1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
4 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "elf/external.h"
25 #include "elf/common.h"
36 #include "gdbthread.h"
39 #include "gdb_assert.h"
43 #include "solib-svr4.h"
45 #include "bfd-target.h"
49 #include "exceptions.h"
51 static struct link_map_offsets *svr4_fetch_link_map_offsets (void);
52 static int svr4_have_link_map_offsets (void);
53 static void svr4_relocate_main_executable (void);
55 /* Link map info to include in an allocated so_list entry */
59 /* Pointer to copy of link map from inferior. The type is char *
60 rather than void *, so that we may use byte offsets to find the
61 various fields without the need for a cast. */
64 /* Amount by which addresses in the binary should be relocated to
65 match the inferior. This could most often be taken directly
66 from lm, but when prelinking is involved and the prelink base
67 address changes, we may need a different offset, we want to
68 warn about the difference and compute it only once. */
71 /* The target location of lm. */
75 /* On SVR4 systems, a list of symbols in the dynamic linker where
76 GDB can try to place a breakpoint to monitor shared library
79 If none of these symbols are found, or other errors occur, then
80 SVR4 systems will fall back to using a symbol as the "startup
81 mapping complete" breakpoint address. */
83 static char *solib_break_names[] =
89 "__dl_rtld_db_dlactivity",
95 static char *bkpt_names[] =
103 static char *main_name_list[] =
109 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
110 the same shared library. */
113 svr4_same_1 (const char *gdb_so_name, const char *inferior_so_name)
115 if (strcmp (gdb_so_name, inferior_so_name) == 0)
118 /* On Solaris, when starting inferior we think that dynamic linker is
119 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
120 contains /lib/ld.so.1. Sometimes one file is a link to another, but
121 sometimes they have identical content, but are not linked to each
122 other. We don't restrict this check for Solaris, but the chances
123 of running into this situation elsewhere are very low. */
124 if (strcmp (gdb_so_name, "/usr/lib/ld.so.1") == 0
125 && strcmp (inferior_so_name, "/lib/ld.so.1") == 0)
128 /* Similarly, we observed the same issue with sparc64, but with
129 different locations. */
130 if (strcmp (gdb_so_name, "/usr/lib/sparcv9/ld.so.1") == 0
131 && strcmp (inferior_so_name, "/lib/sparcv9/ld.so.1") == 0)
138 svr4_same (struct so_list *gdb, struct so_list *inferior)
140 return (svr4_same_1 (gdb->so_original_name, inferior->so_original_name));
143 /* link map access functions */
146 LM_ADDR_FROM_LINK_MAP (struct so_list *so)
148 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
149 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
151 return extract_typed_address (so->lm_info->lm + lmo->l_addr_offset,
156 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
158 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
160 return lmo->l_ld_offset >= 0;
164 LM_DYNAMIC_FROM_LINK_MAP (struct so_list *so)
166 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
167 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
169 return extract_typed_address (so->lm_info->lm + lmo->l_ld_offset,
174 LM_ADDR_CHECK (struct so_list *so, bfd *abfd)
176 if (so->lm_info->l_addr == (CORE_ADDR)-1)
178 struct bfd_section *dyninfo_sect;
179 CORE_ADDR l_addr, l_dynaddr, dynaddr, align = 0x1000;
181 l_addr = LM_ADDR_FROM_LINK_MAP (so);
183 if (! abfd || ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
186 l_dynaddr = LM_DYNAMIC_FROM_LINK_MAP (so);
188 dyninfo_sect = bfd_get_section_by_name (abfd, ".dynamic");
189 if (dyninfo_sect == NULL)
192 dynaddr = bfd_section_vma (abfd, dyninfo_sect);
194 if (dynaddr + l_addr != l_dynaddr)
196 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
198 Elf_Internal_Ehdr *ehdr = elf_tdata (abfd)->elf_header;
199 Elf_Internal_Phdr *phdr = elf_tdata (abfd)->phdr;
204 for (i = 0; i < ehdr->e_phnum; i++)
205 if (phdr[i].p_type == PT_LOAD && phdr[i].p_align > align)
206 align = phdr[i].p_align;
209 /* Turn it into a mask. */
212 /* If the changes match the alignment requirements, we
213 assume we're using a core file that was generated by the
214 same binary, just prelinked with a different base offset.
215 If it doesn't match, we may have a different binary, the
216 same binary with the dynamic table loaded at an unrelated
217 location, or anything, really. To avoid regressions,
218 don't adjust the base offset in the latter case, although
219 odds are that, if things really changed, debugging won't
221 if ((l_addr & align) == ((l_dynaddr - dynaddr) & align))
223 l_addr = l_dynaddr - dynaddr;
225 warning (_(".dynamic section for \"%s\" "
226 "is not at the expected address"), so->so_name);
227 warning (_("difference appears to be caused by prelink, "
228 "adjusting expectations"));
231 warning (_(".dynamic section for \"%s\" "
232 "is not at the expected address "
233 "(wrong library or version mismatch?)"), so->so_name);
237 so->lm_info->l_addr = l_addr;
240 return so->lm_info->l_addr;
244 LM_NEXT (struct so_list *so)
246 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
247 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
249 return extract_typed_address (so->lm_info->lm + lmo->l_next_offset,
254 LM_NAME (struct so_list *so)
256 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
257 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
259 return extract_typed_address (so->lm_info->lm + lmo->l_name_offset,
264 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so)
266 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
267 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
269 /* Assume that everything is a library if the dynamic loader was loaded
270 late by a static executable. */
271 if (exec_bfd && bfd_get_section_by_name (exec_bfd, ".dynamic") == NULL)
274 return extract_typed_address (so->lm_info->lm + lmo->l_prev_offset,
278 /* Per pspace SVR4 specific data. */
282 CORE_ADDR debug_base; /* Base of dynamic linker structures */
284 /* Validity flag for debug_loader_offset. */
285 int debug_loader_offset_p;
287 /* Load address for the dynamic linker, inferred. */
288 CORE_ADDR debug_loader_offset;
290 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
291 char *debug_loader_name;
293 /* Load map address for the main executable. */
294 CORE_ADDR main_lm_addr;
296 CORE_ADDR interp_text_sect_low;
297 CORE_ADDR interp_text_sect_high;
298 CORE_ADDR interp_plt_sect_low;
299 CORE_ADDR interp_plt_sect_high;
302 /* Per-program-space data key. */
303 static const struct program_space_data *solib_svr4_pspace_data;
306 svr4_pspace_data_cleanup (struct program_space *pspace, void *arg)
308 struct svr4_info *info;
310 info = program_space_data (pspace, solib_svr4_pspace_data);
314 /* Get the current svr4 data. If none is found yet, add it now. This
315 function always returns a valid object. */
317 static struct svr4_info *
320 struct svr4_info *info;
322 info = program_space_data (current_program_space, solib_svr4_pspace_data);
326 info = XZALLOC (struct svr4_info);
327 set_program_space_data (current_program_space, solib_svr4_pspace_data, info);
331 /* Local function prototypes */
333 static int match_main (char *);
335 static CORE_ADDR bfd_lookup_symbol (bfd *, char *);
341 bfd_lookup_symbol -- lookup the value for a specific symbol
345 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
349 An expensive way to lookup the value of a single symbol for
350 bfd's that are only temporary anyway. This is used by the
351 shared library support to find the address of the debugger
352 notification routine in the shared library.
