| /* Handle SVR4 shared libraries for GDB, the GNU Debugger. |
| |
| Copyright (C) 1990-2024 Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program 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; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| |
| #include "elf/external.h" |
| #include "elf/common.h" |
| #include "elf/mips.h" |
| |
| #include "exceptions.h" |
| #include "extract-store-integer.h" |
| #include "symtab.h" |
| #include "bfd.h" |
| #include "symfile.h" |
| #include "objfiles.h" |
| #include "gdbcore.h" |
| #include "target.h" |
| #include "inferior.h" |
| #include "infrun.h" |
| #include "regcache.h" |
| #include "observable.h" |
| |
| #include "solist.h" |
| #include "solib.h" |
| #include "solib-svr4.h" |
| |
| #include "bfd-target.h" |
| #include "elf-bfd.h" |
| #include "exec.h" |
| #include "auxv.h" |
| #include "gdb_bfd.h" |
| #include "probe.h" |
| |
| #include <map> |
| |
| static struct link_map_offsets *svr4_fetch_link_map_offsets (void); |
| static int svr4_have_link_map_offsets (void); |
| static void svr4_relocate_main_executable (void); |
| static void probes_table_remove_objfile_probes (struct objfile *objfile); |
| static void svr4_iterate_over_objfiles_in_search_order |
| (gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype cb, |
| objfile *current_objfile); |
| |
| |
| /* On SVR4 systems, a list of symbols in the dynamic linker where |
| GDB can try to place a breakpoint to monitor shared library |
| events. |
| |
| If none of these symbols are found, or other errors occur, then |
| SVR4 systems will fall back to using a symbol as the "startup |
| mapping complete" breakpoint address. */ |
| |
| static const char * const solib_break_names[] = |
| { |
| "r_debug_state", |
| "_r_debug_state", |
| "_dl_debug_state", |
| "rtld_db_dlactivity", |
| "__dl_rtld_db_dlactivity", |
| "_rtld_debug_state", |
| |
| NULL |
| }; |
| |
| static const char * const bkpt_names[] = |
| { |
| "_start", |
| "__start", |
| "main", |
| NULL |
| }; |
| |
| static const char * const main_name_list[] = |
| { |
| "main_$main", |
| NULL |
| }; |
| |
| /* What to do when a probe stop occurs. */ |
| |
| enum probe_action |
| { |
| /* Something went seriously wrong. Stop using probes and |
| revert to using the older interface. */ |
| PROBES_INTERFACE_FAILED, |
| |
| /* No action is required. The shared object list is still |
| valid. */ |
| DO_NOTHING, |
| |
| /* The shared object list should be reloaded entirely. */ |
| FULL_RELOAD, |
| |
| /* Attempt to incrementally update the shared object list. If |
| the update fails or is not possible, fall back to reloading |
| the list in full. */ |
| UPDATE_OR_RELOAD, |
| }; |
| |
| /* A probe's name and its associated action. */ |
| |
| struct probe_info |
| { |
| /* The name of the probe. */ |
| const char *name; |
| |
| /* What to do when a probe stop occurs. */ |
| enum probe_action action; |
| }; |
| |
| /* A list of named probes and their associated actions. If all |
| probes are present in the dynamic linker then the probes-based |
| interface will be used. */ |
| |
| static const struct probe_info probe_info[] = |
| { |
| { "init_start", DO_NOTHING }, |
| { "init_complete", FULL_RELOAD }, |
| { "map_start", DO_NOTHING }, |
| { "map_failed", DO_NOTHING }, |
| { "reloc_complete", UPDATE_OR_RELOAD }, |
| { "unmap_start", DO_NOTHING }, |
| { "unmap_complete", FULL_RELOAD }, |
| }; |
| |
| #define NUM_PROBES ARRAY_SIZE (probe_info) |
| |
| /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent |
| the same shared library. */ |
| |
| static int |
| svr4_same_1 (const char *gdb_so_name, const char *inferior_so_name) |
| { |
| if (strcmp (gdb_so_name, inferior_so_name) == 0) |
| return 1; |
| |
| /* On Solaris, when starting inferior we think that dynamic linker is |
| /usr/lib/ld.so.1, but later on, the table of loaded shared libraries |
| contains /lib/ld.so.1. Sometimes one file is a link to another, but |
| sometimes they have identical content, but are not linked to each |
| other. We don't restrict this check for Solaris, but the chances |
| of running into this situation elsewhere are very low. */ |
| if (strcmp (gdb_so_name, "/usr/lib/ld.so.1") == 0 |
| && strcmp (inferior_so_name, "/lib/ld.so.1") == 0) |
| return 1; |
| |
| /* Similarly, we observed the same issue with amd64 and sparcv9, but with |
| different locations. */ |
| if (strcmp (gdb_so_name, "/usr/lib/amd64/ld.so.1") == 0 |
| && strcmp (inferior_so_name, "/lib/amd64/ld.so.1") == 0) |
| return 1; |
| |
| if (strcmp (gdb_so_name, "/usr/lib/sparcv9/ld.so.1") == 0 |
| && strcmp (inferior_so_name, "/lib/sparcv9/ld.so.1") == 0) |
| return 1; |
| |
| return 0; |
| } |
| |
| static bool |
| svr4_same (const char *gdb_name, const char *inferior_name, |
| const lm_info_svr4 &gdb_lm_info, |
| const lm_info_svr4 &inferior_lm_info) |
| { |
| if (!svr4_same_1 (gdb_name, inferior_name)) |
| return false; |
| |
| /* There may be different instances of the same library, in different |
| namespaces. Each instance, however, must have been loaded at a |
| different address so its relocation offset would be different. */ |
| return gdb_lm_info.l_addr_inferior == inferior_lm_info.l_addr_inferior; |
| } |
| |
| static int |
| svr4_same (const solib &gdb, const solib &inferior) |
| { |
| auto *lmg |
| = gdb::checked_static_cast<const lm_info_svr4 *> (gdb.lm_info.get ()); |
| auto *lmi |
| = gdb::checked_static_cast<const lm_info_svr4 *> (inferior.lm_info.get ()); |
| |
| return svr4_same (gdb.so_original_name.c_str (), |
| inferior.so_original_name.c_str (), *lmg, *lmi); |
| } |
| |
| static lm_info_svr4_up |
| lm_info_read (CORE_ADDR lm_addr) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| lm_info_svr4_up lm_info; |
| |
| gdb::byte_vector lm (lmo->link_map_size); |
| |
| if (target_read_memory (lm_addr, lm.data (), lmo->link_map_size) != 0) |
| warning (_("Error reading shared library list entry at %s"), |
| paddress (current_inferior ()->arch (), lm_addr)); |
| else |
| { |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| |
| lm_info = std::make_unique<lm_info_svr4> (); |
| lm_info->lm_addr = lm_addr; |
| |
| lm_info->l_addr_inferior = extract_typed_address (&lm[lmo->l_addr_offset], |
| ptr_type); |
| lm_info->l_ld = extract_typed_address (&lm[lmo->l_ld_offset], ptr_type); |
| lm_info->l_next = extract_typed_address (&lm[lmo->l_next_offset], |
| ptr_type); |
| lm_info->l_prev = extract_typed_address (&lm[lmo->l_prev_offset], |
| ptr_type); |
| lm_info->l_name = extract_typed_address (&lm[lmo->l_name_offset], |
| ptr_type); |
| } |
| |
| return lm_info; |
| } |
| |
| static int |
| has_lm_dynamic_from_link_map (void) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return lmo->l_ld_offset >= 0; |
| } |
| |
| static CORE_ADDR |
| lm_addr_check (const solib &so, bfd *abfd) |
| { |
| auto *li = gdb::checked_static_cast<lm_info_svr4 *> (so.lm_info.get ()); |
| |
| if (!li->l_addr_p) |
| { |
| struct bfd_section *dyninfo_sect; |
| CORE_ADDR l_addr, l_dynaddr, dynaddr; |
| |
| l_addr = li->l_addr_inferior; |
| |
| if (! abfd || ! has_lm_dynamic_from_link_map ()) |
| goto set_addr; |
| |
| l_dynaddr = li->l_ld; |
| |
| dyninfo_sect = bfd_get_section_by_name (abfd, ".dynamic"); |
| if (dyninfo_sect == NULL) |
| goto set_addr; |
| |
| dynaddr = bfd_section_vma (dyninfo_sect); |
| |
| if (dynaddr + l_addr != l_dynaddr) |
| { |
| CORE_ADDR align = 0x1000; |
| CORE_ADDR minpagesize = align; |
| |
| if (bfd_get_flavour (abfd) == bfd_target_elf_flavour) |
| { |
| Elf_Internal_Ehdr *ehdr = elf_tdata (abfd)->elf_header; |
| Elf_Internal_Phdr *phdr = elf_tdata (abfd)->phdr; |
| int i; |
| |
| align = 1; |
| |
| for (i = 0; i < ehdr->e_phnum; i++) |
| if (phdr[i].p_type == PT_LOAD && phdr[i].p_align > align) |
| align = phdr[i].p_align; |
| |
| minpagesize = get_elf_backend_data (abfd)->minpagesize; |
| } |
| |
| /* Turn it into a mask. */ |
| align--; |
| |
| /* If the changes match the alignment requirements, we |
| assume we're using a core file that was generated by the |
| same binary, just prelinked with a different base offset. |
| If it doesn't match, we may have a different binary, the |
| same binary with the dynamic table loaded at an unrelated |
| location, or anything, really. To avoid regressions, |
| don't adjust the base offset in the latter case, although |
| odds are that, if things really changed, debugging won't |
| quite work. |
| |
| One could expect more the condition |
| ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0) |
| but the one below is relaxed for PPC. The PPC kernel supports |
| either 4k or 64k page sizes. To be prepared for 64k pages, |
| PPC ELF files are built using an alignment requirement of 64k. |
| However, when running on a kernel supporting 4k pages, the memory |
| mapping of the library may not actually happen on a 64k boundary! |
| |
| (In the usual case where (l_addr & align) == 0, this check is |
| equivalent to the possibly expected check above.) |
| |
| Even on PPC it must be zero-aligned at least for MINPAGESIZE. */ |
| |
| l_addr = l_dynaddr - dynaddr; |
| |
| if ((l_addr & (minpagesize - 1)) == 0 |
| && (l_addr & align) == ((l_dynaddr - dynaddr) & align)) |
| { |
| if (info_verbose) |
| gdb_printf (_("Using PIC (Position Independent Code) " |
| "prelink displacement %s for \"%s\".\n"), |
| paddress (current_inferior ()->arch (), l_addr), |
| so.so_name.c_str ()); |
| } |
| else |
| { |
| /* There is no way to verify the library file matches. prelink |
| can during prelinking of an unprelinked file (or unprelinking |
| of a prelinked file) shift the DYNAMIC segment by arbitrary |
| offset without any page size alignment. There is no way to |
| find out the ELF header and/or Program Headers for a limited |
| verification if it they match. One could do a verification |
| of the DYNAMIC segment. Still the found address is the best |
| one GDB could find. */ |
| |
| warning (_(".dynamic section for \"%s\" " |
| "is not at the expected address " |
| "(wrong library or version mismatch?)"), |
| so.so_name.c_str ()); |
| } |
| } |
| |
| set_addr: |
| li->l_addr = l_addr; |
| li->l_addr_p = 1; |
| } |
| |
| return li->l_addr; |
| } |
| |
| struct svr4_so |
| { |
| svr4_so (const char *name, lm_info_svr4_up lm_info) |
| : name (name), lm_info (std::move (lm_info)) |
| {} |
| |
| std::string name; |
| lm_info_svr4_up lm_info; |
| }; |
| |
| /* Per pspace SVR4 specific data. */ |
| |
| struct svr4_info |
| { |
| /* Base of dynamic linker structures in default namespace. */ |
| CORE_ADDR debug_base = 0; |
| |
| /* Validity flag for debug_loader_offset. */ |
| int debug_loader_offset_p = 0; |
| |
| /* Load address for the dynamic linker, inferred. */ |
| CORE_ADDR debug_loader_offset = 0; |
| |
| /* Name of the dynamic linker, valid if debug_loader_offset_p. */ |
| char *debug_loader_name = nullptr; |
| |
| /* Load map address for the main executable in default namespace. */ |
| CORE_ADDR main_lm_addr = 0; |
| |
| CORE_ADDR interp_text_sect_low = 0; |
| CORE_ADDR interp_text_sect_high = 0; |
| CORE_ADDR interp_plt_sect_low = 0; |
| CORE_ADDR interp_plt_sect_high = 0; |
| |
| /* True if the list of objects was last obtained from the target |
| via qXfer:libraries-svr4:read. */ |
| bool using_xfer = false; |
| |
| /* Table of struct probe_and_action instances, used by the |
| probes-based interface to map breakpoint addresses to probes |
| and their associated actions. Lookup is performed using |
| probe_and_action->prob->address. */ |
| htab_up probes_table; |
| |
| /* List of objects loaded into the inferior per namespace, used by the |
| probes-based interface. |
| |
| The namespace is represented by the address of its corresponding |
| r_debug[_ext] object. We get the namespace id as argument to the |
| 'reloc_complete' probe but we don't get it when scanning the load map |
| on attach. |
| |
| The r_debug[_ext] objects may move when ld.so itself moves. In that |
| case, we expect also the global _r_debug to move so we can detect |
| this and reload everything. The r_debug[_ext] objects are not |
| expected to move individually. |
| |
| The special entry zero is reserved for a linear list to support |
| gdbstubs that do not support namespaces. */ |
| std::map<CORE_ADDR, std::vector<svr4_so>> solib_lists; |
| }; |
| |
| /* Per-program-space data key. */ |
| static const registry<program_space>::key<svr4_info> solib_svr4_pspace_data; |
| |
| /* Return whether DEBUG_BASE is the default namespace of INFO. */ |
| |
| static bool |
| svr4_is_default_namespace (const svr4_info *info, CORE_ADDR debug_base) |
| { |
| return (debug_base == info->debug_base); |
| } |
| |
| /* Free the probes table. */ |
| |
| static void |
| free_probes_table (struct svr4_info *info) |
| { |
| info->probes_table.reset (nullptr); |
| } |
| |
| /* Get the svr4 data for program space PSPACE. If none is found yet, add it now. |
| This function always returns a valid object. */ |
| |
| static struct svr4_info * |
| get_svr4_info (program_space *pspace) |
| { |
| struct svr4_info *info = solib_svr4_pspace_data.get (pspace); |
| |
| if (info == NULL) |
| info = solib_svr4_pspace_data.emplace (pspace); |
