->p_align < align)) + align = phdr->p_align; + + if (at_phdr != 0 + && phdr->p_type == PT_LOAD + && (phdr->p_offset & -align) == (ehdr.e_phoff & -align)) + { + /* This is the segment that would map the phdrs. + If we have an AT_PHDR value, reject this executable + if its phdr mapping could not have supplied that. */ + if (mod->e_type == ET_EXEC) + { + if (ehdr.e_phoff - phdr->p_offset + phdr->p_vaddr != at_phdr) + return 0; + } + else + { + /* It could be a PIE. If the AT_PHDR value and our + phdr address don't match modulo ALIGN, then this + could not have been the right PIE. */ + if (((ehdr.e_phoff - phdr->p_offset + phdr->p_vaddr) & -align) + != (at_phdr & -align)) + return 0; + + /* Calculate the bias applied to the PIE's p_vaddr values. */ + GElf_Addr bias = (at_phdr - (ehdr.e_phoff - phdr->p_offset + + phdr->p_vaddr)); + + /* Final sanity check: if we have an AT_ENTRY value, + reject this PIE unless its biased e_entry matches. */ + if (at_entry != 0 && at_entry != ehdr.e_entry + bias) + return 0; + + /* If we're changing the module's address range, + we've just invalidated the module lookup table. */ + GElf_Addr mod_bias = dwfl_adjusted_address (mod, 0); + if (bias != mod_bias) + { + mod->low_addr -= mod_bias; + mod->high_addr -= mod_bias; + mod->low_addr += bias; + mod->high_addr += bias; + + free (mod->dwfl->lookup_module); + mod->dwfl->lookup_module = NULL; + } + } + } + + if (phdr->p_type == PT_DYNAMIC) + { + Elf_Data *data = elf_getdata_rawchunk (mod->main.elf, phdr->p_offset, + phdr->p_filesz, ELF_T_DYN); + if (data == NULL) + continue; + const size_t entsize = gelf_fsize (mod->main.elf, + ELF_T_DYN, 1, EV_CURRENT); + const size_t n = data->d_size / entsize; + for (size_t j = 0; j < n; ++j) + { + GElf_Dyn dyn_mem; + GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem); + if (dyn != NULL && dyn->d_tag == DT_DEBUG) + { + d_val_vaddr = phdr->p_vaddr + entsize * j + entsize / 2; + break; + } + } + } + } + + if (d_val_vaddr != 0) + { + /* Now we have the final address from which to read &r_debug. */ + d_val_vaddr = dwfl_adjusted_address (mod, d_val_vaddr); + + void *buffer = NULL; + size_t buffer_available = addrsize (ehdr.e_ident[EI_CLASS]); + + int segndx = INTUSE(dwfl_addrsegment) (mod->dwfl, d_val_vaddr, NULL); + + if ((*memory_callback) (mod->dwfl, segndx, + &buffer, &buffer_available, + d_val_vaddr, buffer_available, + memory_callback_arg)) + { + const union + { + Elf32_Addr a32; + Elf64_Addr a64; + } *u = buffer; + + GElf_Addr vaddr; + if (ehdr.e_ident[EI_CLASS] == ELFCLASS32) + vaddr = (ehdr.e_ident[EI_DATA] == ELFDATA2MSB + ? BE32 (u->a32) : LE32 (u->a32)); + else + vaddr = (ehdr.e_ident[EI_DATA] == ELFDATA2MSB + ? BE64 (u->a64) : LE64 (u->a64)); + + (*memory_callback) (mod->dwfl, -1, &buffer, &buffer_available, 0, 0, + memory_callback_arg); + + if (*elfclass == ELFCLASSNONE) + *elfclass = ehdr.e_ident[EI_CLASS]; + else if (*elfclass != ehdr.e_ident[EI_CLASS]) + return 0; + + if (*elfdata == ELFDATANONE) + *elfdata = ehdr.e_ident[EI_DATA]; + else if (*elfdata != ehdr.e_ident[EI_DATA]) + return 0; + + return vaddr; + } + } + + return 0; +} + +/* Try to find an existing executable module with a DT_DEBUG. */ +static GElf_Addr +find_executable (Dwfl *dwfl, GElf_Addr at_phdr, GElf_Addr at_entry, + uint_fast8_t *elfclass, uint_fast8_t *elfdata, + Dwfl_Memory_Callback *memory_callback, + void *memory_callback_arg) +{ + for (Dwfl_Module *mod = dwfl->modulelist; mod != NULL; mod = mod->next) + if (mod->main.elf != NULL) + { + GElf_Addr r_debug_vaddr = consider_executable (mod, at_phdr, at_entry, + elfclass, elfdata, + memory_callback, + memory_callback_arg); + if (r_debug_vaddr != 0) + return r_debug_vaddr; + } + + return 0; +} + + +int +dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size, + Dwfl_Memory_Callback *memory_callback, + void *memory_callback_arg) +{ + GElf_Addr r_debug_vaddr = 0; + + uint_fast8_t elfclass = ELFCLASSNONE; + uint_fast8_t elfdata = ELFDATANONE; + if (likely (auxv != NULL) + && likely (auxv_format_probe (auxv, auxv_size, &elfclass, &elfdata))) + { + GElf_Addr entry = 0; + GElf_Addr phdr = 0; + GElf_Xword phent = 0; + GElf_Xword phnum = 0; + +#define AUXV_SCAN(NN, BL) do \ + { \ + const Elf##NN##_auxv_t *av = auxv; \ + for (size_t i = 0; i < auxv_size / sizeof av[0]; ++i) \ + { \ + Elf##NN##_Addr val = BL##NN (av[i].a_un.a_val); \ + if (av[i].a_type == BL##NN (AT_ENTRY)) \ + entry = val; \ + else if (av[i].a_type == BL##NN (AT_PHDR)) \ + phdr = val; \ + else if (av[i].a_type == BL##NN (AT_PHNUM)) \ + phnum = val; \ + else if (av[i].a_type == BL##NN (AT_PHENT)) \ + phent = val; \ + else if (av[i].a_type == BL##NN (AT_PAGESZ)) \ + { \ + if (val > 1 \ + && (dwfl->segment_align == 0 \ + || val < dwfl->segment_align)) \ + dwfl->segment_align = val; \ + } \ + } \ + } \ + while (0) + + if (elfclass == ELFCLASS32) + { + if (elfdata == ELFDATA2MSB) + AUXV_SCAN (32, BE); + else + AUXV_SCAN (32, LE); + } + else + { + if (elfdata == ELFDATA2MSB) + AUXV_SCAN (64, BE); + else + AUXV_SCAN (64, LE); + } + + /* If we found the phdr dimensions, search phdrs for PT_DYNAMIC. */ + GElf_Addr dyn_vaddr = 0; + GElf_Xword dyn_filesz = 0; + GElf_Addr dyn_bias = (GElf_Addr) -1; + + inline bool consider_phdr (GElf_Word type, + GElf_Addr vaddr, GElf_Xword filesz) + { + switch (type) + { + case PT_PHDR: + if (dyn_bias == (GElf_Addr) -1 + /* Do a sanity check on the putative address. */ + && ((vaddr & (dwfl->segment_align - 1)) + == (phdr & (dwfl->segment_align - 1)))) + { + dyn_bias = phdr - vaddr; + return dyn_vaddr != 0; + } + break; + + case PT_DYNAMIC: + dyn_vaddr = vaddr; + dyn_filesz = filesz; + return dyn_bias != (GElf_Addr) -1; + } + + return false; + } + + if (phdr != 0 && phnum != 0) + { + Dwfl_Module *phdr_mod; + int phdr_segndx = INTUSE(dwfl_addrsegment) (dwfl, phdr, &phdr_mod); + Elf_Data in = + { + .d_type = ELF_T_PHDR, + .d_version = EV_CURRENT, + .d_size = phnum * phent, + .d_buf = NULL + }; + if ((*memory_callback) (dwfl, phdr_segndx, &in.d_buf, &in.d_size, + phdr, phnum * phent, memory_callback_arg)) + { + union + { + Elf32_Phdr p32; + Elf64_Phdr p64; + char data[phnum * phent]; + } buf; + Elf_Data out = + { + .d_type = ELF_T_PHDR, + .d_version = EV_CURRENT, + .d_size = phnum * phent, + .d_buf = &buf + }; + in.d_size = out.d_size; + if (likely ((elfclass == ELFCLASS32 + ? elf32_xlatetom : elf64_xlatetom) + (&out, &in, elfdata) != NULL)) + { + /* We are looking for PT_DYNAMIC. */ + const union + { + Elf32_Phdr p32[phnum]; + Elf64_Phdr p64[phnum]; + } *u = (void *) &buf; + if (elfclass == ELFCLASS32) + { + for (size_t i = 0; i < phnum; ++i) + if (consider_phdr (u->p32[i].p_type, + u->p32[i].p_vaddr, + u->p32[i].p_filesz)) + break; + } + else + { + for (size_t i = 0; i < phnum; ++i) + if (consider_phdr (u->p64[i].p_type, + u->p64[i].p_vaddr, + u->p64[i].p_filesz)) + break; + } + } + + (*memory_callback) (dwfl, -1, &in.d_buf, &in.d_size, 0, 0, + memory_callback_arg); + } + else + /* We could not read the executable's phdrs from the + memory image. If we have a presupplied executable, + we can still use the AT_PHDR and AT_ENTRY values to + verify it, and to adjust its bias if it's a PIE. + + If there was an ET_EXEC module presupplied that contains + the AT_PHDR address, then we only consider that one. + We'll either accept it if its phdr location and e_entry + make sense or reject it if they don't. If there is no + presupplied ET_EXEC, then look for a presupplied module, + which might be a PIE (ET_DYN) that needs its bias adjusted. */ + r_debug_vaddr = ((phdr_mod == NULL + || phdr_mod->main.elf == NULL + || phdr_mod->e_type != ET_EXEC) + ? find_executable (dwfl, phdr, entry, + &elfclass, &elfdata, + memory_callback, + memory_callback_arg) + : consider_executable (phdr_mod, phdr, entry, + &elfclass, &elfdata, + memory_callback, + memory_callback_arg)); + } + + /* If we found PT_DYNAMIC, search it for DT_DEBUG. */ + if (dyn_filesz != 0) + { + if (dyn_bias != (GElf_Addr) -1) + dyn_vaddr += dyn_bias; + + Elf_Data in = + { + .d_type = ELF_T_DYN, + .d_version = EV_CURRENT, + .d_size = dyn_filesz, + .d_buf = NULL + }; + int dyn_segndx = dwfl_addrsegment (dwfl, dyn_vaddr, NULL); + if ((*memory_callback) (dwfl, dyn_segndx, &in.d_buf, &in.d_size, + dyn_vaddr, dyn_filesz, memory_callback_arg)) + { + union + { + Elf32_Dyn d32; + Elf64_Dyn d64; + char data[dyn_filesz]; + } buf; + Elf_Data out = + { + .d_type = ELF_T_DYN, + .d_version = EV_CURRENT, + .d_size = dyn_filesz, + .d_buf = &buf + }; + in.d_size = out.d_size; + if (likely ((elfclass == ELFCLASS32 + ? elf32_xlatetom : elf64_xlatetom) + (&out, &in, elfdata) != NULL)) + { + /* We are looking for DT_DEBUG. */ + const union + { + Elf32_Dyn d32[dyn_filesz / sizeof (Elf32_Dyn)]; + Elf64_Dyn d64[dyn_filesz / sizeof (Elf64_Dyn)]; + } *u = (void *) &buf; + if (elfclass == ELFCLASS32) + { + size_t n = dyn_filesz / sizeof (Elf32_Dyn); + for (size_t i = 0; i < n; ++i) + if (u->d32[i].d_tag == DT_DEBUG) + { + r_debug_vaddr = u->d32[i].d_un.d_val; + break; + } + } + else + { + size_t n = dyn_filesz / sizeof (Elf64_Dyn); + for (size_t i = 0; i < n; ++i) + if (u->d64[i].d_tag == DT_DEBUG) + { + r_debug_vaddr = u->d64[i].d_un.d_val; + break; + } + } + } + + (*memory_callback) (dwfl, -1, &in.d_buf, &in.d_size, 0, 0, + memory_callback_arg); + } + } + } + else + /* We have to look for a presupplied executable file to determine + the vaddr of its dynamic section and DT_DEBUG therein. */ + r_debug_vaddr = find_executable (dwfl, 0, 0, &elfclass, &elfdata, + memory_callback, memory_callback_arg); + + if (r_debug_vaddr == 0) + return 0; + + /* For following pointers from struct link_map, we will use an + integrated memory access callback that can consult module text + elided from the core file. This is necessary when the l_name + pointer for the dynamic linker's own entry is a pointer into the + executable's .interp section. */ + struct integrated_memory_callback mcb = + { + .memory_callback = memory_callback, + .memory_callback_arg = memory_callback_arg + }; + + /* Now we can follow the dynamic linker's library list. */ + return report_r_debug (elfclass, elfdata, dwfl, r_debug_vaddr, + &integrated_memory_callback, &mcb); +} +INTDEF (dwfl_link_map_report) |