354 The returned symbol may be in a code or data section; functions
355 will normally be in a code section, but may be in a data section
356 if this architecture uses function descriptors.
358 Note that 0 is specifically allowed as an error return (no
363 bfd_lookup_symbol (bfd *abfd, char *symname)
367 asymbol **symbol_table;
368 unsigned int number_of_symbols;
370 struct cleanup *back_to;
371 CORE_ADDR symaddr = 0;
373 storage_needed = bfd_get_symtab_upper_bound (abfd);
375 if (storage_needed > 0)
377 symbol_table = (asymbol **) xmalloc (storage_needed);
378 back_to = make_cleanup (xfree, symbol_table);
379 number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
381 for (i = 0; i < number_of_symbols; i++)
383 sym = *symbol_table++;
384 if (strcmp (sym->name, symname) == 0
385 && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0)
387 /* BFD symbols are section relative. */
388 symaddr = sym->value + sym->section->vma;
392 do_cleanups (back_to);
398 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
399 have to check the dynamic string table too. */
401 storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd);
403 if (storage_needed > 0)
405 symbol_table = (asymbol **) xmalloc (storage_needed);
406 back_to = make_cleanup (xfree, symbol_table);
407 number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table);
409 for (i = 0; i < number_of_symbols; i++)
411 sym = *symbol_table++;
413 if (strcmp (sym->name, symname) == 0
414 && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0)
416 /* BFD symbols are section relative. */
417 symaddr = sym->value + sym->section->vma;
421 do_cleanups (back_to);
428 /* Read program header TYPE from inferior memory. The header is found
429 by scanning the OS auxillary vector.
431 Return a pointer to allocated memory holding the program header contents,
432 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
433 size of those contents is returned to P_SECT_SIZE. Likewise, the target
434 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
437 read_program_header (int type, int *p_sect_size, int *p_arch_size)
439 enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
440 CORE_ADDR at_phdr, at_phent, at_phnum;
441 int arch_size, sect_size;
445 /* Get required auxv elements from target. */
446 if (target_auxv_search (¤t_target, AT_PHDR, &at_phdr) <= 0)
448 if (target_auxv_search (¤t_target, AT_PHENT, &at_phent) <= 0)
450 if (target_auxv_search (¤t_target, AT_PHNUM, &at_phnum) <= 0)
452 if (!at_phdr || !at_phnum)
455 /* Determine ELF architecture type. */
456 if (at_phent == sizeof (Elf32_External_Phdr))
458 else if (at_phent == sizeof (Elf64_External_Phdr))
463 /* Find .dynamic section via the PT_DYNAMIC PHDR. */
466 Elf32_External_Phdr phdr;
469 /* Search for requested PHDR. */
470 for (i = 0; i < at_phnum; i++)
472 if (target_read_memory (at_phdr + i * sizeof (phdr),
473 (gdb_byte *)&phdr, sizeof (phdr)))
476 if (extract_unsigned_integer ((gdb_byte *)phdr.p_type,
477 4, byte_order) == type)
484 /* Retrieve address and size. */
485 sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr,
487 sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz,
492 Elf64_External_Phdr phdr;
495 /* Search for requested PHDR. */
496 for (i = 0; i < at_phnum; i++)
498 if (target_read_memory (at_phdr + i * sizeof (phdr),
499 (gdb_byte *)&phdr, sizeof (phdr)))
502 if (extract_unsigned_integer ((gdb_byte *)phdr.p_type,
503 4, byte_order) == type)
510 /* Retrieve address and size. */
511 sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr,
513 sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz,
517 /* Read in requested program header. */
518 buf = xmalloc (sect_size);
519 if (target_read_memory (sect_addr, buf, sect_size))
526 *p_arch_size = arch_size;
528 *p_sect_size = sect_size;
534 /* Return program interpreter string. */
536 find_program_interpreter (void)
538 gdb_byte *buf = NULL;
540 /* If we have an exec_bfd, use its section table. */
542 && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)
544 struct bfd_section *interp_sect;
546 interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
547 if (interp_sect != NULL)
549 CORE_ADDR sect_addr = bfd_section_vma (exec_bfd, interp_sect);
550 int sect_size = bfd_section_size (exec_bfd, interp_sect);
552 buf = xmalloc (sect_size);
553 bfd_get_section_contents (exec_bfd, interp_sect, buf, 0, sect_size);
557 /* If we didn't find it, use the target auxillary vector. */
559 buf = read_program_header (PT_INTERP, NULL, NULL);
565 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
566 returned and the corresponding PTR is set. */
569 scan_dyntag (int dyntag, bfd *abfd, CORE_ADDR *ptr)
571 int arch_size, step, sect_size;
573 CORE_ADDR dyn_ptr, dyn_addr;
574 gdb_byte *bufend, *bufstart, *buf;
575 Elf32_External_Dyn *x_dynp_32;
576 Elf64_External_Dyn *x_dynp_64;
577 struct bfd_section *sect;
578 struct target_section *target_section;
583 if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
586 arch_size = bfd_get_arch_size (abfd);
590 /* Find the start address of the .dynamic section. */
591 sect = bfd_get_section_by_name (abfd, ".dynamic");
595 for (target_section = current_target_sections->sections;
596 target_section < current_target_sections->sections_end;
598 if (sect == target_section->the_bfd_section)
600 if (target_section < current_target_sections->sections_end)
601 dyn_addr = target_section->addr;
604 /* ABFD may come from OBJFILE acting only as a symbol file without being
605 loaded into the target (see add_symbol_file_command). This case is
606 such fallback to the file VMA address without the possibility of
607 having the section relocated to its actual in-memory address. */
609 dyn_addr = bfd_section_vma (abfd, sect);
612 /* Read in .dynamic from the BFD. We will get the actual value
613 from memory later. */
614 sect_size = bfd_section_size (abfd, sect);
615 buf = bufstart = alloca (sect_size);