| |
| return info; |
| } |
| |
| /* Local function prototypes */ |
| |
| static int match_main (const char *); |
| |
| /* Read program header TYPE from inferior memory. The header is found |
| by scanning the OS auxiliary vector. |
| |
| If TYPE == -1, return the program headers instead of the contents of |
| one program header. |
| |
| Return vector of bytes holding the program header contents, or an empty |
| optional on failure. If successful and P_ARCH_SIZE is non-NULL, the target |
| architecture size (32-bit or 64-bit) is returned to *P_ARCH_SIZE. Likewise, |
| the base address of the section is returned in *BASE_ADDR. */ |
| |
| static std::optional<gdb::byte_vector> |
| read_program_header (int type, int *p_arch_size, CORE_ADDR *base_addr) |
| { |
| bfd_endian byte_order = gdbarch_byte_order (current_inferior ()->arch ()); |
| CORE_ADDR at_phdr, at_phent, at_phnum, pt_phdr = 0; |
| int arch_size, sect_size; |
| CORE_ADDR sect_addr; |
| int pt_phdr_p = 0; |
| |
| /* Get required auxv elements from target. */ |
| if (target_auxv_search (AT_PHDR, &at_phdr) <= 0) |
| return {}; |
| if (target_auxv_search (AT_PHENT, &at_phent) <= 0) |
| return {}; |
| if (target_auxv_search (AT_PHNUM, &at_phnum) <= 0) |
| return {}; |
| if (!at_phdr || !at_phnum) |
| return {}; |
| |
| /* Determine ELF architecture type. */ |
| if (at_phent == sizeof (Elf32_External_Phdr)) |
| arch_size = 32; |
| else if (at_phent == sizeof (Elf64_External_Phdr)) |
| arch_size = 64; |
| else |
| return {}; |
| |
| /* Find the requested segment. */ |
| if (type == -1) |
| { |
| sect_addr = at_phdr; |
| sect_size = at_phent * at_phnum; |
| } |
| else if (arch_size == 32) |
| { |
| Elf32_External_Phdr phdr; |
| int i; |
| |
| /* Search for requested PHDR. */ |
| for (i = 0; i < at_phnum; i++) |
| { |
| int p_type; |
| |
| if (target_read_memory (at_phdr + i * sizeof (phdr), |
| (gdb_byte *)&phdr, sizeof (phdr))) |
| return {}; |
| |
| p_type = extract_unsigned_integer ((gdb_byte *) phdr.p_type, |
| 4, byte_order); |
| |
| if (p_type == PT_PHDR) |
| { |
| pt_phdr_p = 1; |
| pt_phdr = extract_unsigned_integer ((gdb_byte *) phdr.p_vaddr, |
| 4, byte_order); |
| } |
| |
| if (p_type == type) |
| break; |
| } |
| |
| if (i == at_phnum) |
| return {}; |
| |
| /* Retrieve address and size. */ |
| sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr, |
| 4, byte_order); |
| sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz, |
| 4, byte_order); |
| } |
| else |
| { |
| Elf64_External_Phdr phdr; |
| int i; |
| |
| /* Search for requested PHDR. */ |
| for (i = 0; i < at_phnum; i++) |
| { |
| int p_type; |
| |
| if (target_read_memory (at_phdr + i * sizeof (phdr), |
| (gdb_byte *)&phdr, sizeof (phdr))) |
| return {}; |
| |
| p_type = extract_unsigned_integer ((gdb_byte *) phdr.p_type, |
| 4, byte_order); |
| |
| if (p_type == PT_PHDR) |
| { |
| pt_phdr_p = 1; |
| pt_phdr = extract_unsigned_integer ((gdb_byte *) phdr.p_vaddr, |
| 8, byte_order); |
| } |
| |
| if (p_type == type) |
| break; |
| } |
| |
| if (i == at_phnum) |
| return {}; |
| |
| /* Retrieve address and size. */ |
| sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr, |
| 8, byte_order); |
| sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz, |
| 8, byte_order); |
| } |
| |
| /* PT_PHDR is optional, but we really need it |
| for PIE to make this work in general. */ |
| |
| if (pt_phdr_p) |
| { |
| /* at_phdr is real address in memory. pt_phdr is what pheader says it is. |
| Relocation offset is the difference between the two. */ |
| sect_addr = sect_addr + (at_phdr - pt_phdr); |
| } |
| |
| /* Read in requested program header. */ |
| gdb::byte_vector buf (sect_size); |
| if (target_read_memory (sect_addr, buf.data (), sect_size)) |
| return {}; |
| |
| if (p_arch_size) |
| *p_arch_size = arch_size; |
| if (base_addr) |
| *base_addr = sect_addr; |
| |
| return buf; |
| } |
| |
| |
| /* Return program interpreter string. */ |
| static std::optional<gdb::byte_vector> |
| find_program_interpreter (void) |
| { |
| /* If we have a current exec_bfd, use its section table. */ |
| if (current_program_space->exec_bfd () |
| && (bfd_get_flavour (current_program_space->exec_bfd ()) |
| == bfd_target_elf_flavour)) |
| { |
| struct bfd_section *interp_sect; |
| |
| interp_sect = bfd_get_section_by_name (current_program_space->exec_bfd (), |
| ".interp"); |
| if (interp_sect != NULL) |
| { |
| int sect_size = bfd_section_size (interp_sect); |
| |
| gdb::byte_vector buf (sect_size); |
| bool res |
| = bfd_get_section_contents (current_program_space->exec_bfd (), |
| interp_sect, buf.data (), 0, sect_size); |
| if (res) |
| return buf; |
| } |
| } |
| |
| /* If we didn't find it, use the target auxiliary vector. */ |
| return read_program_header (PT_INTERP, NULL, NULL); |
| } |
| |
| |
| /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable, |
| found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1 |
| is returned and the corresponding PTR is set. */ |
| |
| static int |
| scan_dyntag_auxv (const int desired_dyntag, CORE_ADDR *ptr, |
| CORE_ADDR *ptr_addr) |
| { |
| bfd_endian byte_order = gdbarch_byte_order (current_inferior ()->arch ()); |
| int arch_size, step; |
| long current_dyntag; |
| CORE_ADDR dyn_ptr; |
| CORE_ADDR base_addr; |
| |
| /* Read in .dynamic section. */ |
| std::optional<gdb::byte_vector> ph_data |
| = read_program_header (PT_DYNAMIC, &arch_size, &base_addr); |
| if (!ph_data) |
| return 0; |
| |
| /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */ |
| step = (arch_size == 32) ? sizeof (Elf32_External_Dyn) |
| : sizeof (Elf64_External_Dyn); |
| for (gdb_byte *buf = ph_data->data (), *bufend = buf + ph_data->size (); |
| buf < bufend; buf += step) |
| { |
| if (arch_size == 32) |
| { |
| Elf32_External_Dyn *dynp = (Elf32_External_Dyn *) buf; |
| |
| current_dyntag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag, |
| 4, byte_order); |
| dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr, |
| 4, byte_order); |
| } |
| else |
| { |
| Elf64_External_Dyn *dynp = (Elf64_External_Dyn *) buf; |
| |
| current_dyntag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag, |
| 8, byte_order); |
| dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr, |
| 8, byte_order); |
| } |
| if (current_dyntag == DT_NULL) |
| break; |
| |
| if (current_dyntag == desired_dyntag) |
| { |
| if (ptr) |
| *ptr = dyn_ptr; |
| |
| if (ptr_addr) |
| *ptr_addr = base_addr + buf - ph_data->data (); |
| |
| return 1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* Locate the base address of dynamic linker structs for SVR4 elf |
| targets. |
| |
| For SVR4 elf targets the address of the dynamic linker's runtime |
| structure is contained within the dynamic info section in the |
| executable file. The dynamic section is also mapped into the |
| inferior address space. Because the runtime loader fills in the |
| real address before starting the inferior, we have to read in the |
| dynamic info section from the inferior address space. |
| If there are any errors while trying to find the address, we |
| silently return 0, otherwise the found address is returned. */ |
| |
| static CORE_ADDR |
| elf_locate_base (void) |
| { |
| CORE_ADDR dyn_ptr, dyn_ptr_addr; |
| |
| if (!svr4_have_link_map_offsets ()) |
| return 0; |
| |
| /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this |
| instead of DT_DEBUG, although they sometimes contain an unused |
| DT_DEBUG. */ |
| if (gdb_bfd_scan_elf_dyntag (DT_MIPS_RLD_MAP, |
| current_program_space->exec_bfd (), |
| &dyn_ptr, NULL) |
| || scan_dyntag_auxv (DT_MIPS_RLD_MAP, &dyn_ptr, NULL)) |
| { |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| gdb_byte *pbuf; |
| int pbuf_size = ptr_type->length (); |
| |
| pbuf = (gdb_byte *) alloca (pbuf_size); |
| /* DT_MIPS_RLD_MAP contains a pointer to the address |
| of the dynamic link structure. */ |
| if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) |
| return 0; |
| return extract_typed_address (pbuf, ptr_type); |
| } |
| |
| /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form |
| because of needing to support PIE. DT_MIPS_RLD_MAP will also exist |
| in non-PIE. */ |
| if (gdb_bfd_scan_elf_dyntag (DT_MIPS_RLD_MAP_REL, |
| current_program_space->exec_bfd (), |
| &dyn_ptr, &dyn_ptr_addr) |
| || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL, &dyn_ptr, &dyn_ptr_addr)) |
| { |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| gdb_byte *pbuf; |
| int pbuf_size = ptr_type->length (); |
| |
| pbuf = (gdb_byte *) alloca (pbuf_size); |
| /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the |
| DT slot to the address of the dynamic link structure. */ |
| if (target_read_memory (dyn_ptr + dyn_ptr_addr, pbuf, pbuf_size)) |
| return 0; |
| return extract_typed_address (pbuf, ptr_type); |
| } |
| |
| /* Find DT_DEBUG. */ |
| if (gdb_bfd_scan_elf_dyntag (DT_DEBUG, current_program_space->exec_bfd (), |
| &dyn_ptr, NULL) |
| || scan_dyntag_auxv (DT_DEBUG, &dyn_ptr, NULL)) |
| return dyn_ptr; |
| |
| /* This may be a static executable. Look for the symbol |
| conventionally named _r_debug, as a last resort. */ |
| bound_minimal_symbol msymbol |
| = lookup_minimal_symbol (current_program_space, "_r_debug", |
| current_program_space->symfile_object_file); |
| if (msymbol.minsym != NULL) |
| return msymbol.value_address (); |
| |
| /* DT_DEBUG entry not found. */ |
| return 0; |
| } |
| |
| /* Find the first element in the inferior's dynamic link map, and |
| return its address in the inferior. Return zero if the address |
| could not be determined. |
| |
| FIXME: Perhaps we should validate the info somehow, perhaps by |
| checking r_version for a known version number, or r_state for |
| RT_CONSISTENT. */ |
| |
| static CORE_ADDR |
| solib_svr4_r_map (CORE_ADDR debug_base) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| CORE_ADDR addr = 0; |
| |
| try |
| { |
| addr = read_memory_typed_address (debug_base + lmo->r_map_offset, |
| ptr_type); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| } |
| |
| return addr; |
| } |
| |
| /* Find r_brk from the inferior's debug base. */ |
| |
| static CORE_ADDR |
| solib_svr4_r_brk (struct svr4_info *info) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| |
| return read_memory_typed_address (info->debug_base + lmo->r_brk_offset, |
| ptr_type); |
| } |
| |
| /* Find the link map for the dynamic linker (if it is not in the |
| normal list of loaded shared objects). */ |
| |
| static CORE_ADDR |
| solib_svr4_r_ldsomap (struct svr4_info *info) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| enum bfd_endian byte_order = type_byte_order (ptr_type); |
| ULONGEST version = 0; |
| |
| try |
| { |
| /* Check version, and return zero if `struct r_debug' doesn't have |
| the r_ldsomap member. */ |
| version |
| = read_memory_unsigned_integer (info->debug_base + lmo->r_version_offset, |
| lmo->r_version_size, byte_order); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| } |
| |
| if (version < 2 || lmo->r_ldsomap_offset == -1) |
| return 0; |
| |
| return read_memory_typed_address (info->debug_base + lmo->r_ldsomap_offset, |
| ptr_type); |
| } |
| |
| /* Find the next namespace from the r_next field. */ |
| |
| static CORE_ADDR |
| solib_svr4_r_next (CORE_ADDR debug_base) |
| { |
| link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| bfd_endian byte_order = type_byte_order (ptr_type); |
| ULONGEST version = 0; |
| |
| try |
| { |
| version |
| = read_memory_unsigned_integer (debug_base + lmo->r_version_offset, |
| lmo->r_version_size, byte_order); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| } |
| |
| /* The r_next field is added with r_version == 2. */ |
| if (version < 2 || lmo->r_next_offset == -1) |
| return 0; |
| |
| return read_memory_typed_address (debug_base + lmo->r_next_offset, |
| ptr_type); |
| } |
| |
| /* On Solaris systems with some versions of the dynamic linker, |
| ld.so's l_name pointer points to the SONAME in the string table |
| rather than into writable memory. So that GDB can find shared |
| libraries when loading a core file generated by gcore, ensure that |
| memory areas containing the l_name string are saved in the core |
| file. */ |
| |
| static int |
| svr4_keep_data_in_core (CORE_ADDR vaddr, unsigned long size) |
| { |
| struct svr4_info *info; |
| CORE_ADDR ldsomap; |
| CORE_ADDR name_lm; |
| |
| info = get_svr4_info (current_program_space); |
| |
| info->debug_base = elf_locate_base (); |
| if (info->debug_base == 0) |
| return 0; |
| |
| ldsomap = solib_svr4_r_ldsomap (info); |
| if (!ldsomap) |
| return 0; |
| |
| std::unique_ptr<lm_info_svr4> li = lm_info_read (ldsomap); |
| name_lm = li != NULL ? li->l_name : 0; |
| |
| return (name_lm >= vaddr && name_lm < vaddr + size); |
| } |
| |
| /* See solist.h. */ |
| |
| static int |
| open_symbol_file_object (int from_tty) |
| { |
| CORE_ADDR lm, l_name; |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| type *ptr_type |
| = builtin_type (current_inferior ()->arch ())->builtin_data_ptr; |
| int l_name_size = ptr_type->length (); |
| gdb::byte_vector l_name_buf (l_name_size); |