616 if (!bfd_get_section_contents (abfd, sect,
620 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
621 step = (arch_size == 32) ? sizeof (Elf32_External_Dyn)
622 : sizeof (Elf64_External_Dyn);
623 for (bufend = buf + sect_size;
629 x_dynp_32 = (Elf32_External_Dyn *) buf;
630 dyn_tag = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp_32->d_tag);
631 dyn_ptr = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp_32->d_un.d_ptr);
635 x_dynp_64 = (Elf64_External_Dyn *) buf;
636 dyn_tag = bfd_h_get_64 (abfd, (bfd_byte *) x_dynp_64->d_tag);
637 dyn_ptr = bfd_h_get_64 (abfd, (bfd_byte *) x_dynp_64->d_un.d_ptr);
639 if (dyn_tag == DT_NULL)
641 if (dyn_tag == dyntag)
643 /* If requested, try to read the runtime value of this .dynamic
647 struct type *ptr_type;
651 ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
652 ptr_addr = dyn_addr + (buf - bufstart) + arch_size / 8;
653 if (target_read_memory (ptr_addr, ptr_buf, arch_size / 8) == 0)
654 dyn_ptr = extract_typed_address (ptr_buf, ptr_type);
664 /* Scan for DYNTAG in .dynamic section of the target's main executable,
665 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
666 returned and the corresponding PTR is set. */
669 scan_dyntag_auxv (int dyntag, CORE_ADDR *ptr)
671 enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
672 int sect_size, arch_size, step;
675 gdb_byte *bufend, *bufstart, *buf;
677 /* Read in .dynamic section. */
678 buf = bufstart = read_program_header (PT_DYNAMIC, §_size, &arch_size);
682 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
683 step = (arch_size == 32) ? sizeof (Elf32_External_Dyn)
684 : sizeof (Elf64_External_Dyn);
685 for (bufend = buf + sect_size;
691 Elf32_External_Dyn *dynp = (Elf32_External_Dyn *) buf;
692 dyn_tag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag,
694 dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr,
699 Elf64_External_Dyn *dynp = (Elf64_External_Dyn *) buf;
700 dyn_tag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag,
702 dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr,
705 if (dyn_tag == DT_NULL)
708 if (dyn_tag == dyntag)
727 elf_locate_base -- locate the base address of dynamic linker structs
728 for SVR4 elf targets.
732 CORE_ADDR elf_locate_base (void)
736 For SVR4 elf targets the address of the dynamic linker's runtime
737 structure is contained within the dynamic info section in the
738 executable file. The dynamic section is also mapped into the
739 inferior address space. Because the runtime loader fills in the
740 real address before starting the inferior, we have to read in the
741 dynamic info section from the inferior address space.
742 If there are any errors while trying to find the address, we
743 silently return 0, otherwise the found address is returned.
748 elf_locate_base (void)
750 struct minimal_symbol *msymbol;
753 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
754 instead of DT_DEBUG, although they sometimes contain an unused
756 if (scan_dyntag (DT_MIPS_RLD_MAP, exec_bfd, &dyn_ptr)
757 || scan_dyntag_auxv (DT_MIPS_RLD_MAP, &dyn_ptr))
759 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
761 int pbuf_size = TYPE_LENGTH (ptr_type);
762 pbuf = alloca (pbuf_size);
763 /* DT_MIPS_RLD_MAP contains a pointer to the address
764 of the dynamic link structure. */
765 if (target_read_memory (dyn_ptr, pbuf, pbuf_size))
767 return extract_typed_address (pbuf, ptr_type);
771 if (scan_dyntag (DT_DEBUG, exec_bfd, &dyn_ptr)
772 || scan_dyntag_auxv (DT_DEBUG, &dyn_ptr))
775 /* This may be a static executable. Look for the symbol
776 conventionally named _r_debug, as a last resort. */
777 msymbol = lookup_minimal_symbol ("_r_debug", NULL, symfile_objfile);
779 return SYMBOL_VALUE_ADDRESS (msymbol);
781 /* DT_DEBUG entry not found. */
789 locate_base -- locate the base address of dynamic linker structs
793 CORE_ADDR locate_base (struct svr4_info *)
797 For both the SunOS and SVR4 shared library implementations, if the
798 inferior executable has been linked dynamically, there is a single
799 address somewhere in the inferior's data space which is the key to
800 locating all of the dynamic linker's runtime structures. This
801 address is the value of the debug base symbol. The job of this
802 function is to find and return that address, or to return 0 if there
803 is no such address (the executable is statically linked for example).
805 For SunOS, the job is almost trivial, since the dynamic linker and
806 all of it's structures are statically linked to the executable at
807 link time. Thus the symbol for the address we are looking for has
808 already been added to the minimal symbol table for the executable's
809 objfile at the time the symbol file's symbols were read, and all we
810 have to do is look it up there. Note that we explicitly do NOT want
811 to find the copies in the shared library.
813 The SVR4 version is a bit more complicated because the address
814 is contained somewhere in the dynamic info section. We have to go
815 to a lot more work to discover the address of the debug base symbol.
816 Because of this complexity, we cache the value we find and return that
817 value on subsequent invocations. Note there is no copy in the
818 executable symbol tables.
823 locate_base (struct svr4_info *info)
825 /* Check to see if we have a currently valid address, and if so, avoid
826 doing all this work again and just return the cached address. If
827 we have no cached address, try to locate it in the dynamic info
828 section for ELF executables. There's no point in doing any of this
829 though if we don't have some link map offsets to work with. */
831 if (info->debug_base == 0 && svr4_have_link_map_offsets ())
832 info->debug_base = elf_locate_base ();
833 return info->debug_base;
836 /* Find the first element in the inferior's dynamic link map, and
837 return its address in the inferior.
839 FIXME: Perhaps we should validate the info somehow, perhaps by
840 checking r_version for a known version number, or r_state for
844 solib_svr4_r_map (struct svr4_info *info)
846 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
847 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
849 return read_memory_typed_address (info->debug_base + lmo->r_map_offset,
853 /* Find r_brk from the inferior's debug base. */
856 solib_svr4_r_brk (struct svr4_info *info)
858 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
859 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
861 return read_memory_typed_address (info->debug_base + lmo->r_brk_offset,
865 /* Find the link map for the dynamic linker (if it is not in the
866 normal list of loaded shared objects). */
869 solib_svr4_r_ldsomap (struct svr4_info *info)
871 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
872 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
873 enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
876 /* Check version, and return zero if `struct r_debug' doesn't have
877 the r_ldsomap member. */
879 = read_memory_unsigned_integer (info->debug_base + lmo->r_version_offset,
880 lmo->r_version_size, byte_order);
881 if (version < 2 || lmo->r_ldsomap_offset == -1)
884 return read_memory_typed_address (info->debug_base + lmo->r_ldsomap_offset,
888 /* On Solaris systems with some versions of the dynamic linker,
889 ld.so's l_name pointer points to the SONAME in the string table
890 rather than into writable memory. So that GDB can find shared
891 libraries when loading a core file generated by gcore, ensure that
892 memory areas containing the l_name string are saved in the core
896 svr4_keep_data_in_core (CORE_ADDR vaddr, unsigned long size)
898 struct svr4_info *info;
901 struct cleanup *old_chain;
902 struct link_map_offsets *lmo;
905 info = get_svr4_info ();
907 info->debug_base = 0;
909 if (!info->debug_base)
912 ldsomap = solib_svr4_r_ldsomap (info);
916 lmo = svr4_fetch_link_map_offsets ();
917 new = XZALLOC (struct so_list);
918 old_chain = make_cleanup (xfree, new);
919 new->lm_info = xmalloc (sizeof (struct lm_info));
920 make_cleanup (xfree, new->lm_info);
921 new->lm_info->l_addr = (CORE_ADDR)-1;
922 new->lm_info->lm_addr = ldsomap;
923 new->lm_info->lm = xzalloc (lmo->link_map_size);
924 make_cleanup (xfree, new->lm_info->lm);
925 read_memory (ldsomap, new->lm_info->lm, lmo->link_map_size);
926 lm_name = LM_NAME (new);
927 do_cleanups (old_chain);
929 return (lm_name >= vaddr && lm_name < vaddr + size);
936 open_symbol_file_object
940 void open_symbol_file_object (void *from_tty)
944 If no open symbol file, attempt to locate and open the main symbol
945 file. On SVR4 systems, this is the first link map entry. If its
946 name is here, we can open it. Useful when attaching to a process
947 without first loading its symbol file.
949 If FROM_TTYP dereferences to a non-zero integer, allow messages to
950 be printed. This parameter is a pointer rather than an int because
951 open_symbol_file_object() is called via catch_errors() and
952 catch_errors() requires a pointer argument. */
955 open_symbol_file_object (void *from_ttyp)
957 CORE_ADDR lm, l_name;
960 int from_tty = *(int *)from_ttyp;
961 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
962 struct type *ptr_type = builtin_type (target_gdbarch)->builtin_data_ptr;
963 int l_name_size = TYPE_LENGTH (ptr_type);
964 gdb_byte *l_name_buf = xmalloc (l_name_size);
965 struct cleanup *cleanups = make_cleanup (xfree, l_name_buf);
966 struct svr4_info *info = get_svr4_info ();
969 if (!query (_("Attempt to reload symbols from process? ")))
972 /* Always locate the debug struct, in case it has moved. */
973 info->debug_base = 0;
974 if (locate_base (info) == 0)
975 return 0; /* failed somehow... */
977 /* First link map member should be the executable. */
978 lm = solib_svr4_r_map (info);
980 return 0; /* failed somehow... */
982 /* Read address of name from target memory to GDB. */
983 read_memory (lm + lmo->l_name_offset, l_name_buf, l_name_size);
985 /* Convert the address to host format. */
986 l_name = extract_typed_address (l_name_buf, ptr_type);
988 /* Free l_name_buf. */
989 do_cleanups (cleanups);
992 return 0; /* No filename. */
994 /* Now fetch the filename from target memory. */
995 target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode);
996 make_cleanup (xfree, filename);
1000 warning (_("failed to read exec filename from attached file: %s"),
1001 safe_strerror (errcode));
1005 /* Have a pathname: read the symbol file. */
1006 symbol_file_add_main (filename, from_tty);
1011 /* If no shared library information is available from the dynamic
1012 linker, build a fallback list from other sources. */
1014 static struct so_list *
1015 svr4_default_sos (void)
1017 struct svr4_info *info = get_svr4_info ();
1019 struct so_list *head = NULL;
1020 struct so_list **link_ptr = &head;
1022 if (info->debug_loader_offset_p)
1024 struct so_list *new = XZALLOC (struct so_list);
1026 new->lm_info = xmalloc (sizeof (struct lm_info));
1028 /* Nothing will ever check the cached copy of the link
1029 map if we set l_addr. */
1030 new->lm_info->l_addr = info->debug_loader_offset;
1031 new->lm_info->lm_addr = 0;
1032 new->lm_info->lm = NULL;
1034 strncpy (new->so_name, info->debug_loader_name,
1035 SO_NAME_MAX_PATH_SIZE - 1);
1036 new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
1037 strcpy (new->so_original_name, new->so_name);
1040 link_ptr = &new->next;
1048 current_sos -- build a list of currently loaded shared objects
1052 struct so_list *current_sos ()
1056 Build a list of `struct so_list' objects describing the shared
1057 objects currently loaded in the inferior. This list does not
1058 include an entry for the main executable file.