| struct svr4_info *info = get_svr4_info (current_program_space); |
| symfile_add_flags add_flags = 0; |
| |
| if (from_tty) |
| add_flags |= SYMFILE_VERBOSE; |
| |
| if (current_program_space->symfile_object_file) |
| if (!query (_("Attempt to reload symbols from process? "))) |
| return 0; |
| |
| /* Always locate the debug struct, in case it has moved. */ |
| info->debug_base = elf_locate_base (); |
| if (info->debug_base == 0) |
| return 0; /* failed somehow... */ |
| |
| /* First link map member should be the executable. */ |
| lm = solib_svr4_r_map (info->debug_base); |
| if (lm == 0) |
| return 0; /* failed somehow... */ |
| |
| /* Read address of name from target memory to GDB. */ |
| read_memory (lm + lmo->l_name_offset, l_name_buf.data (), l_name_size); |
| |
| /* Convert the address to host format. */ |
| l_name = extract_typed_address (l_name_buf.data (), ptr_type); |
| |
| if (l_name == 0) |
| return 0; /* No filename. */ |
| |
| /* Now fetch the filename from target memory. */ |
| gdb::unique_xmalloc_ptr<char> filename |
| = target_read_string (l_name, SO_NAME_MAX_PATH_SIZE - 1); |
| |
| if (filename == nullptr) |
| { |
| warning (_("failed to read exec filename from attached file")); |
| return 0; |
| } |
| |
| /* Have a pathname: read the symbol file. */ |
| symbol_file_add_main (filename.get (), add_flags); |
| |
| return 1; |
| } |
| |
| /* Data exchange structure for the XML parser as returned by |
| svr4_current_sos_via_xfer_libraries. */ |
| |
| struct svr4_library_list |
| { |
| /* The so list for the current namespace. This is internal to XML |
| parsing. */ |
| std::vector<svr4_so> *cur_list; |
| |
| /* Inferior address of struct link_map used for the main executable. It is |
| NULL if not known. */ |
| CORE_ADDR main_lm; |
| |
| /* List of objects loaded into the inferior per namespace. This does |
| not include any default sos. |
| |
| See comment on struct svr4_info.solib_lists. */ |
| std::map<CORE_ADDR, std::vector<svr4_so>> solib_lists; |
| }; |
| |
| /* This module's 'free_objfile' observer. */ |
| |
| static void |
| svr4_free_objfile_observer (struct objfile *objfile) |
| { |
| probes_table_remove_objfile_probes (objfile); |
| } |
| |
| /* Implement solib_ops.clear_so. */ |
| |
| static void |
| svr4_clear_so (const solib &so) |
| { |
| auto *li = gdb::checked_static_cast<lm_info_svr4 *> (so.lm_info.get ()); |
| |
| if (li != NULL) |
| li->l_addr_p = 0; |
| } |
| |
| /* Create the so_list objects equivalent to the svr4_sos in SOS. */ |
| |
| static intrusive_list<solib> |
| so_list_from_svr4_sos (const std::vector<svr4_so> &sos) |
| { |
| intrusive_list<solib> dst; |
| |
| for (const svr4_so &so : sos) |
| { |
| struct solib *newobj = new struct solib; |
| |
| newobj->so_name = so.name; |
| newobj->so_original_name = so.name; |
| newobj->lm_info = std::make_unique<lm_info_svr4> (*so.lm_info); |
| |
| dst.push_back (*newobj); |
| } |
| |
| return dst; |
| } |
| |
| #ifdef HAVE_LIBEXPAT |
| |
| #include "xml-support.h" |
| |
| /* Handle the start of a <library> element. Note: new elements are added |
| at the tail of the list, keeping the list in order. */ |
| |
| static void |
| library_list_start_library (struct gdb_xml_parser *parser, |
| const struct gdb_xml_element *element, |
| void *user_data, |
| std::vector<gdb_xml_value> &attributes) |
| { |
| struct svr4_library_list *list = (struct svr4_library_list *) user_data; |
| const char *name |
| = (const char *) xml_find_attribute (attributes, "name")->value.get (); |
| ULONGEST *lmp |
| = (ULONGEST *) xml_find_attribute (attributes, "lm")->value.get (); |
| ULONGEST *l_addrp |
| = (ULONGEST *) xml_find_attribute (attributes, "l_addr")->value.get (); |
| ULONGEST *l_ldp |
| = (ULONGEST *) xml_find_attribute (attributes, "l_ld")->value.get (); |
| |
| lm_info_svr4_up li = std::make_unique<lm_info_svr4> (); |
| li->lm_addr = *lmp; |
| li->l_addr_inferior = *l_addrp; |
| li->l_ld = *l_ldp; |
| |
| std::vector<svr4_so> *solist; |
| |
| /* Older versions did not supply lmid. Put the element into the flat |
| list of the special namespace zero in that case. */ |
| gdb_xml_value *at_lmid = xml_find_attribute (attributes, "lmid"); |
| if (at_lmid == nullptr) |
| solist = list->cur_list; |
| else |
| { |
| ULONGEST lmid = *(ULONGEST *) at_lmid->value.get (); |
| solist = &list->solib_lists[lmid]; |
| } |
| |
| solist->emplace_back (name, std::move (li)); |
| } |
| |
| /* Handle the start of a <library-list-svr4> element. */ |
| |
| static void |
| svr4_library_list_start_list (struct gdb_xml_parser *parser, |
| const struct gdb_xml_element *element, |
| void *user_data, |
| std::vector<gdb_xml_value> &attributes) |
| { |
| struct svr4_library_list *list = (struct svr4_library_list *) user_data; |
| const char *version |
| = (const char *) xml_find_attribute (attributes, "version")->value.get (); |
| struct gdb_xml_value *main_lm = xml_find_attribute (attributes, "main-lm"); |
| |
| if (strcmp (version, "1.0") != 0) |
| gdb_xml_error (parser, |
| _("SVR4 Library list has unsupported version \"%s\""), |
| version); |
| |
| if (main_lm) |
| list->main_lm = *(ULONGEST *) main_lm->value.get (); |
| |
| /* Older gdbserver do not support namespaces. We use the special |
| namespace zero for a linear list of libraries. */ |
| list->cur_list = &list->solib_lists[0]; |
| } |
| |
| /* The allowed elements and attributes for an XML library list. |
| The root element is a <library-list>. */ |
| |
| static const struct gdb_xml_attribute svr4_library_attributes[] = |
| { |
| { "name", GDB_XML_AF_NONE, NULL, NULL }, |
| { "lm", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, |
| { "l_addr", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, |
| { "l_ld", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, |
| { "lmid", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, |
| { NULL, GDB_XML_AF_NONE, NULL, NULL } |
| }; |
| |
| static const struct gdb_xml_element svr4_library_list_children[] = |
| { |
| { |
| "library", svr4_library_attributes, NULL, |
| GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL, |
| library_list_start_library, NULL |
| }, |
| { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL } |
| }; |
| |
| static const struct gdb_xml_attribute svr4_library_list_attributes[] = |
| { |
| { "version", GDB_XML_AF_NONE, NULL, NULL }, |
| { "main-lm", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL }, |
| { NULL, GDB_XML_AF_NONE, NULL, NULL } |
| }; |
| |
| static const struct gdb_xml_element svr4_library_list_elements[] = |
| { |
| { "library-list-svr4", svr4_library_list_attributes, svr4_library_list_children, |
| GDB_XML_EF_NONE, svr4_library_list_start_list, NULL }, |
| { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL } |
| }; |
| |
| /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if |
| |
| Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such |
| case. Return 1 if *SO_LIST_RETURN contains the library list, it may be |
| empty, caller is responsible for freeing all its entries. */ |
| |
| static int |
| svr4_parse_libraries (const char *document, struct svr4_library_list *list) |
| { |
| auto cleanup = make_scope_exit ([list] () |
| { list->solib_lists.clear (); }); |
| |
| list->cur_list = nullptr; |
| list->main_lm = 0; |
| list->solib_lists.clear (); |
| if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd", |
| svr4_library_list_elements, document, list) == 0) |
| { |
| /* Parsed successfully, keep the result. */ |
| cleanup.release (); |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet. |
| |
| Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such |
| case. Return 1 if *SO_LIST_RETURN contains the library list, it may be |
| empty, caller is responsible for freeing all its entries. |
| |
| Note that ANNEX must be NULL if the remote does not explicitly allow |
| qXfer:libraries-svr4:read packets with non-empty annexes. Support for |
| this can be checked using target_augmented_libraries_svr4_read (). */ |
| |
| static int |
| svr4_current_sos_via_xfer_libraries (struct svr4_library_list *list, |
| const char *annex) |
| { |
| gdb_assert (annex == NULL || target_augmented_libraries_svr4_read ()); |
| |
| /* Fetch the list of shared libraries. */ |
| std::optional<gdb::char_vector> svr4_library_document |
| = target_read_stralloc (current_inferior ()->top_target (), |
| TARGET_OBJECT_LIBRARIES_SVR4, |
| annex); |
| if (!svr4_library_document) |
| return 0; |
| |
| return svr4_parse_libraries (svr4_library_document->data (), list); |
| } |
| |
| #else |
| |
| static int |
| svr4_current_sos_via_xfer_libraries (struct svr4_library_list *list, |
| const char *annex) |
| { |
| return 0; |
| } |
| |
| #endif |
| |
| /* If no shared library information is available from the dynamic |
| linker, build a fallback list from other sources. */ |
| |
| static intrusive_list<solib> |
| svr4_default_sos (svr4_info *info) |
| { |
| if (!info->debug_loader_offset_p) |
| return {}; |
| |
| solib *newobj = new solib; |
| auto li = std::make_unique<lm_info_svr4> (); |
| |
| /* Nothing will ever check the other fields if we set l_addr_p. */ |
| li->l_addr = li->l_addr_inferior = info->debug_loader_offset; |
| li->l_addr_p = 1; |
| |
| newobj->lm_info = std::move (li); |
| newobj->so_name = info->debug_loader_name; |
| newobj->so_original_name = newobj->so_name; |
| |
| intrusive_list<solib> sos; |
| sos.push_back (*newobj); |
| |
| return sos; |
| } |
| |
| /* Read the whole inferior libraries chain starting at address LM. |
| Expect the first entry in the chain's previous entry to be PREV_LM. |
| Add the entries to SOS. Ignore the first entry if IGNORE_FIRST and set |
| global MAIN_LM_ADDR according to it. Returns nonzero upon success. If zero |
| is returned the entries stored to LINK_PTR_PTR are still valid although they may |
| represent only part of the inferior library list. */ |
| |
| static int |
| svr4_read_so_list (svr4_info *info, CORE_ADDR lm, CORE_ADDR prev_lm, |
| std::vector<svr4_so> &sos, int ignore_first) |
| { |
| CORE_ADDR first_l_name = 0; |
| CORE_ADDR next_lm; |
| |
| for (; lm != 0; prev_lm = lm, lm = next_lm) |
| { |
| lm_info_svr4_up li = lm_info_read (lm); |
| if (li == NULL) |
| return 0; |
| |
| next_lm = li->l_next; |
| |
| if (li->l_prev != prev_lm) |
| { |
| warning (_("Corrupted shared library list: %s != %s"), |
| paddress (current_inferior ()->arch (), prev_lm), |
| paddress (current_inferior ()->arch (), li->l_prev)); |
| return 0; |
| } |
| |
| /* For SVR4 versions, the first entry in the link map is for the |
| inferior executable, so we must ignore it. For some versions of |
| SVR4, it has no name. For others (Solaris 2.3 for example), it |
| does have a name, so we can no longer use a missing name to |
| decide when to ignore it. */ |
| if (ignore_first && li->l_prev == 0) |
| { |
| first_l_name = li->l_name; |
| info->main_lm_addr = li->lm_addr; |
| continue; |
| } |
| |
| /* Extract this shared object's name. */ |
| gdb::unique_xmalloc_ptr<char> name |
| = target_read_string (li->l_name, SO_NAME_MAX_PATH_SIZE - 1); |
| if (name == nullptr) |
| { |
| /* If this entry's l_name address matches that of the |
| inferior executable, then this is not a normal shared |
| object, but (most likely) a vDSO. In this case, silently |
| skip it; otherwise emit a warning. */ |
| if (first_l_name == 0 || li->l_name != first_l_name) |
| warning (_("Can't read pathname for load map.")); |
| continue; |
| } |
| |
| /* If this entry has no name, or its name matches the name |
| for the main executable, don't include it in the list. */ |
| if (*name == '\0' || match_main (name.get ())) |
| continue; |
| |
| sos.emplace_back (name.get (), std::move (li)); |
| } |
| |
| return 1; |
| } |
| |
| /* Read the full list of currently loaded shared objects directly |
| from the inferior, without referring to any libraries read and |
| stored by the probes interface. Handle special cases relating |
| to the first elements of the list in default namespace. */ |
| |
| static void |
| svr4_current_sos_direct (struct svr4_info *info) |
| { |
| CORE_ADDR lm; |
| bool ignore_first; |
| struct svr4_library_list library_list; |
| |
| /* Remove any old libraries. We're going to read them back in again. */ |
| info->solib_lists.clear (); |
| |
| /* Fall back to manual examination of the target if the packet is not |
| supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp |
| tests a case where gdbserver cannot find the shared libraries list while |
| GDB itself is able to find it via SYMFILE_OBJFILE. |
| |
| Unfortunately statically linked inferiors will also fall back through this |
| suboptimal code path. */ |
| |
| info->using_xfer = svr4_current_sos_via_xfer_libraries (&library_list, |
| NULL); |
| if (info->using_xfer) |
| { |
| if (library_list.main_lm) |
| info->main_lm_addr = library_list.main_lm; |
| |
| /* Remove an empty special zero namespace so we know that when there |
| is one, it is actually used, and we have a flat list without |
| namespace information. */ |
| auto it_0 = library_list.solib_lists.find (0); |
| if (it_0 != library_list.solib_lists.end () |
| && it_0->second.empty ()) |