1060 Note that we only gather information directly available from the
1061 inferior --- we don't examine any of the shared library files
1062 themselves. The declaration of `struct so_list' says which fields
1063 we provide values for. */
1065 static struct so_list *
1066 svr4_current_sos (void)
1069 struct so_list *head = 0;
1070 struct so_list **link_ptr = &head;
1071 CORE_ADDR ldsomap = 0;
1072 struct svr4_info *info;
1074 info = get_svr4_info ();
1076 /* Always locate the debug struct, in case it has moved. */
1077 info->debug_base = 0;
1080 /* If we can't find the dynamic linker's base structure, this
1081 must not be a dynamically linked executable. Hmm. */
1082 if (! info->debug_base)
1083 return svr4_default_sos ();
1085 /* Walk the inferior's link map list, and build our list of
1086 `struct so_list' nodes. */
1087 lm = solib_svr4_r_map (info);
1091 struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
1092 struct so_list *new = XZALLOC (struct so_list);
1093 struct cleanup *old_chain = make_cleanup (xfree, new);
1095 new->lm_info = xmalloc (sizeof (struct lm_info));
1096 make_cleanup (xfree, new->lm_info);
1098 new->lm_info->l_addr = (CORE_ADDR)-1;
1099 new->lm_info->lm_addr = lm;
1100 new->lm_info->lm = xzalloc (lmo->link_map_size);
1101 make_cleanup (xfree, new->lm_info->lm);
1103 read_memory (lm, new->lm_info->lm, lmo->link_map_size);
1107 /* For SVR4 versions, the first entry in the link map is for the
1108 inferior executable, so we must ignore it. For some versions of
1109 SVR4, it has no name. For others (Solaris 2.3 for example), it
1110 does have a name, so we can no longer use a missing name to
1111 decide when to ignore it. */
1112 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap == 0)
1114 info->main_lm_addr = new->lm_info->lm_addr;
1122 /* Extract this shared object's name. */
1123 target_read_string (LM_NAME (new), &buffer,
1124 SO_NAME_MAX_PATH_SIZE - 1, &errcode);
1126 warning (_("Can't read pathname for load map: %s."),
1127 safe_strerror (errcode));
1130 strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);
1131 new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
1132 strcpy (new->so_original_name, new->so_name);
1136 /* If this entry has no name, or its name matches the name
1137 for the main executable, don't include it in the list. */
1138 if (! new->so_name[0]
1139 || match_main (new->so_name))
1145 link_ptr = &new->next;
1149 /* On Solaris, the dynamic linker is not in the normal list of
1150 shared objects, so make sure we pick it up too. Having
1151 symbol information for the dynamic linker is quite crucial
1152 for skipping dynamic linker resolver code. */
1153 if (lm == 0 && ldsomap == 0)
1154 lm = ldsomap = solib_svr4_r_ldsomap (info);
1156 discard_cleanups (old_chain);
1160 return svr4_default_sos ();
1165 /* Get the address of the link_map for a given OBJFILE. */
1168 svr4_fetch_objfile_link_map (struct objfile *objfile)
1171 struct svr4_info *info = get_svr4_info ();
1173 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1174 if (info->main_lm_addr == 0)
1175 solib_add (NULL, 0, ¤t_target, auto_solib_add);
1177 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1178 if (objfile == symfile_objfile)
1179 return info->main_lm_addr;
1181 /* The other link map addresses may be found by examining the list
1182 of shared libraries. */
1183 for (so = master_so_list (); so; so = so->next)
1184 if (so->objfile == objfile)
1185 return so->lm_info->lm_addr;
1191 /* On some systems, the only way to recognize the link map entry for
1192 the main executable file is by looking at its name. Return
1193 non-zero iff SONAME matches one of the known main executable names. */
1196 match_main (char *soname)
1200 for (mainp = main_name_list; *mainp != NULL; mainp++)
1202 if (strcmp (soname, *mainp) == 0)
1209 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1210 SVR4 run time loader. */
1213 svr4_in_dynsym_resolve_code (CORE_ADDR pc)
1215 struct svr4_info *info = get_svr4_info ();
1217 return ((pc >= info->interp_text_sect_low
1218 && pc < info->interp_text_sect_high)
1219 || (pc >= info->interp_plt_sect_low
1220 && pc < info->interp_plt_sect_high)
1221 || in_plt_section (pc, NULL));
1224 /* Given an executable's ABFD and target, compute the entry-point
1228 exec_entry_point (struct bfd *abfd, struct target_ops *targ)
1230 /* KevinB wrote ... for most targets, the address returned by
1231 bfd_get_start_address() is the entry point for the start
1232 function. But, for some targets, bfd_get_start_address() returns
1233 the address of a function descriptor from which the entry point
1234 address may be extracted. This address is extracted by
1235 gdbarch_convert_from_func_ptr_addr(). The method
1236 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1237 function for targets which don't use function descriptors. */
1238 return gdbarch_convert_from_func_ptr_addr (target_gdbarch,
1239 bfd_get_start_address (abfd),
1247 enable_break -- arrange for dynamic linker to hit breakpoint
1251 int enable_break (void)
1255 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1256 debugger interface, support for arranging for the inferior to hit
1257 a breakpoint after mapping in the shared libraries. This function
1258 enables that breakpoint.
1260 For SunOS, there is a special flag location (in_debugger) which we
1261 set to 1. When the dynamic linker sees this flag set, it will set
1262 a breakpoint at a location known only to itself, after saving the
1263 original contents of that place and the breakpoint address itself,
1264 in it's own internal structures. When we resume the inferior, it
1265 will eventually take a SIGTRAP when it runs into the breakpoint.
1266 We handle this (in a different place) by restoring the contents of
1267 the breakpointed location (which is only known after it stops),
1268 chasing around to locate the shared libraries that have been
1269 loaded, then resuming.
1271 For SVR4, the debugger interface structure contains a member (r_brk)
1272 which is statically initialized at the time the shared library is
1273 built, to the offset of a function (_r_debug_state) which is guaran-
1274 teed to be called once before mapping in a library, and again when
1275 the mapping is complete. At the time we are examining this member,
1276 it contains only the unrelocated offset of the function, so we have
1277 to do our own relocation. Later, when the dynamic linker actually
1278 runs, it relocates r_brk to be the actual address of _r_debug_state().
1280 The debugger interface structure also contains an enumeration which
1281 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1282 depending upon whether or not the library is being mapped or unmapped,
1283 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1287 enable_break (struct svr4_info *info, int from_tty)
1289 struct minimal_symbol *msymbol;
1291 asection *interp_sect;
1292 gdb_byte *interp_name;
1295 /* First, remove all the solib event breakpoints. Their addresses
1296 may have changed since the last time we ran the program. */
1297 remove_solib_event_breakpoints ();
1299 info->interp_text_sect_low = info->interp_text_sect_high = 0;
1300 info->interp_plt_sect_low = info->interp_plt_sect_high = 0;
1302 /* If we already have a shared library list in the target, and
1303 r_debug contains r_brk, set the breakpoint there - this should
1304 mean r_brk has already been relocated. Assume the dynamic linker
1305 is the object containing r_brk. */
1307 solib_add (NULL, from_tty, ¤t_target, auto_solib_add);
1309 if (info->debug_base && solib_svr4_r_map (info) != 0)
1310 sym_addr = solib_svr4_r_brk (info);
1314 struct obj_section *os;
1316 sym_addr = gdbarch_addr_bits_remove
1317 (target_gdbarch, gdbarch_convert_from_func_ptr_addr (target_gdbarch,
1321 os = find_pc_section (sym_addr);
1324 /* Record the relocated start and end address of the dynamic linker
1325 text and plt section for svr4_in_dynsym_resolve_code. */
1327 CORE_ADDR load_addr;
1329 tmp_bfd = os->objfile->obfd;
1330 load_addr = ANOFFSET (os->objfile->section_offsets,
1331 os->objfile->sect_index_text);
1333 interp_sect = bfd_get_section_by_name (tmp_bfd, ".text");
1336 info->interp_text_sect_low =
1337 bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
1338 info->interp_text_sect_high =
1339 info->interp_text_sect_low
1340 + bfd_section_size (tmp_bfd, interp_sect);
1342 interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt");
1345 info->interp_plt_sect_low =
1346 bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
1347 info->interp_plt_sect_high =
1348 info->interp_plt_sect_low
1349 + bfd_section_size (tmp_bfd, interp_sect);
1352 create_solib_event_breakpoint (target_gdbarch, sym_addr);
1357 /* Find the program interpreter; if not found, warn the user and drop
1358 into the old breakpoint at symbol code. */
1359 interp_name = find_program_interpreter ();
1362 CORE_ADDR load_addr = 0;
1363 int load_addr_found = 0;
1364 int loader_found_in_list = 0;
1366 bfd *tmp_bfd = NULL;
1367 struct target_ops *tmp_bfd_target;
1368 volatile struct gdb_exception ex;
1372 /* Now we need to figure out where the dynamic linker was
1373 loaded so that we can load its symbols and place a breakpoint
1374 in the dynamic linker itself.
1376 This address is stored on the stack. However, I've been unable
1377 to find any magic formula to find it for Solaris (appears to
1378 be trivial on GNU/Linux). Therefore, we have to try an alternate
1379 mechanism to find the dynamic linker's base address. */
1381 TRY_CATCH (ex, RETURN_MASK_ALL)
1383 tmp_bfd = solib_bfd_open (interp_name);
1385 if (tmp_bfd == NULL)
1386 goto bkpt_at_symbol;
1388 /* Now convert the TMP_BFD into a target. That way target, as
1389 well as BFD operations can be used. Note that closing the
1390 target will also close the underlying bfd. */
1391 tmp_bfd_target = target_bfd_reopen (tmp_bfd);
1393 /* On a running target, we can get the dynamic linker's base
1394 address from the shared library table. */
1395 so = master_so_list ();
1398 if (svr4_same_1 (interp_name, so->so_original_name))
1400 load_addr_found = 1;
1401 loader_found_in_list = 1;
1402 load_addr = LM_ADDR_CHECK (so, tmp_bfd);
1408 /* If we were not able to find the base address of the loader
1409 from our so_list, then try using the AT_BASE auxilliary entry. */
1410 if (!load_addr_found)
1411 if (target_auxv_search (¤t_target, AT_BASE, &load_addr) > 0)
1412 load_addr_found = 1;
1414 /* Otherwise we find the dynamic linker's base address by examining
1415 the current pc (which should point at the entry point for the
1416 dynamic linker) and subtracting the offset of the entry point.
1418 This is more fragile than the previous approaches, but is a good
1419 fallback method because it has actually been working well in
1421 if (!load_addr_found)
1423 struct regcache *regcache
1424 = get_thread_arch_regcache (inferior_ptid, target_gdbarch);
1425 load_addr = (regcache_read_pc (regcache)
1426 - exec_entry_point (tmp_bfd, tmp_bfd_target));
1429 if (!loader_found_in_list)
1431 info->debug_loader_name = xstrdup (interp_name);
1432 info->debug_loader_offset_p = 1;
1433 info->debug_loader_offset = load_addr;
1434 solib_add (NULL, from_tty, ¤t_target, auto_solib_add);
1437 /* Record the relocated start and end address of the dynamic linker
1438 text and plt section for svr4_in_dynsym_resolve_code. */
1439 interp_sect = bfd_get_section_by_name (tmp_bfd, ".text");
1442 info->interp_text_sect_low =
1443 bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
1444 info->interp_text_sect_high =
1445 info->interp_text_sect_low
1446 + bfd_section_size (tmp_bfd, interp_sect);
1448 interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt");
1451 info->interp_plt_sect_low =
1452 bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
1453 info->interp_plt_sect_high =
1454 info->interp_plt_sect_low
1455 + bfd_section_size (tmp_bfd, interp_sect);
1458 /* Now try to set a breakpoint in the dynamic linker. */
1459 for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++)
1461 sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep);
1467 /* Convert 'sym_addr' from a function pointer to an address.
1468 Because we pass tmp_bfd_target instead of the current
1469 target, this will always produce an unrelocated value. */
1470 sym_addr = gdbarch_convert_from_func_ptr_addr (target_gdbarch,
1474 /* We're done with both the temporary bfd and target. Remember,
1475 closing the target closes the underlying bfd. */
1476 target_close (tmp_bfd_target, 0);
1480 create_solib_event_breakpoint (target_gdbarch, load_addr + sym_addr);
1481 xfree (interp_name);
1485 /* For whatever reason we couldn't set a breakpoint in the dynamic
1486 linker. Warn and drop into the old code. */
1488 xfree (interp_name);
1489 warning (_("Unable to find dynamic linker breakpoint function.\n"
1490 "GDB will be unable to debug shared library initializers\n"
1491 "and track explicitly loaded dynamic code."));
1494 /* Scan through the lists of symbols, trying to look up the symbol and
1495 set a breakpoint there. Terminate loop when we/if we succeed. */
1497 for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++)
1499 msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile);
1500 if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
1502 sym_addr = SYMBOL_VALUE_ADDRESS (msymbol);
1503 sym_addr = gdbarch_convert_from_func_ptr_addr (target_gdbarch,
1506 create_solib_event_breakpoint (target_gdbarch, sym_addr);
1511 for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++)
1513 msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile);
1514 if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
1516 sym_addr = SYMBOL_VALUE_ADDRESS (msymbol);
1517 sym_addr = gdbarch_convert_from_func_ptr_addr (target_gdbarch,
1520 create_solib_event_breakpoint (target_gdbarch, sym_addr);
1531 special_symbol_handling -- additional shared library symbol handling
1535 void special_symbol_handling ()
1539 Once the symbols from a shared object have been loaded in the usual
1540 way, we are called to do any system specific symbol handling that
1543 For SunOS4, this consisted of grunging around in the dynamic
1544 linkers structures to find symbol definitions for "common" symbols
1545 and adding them to the minimal symbol table for the runtime common
1548 However, for SVR4, there's nothing to do.
1553 svr4_special_symbol_handling (void)
1555 svr4_relocate_main_executable ();
1558 /* Decide if the objfile needs to be relocated. As indicated above,
1559 we will only be here when execution is stopped at the beginning
1560 of the program. Relocation is necessary if the address at which
1561 we are presently stopped differs from the start address stored in
1562 the executable AND there's no interpreter section. The condition
1563 regarding the interpreter section is very important because if
1564 there *is* an interpreter section, execution will begin there
1565 instead. When there is an interpreter section, the start address
1566 is (presumably) used by the interpreter at some point to start
1567 execution of the program.
1569 If there is an interpreter, it is normal for it to be set to an
1570 arbitrary address at the outset. The job of finding it is
1571 handled in enable_break().