| library_list.solib_lists.erase (it_0); |
| |
| /* Replace the (empty) solib_lists in INFO with the one generated |
| from the target. We don't want to copy it on assignment and then |
| delete the original afterwards, so let's just swap the |
| internals. */ |
| std::swap (info->solib_lists, library_list.solib_lists); |
| return; |
| } |
| |
| /* If we can't find the dynamic linker's base structure, this |
| must not be a dynamically linked executable. Hmm. */ |
| info->debug_base = elf_locate_base (); |
| if (info->debug_base == 0) |
| return; |
| |
| /* Assume that everything is a library if the dynamic loader was loaded |
| late by a static executable. */ |
| if (current_program_space->exec_bfd () |
| && bfd_get_section_by_name (current_program_space->exec_bfd (), |
| ".dynamic") == NULL) |
| ignore_first = false; |
| else |
| ignore_first = true; |
| |
| auto cleanup = make_scope_exit ([info] () |
| { info->solib_lists.clear (); }); |
| |
| /* Collect the sos in each namespace. */ |
| CORE_ADDR debug_base = info->debug_base; |
| for (; debug_base != 0; |
| ignore_first = false, debug_base = solib_svr4_r_next (debug_base)) |
| { |
| /* Walk the inferior's link map list, and build our so_list list. */ |
| lm = solib_svr4_r_map (debug_base); |
| if (lm != 0) |
| svr4_read_so_list (info, lm, 0, info->solib_lists[debug_base], |
| ignore_first); |
| } |
| |
| /* On Solaris, the dynamic linker is not in the normal list of |
| shared objects, so make sure we pick it up too. Having |
| symbol information for the dynamic linker is quite crucial |
| for skipping dynamic linker resolver code. |
| |
| Note that we interpret the ldsomap load map address as 'virtual' |
| r_debug object. If we added it to the default namespace (as it was), |
| we would probably run into inconsistencies with the load map's |
| prev/next links (I wonder if we did). */ |
| debug_base = solib_svr4_r_ldsomap (info); |
| if (debug_base != 0) |
| { |
| /* Add the dynamic linker's namespace unless we already did. */ |
| if (info->solib_lists.find (debug_base) == info->solib_lists.end ()) |
| svr4_read_so_list (info, debug_base, 0, info->solib_lists[debug_base], |
| 0); |
| } |
| |
| cleanup.release (); |
| } |
| |
| /* Collect sos read and stored by the probes interface. */ |
| |
| static intrusive_list<solib> |
| svr4_collect_probes_sos (svr4_info *info) |
| { |
| intrusive_list<solib> res; |
| |
| for (const auto &tuple : info->solib_lists) |
| { |
| const std::vector<svr4_so> &sos = tuple.second; |
| res.splice (so_list_from_svr4_sos (sos)); |
| } |
| |
| return res; |
| } |
| |
| /* Implement the main part of the "current_sos" solib_ops |
| method. */ |
| |
| static intrusive_list<solib> |
| svr4_current_sos_1 (svr4_info *info) |
| { |
| intrusive_list<solib> sos; |
| |
| /* If we're using the probes interface, we can use the cache as it will |
| be maintained by probe update/reload actions. */ |
| if (info->probes_table != nullptr) |
| sos = svr4_collect_probes_sos (info); |
| |
| /* If we're not using the probes interface or if we didn't cache |
| anything, read the sos to fill the cache, then collect them from the |
| cache. */ |
| if (sos.empty ()) |
| { |
| svr4_current_sos_direct (info); |
| |
| sos = svr4_collect_probes_sos (info); |
| if (sos.empty ()) |
| sos = svr4_default_sos (info); |
| } |
| |
| return sos; |
| } |
| |
| /* Implement the "current_sos" solib_ops method. */ |
| |
| static intrusive_list<solib> |
| svr4_current_sos () |
| { |
| svr4_info *info = get_svr4_info (current_program_space); |
| intrusive_list<solib> sos = svr4_current_sos_1 (info); |
| struct mem_range vsyscall_range; |
| |
| /* Filter out the vDSO module, if present. Its symbol file would |
| not be found on disk. The vDSO/vsyscall's OBJFILE is instead |
| managed by symfile-mem.c:add_vsyscall_page. */ |
| if (gdbarch_vsyscall_range (current_inferior ()->arch (), &vsyscall_range) |
| && vsyscall_range.length != 0) |
| { |
| for (auto so = sos.begin (); so != sos.end (); ) |
| { |
| /* We can't simply match the vDSO by starting address alone, |
| because lm_info->l_addr_inferior (and also l_addr) do not |
| necessarily represent the real starting address of the |
| ELF if the vDSO's ELF itself is "prelinked". The l_ld |
| field (the ".dynamic" section of the shared object) |
| always points at the absolute/resolved address though. |
| So check whether that address is inside the vDSO's |
| mapping instead. |
| |
| E.g., on Linux 3.16 (x86_64) the vDSO is a regular |
| 0-based ELF, and we see: |
| |
| (gdb) info auxv |
| 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000 |
| (gdb) p/x *_r_debug.r_map.l_next |
| $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...} |
| |
| And on Linux 2.6.32 (x86_64) we see: |
| |
| (gdb) info auxv |
| 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000 |
| (gdb) p/x *_r_debug.r_map.l_next |
| $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... } |
| |
| Dumping that vDSO shows: |
| |
| (gdb) info proc mappings |
| 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso] |
| (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000 |
| # readelf -Wa vdso.bin |
| [...] |
| Entry point address: 0xffffffffff700700 |
| [...] |
| Section Headers: |
| [Nr] Name Type Address Off Size |
| [ 0] NULL 0000000000000000 000000 000000 |
| [ 1] .hash HASH ffffffffff700120 000120 000038 |
| [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8 |
| [...] |
| [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0 |
| */ |
| |
| auto *li = gdb::checked_static_cast<lm_info_svr4 *> (so->lm_info.get ()); |
| |
| if (vsyscall_range.contains (li->l_ld)) |
| { |
| auto next = sos.erase (so); |
| delete &*so; |
| so = next; |
| break; |
| } |
| |
| ++so; |
| } |
| } |
| |
| return sos; |
| } |
| |
| /* Get the address of the link_map for a given OBJFILE. */ |
| |
| CORE_ADDR |
| svr4_fetch_objfile_link_map (struct objfile *objfile) |
| { |
| struct svr4_info *info = get_svr4_info (objfile->pspace ()); |
| |
| /* Cause svr4_current_sos() to be run if it hasn't been already. */ |
| if (info->main_lm_addr == 0) |
| solib_add (NULL, 0, auto_solib_add); |
| |
| /* svr4_current_sos() will set main_lm_addr for the main executable. */ |
| if (objfile == current_program_space->symfile_object_file) |
| return info->main_lm_addr; |
| |
| /* The other link map addresses may be found by examining the list |
| of shared libraries. */ |
| for (const solib &so : current_program_space->solibs ()) |
| if (so.objfile == objfile) |
| { |
| auto *li |
| = gdb::checked_static_cast<lm_info_svr4 *> (so.lm_info.get ()); |
| |
| return li->lm_addr; |
| } |
| |
| /* Not found! */ |
| return 0; |
| } |
| |
| /* On some systems, the only way to recognize the link map entry for |
| the main executable file is by looking at its name. Return |
| non-zero iff SONAME matches one of the known main executable names. */ |
| |
| static int |
| match_main (const char *soname) |
| { |
| const char * const *mainp; |
| |
| for (mainp = main_name_list; *mainp != NULL; mainp++) |
| { |
| if (strcmp (soname, *mainp) == 0) |
| return (1); |
| } |
| |
| return (0); |
| } |
| |
| /* Return 1 if PC lies in the dynamic symbol resolution code of the |
| SVR4 run time loader. */ |
| |
| int |
| svr4_in_dynsym_resolve_code (CORE_ADDR pc) |
| { |
| struct svr4_info *info = get_svr4_info (current_program_space); |
| |
| return ((pc >= info->interp_text_sect_low |
| && pc < info->interp_text_sect_high) |
| || (pc >= info->interp_plt_sect_low |
| && pc < info->interp_plt_sect_high) |
| || in_plt_section (pc) |
| || in_gnu_ifunc_stub (pc)); |
| } |
| |
| /* Given an executable's ABFD and target, compute the entry-point |
| address. */ |
| |
| static CORE_ADDR |
| exec_entry_point (struct bfd *abfd, struct target_ops *targ) |
| { |
| CORE_ADDR addr; |
| |
| /* KevinB wrote ... for most targets, the address returned by |
| bfd_get_start_address() is the entry point for the start |
| function. But, for some targets, bfd_get_start_address() returns |
| the address of a function descriptor from which the entry point |
| address may be extracted. This address is extracted by |
| gdbarch_convert_from_func_ptr_addr(). The method |
| gdbarch_convert_from_func_ptr_addr() is the merely the identify |
| function for targets which don't use function descriptors. */ |
| addr = gdbarch_convert_from_func_ptr_addr (current_inferior ()->arch (), |
| bfd_get_start_address (abfd), |
| targ); |
| return gdbarch_addr_bits_remove (current_inferior ()->arch (), addr); |
| } |
| |
| /* A probe and its associated action. */ |
| |
| struct probe_and_action |
| { |
| /* The probe. */ |
| probe *prob; |
| |
| /* The relocated address of the probe. */ |
| CORE_ADDR address; |
| |
| /* The action. */ |
| enum probe_action action; |
| |
| /* The objfile where this probe was found. */ |
| struct objfile *objfile; |
| }; |
| |
| /* Returns a hash code for the probe_and_action referenced by p. */ |
| |
| static hashval_t |
| hash_probe_and_action (const void *p) |
| { |
| const struct probe_and_action *pa = (const struct probe_and_action *) p; |
| |
| return (hashval_t) pa->address; |
| } |
| |
| /* Returns non-zero if the probe_and_actions referenced by p1 and p2 |
| are equal. */ |
| |
| static int |
| equal_probe_and_action (const void *p1, const void *p2) |
| { |
| const struct probe_and_action *pa1 = (const struct probe_and_action *) p1; |
| const struct probe_and_action *pa2 = (const struct probe_and_action *) p2; |
| |
| return pa1->address == pa2->address; |
| } |
| |
| /* Traversal function for probes_table_remove_objfile_probes. */ |
| |
| static int |
| probes_table_htab_remove_objfile_probes (void **slot, void *info) |
| { |
| probe_and_action *pa = (probe_and_action *) *slot; |
| struct objfile *objfile = (struct objfile *) info; |
| |
| if (pa->objfile == objfile) |
| htab_clear_slot (get_svr4_info (objfile->pspace ())->probes_table.get (), |
| slot); |
| |
| return 1; |
| } |
| |
| /* Remove all probes that belong to OBJFILE from the probes table. */ |
| |
| static void |
| probes_table_remove_objfile_probes (struct objfile *objfile) |
| { |
| svr4_info *info = get_svr4_info (objfile->pspace ()); |
| if (info->probes_table != nullptr) |
| htab_traverse_noresize (info->probes_table.get (), |
| probes_table_htab_remove_objfile_probes, objfile); |
| } |
| |
| /* Register a solib event probe and its associated action in the |
| probes table. */ |
| |
| static void |
| register_solib_event_probe (svr4_info *info, struct objfile *objfile, |
| probe *prob, CORE_ADDR address, |
| enum probe_action action) |
| { |
| struct probe_and_action lookup, *pa; |
| void **slot; |
| |
| /* Create the probes table, if necessary. */ |
| if (info->probes_table == NULL) |
| info->probes_table.reset (htab_create_alloc (1, hash_probe_and_action, |
| equal_probe_and_action, |
| xfree, xcalloc, xfree)); |
| |
| lookup.address = address; |
| slot = htab_find_slot (info->probes_table.get (), &lookup, INSERT); |
| gdb_assert (*slot == HTAB_EMPTY_ENTRY); |
| |
| pa = XCNEW (struct probe_and_action); |
| pa->prob = prob; |
| pa->address = address; |
| pa->action = action; |
| pa->objfile = objfile; |
| |
| *slot = pa; |
| } |
| |
| /* Get the solib event probe at the specified location, and the |
| action associated with it. Returns NULL if no solib event probe |
| was found. */ |
| |
| static struct probe_and_action * |
| solib_event_probe_at (struct svr4_info *info, CORE_ADDR address) |
| { |
| struct probe_and_action lookup; |
| void **slot; |
| |
| lookup.address = address; |
| slot = htab_find_slot (info->probes_table.get (), &lookup, NO_INSERT); |
| |
| if (slot == NULL) |
| return NULL; |
| |
| return (struct probe_and_action *) *slot; |
| } |
| |
| /* Decide what action to take when the specified solib event probe is |
| hit. */ |
| |
| static enum probe_action |
| solib_event_probe_action (struct probe_and_action *pa) |
| { |
| enum probe_action action; |
| unsigned probe_argc = 0; |
| frame_info_ptr frame = get_current_frame (); |
| |
| action = pa->action; |
| if (action == DO_NOTHING || action == PROBES_INTERFACE_FAILED) |
| return action; |
| |
| gdb_assert (action == FULL_RELOAD || action == UPDATE_OR_RELOAD); |
| |
| /* Check that an appropriate number of arguments has been supplied. |
| We expect: |
| arg0: Lmid_t lmid (mandatory) |
| arg1: struct r_debug *debug_base (mandatory) |
| arg2: struct link_map *new (optional, for incremental updates) */ |
| try |
| { |
| probe_argc = pa->prob->get_argument_count (get_frame_arch (frame)); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| probe_argc = 0; |
| } |
| |
| /* If get_argument_count throws an exception, probe_argc will be set |
| to zero. However, if pa->prob does not have arguments, then |
| get_argument_count will succeed but probe_argc will also be zero. |
| Both cases happen because of different things, but they are |
| treated equally here: action will be set to |
| PROBES_INTERFACE_FAILED. */ |
| if (probe_argc == 2) |
| action = FULL_RELOAD; |
| else if (probe_argc < 2) |
| action = PROBES_INTERFACE_FAILED; |
| |
| return action; |
| } |
| |
| /* Populate the shared object list by reading the entire list of |
| shared objects from the inferior. Handle special cases relating |
| to the first elements of the list. Returns nonzero on success. */ |
| |
| static int |
| solist_update_full (struct svr4_info *info) |
| { |
| svr4_current_sos_direct (info); |
| |
| return 1; |
| } |
| |
| /* Update the shared object list starting from the link-map entry |
| passed by the linker in the probe's third argument. Returns |
| nonzero if the list was successfully updated, or zero to indicate |
| failure. */ |
| |
| static int |
| solist_update_incremental (svr4_info *info, CORE_ADDR debug_base, |
| CORE_ADDR lm) |
| { |
| /* Fall back to a full update if we are using a remote target |
| that does not support incremental transfers. */ |
| if (info->using_xfer && !target_augmented_libraries_svr4_read ()) |
| return 0; |
| |
| /* Fall back to a full update if we used the special namespace zero. We |
| wouldn't be able to find the last item in the DEBUG_BASE namespace |
| and hence get the prev link wrong. */ |
| if (info->solib_lists.find (0) != info->solib_lists.end ()) |
| return 0; |
| |
| std::vector<svr4_so> &solist = info->solib_lists[debug_base]; |
| CORE_ADDR prev_lm; |
| |
| if (solist.empty ()) |
| { |
| /* svr4_current_sos_direct contains logic to handle a number of |
| special cases relating to the first elements of the list in |
| default namespace. To avoid duplicating this logic we defer to |
| solist_update_full in this case. */ |
| if (svr4_is_default_namespace (info, debug_base)) |
| return 0; |
| |
| prev_lm = 0; |
| } |
| else |
| prev_lm = solist.back ().lm_info->lm_addr; |
| |
| /* Read the new objects. */ |
| if (info->using_xfer) |
| { |
| struct svr4_library_list library_list; |
| char annex[64]; |
| |
| /* Unknown key=value pairs are ignored by the gdbstub. */ |
| xsnprintf (annex, sizeof (annex), "lmid=%s;start=%s;prev=%s", |
| phex_nz (debug_base, sizeof (debug_base)), |
| phex_nz (lm, sizeof (lm)), |
| phex_nz (prev_lm, sizeof (prev_lm))); |
| if (!svr4_current_sos_via_xfer_libraries (&library_list, annex)) |
| return 0; |
| |
| /* Get the so list from the target. We replace the list in the |
| target response so we can easily check that the response only |
| covers one namespace. |
| |
| We expect gdbserver to provide updates for the namespace that |
| contains LM, which would be this namespace... */ |
| std::vector<svr4_so> sos; |
| auto it_debug_base = library_list.solib_lists.find (debug_base); |
| if (it_debug_base != library_list.solib_lists.end ()) |
| std::swap (sos, it_debug_base->second); |
| else |
| { |
| /* ...or for the special zero namespace for earlier versions... */ |
| auto it_0 = library_list.solib_lists.find (0); |
| if (it_0 != library_list.solib_lists.end ()) |
| std::swap (sos, it_0->second); |
| } |
| |
| /* ...but nothing else. */ |
| for (const auto &tuple : library_list.solib_lists) |
| gdb_assert (tuple.second.empty ()); |
| |
| std::move (sos.begin (), sos.end (), std::back_inserter (solist)); |
| } |
| else |
| { |
| /* IGNORE_FIRST may safely be set to zero here because the |
| above check and deferral to solist_update_full ensures |
| that this call to svr4_read_so_list will never see the |
| first element. */ |
| if (!svr4_read_so_list (info, lm, prev_lm, solist, 0)) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| /* Disable the probes-based linker interface and revert to the |
| original interface. We don't reset the breakpoints as the |
| ones set up for the probes-based interface are adequate. */ |
| |
| static void |
| disable_probes_interface (svr4_info *info) |
| { |
| warning (_("Probes-based dynamic linker interface failed.\n" |
| "Reverting to original interface.")); |
| |
| free_probes_table (info); |
| info->solib_lists.clear (); |
| } |
| |
| /* Update the solib list as appropriate when using the |
| probes-based linker interface. Do nothing if using the |
| standard interface. */ |
| |
| static void |
| svr4_handle_solib_event (void) |
| { |
| struct svr4_info *info = get_svr4_info (current_program_space); |
| struct probe_and_action *pa; |
| enum probe_action action; |
| struct value *val = NULL; |
| CORE_ADDR pc, debug_base, lm = 0; |
| frame_info_ptr frame = get_current_frame (); |
| |
| /* Do nothing if not using the probes interface. */ |
| if (info->probes_table == NULL) |
| return; |
| |
| pc = regcache_read_pc (get_thread_regcache (inferior_thread ())); |
| pa = solib_event_probe_at (info, pc); |
| if (pa == nullptr) |
| { |
| /* When some solib ops sits above us, it can respond to a solib event |
| by calling in here. This is done assuming that if the current event |
| is not an SVR4 solib event, calling here should be a no-op. */ |
| return; |
| } |
| |
| /* If anything goes wrong we revert to the original linker |
| interface. */ |
| auto cleanup = make_scope_exit ([info] () |
| { |
| disable_probes_interface (info); |
| }); |
| |
| action = solib_event_probe_action (pa); |
| if (action == PROBES_INTERFACE_FAILED) |
| return; |
| |
| if (action == DO_NOTHING) |
| { |
| cleanup.release (); |
| return; |
| } |
| |
| /* evaluate_argument looks up symbols in the dynamic linker |
| using find_pc_section. find_pc_section is accelerated by a cache |
| called the section map. The section map is invalidated every |
| time a shared library is loaded or unloaded, and if the inferior |
| is generating a lot of shared library events then the section map |
| will be updated every time svr4_handle_solib_event is called. |
| We called find_pc_section in svr4_create_solib_event_breakpoints, |
| so we can guarantee that the dynamic linker's sections are in the |
| section map. We can therefore inhibit section map updates across |
| these calls to evaluate_argument and save a lot of time. */ |
| { |
| scoped_restore inhibit_updates |
| = inhibit_section_map_updates (current_program_space); |
| |
| try |
| { |
| val = pa->prob->evaluate_argument (1, frame); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| val = NULL; |
| } |
| |
| if (val == NULL) |
| return; |
| |
| debug_base = value_as_address (val); |
| if (debug_base == 0) |
| return; |
| |
| /* If the global _r_debug object moved, we need to reload everything |
| since we cannot identify namespaces (by the location of their |
| r_debug_ext object) anymore. */ |
| CORE_ADDR global_debug_base = elf_locate_base (); |
| if (global_debug_base != info->debug_base) |
| { |
| info->debug_base = global_debug_base; |
| action = FULL_RELOAD; |
| } |
| |
| if (info->debug_base == 0) |
| { |
| /* It's possible for the reloc_complete probe to be triggered before |
| the linker has set the DT_DEBUG pointer (for example, when the |
| linker has finished relocating an LD_AUDIT library or its |
| dependencies). Since we can't yet handle libraries from other link |
| namespaces, we don't lose anything by ignoring them here. */ |
| struct value *link_map_id_val; |
| try |
| { |
| link_map_id_val = pa->prob->evaluate_argument (0, frame); |
| } |
| catch (const gdb_exception_error &) |
| { |
| link_map_id_val = NULL; |
| } |
| /* glibc and illumos' libc both define LM_ID_BASE as zero. */ |
| if (link_map_id_val != NULL && value_as_long (link_map_id_val) != 0) |
| action = DO_NOTHING; |
| else |
| return; |
| } |
| |
| if (action == UPDATE_OR_RELOAD) |
| { |
| try |
| { |
| val = pa->prob->evaluate_argument (2, frame); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| return; |
| } |
| |
| if (val != NULL) |
| lm = value_as_address (val); |
| |
| if (lm == 0) |
| action = FULL_RELOAD; |
| } |
| |
| /* Resume section map updates. Closing the scope is |
| sufficient. */ |
| } |
| |
| if (action == UPDATE_OR_RELOAD) |
| { |
| if (!solist_update_incremental (info, debug_base, lm)) |
| action = FULL_RELOAD; |
| } |
| |
| if (action == FULL_RELOAD) |
| { |
| if (!solist_update_full (info)) |
| return; |
| } |
| |
| cleanup.release (); |
| } |
| |
| /* Helper function for svr4_update_solib_event_breakpoints. */ |
| |
| static bool |
| svr4_update_solib_event_breakpoint (struct breakpoint *b) |
| { |
| if (b->type != bp_shlib_event) |
| { |
| /* Continue iterating. */ |
| return false; |
| } |
| |
| for (bp_location &loc : b->locations ()) |
| { |
| struct svr4_info *info; |
| struct probe_and_action *pa; |
| |
| info = solib_svr4_pspace_data.get (loc.pspace); |
| if (info == NULL || info->probes_table == NULL) |
| continue; |
| |
| pa = solib_event_probe_at (info, loc.address); |
| if (pa == NULL) |
| continue; |
| |
| if (pa->action == DO_NOTHING) |
| { |
| if (b->enable_state == bp_disabled && stop_on_solib_events) |
| enable_breakpoint (b); |
| else if (b->enable_state == bp_enabled && !stop_on_solib_events) |
| disable_breakpoint (b); |
| } |
| |
| break; |
| } |
| |
| /* Continue iterating. */ |
| return false; |
| } |
| |
| /* Enable or disable optional solib event breakpoints as appropriate. |
| Called whenever stop_on_solib_events is changed. */ |
| |
| static void |
| svr4_update_solib_event_breakpoints (void) |
| { |
| for (breakpoint &bp : all_breakpoints_safe ()) |
| svr4_update_solib_event_breakpoint (&bp); |
| } |
| |
| /* Create and register solib event breakpoints. PROBES is an array |
| of NUM_PROBES elements, each of which is vector of probes. A |
| solib event breakpoint will be created and registered for each |
| probe. */ |
| |
| static void |
| svr4_create_probe_breakpoints (svr4_info *info, struct gdbarch *gdbarch, |
| const std::vector<probe *> *probes, |
| struct objfile *objfile) |
| { |
| for (int i = 0; i < NUM_PROBES; i++) |
| { |
| enum probe_action action = probe_info[i].action; |
| |
| for (probe *p : probes[i]) |
| { |
| CORE_ADDR address = p->get_relocated_address (objfile); |
| |
| solib_debug_printf ("name=%s, addr=%s", probe_info[i].name, |
| paddress (gdbarch, address)); |
| |
| create_solib_event_breakpoint (gdbarch, address); |
| register_solib_event_probe (info, objfile, p, address, action); |
| } |
| } |
| |
| svr4_update_solib_event_breakpoints (); |
| } |
| |
| /* Find all the glibc named probes. Only if all of the probes are found, then |
| create them and return true. Otherwise return false. If WITH_PREFIX is set |
| then add "rtld" to the front of the probe names. */ |
| static bool |
| svr4_find_and_create_probe_breakpoints (svr4_info *info, |
| struct gdbarch *gdbarch, |
| struct obj_section *os, |
| bool with_prefix) |
| { |
| SOLIB_SCOPED_DEBUG_START_END ("objfile=%s, with_prefix=%d", |
| os->objfile->original_name, with_prefix); |
| |
| std::vector<probe *> probes[NUM_PROBES]; |
| |
| for (int i = 0; i < NUM_PROBES; i++) |
| { |
| const char *name = probe_info[i].name; |
| char buf[32]; |
| |
| /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4 shipped with an early |
| version of the probes code in which the probes' names were prefixed |
| with "rtld_" and the "map_failed" probe did not exist. The locations |
| of the probes are otherwise the same, so we check for probes with |
| prefixed names if probes with unprefixed names are not present. */ |
| if (with_prefix) |
| { |
| xsnprintf (buf, sizeof (buf), "rtld_%s", name); |
| name = buf; |
| } |
| |
| probes[i] = find_probes_in_objfile (os->objfile, "rtld", name); |
| solib_debug_printf ("probe=%s, num found=%zu", name, probes[i].size ()); |
| |
| /* Ensure at least one probe for the current name was found. */ |
| if (probes[i].empty ()) |
| { |
| /* The "map_failed" probe did not exist in early versions of the |
| probes code in which the probes' names were prefixed with |
| "rtld_". |
| |
| Additionally, the "map_failed" probe was accidentally removed |
| from glibc 2.35 and 2.36, when changes in glibc meant the |
| probe could no longer be reached, and the compiler optimized |
| the probe away. In this case the probe name doesn't have the |
| "rtld_" prefix. |
| |
| To handle this, and give GDB as much flexibility as possible, |
| we make the rule that, if a probe isn't required for the |
| correct operation of GDB (i.e. its action is DO_NOTHING), then |
| we will still use the probes interface, even if that probe is |
| missing. |
| |
| The only (possible) downside of this is that, if the user has |
| 'set stop-on-solib-events on' in effect, then they might get |
| fewer events using the probes interface than with the classic |
| non-probes interface. */ |
| if (probe_info[i].action == DO_NOTHING) |
| continue; |
| else |
| return false; |
| } |
| |
| /* Ensure probe arguments can be evaluated. */ |
| for (probe *p : probes[i]) |
| { |
| if (!p->can_evaluate_arguments ()) |
| return false; |
| /* This will fail if the probe is invalid. This has been seen on Arm |
| due to references to symbols that have been resolved away. */ |
| try |
| { |
| p->get_argument_count (gdbarch); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| warning (_("Initializing probes-based dynamic linker interface " |
| "failed.\nReverting to original interface.")); |
| return false; |
| } |
| } |
| } |
| |
| /* All probes found. Now create them. */ |
| solib_debug_printf ("using probes interface"); |
| svr4_create_probe_breakpoints (info, gdbarch, probes, os->objfile); |