1573 So, to summarize, relocations are necessary when there is no
1574 interpreter section and the start address obtained from the
1575 executable is different from the address at which GDB is
1578 [ The astute reader will note that we also test to make sure that
1579 the executable in question has the DYNAMIC flag set. It is my
1580 opinion that this test is unnecessary (undesirable even). It
1581 was added to avoid inadvertent relocation of an executable
1582 whose e_type member in the ELF header is not ET_DYN. There may
1583 be a time in the future when it is desirable to do relocations
1584 on other types of files as well in which case this condition
1585 should either be removed or modified to accomodate the new file
1586 type. (E.g, an ET_EXEC executable which has been built to be
1587 position-independent could safely be relocated by the OS if
1588 desired. It is true that this violates the ABI, but the ABI
1589 has been known to be bent from time to time.) - Kevin, Nov 2000. ]
1593 svr4_static_exec_displacement (void)
1595 asection *interp_sect;
1596 struct regcache *regcache
1597 = get_thread_arch_regcache (inferior_ptid, target_gdbarch);
1598 CORE_ADDR pc = regcache_read_pc (regcache);
1600 interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
1601 if (interp_sect == NULL
1602 && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0
1603 && (exec_entry_point (exec_bfd, &exec_ops) != pc))
1604 return pc - exec_entry_point (exec_bfd, &exec_ops);
1609 /* We relocate all of the sections by the same amount. This
1610 behavior is mandated by recent editions of the System V ABI.
1611 According to the System V Application Binary Interface,
1612 Edition 4.1, page 5-5:
1614 ... Though the system chooses virtual addresses for
1615 individual processes, it maintains the segments' relative
1616 positions. Because position-independent code uses relative
1617 addressesing between segments, the difference between
1618 virtual addresses in memory must match the difference
1619 between virtual addresses in the file. The difference
1620 between the virtual address of any segment in memory and
1621 the corresponding virtual address in the file is thus a
1622 single constant value for any one executable or shared
1623 object in a given process. This difference is the base
1624 address. One use of the base address is to relocate the
1625 memory image of the program during dynamic linking.
1627 The same language also appears in Edition 4.0 of the System V
1628 ABI and is left unspecified in some of the earlier editions. */
1631 svr4_exec_displacement (void)
1634 /* ENTRY_POINT is a possible function descriptor - before
1635 a call to gdbarch_convert_from_func_ptr_addr. */
1636 CORE_ADDR entry_point;
1638 if (exec_bfd == NULL)
1641 if (target_auxv_search (¤t_target, AT_ENTRY, &entry_point) == 1)
1642 return entry_point - bfd_get_start_address (exec_bfd);
1644 return svr4_static_exec_displacement ();
1647 /* Relocate the main executable. This function should be called upon
1648 stopping the inferior process at the entry point to the program.
1649 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
1650 different, the main executable is relocated by the proper amount. */
1653 svr4_relocate_main_executable (void)
1655 CORE_ADDR displacement = svr4_exec_displacement ();
1657 /* Even if DISPLACEMENT is 0 still try to relocate it as this is a new
1658 difference of in-memory vs. in-file addresses and we could already
1659 relocate the executable at this function to improper address before. */
1661 if (symfile_objfile)
1663 struct section_offsets *new_offsets;
1666 new_offsets = alloca (symfile_objfile->num_sections
1667 * sizeof (*new_offsets));
1669 for (i = 0; i < symfile_objfile->num_sections; i++)
1670 new_offsets->offsets[i] = displacement;
1672 objfile_relocate (symfile_objfile, new_offsets);
1678 for (asect = exec_bfd->sections; asect != NULL; asect = asect->next)
1679 exec_set_section_address (bfd_get_filename (exec_bfd), asect->index,
1680 (bfd_section_vma (exec_bfd, asect)
1689 svr4_solib_create_inferior_hook -- shared library startup support
1693 void svr4_solib_create_inferior_hook (int from_tty)
1697 When gdb starts up the inferior, it nurses it along (through the
1698 shell) until it is ready to execute it's first instruction. At this
1699 point, this function gets called via expansion of the macro
1700 SOLIB_CREATE_INFERIOR_HOOK.
1702 For SunOS executables, this first instruction is typically the
1703 one at "_start", or a similar text label, regardless of whether
1704 the executable is statically or dynamically linked. The runtime
1705 startup code takes care of dynamically linking in any shared
1706 libraries, once gdb allows the inferior to continue.
1708 For SVR4 executables, this first instruction is either the first
1709 instruction in the dynamic linker (for dynamically linked
1710 executables) or the instruction at "start" for statically linked
1711 executables. For dynamically linked executables, the system
1712 first exec's /lib/libc.so.N, which contains the dynamic linker,
1713 and starts it running. The dynamic linker maps in any needed
1714 shared libraries, maps in the actual user executable, and then
1715 jumps to "start" in the user executable.
1717 For both SunOS shared libraries, and SVR4 shared libraries, we
1718 can arrange to cooperate with the dynamic linker to discover the
1719 names of shared libraries that are dynamically linked, and the
1720 base addresses to which they are linked.
1722 This function is responsible for discovering those names and
1723 addresses, and saving sufficient information about them to allow
1724 their symbols to be read at a later time.
1728 Between enable_break() and disable_break(), this code does not
1729 properly handle hitting breakpoints which the user might have
1730 set in the startup code or in the dynamic linker itself. Proper
1731 handling will probably have to wait until the implementation is
1732 changed to use the "breakpoint handler function" method.
1734 Also, what if child has exit()ed? Must exit loop somehow.
1738 svr4_solib_create_inferior_hook (int from_tty)
1740 struct inferior *inf;
1741 struct thread_info *tp;
1742 struct svr4_info *info;
1744 info = get_svr4_info ();
1746 /* Relocate the main executable if necessary. */
1747 if (current_inferior ()->attach_flag == 0)
1748 svr4_relocate_main_executable ();
1750 if (!svr4_have_link_map_offsets ())
1753 if (!enable_break (info, from_tty))
1756 #if defined(_SCO_DS)
1757 /* SCO needs the loop below, other systems should be using the
1758 special shared library breakpoints and the shared library breakpoint
1761 Now run the target. It will eventually hit the breakpoint, at
1762 which point all of the libraries will have been mapped in and we
1763 can go groveling around in the dynamic linker structures to find
1764 out what we need to know about them. */
1766 inf = current_inferior ();
1767 tp = inferior_thread ();
1769 clear_proceed_status ();
1770 inf->stop_soon = STOP_QUIETLY;
1771 tp->stop_signal = TARGET_SIGNAL_0;
1774 target_resume (pid_to_ptid (-1), 0, tp->stop_signal);
1775 wait_for_inferior (0);
1777 while (tp->stop_signal != TARGET_SIGNAL_TRAP);
1778 inf->stop_soon = NO_STOP_QUIETLY;
1779 #endif /* defined(_SCO_DS) */
1783 svr4_clear_solib (void)
1785 struct svr4_info *info;
1787 info = get_svr4_info ();
1788 info->debug_base = 0;
1789 info->debug_loader_offset_p = 0;
1790 info->debug_loader_offset = 0;
1791 xfree (info->debug_loader_name);
1792 info->debug_loader_name = NULL;
1796 svr4_free_so (struct so_list *so)
1798 xfree (so->lm_info->lm);
1799 xfree (so->lm_info);
1803 /* Clear any bits of ADDR that wouldn't fit in a target-format
1804 data pointer. "Data pointer" here refers to whatever sort of
1805 address the dynamic linker uses to manage its sections. At the
1806 moment, we don't support shared libraries on any processors where
1807 code and data pointers are different sizes.