| return true; |
| } |
| |
| /* Both the SunOS and the SVR4 dynamic linkers call a marker function |
| before and after mapping and unmapping shared libraries. The sole |
| purpose of this method is to allow debuggers to set a breakpoint so |
| they can track these changes. |
| |
| Some versions of the glibc dynamic linker contain named probes |
| to allow more fine grained stopping. Given the address of the |
| original marker function, this function attempts to find these |
| probes, and if found, sets breakpoints on those instead. If the |
| probes aren't found, a single breakpoint is set on the original |
| marker function. */ |
| |
| static void |
| svr4_create_solib_event_breakpoints (svr4_info *info, struct gdbarch *gdbarch, |
| CORE_ADDR address) |
| { |
| struct obj_section *os = find_pc_section (address); |
| |
| if (os == nullptr |
| || (!svr4_find_and_create_probe_breakpoints (info, gdbarch, os, false) |
| && !svr4_find_and_create_probe_breakpoints (info, gdbarch, os, true))) |
| { |
| solib_debug_printf ("falling back to r_brk breakpoint: addr=%s", |
| paddress (gdbarch, address)); |
| create_solib_event_breakpoint (gdbarch, address); |
| } |
| } |
| |
| /* Arrange for dynamic linker to hit breakpoint. |
| |
| Both the SunOS and the SVR4 dynamic linkers have, as part of their |
| debugger interface, support for arranging for the inferior to hit |
| a breakpoint after mapping in the shared libraries. This function |
| enables that breakpoint. |
| |
| For SunOS, there is a special flag location (in_debugger) which we |
| set to 1. When the dynamic linker sees this flag set, it will set |
| a breakpoint at a location known only to itself, after saving the |
| original contents of that place and the breakpoint address itself, |
| in its own internal structures. When we resume the inferior, it |
| will eventually take a SIGTRAP when it runs into the breakpoint. |
| We handle this (in a different place) by restoring the contents of |
| the breakpointed location (which is only known after it stops), |
| chasing around to locate the shared libraries that have been |
| loaded, then resuming. |
| |
| For SVR4, the debugger interface structure contains a member (r_brk) |
| which is statically initialized at the time the shared library is |
| built, to the offset of a function (_r_debug_state) which is guaran- |
| teed to be called once before mapping in a library, and again when |
| the mapping is complete. At the time we are examining this member, |
| it contains only the unrelocated offset of the function, so we have |
| to do our own relocation. Later, when the dynamic linker actually |
| runs, it relocates r_brk to be the actual address of _r_debug_state(). |
| |
| The debugger interface structure also contains an enumeration which |
| is set to either RT_ADD or RT_DELETE prior to changing the mapping, |
| depending upon whether or not the library is being mapped or unmapped, |
| and then set to RT_CONSISTENT after the library is mapped/unmapped. */ |
| |
| static int |
| enable_break (struct svr4_info *info, int from_tty) |
| { |
| const char * const *bkpt_namep; |
| asection *interp_sect; |
| CORE_ADDR sym_addr; |
| |
| info->interp_text_sect_low = info->interp_text_sect_high = 0; |
| info->interp_plt_sect_low = info->interp_plt_sect_high = 0; |
| |
| /* If we already have a shared library list in the target, and |
| r_debug contains r_brk, set the breakpoint there - this should |
| mean r_brk has already been relocated. Assume the dynamic linker |
| is the object containing r_brk. */ |
| |
| solib_add (NULL, from_tty, auto_solib_add); |
| sym_addr = 0; |
| if (info->debug_base && solib_svr4_r_map (info->debug_base) != 0) |
| sym_addr = solib_svr4_r_brk (info); |
| |
| if (sym_addr != 0) |
| { |
| struct obj_section *os; |
| |
| sym_addr = gdbarch_addr_bits_remove |
| (current_inferior ()->arch (), |
| gdbarch_convert_from_func_ptr_addr |
| (current_inferior ()->arch (), sym_addr, |
| current_inferior ()->top_target ())); |
| |
| /* On at least some versions of Solaris there's a dynamic relocation |
| on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if |
| we get control before the dynamic linker has self-relocated. |
| Check if SYM_ADDR is in a known section, if it is assume we can |
| trust its value. This is just a heuristic though, it could go away |
| or be replaced if it's getting in the way. |
| |
| On ARM we need to know whether the ISA of rtld_db_dlactivity (or |
| however it's spelled in your particular system) is ARM or Thumb. |
| That knowledge is encoded in the address, if it's Thumb the low bit |
| is 1. However, we've stripped that info above and it's not clear |
| what all the consequences are of passing a non-addr_bits_remove'd |
| address to svr4_create_solib_event_breakpoints. The call to |
| find_pc_section verifies we know about the address and have some |
| hope of computing the right kind of breakpoint to use (via |
| symbol info). It does mean that GDB needs to be pointed at a |
| non-stripped version of the dynamic linker in order to obtain |
| information it already knows about. Sigh. */ |
| |
| os = find_pc_section (sym_addr); |
| if (os != NULL) |
| { |
| /* Record the relocated start and end address of the dynamic linker |
| text and plt section for svr4_in_dynsym_resolve_code. */ |
| bfd *tmp_bfd; |
| CORE_ADDR load_addr; |
| |
| tmp_bfd = os->objfile->obfd.get (); |
| load_addr = os->objfile->text_section_offset (); |
| |
| interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
| if (interp_sect) |
| { |
| info->interp_text_sect_low |
| = bfd_section_vma (interp_sect) + load_addr; |
| info->interp_text_sect_high |
| = info->interp_text_sect_low + bfd_section_size (interp_sect); |
| } |
| interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); |
| if (interp_sect) |
| { |
| info->interp_plt_sect_low |
| = bfd_section_vma (interp_sect) + load_addr; |
| info->interp_plt_sect_high |
| = info->interp_plt_sect_low + bfd_section_size (interp_sect); |
| } |
| |
| svr4_create_solib_event_breakpoints |
| (info, current_inferior ()->arch (), sym_addr); |
| return 1; |
| } |
| } |
| |
| /* Find the program interpreter; if not found, warn the user and drop |
| into the old breakpoint at symbol code. */ |
| std::optional<gdb::byte_vector> interp_name_holder |
| = find_program_interpreter (); |
| if (interp_name_holder) |
| { |
| const char *interp_name = (const char *) interp_name_holder->data (); |
| CORE_ADDR load_addr = 0; |
| int load_addr_found = 0; |
| int loader_found_in_list = 0; |
| target_ops_up tmp_bfd_target; |
| |
| sym_addr = 0; |
| |
| /* Now we need to figure out where the dynamic linker was |
| loaded so that we can load its symbols and place a breakpoint |
| in the dynamic linker itself. |
| |
| This address is stored on the stack. However, I've been unable |
| to find any magic formula to find it for Solaris (appears to |
| be trivial on GNU/Linux). Therefore, we have to try an alternate |
| mechanism to find the dynamic linker's base address. */ |
| |
| gdb_bfd_ref_ptr tmp_bfd; |
| try |
| { |
| tmp_bfd = solib_bfd_open (interp_name); |
| } |
| catch (const gdb_exception &ex) |
| { |
| } |
| |
| if (tmp_bfd == NULL) |
| goto bkpt_at_symbol; |
| |
| /* Now convert the TMP_BFD into a target. That way target, as |
| well as BFD operations can be used. */ |
| tmp_bfd_target = target_bfd_reopen (tmp_bfd); |
| |
| /* On a running target, we can get the dynamic linker's base |
| address from the shared library table. */ |
| for (const solib &so : current_program_space->solibs ()) |
| { |
| if (svr4_same_1 (interp_name, so.so_original_name.c_str ())) |
| { |
| load_addr_found = 1; |
| loader_found_in_list = 1; |
| load_addr = lm_addr_check (so, tmp_bfd.get ()); |
| break; |
| } |
| } |
| |
| /* If we were not able to find the base address of the loader |
| from our so_list, then try using the AT_BASE auxilliary entry. */ |
| if (!load_addr_found) |
| if (target_auxv_search (AT_BASE, &load_addr) > 0) |
| { |
| int addr_bit = gdbarch_addr_bit (current_inferior ()->arch ()); |
| |
| /* Ensure LOAD_ADDR has proper sign in its possible upper bits so |
| that `+ load_addr' will overflow CORE_ADDR width not creating |
| invalid addresses like 0x101234567 for 32bit inferiors on 64bit |
| GDB. */ |
| |
| if (addr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT)) |
| { |
| CORE_ADDR space_size = (CORE_ADDR) 1 << addr_bit; |
| CORE_ADDR tmp_entry_point |
| = exec_entry_point (tmp_bfd.get (), tmp_bfd_target.get ()); |
| |
| gdb_assert (load_addr < space_size); |
| |
| /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked |
| 64bit ld.so with 32bit executable, it should not happen. */ |
| |
| if (tmp_entry_point < space_size |
| && tmp_entry_point + load_addr >= space_size) |
| load_addr -= space_size; |
| } |
| |
| load_addr_found = 1; |
| } |
| |
| /* Otherwise we find the dynamic linker's base address by examining |
| the current pc (which should point at the entry point for the |
| dynamic linker) and subtracting the offset of the entry point. |
| |
| This is more fragile than the previous approaches, but is a good |
| fallback method because it has actually been working well in |
| most cases. */ |
| if (!load_addr_found) |
| { |
| regcache *regcache |
| = get_thread_arch_regcache (current_inferior (), inferior_ptid, |
| current_inferior ()->arch ()); |
| |
| load_addr = (regcache_read_pc (regcache) |
| - exec_entry_point (tmp_bfd.get (), |
| tmp_bfd_target.get ())); |
| } |
| |
| if (!loader_found_in_list) |
| { |
| info->debug_loader_name = xstrdup (interp_name); |
| info->debug_loader_offset_p = 1; |
| info->debug_loader_offset = load_addr; |
| solib_add (NULL, from_tty, auto_solib_add); |
| } |
| |
| /* Record the relocated start and end address of the dynamic linker |
| text and plt section for svr4_in_dynsym_resolve_code. */ |
| interp_sect = bfd_get_section_by_name (tmp_bfd.get (), ".text"); |
| if (interp_sect) |
| { |
| info->interp_text_sect_low |
| = bfd_section_vma (interp_sect) + load_addr; |
| info->interp_text_sect_high |
| = info->interp_text_sect_low + bfd_section_size (interp_sect); |
| } |
| interp_sect = bfd_get_section_by_name (tmp_bfd.get (), ".plt"); |
| if (interp_sect) |
| { |
| info->interp_plt_sect_low |
| = bfd_section_vma (interp_sect) + load_addr; |
| info->interp_plt_sect_high |
| = info->interp_plt_sect_low + bfd_section_size (interp_sect); |
| } |
| |
| /* Now try to set a breakpoint in the dynamic linker. */ |
| for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) |
| { |
| sym_addr |
| = (gdb_bfd_lookup_symbol |
| (tmp_bfd.get (), |
| [=] (const asymbol *sym) |
| { |
| return (strcmp (sym->name, *bkpt_namep) == 0 |
| && ((sym->section->flags & (SEC_CODE | SEC_DATA)) |
| != 0)); |
| })); |
| if (sym_addr != 0) |
| break; |
| } |
| |
| if (sym_addr != 0) |
| /* Convert 'sym_addr' from a function pointer to an address. |
| Because we pass tmp_bfd_target instead of the current |
| target, this will always produce an unrelocated value. */ |
| sym_addr = gdbarch_convert_from_func_ptr_addr |
| (current_inferior ()->arch (), sym_addr, |
| tmp_bfd_target.get ()); |
| |
| if (sym_addr != 0) |
| { |
| svr4_create_solib_event_breakpoints (info, |
| current_inferior ()->arch (), |
| load_addr + sym_addr); |
| return 1; |
| } |
| |
| /* For whatever reason we couldn't set a breakpoint in the dynamic |
| linker. Warn and drop into the old code. */ |
| bkpt_at_symbol: |
| warning (_("Unable to find dynamic linker breakpoint function.\n" |
| "GDB will be unable to debug shared library initializers\n" |
| "and track explicitly loaded dynamic code.")); |
| } |
| |
| /* Scan through the lists of symbols, trying to look up the symbol and |
| set a breakpoint there. Terminate loop when we/if we succeed. */ |
| |
| objfile *objf = current_program_space->symfile_object_file; |
| for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) |
| { |
| bound_minimal_symbol msymbol |
| = lookup_minimal_symbol (current_program_space, *bkpt_namep, objf); |
| if ((msymbol.minsym != NULL) |
| && (msymbol.value_address () != 0)) |
| { |
| sym_addr = msymbol.value_address (); |
| sym_addr = gdbarch_convert_from_func_ptr_addr |
| (current_inferior ()->arch (), sym_addr, |
| current_inferior ()->top_target ()); |
| svr4_create_solib_event_breakpoints (info, |
| current_inferior ()->arch (), |
| sym_addr); |
| return 1; |
| } |
| } |
| |
| if (interp_name_holder && !current_inferior ()->attach_flag) |
| { |
| for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) |
| { |
| bound_minimal_symbol msymbol |
| = lookup_minimal_symbol (current_program_space, *bkpt_namep, objf); |
| if ((msymbol.minsym != NULL) |
| && (msymbol.value_address () != 0)) |
| { |
| sym_addr = msymbol.value_address (); |
| sym_addr = gdbarch_convert_from_func_ptr_addr |
| (current_inferior ()->arch (), sym_addr, |
| current_inferior ()->top_target ()); |
| svr4_create_solib_event_breakpoints |
| (info, current_inferior ()->arch (), sym_addr); |
| return 1; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /* Read the ELF program headers from ABFD. */ |
| |