1809 This isn't really the right solution. What we really need here is
1810 a way to do arithmetic on CORE_ADDR values that respects the
1811 natural pointer/address correspondence. (For example, on the MIPS,
1812 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1813 sign-extend the value. There, simply truncating the bits above
1814 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1815 be a new gdbarch method or something. */
1817 svr4_truncate_ptr (CORE_ADDR addr)
1819 if (gdbarch_ptr_bit (target_gdbarch) == sizeof (CORE_ADDR) * 8)
1820 /* We don't need to truncate anything, and the bit twiddling below
1821 will fail due to overflow problems. */
1824 return addr & (((CORE_ADDR) 1 << gdbarch_ptr_bit (target_gdbarch)) - 1);
1829 svr4_relocate_section_addresses (struct so_list *so,
1830 struct target_section *sec)
1832 sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR_CHECK (so,
1834 sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR_CHECK (so,
1839 /* Architecture-specific operations. */
1841 /* Per-architecture data key. */
1842 static struct gdbarch_data *solib_svr4_data;
1844 struct solib_svr4_ops
1846 /* Return a description of the layout of `struct link_map'. */
1847 struct link_map_offsets *(*fetch_link_map_offsets)(void);
1850 /* Return a default for the architecture-specific operations. */
1853 solib_svr4_init (struct obstack *obstack)
1855 struct solib_svr4_ops *ops;
1857 ops = OBSTACK_ZALLOC (obstack, struct solib_svr4_ops);
1858 ops->fetch_link_map_offsets = NULL;
1862 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1863 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1866 set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch,
1867 struct link_map_offsets *(*flmo) (void))
1869 struct solib_svr4_ops *ops = gdbarch_data (gdbarch, solib_svr4_data);
1871 ops->fetch_link_map_offsets = flmo;
1873 set_solib_ops (gdbarch, &svr4_so_ops);
1876 /* Fetch a link_map_offsets structure using the architecture-specific
1877 `struct link_map_offsets' fetcher. */
1879 static struct link_map_offsets *
1880 svr4_fetch_link_map_offsets (void)
1882 struct solib_svr4_ops *ops = gdbarch_data (target_gdbarch, solib_svr4_data);
1884 gdb_assert (ops->fetch_link_map_offsets);
1885 return ops->fetch_link_map_offsets ();
1888 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
1891 svr4_have_link_map_offsets (void)
1893 struct solib_svr4_ops *ops = gdbarch_data (target_gdbarch, solib_svr4_data);
1894 return (ops->fetch_link_map_offsets != NULL);
1898 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
1899 `struct r_debug' and a `struct link_map' that are binary compatible
1900 with the origional SVR4 implementation. */
1902 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1903 for an ILP32 SVR4 system. */
1905 struct link_map_offsets *
1906 svr4_ilp32_fetch_link_map_offsets (void)
1908 static struct link_map_offsets lmo;
1909 static struct link_map_offsets *lmp = NULL;
1915 lmo.r_version_offset = 0;
1916 lmo.r_version_size = 4;
1917 lmo.r_map_offset = 4;
1918 lmo.r_brk_offset = 8;
1919 lmo.r_ldsomap_offset = 20;
1921 /* Everything we need is in the first 20 bytes. */
1922 lmo.link_map_size = 20;
1923 lmo.l_addr_offset = 0;
1924 lmo.l_name_offset = 4;
1925 lmo.l_ld_offset = 8;
1926 lmo.l_next_offset = 12;
1927 lmo.l_prev_offset = 16;
1933 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1934 for an LP64 SVR4 system. */
1936 struct link_map_offsets *
1937 svr4_lp64_fetch_link_map_offsets (void)
1939 static struct link_map_offsets lmo;
1940 static struct link_map_offsets *lmp = NULL;
1946 lmo.r_version_offset = 0;
1947 lmo.r_version_size = 4;
1948 lmo.r_map_offset = 8;
1949 lmo.r_brk_offset = 16;
1950 lmo.r_ldsomap_offset = 40;
1952 /* Everything we need is in the first 40 bytes. */
1953 lmo.link_map_size = 40;
1954 lmo.l_addr_offset = 0;
1955 lmo.l_name_offset = 8;
1956 lmo.l_ld_offset = 16;
1957 lmo.l_next_offset = 24;
1958 lmo.l_prev_offset = 32;
1965 struct target_so_ops svr4_so_ops;
1967 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
1968 different rule for symbol lookup. The lookup begins here in the DSO, not in
1969 the main executable. */
1971 static struct symbol *
1972 elf_lookup_lib_symbol (const struct objfile *objfile,
1974 const char *linkage_name,
1975 const domain_enum domain)
1979 if (objfile == symfile_objfile)
1983 /* OBJFILE should have been passed as the non-debug one. */
1984 gdb_assert (objfile->separate_debug_objfile_backlink == NULL);
1986 abfd = objfile->obfd;
1989 if (abfd == NULL || scan_dyntag (DT_SYMBOLIC, abfd, NULL) != 1)
1992 return lookup_global_symbol_from_objfile
1993 (objfile, name, linkage_name, domain);
1996 extern initialize_file_ftype _initialize_svr4_solib; /* -Wmissing-prototypes */
1999 _initialize_svr4_solib (void)
2001 solib_svr4_data = gdbarch_data_register_pre_init (solib_svr4_init);
2002 solib_svr4_pspace_data
2003 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup);
2005 svr4_so_ops.relocate_section_addresses = svr4_relocate_section_addresses;
2006 svr4_so_ops.free_so = svr4_free_so;
2007 svr4_so_ops.clear_solib = svr4_clear_solib;
2008 svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook;
2009 svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling;
2010 svr4_so_ops.current_sos = svr4_current_sos;
2011 svr4_so_ops.open_symbol_file_object = open_symbol_file_object;
2012 svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code;
2013 svr4_so_ops.bfd_open = solib_bfd_open;
2014 svr4_so_ops.lookup_lib_global_symbol = elf_lookup_lib_symbol;
2015 svr4_so_ops.same = svr4_same;
2016 svr4_so_ops.keep_data_in_core = svr4_keep_data_in_core;