| static std::optional<gdb::byte_vector> |
| read_program_headers_from_bfd (bfd *abfd) |
| { |
| Elf_Internal_Ehdr *ehdr = elf_elfheader (abfd); |
| int phdrs_size = ehdr->e_phnum * ehdr->e_phentsize; |
| if (phdrs_size == 0) |
| return {}; |
| |
| gdb::byte_vector buf (phdrs_size); |
| if (bfd_seek (abfd, ehdr->e_phoff, SEEK_SET) != 0 |
| || bfd_read (buf.data (), phdrs_size, abfd) != phdrs_size) |
| return {}; |
| |
| return buf; |
| } |
| |
| /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior |
| exec_bfd. Otherwise return 0. |
| |
| We relocate all of the sections by the same amount. This |
| behavior is mandated by recent editions of the System V ABI. |
| According to the System V Application Binary Interface, |
| Edition 4.1, page 5-5: |
| |
| ... Though the system chooses virtual addresses for |
| individual processes, it maintains the segments' relative |
| positions. Because position-independent code uses relative |
| addressing between segments, the difference between |
| virtual addresses in memory must match the difference |
| between virtual addresses in the file. The difference |
| between the virtual address of any segment in memory and |
| the corresponding virtual address in the file is thus a |
| single constant value for any one executable or shared |
| object in a given process. This difference is the base |
| address. One use of the base address is to relocate the |
| memory image of the program during dynamic linking. |
| |
| The same language also appears in Edition 4.0 of the System V |
| ABI and is left unspecified in some of the earlier editions. |
| |
| Decide if the objfile needs to be relocated. As indicated above, we will |
| only be here when execution is stopped. But during attachment PC can be at |
| arbitrary address therefore regcache_read_pc can be misleading (contrary to |
| the auxv AT_ENTRY value). Moreover for executable with interpreter section |
| regcache_read_pc would point to the interpreter and not the main executable. |
| |
| So, to summarize, relocations are necessary when the start address obtained |
| from the executable is different from the address in auxv AT_ENTRY entry. |
| |
| [ The astute reader will note that we also test to make sure that |
| the executable in question has the DYNAMIC flag set. It is my |
| opinion that this test is unnecessary (undesirable even). It |
| was added to avoid inadvertent relocation of an executable |
| whose e_type member in the ELF header is not ET_DYN. There may |
| be a time in the future when it is desirable to do relocations |
| on other types of files as well in which case this condition |
| should either be removed or modified to accommodate the new file |
| type. - Kevin, Nov 2000. ] */ |
| |
| static int |
| svr4_exec_displacement (CORE_ADDR *displacementp) |
| { |
| /* ENTRY_POINT is a possible function descriptor - before |
| a call to gdbarch_convert_from_func_ptr_addr. */ |
| CORE_ADDR entry_point, exec_displacement; |
| |
| if (current_program_space->exec_bfd () == NULL) |
| return 0; |
| |
| /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries |
| being executed themselves and PIE (Position Independent Executable) |
| executables are ET_DYN. */ |
| |
| if ((bfd_get_file_flags (current_program_space->exec_bfd ()) & DYNAMIC) == 0) |
| return 0; |
| |
| if (target_auxv_search (AT_ENTRY, &entry_point) <= 0) |
| return 0; |
| |
| exec_displacement |
| = entry_point - bfd_get_start_address (current_program_space->exec_bfd ()); |
| |
| /* Verify the EXEC_DISPLACEMENT candidate complies with the required page |
| alignment. It is cheaper than the program headers comparison below. */ |
| |
| if (bfd_get_flavour (current_program_space->exec_bfd ()) |
| == bfd_target_elf_flavour) |
| { |
| const struct elf_backend_data *elf |
| = get_elf_backend_data (current_program_space->exec_bfd ()); |
| |
| /* p_align of PT_LOAD segments does not specify any alignment but |
| only congruency of addresses: |
| p_offset % p_align == p_vaddr % p_align |
| Kernel is free to load the executable with lower alignment. */ |
| |
| if ((exec_displacement & (elf->minpagesize - 1)) != 0) |
| return 0; |
| } |
| |
| /* Verify that the auxilliary vector describes the same file as exec_bfd, by |
| comparing their program headers. If the program headers in the auxilliary |
| vector do not match the program headers in the executable, then we are |
| looking at a different file than the one used by the kernel - for |
| instance, "gdb program" connected to "gdbserver :PORT ld.so program". */ |
| |
| if (bfd_get_flavour (current_program_space->exec_bfd ()) |
| == bfd_target_elf_flavour) |
| { |
| /* Be optimistic and return 0 only if GDB was able to verify the headers |
| really do not match. */ |
| int arch_size; |
| |
| std::optional<gdb::byte_vector> phdrs_target |
| = read_program_header (-1, &arch_size, NULL); |
| std::optional<gdb::byte_vector> phdrs_binary |
| = read_program_headers_from_bfd (current_program_space->exec_bfd ()); |
| if (phdrs_target && phdrs_binary) |
| { |
| bfd_endian byte_order = gdbarch_byte_order (current_inferior ()->arch ()); |
| |
| /* We are dealing with three different addresses. EXEC_BFD |
| represents current address in on-disk file. target memory content |
| may be different from EXEC_BFD as the file may have been prelinked |
| to a different address after the executable has been loaded. |
| Moreover the address of placement in target memory can be |
| different from what the program headers in target memory say - |
| this is the goal of PIE. |
| |
| Detected DISPLACEMENT covers both the offsets of PIE placement and |
| possible new prelink performed after start of the program. Here |
| relocate BUF and BUF2 just by the EXEC_BFD vs. target memory |
| content offset for the verification purpose. */ |
| |
| if (phdrs_target->size () != phdrs_binary->size () |
| || bfd_get_arch_size (current_program_space->exec_bfd ()) != arch_size) |
| return 0; |
| else if (arch_size == 32 |
| && phdrs_target->size () >= sizeof (Elf32_External_Phdr) |
| && phdrs_target->size () % sizeof (Elf32_External_Phdr) == 0) |
| { |
| Elf_Internal_Ehdr *ehdr2 |
| = elf_tdata (current_program_space->exec_bfd ())->elf_header; |
| Elf_Internal_Phdr *phdr2 |
| = elf_tdata (current_program_space->exec_bfd ())->phdr; |
| CORE_ADDR displacement = 0; |
| int i; |
| |
| /* DISPLACEMENT could be found more easily by the difference of |
| ehdr2->e_entry. But we haven't read the ehdr yet, and we |
| already have enough information to compute that displacement |
| with what we've read. */ |
| |
| for (i = 0; i < ehdr2->e_phnum; i++) |
| if (phdr2[i].p_type == PT_LOAD) |
| { |
| Elf32_External_Phdr *phdrp; |
| gdb_byte *buf_vaddr_p, *buf_paddr_p; |
| CORE_ADDR vaddr, paddr; |
| CORE_ADDR displacement_vaddr = 0; |
| CORE_ADDR displacement_paddr = 0; |
| |
| phdrp = &((Elf32_External_Phdr *) phdrs_target->data ())[i]; |
| buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr; |
| buf_paddr_p = (gdb_byte *) &phdrp->p_paddr; |
| |
| vaddr = extract_unsigned_integer (buf_vaddr_p, 4, |
| byte_order); |
| displacement_vaddr = vaddr - phdr2[i].p_vaddr; |
| |
| paddr = extract_unsigned_integer (buf_paddr_p, 4, |
| byte_order); |
| displacement_paddr = paddr - phdr2[i].p_paddr; |
| |
| if (displacement_vaddr == displacement_paddr) |
| displacement = displacement_vaddr; |
| |
| break; |
| } |
| |
| /* Now compare program headers from the target and the binary |
| with optional DISPLACEMENT. */ |
| |
| for (i = 0; |
| i < phdrs_target->size () / sizeof (Elf32_External_Phdr); |
| i++) |
| { |
| Elf32_External_Phdr *phdrp; |
| Elf32_External_Phdr *phdr2p; |
| gdb_byte *buf_vaddr_p, *buf_paddr_p; |
| CORE_ADDR vaddr, paddr; |
| asection *plt2_asect; |
| |
| phdrp = &((Elf32_External_Phdr *) phdrs_target->data ())[i]; |
| buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr; |
| buf_paddr_p = (gdb_byte *) &phdrp->p_paddr; |
| phdr2p = &((Elf32_External_Phdr *) phdrs_binary->data ())[i]; |
| |
| /* PT_GNU_STACK is an exception by being never relocated by |
| prelink as its addresses are always zero. */ |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| |
| /* Check also other adjustment combinations - PR 11786. */ |
| |
| vaddr = extract_unsigned_integer (buf_vaddr_p, 4, |
| byte_order); |
| vaddr -= displacement; |
| store_unsigned_integer (buf_vaddr_p, 4, byte_order, vaddr); |
| |
| paddr = extract_unsigned_integer (buf_paddr_p, 4, |
| byte_order); |
| paddr -= displacement; |
| store_unsigned_integer (buf_paddr_p, 4, byte_order, paddr); |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| |
| /* Strip modifies the flags and alignment of PT_GNU_RELRO. |
| CentOS-5 has problems with filesz, memsz as well. |
| Strip also modifies memsz of PT_TLS. |
| See PR 11786. */ |
| if (phdr2[i].p_type == PT_GNU_RELRO |
| || phdr2[i].p_type == PT_TLS) |
| { |
| Elf32_External_Phdr tmp_phdr = *phdrp; |
| Elf32_External_Phdr tmp_phdr2 = *phdr2p; |
| |
| memset (tmp_phdr.p_filesz, 0, 4); |
| memset (tmp_phdr.p_memsz, 0, 4); |
| memset (tmp_phdr.p_flags, 0, 4); |
| memset (tmp_phdr.p_align, 0, 4); |
| memset (tmp_phdr2.p_filesz, 0, 4); |
| memset (tmp_phdr2.p_memsz, 0, 4); |
| memset (tmp_phdr2.p_flags, 0, 4); |
| memset (tmp_phdr2.p_align, 0, 4); |
| |
| if (memcmp (&tmp_phdr, &tmp_phdr2, sizeof (tmp_phdr)) |
| == 0) |
| continue; |
| } |
| |
| /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */ |
| bfd *exec_bfd = current_program_space->exec_bfd (); |
| plt2_asect = bfd_get_section_by_name (exec_bfd, ".plt"); |
| if (plt2_asect) |
| { |
| int content2; |
| gdb_byte *buf_filesz_p = (gdb_byte *) &phdrp->p_filesz; |
| CORE_ADDR filesz; |
| |
| content2 = (bfd_section_flags (plt2_asect) |
| & SEC_HAS_CONTENTS) != 0; |
| |
| filesz = extract_unsigned_integer (buf_filesz_p, 4, |
| byte_order); |
| |
| /* PLT2_ASECT is from on-disk file (exec_bfd) while |
| FILESZ is from the in-memory image. */ |
| if (content2) |
| filesz += bfd_section_size (plt2_asect); |
| else |
| filesz -= bfd_section_size (plt2_asect); |
| |
| store_unsigned_integer (buf_filesz_p, 4, byte_order, |
| filesz); |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| } |
| |
| return 0; |
| } |
| } |
| else if (arch_size == 64 |
| && phdrs_target->size () >= sizeof (Elf64_External_Phdr) |
| && phdrs_target->size () % sizeof (Elf64_External_Phdr) == 0) |
| { |
| Elf_Internal_Ehdr *ehdr2 |
| = elf_tdata (current_program_space->exec_bfd ())->elf_header; |
| Elf_Internal_Phdr *phdr2 |
| = elf_tdata (current_program_space->exec_bfd ())->phdr; |
| CORE_ADDR displacement = 0; |
| int i; |
| |
| /* DISPLACEMENT could be found more easily by the difference of |
| ehdr2->e_entry. But we haven't read the ehdr yet, and we |
| already have enough information to compute that displacement |
| with what we've read. */ |
| |
| for (i = 0; i < ehdr2->e_phnum; i++) |
| if (phdr2[i].p_type == PT_LOAD) |
| { |
| Elf64_External_Phdr *phdrp; |
| gdb_byte *buf_vaddr_p, *buf_paddr_p; |
| CORE_ADDR vaddr, paddr; |
| CORE_ADDR displacement_vaddr = 0; |
| CORE_ADDR displacement_paddr = 0; |
| |
| phdrp = &((Elf64_External_Phdr *) phdrs_target->data ())[i]; |
| buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr; |
| buf_paddr_p = (gdb_byte *) &phdrp->p_paddr; |
| |
| vaddr = extract_unsigned_integer (buf_vaddr_p, 8, |
| byte_order); |
| displacement_vaddr = vaddr - phdr2[i].p_vaddr; |
| |
| paddr = extract_unsigned_integer (buf_paddr_p, 8, |
| byte_order); |
| displacement_paddr = paddr - phdr2[i].p_paddr; |
| |
| if (displacement_vaddr == displacement_paddr) |
| displacement = displacement_vaddr; |
| |
| break; |
| } |
| |
| /* Now compare BUF and BUF2 with optional DISPLACEMENT. */ |
| |
| for (i = 0; |
| i < phdrs_target->size () / sizeof (Elf64_External_Phdr); |
| i++) |
| { |
| Elf64_External_Phdr *phdrp; |
| Elf64_External_Phdr *phdr2p; |
| gdb_byte *buf_vaddr_p, *buf_paddr_p; |
| CORE_ADDR vaddr, paddr; |
| asection *plt2_asect; |
| |
| phdrp = &((Elf64_External_Phdr *) phdrs_target->data ())[i]; |
| buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr; |
| buf_paddr_p = (gdb_byte *) &phdrp->p_paddr; |
| phdr2p = &((Elf64_External_Phdr *) phdrs_binary->data ())[i]; |
| |
| /* PT_GNU_STACK is an exception by being never relocated by |
| prelink as its addresses are always zero. */ |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| |
| /* Check also other adjustment combinations - PR 11786. */ |
| |
| vaddr = extract_unsigned_integer (buf_vaddr_p, 8, |
| byte_order); |
| vaddr -= displacement; |
| store_unsigned_integer (buf_vaddr_p, 8, byte_order, vaddr); |
| |
| paddr = extract_unsigned_integer (buf_paddr_p, 8, |
| byte_order); |
| paddr -= displacement; |
| store_unsigned_integer (buf_paddr_p, 8, byte_order, paddr); |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| |
| /* Strip modifies the flags and alignment of PT_GNU_RELRO. |
| CentOS-5 has problems with filesz, memsz as well. |
| Strip also modifies memsz of PT_TLS. |
| See PR 11786. */ |
| if (phdr2[i].p_type == PT_GNU_RELRO |
| || phdr2[i].p_type == PT_TLS) |
| { |
| Elf64_External_Phdr tmp_phdr = *phdrp; |
| Elf64_External_Phdr tmp_phdr2 = *phdr2p; |
| |
| memset (tmp_phdr.p_filesz, 0, 8); |
| memset (tmp_phdr.p_memsz, 0, 8); |
| memset (tmp_phdr.p_flags, 0, 4); |
| memset (tmp_phdr.p_align, 0, 8); |
| memset (tmp_phdr2.p_filesz, 0, 8); |
| memset (tmp_phdr2.p_memsz, 0, 8); |
| memset (tmp_phdr2.p_flags, 0, 4); |
| memset (tmp_phdr2.p_align, 0, 8); |
| |
| if (memcmp (&tmp_phdr, &tmp_phdr2, sizeof (tmp_phdr)) |
| == 0) |
| continue; |
| } |
| |
| /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */ |
| plt2_asect |
| = bfd_get_section_by_name (current_program_space->exec_bfd (), |
| ".plt"); |
| if (plt2_asect) |
| { |
| int content2; |
| gdb_byte *buf_filesz_p = (gdb_byte *) &phdrp->p_filesz; |
| CORE_ADDR filesz; |
| |
| content2 = (bfd_section_flags (plt2_asect) |
| & SEC_HAS_CONTENTS) != 0; |
| |
| filesz = extract_unsigned_integer (buf_filesz_p, 8, |
| byte_order); |
| |
| /* PLT2_ASECT is from on-disk file (current |
| exec_bfd) while FILESZ is from the in-memory |
| image. */ |
| if (content2) |
| filesz += bfd_section_size (plt2_asect); |
| else |
| filesz -= bfd_section_size (plt2_asect); |
| |
| store_unsigned_integer (buf_filesz_p, 8, byte_order, |
| filesz); |
| |
| if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0) |
| continue; |
| } |
| |
| return 0; |
| } |
| } |
| else |
| return 0; |
| } |
| } |
| |
| if (info_verbose) |
| { |
| /* It can be printed repeatedly as there is no easy way to check |
| the executable symbols/file has been already relocated to |
| displacement. */ |
| |
| gdb_printf (_("Using PIE (Position Independent Executable) " |
| "displacement %s for \"%s\".\n"), |
| paddress (current_inferior ()->arch (), exec_displacement), |
| bfd_get_filename (current_program_space->exec_bfd ())); |
| } |
| |
| *displacementp = exec_displacement; |
| return 1; |
| } |
| |
| /* Relocate the main executable. This function should be called upon |
| stopping the inferior process at the entry point to the program. |
| The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are |
| different, the main executable is relocated by the proper amount. */ |
| |
| static void |
| svr4_relocate_main_executable (void) |
| { |
| CORE_ADDR displacement; |
| |
| /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS |
| probably contains the offsets computed using the PIE displacement |
| from the previous run, which of course are irrelevant for this run. |
| So we need to determine the new PIE displacement and recompute the |
| section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS |
| already contains pre-computed offsets. |
| |
| If we cannot compute the PIE displacement, either: |
| |
| - The executable is not PIE. |
| |
| - SYMFILE_OBJFILE does not match the executable started in the target. |
| This can happen for main executable symbols loaded at the host while |
| `ld.so --ld-args main-executable' is loaded in the target. |
| |
| Then we leave the section offsets untouched and use them as is for |
| this run. Either: |
| |
| - These section offsets were properly reset earlier, and thus |
| already contain the correct values. This can happen for instance |
| when reconnecting via the remote protocol to a target that supports |
| the `qOffsets' packet. |
| |
| - The section offsets were not reset earlier, and the best we can |
| hope is that the old offsets are still applicable to the new run. */ |
| |
| if (! svr4_exec_displacement (&displacement)) |
| return; |
| |
| /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file |
| addresses. */ |
| |
| objfile *objf = current_program_space->symfile_object_file; |
| if (objf) |
| { |
| section_offsets new_offsets (objf->section_offsets.size (), |
| displacement); |
| objfile_relocate (objf, new_offsets); |
| } |
| else if (current_program_space->exec_bfd ()) |
| { |
| asection *asect; |
| |
| bfd *exec_bfd = current_program_space->exec_bfd (); |
| for (asect = exec_bfd->sections; asect != NULL; asect = asect->next) |
| exec_set_section_address (bfd_get_filename (exec_bfd), asect->index, |
| bfd_section_vma (asect) + displacement); |
| } |
| } |
| |
| /* Implement the "create_inferior_hook" target_solib_ops method. |
| |
| For SVR4 executables, this first instruction is either the first |
| instruction in the dynamic linker (for dynamically linked |
| executables) or the instruction at "start" for statically linked |
| executables. For dynamically linked executables, the system |
| first exec's /lib/libc.so.N, which contains the dynamic linker, |
| and starts it running. The dynamic linker maps in any needed |
| shared libraries, maps in the actual user executable, and then |
| jumps to "start" in the user executable. |
| |
| We can arrange to cooperate with the dynamic linker to discover the |
| names of shared libraries that are dynamically linked, and the base |
| addresses to which they are linked. |
| |
| This function is responsible for discovering those names and |
| addresses, and saving sufficient information about them to allow |
| their symbols to be read at a later time. */ |
| |
| static void |
| svr4_solib_create_inferior_hook (int from_tty) |
| { |
| struct svr4_info *info; |
| |
| info = get_svr4_info (current_program_space); |
| |
| /* Clear the probes-based interface's state. */ |
| free_probes_table (info); |
| info->solib_lists.clear (); |
| |
| /* Relocate the main executable if necessary. */ |
| svr4_relocate_main_executable (); |
| |
| /* No point setting a breakpoint in the dynamic linker if we can't |
| hit it (e.g., a core file, or a trace file). */ |
| if (!target_has_execution ()) |
| return; |
| |
| if (!svr4_have_link_map_offsets ()) |
| return; |
| |
| if (!enable_break (info, from_tty)) |
| return; |
| } |
| |
| static void |
| svr4_clear_solib (program_space *pspace) |
| { |
| svr4_info *info = get_svr4_info (pspace); |
| info->debug_base = 0; |
| info->debug_loader_offset_p = 0; |
| info->debug_loader_offset = 0; |
| xfree (info->debug_loader_name); |
| info->debug_loader_name = NULL; |
| } |
| |
| /* Clear any bits of ADDR that wouldn't fit in a target-format |
| data pointer. "Data pointer" here refers to whatever sort of |
| address the dynamic linker uses to manage its sections. At the |
| moment, we don't support shared libraries on any processors where |
| code and data pointers are different sizes. |
| |
| This isn't really the right solution. What we really need here is |
| a way to do arithmetic on CORE_ADDR values that respects the |
| natural pointer/address correspondence. (For example, on the MIPS, |
| converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to |
| sign-extend the value. There, simply truncating the bits above |
| gdbarch_ptr_bit, as we do below, is no good.) This should probably |
| be a new gdbarch method or something. */ |
| static CORE_ADDR |
| svr4_truncate_ptr (CORE_ADDR addr) |
| { |
| if (gdbarch_ptr_bit (current_inferior ()->arch ()) == sizeof (CORE_ADDR) * 8) |
| /* We don't need to truncate anything, and the bit twiddling below |
| will fail due to overflow problems. */ |
| return addr; |
| else |
| return addr & (((CORE_ADDR) 1 << gdbarch_ptr_bit (current_inferior ()->arch ())) - 1); |
| } |
| |
| |
| static void |
| svr4_relocate_section_addresses (solib &so, target_section *sec) |
| { |
| bfd *abfd = sec->the_bfd_section->owner; |
| |
| sec->addr = svr4_truncate_ptr (sec->addr + lm_addr_check (so, abfd)); |
| sec->endaddr = svr4_truncate_ptr (sec->endaddr + lm_addr_check (so, abfd)); |
| } |
| |
| |
| /* Architecture-specific operations. */ |
| |
| struct solib_svr4_ops |
| { |
| /* Return a description of the layout of `struct link_map'. */ |
| struct link_map_offsets *(*fetch_link_map_offsets)(void) = nullptr; |
| }; |
| |
| /* Per-architecture data key. */ |
| static const registry<gdbarch>::key<struct solib_svr4_ops> solib_svr4_data; |
| |
| /* Return a default for the architecture-specific operations. */ |
| |
| static struct solib_svr4_ops * |
| get_ops (struct gdbarch *gdbarch) |
| { |
| struct solib_svr4_ops *ops = solib_svr4_data.get (gdbarch); |
| if (ops == nullptr) |
| ops = solib_svr4_data.emplace (gdbarch); |
| return ops; |
| } |
| |
| /* Set the architecture-specific `struct link_map_offsets' fetcher for |
| GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */ |
| |
| void |
| set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch, |
| struct link_map_offsets *(*flmo) (void)) |
| { |
| struct solib_svr4_ops *ops = get_ops (gdbarch); |
| |
| ops->fetch_link_map_offsets = flmo; |
| |
| set_gdbarch_so_ops (gdbarch, &svr4_so_ops); |
| set_gdbarch_iterate_over_objfiles_in_search_order |
| (gdbarch, svr4_iterate_over_objfiles_in_search_order); |
| } |
| |
| /* Fetch a link_map_offsets structure using the architecture-specific |
| `struct link_map_offsets' fetcher. */ |
| |
| static struct link_map_offsets * |
| svr4_fetch_link_map_offsets (void) |
| { |
| struct solib_svr4_ops *ops = get_ops (current_inferior ()->arch ()); |
| |
| gdb_assert (ops->fetch_link_map_offsets); |
| return ops->fetch_link_map_offsets (); |
| } |
| |
| /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */ |
| |
| static int |
| svr4_have_link_map_offsets (void) |
| { |
| struct solib_svr4_ops *ops = get_ops (current_inferior ()->arch ()); |
| |
| return (ops->fetch_link_map_offsets != NULL); |
| } |
| |
| |
| /* Most OS'es that have SVR4-style ELF dynamic libraries define a |
| `struct r_debug' and a `struct link_map' that are binary compatible |
| with the original SVR4 implementation. */ |
| |
| /* Fetch (and possibly build) an appropriate `struct link_map_offsets' |
| for an ILP32 SVR4 system. */ |
| |
| struct link_map_offsets * |
| svr4_ilp32_fetch_link_map_offsets (void) |
| { |
| static struct link_map_offsets lmo; |
| static struct link_map_offsets *lmp = NULL; |
| |
| if (lmp == NULL) |
| { |
| lmp = &lmo; |
| |
| lmo.r_version_offset = 0; |
| lmo.r_version_size = 4; |
| lmo.r_map_offset = 4; |
| lmo.r_brk_offset = 8; |
| lmo.r_ldsomap_offset = 20; |
| lmo.r_next_offset = -1; |
| |
| /* Everything we need is in the first 20 bytes. */ |
| lmo.link_map_size = 20; |
| lmo.l_addr_offset = 0; |
| lmo.l_name_offset = 4; |
| lmo.l_ld_offset = 8; |
| lmo.l_next_offset = 12; |
| lmo.l_prev_offset = 16; |
| } |
| |
| return lmp; |
| } |
| |
| /* Fetch (and possibly build) an appropriate `struct link_map_offsets' |
| for an LP64 SVR4 system. */ |
| |
| struct link_map_offsets * |
| svr4_lp64_fetch_link_map_offsets (void) |
| { |
| static struct link_map_offsets lmo; |
| static struct link_map_offsets *lmp = NULL; |
| |
| if (lmp == NULL) |
| { |
| lmp = &lmo; |
| |
| lmo.r_version_offset = 0; |
| lmo.r_version_size = 4; |
| lmo.r_map_offset = 8; |
| lmo.r_brk_offset = 16; |
| lmo.r_ldsomap_offset = 40; |
| lmo.r_next_offset = -1; |
| |
| /* Everything we need is in the first 40 bytes. */ |
| lmo.link_map_size = 40; |
| lmo.l_addr_offset = 0; |
| lmo.l_name_offset = 8; |
| lmo.l_ld_offset = 16; |
| lmo.l_next_offset = 24; |
| lmo.l_prev_offset = 32; |
| } |
| |
| return lmp; |
| } |
| |
| |
| /* Return the DSO matching OBJFILE or nullptr if none can be found. */ |
| |
| static const solib * |
| find_solib_for_objfile (struct objfile *objfile) |
| { |
| if (objfile == nullptr) |
| return nullptr; |
| |
| /* If OBJFILE is a separate debug object file, look for the original |
| object file. */ |
| if (objfile->separate_debug_objfile_backlink != nullptr) |
| objfile = objfile->separate_debug_objfile_backlink; |
| |
| for (const solib &so : current_program_space->solibs ()) |
| if (so.objfile == objfile) |
| return &so; |
| |
| return nullptr; |
| } |
| |
| /* Return the address of the r_debug object for the namespace containing |
| SOLIB or zero if it cannot be found. This may happen when symbol files |
| are added manually, for example, or with the main executable. |
| |
| Current callers treat zero as initial namespace so they are doing the |
| right thing for the main executable. */ |
| |
| static CORE_ADDR |
| find_debug_base_for_solib (const solib *solib) |
| { |
| if (solib == nullptr) |
| return 0; |
| |
| svr4_info *info = get_svr4_info (current_program_space); |
| gdb_assert (info != nullptr); |
| |
| auto *lm_info |
| = gdb::checked_static_cast<const lm_info_svr4 *> (solib->lm_info.get ()); |
| |
| for (const auto &tuple : info->solib_lists) |
| { |
| CORE_ADDR debug_base = tuple.first; |
| const std::vector<svr4_so> &sos = tuple.second; |
| |
| for (const svr4_so &so : sos) |
| if (svr4_same (solib->so_original_name.c_str (), so.name.c_str (), |
| *lm_info, *so.lm_info)) |
| return debug_base; |
| } |
| |
| return 0; |
| } |
| |
| /* Search order for ELF DSOs linked with -Bsymbolic. Those DSOs have a |
| different rule for symbol lookup. The lookup begins here in the DSO, |
| not in the main executable. When starting from CURRENT_OBJFILE, we |
| stay in the same namespace as that file. Otherwise, we only consider |
| the initial namespace. */ |
| |
| static void |
| svr4_iterate_over_objfiles_in_search_order |
| (gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype cb, |
| objfile *current_objfile) |
| { |
| bool checked_current_objfile = false; |
| if (current_objfile != nullptr) |
|
|