| /* Handle SVR4 shared libraries for GDB, the GNU Debugger. |
| |
| Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, |
| 2001, 2003, 2004, 2005, 2006, 2007, 2008 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 "defs.h" |
| |
| #include "elf/external.h" |
| #include "elf/common.h" |
| #include "elf/mips.h" |
| |
| #include "symtab.h" |
| #include "bfd.h" |
| #include "symfile.h" |
| #include "objfiles.h" |
| #include "gdbcore.h" |
| #include "target.h" |
| #include "inferior.h" |
| |
| #include "gdb_assert.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" |
| |
| static struct link_map_offsets *svr4_fetch_link_map_offsets (void); |
| static int svr4_have_link_map_offsets (void); |
| |
| /* Link map info to include in an allocated so_list entry */ |
| |
| struct lm_info |
| { |
| /* Pointer to copy of link map from inferior. The type is char * |
| rather than void *, so that we may use byte offsets to find the |
| various fields without the need for a cast. */ |
| gdb_byte *lm; |
| |
| /* Amount by which addresses in the binary should be relocated to |
| match the inferior. This could most often be taken directly |
| from lm, but when prelinking is involved and the prelink base |
| address changes, we may need a different offset, we want to |
| warn about the difference and compute it only once. */ |
| CORE_ADDR l_addr; |
| }; |
| |
| /* 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 char *solib_break_names[] = |
| { |
| "r_debug_state", |
| "_r_debug_state", |
| "_dl_debug_state", |
| "rtld_db_dlactivity", |
| "_rtld_debug_state", |
| |
| NULL |
| }; |
| |
| #define BKPT_AT_SYMBOL 1 |
| |
| #if defined (BKPT_AT_SYMBOL) |
| static char *bkpt_names[] = |
| { |
| #ifdef SOLIB_BKPT_NAME |
| SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ |
| #endif |
| "_start", |
| "__start", |
| "main", |
| NULL |
| }; |
| #endif |
| |
| static char *main_name_list[] = |
| { |
| "main_$main", |
| NULL |
| }; |
| |
| /* link map access functions */ |
| |
| static CORE_ADDR |
| LM_ADDR_FROM_LINK_MAP (struct so_list *so) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return extract_typed_address (so->lm_info->lm + lmo->l_addr_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| static int |
| HAS_LM_DYNAMIC_FROM_LINK_MAP () |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return lmo->l_ld_offset >= 0; |
| } |
| |
| static CORE_ADDR |
| LM_DYNAMIC_FROM_LINK_MAP (struct so_list *so) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return extract_typed_address (so->lm_info->lm + lmo->l_ld_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| static CORE_ADDR |
| LM_ADDR_CHECK (struct so_list *so, bfd *abfd) |
| { |
| if (so->lm_info->l_addr == (CORE_ADDR)-1) |
| { |
| struct bfd_section *dyninfo_sect; |
| CORE_ADDR l_addr, l_dynaddr, dynaddr, align = 0x1000; |
| |
| l_addr = LM_ADDR_FROM_LINK_MAP (so); |
| |
| if (! abfd || ! HAS_LM_DYNAMIC_FROM_LINK_MAP ()) |
| goto set_addr; |
| |
| l_dynaddr = LM_DYNAMIC_FROM_LINK_MAP (so); |
| |
| dyninfo_sect = bfd_get_section_by_name (abfd, ".dynamic"); |
| if (dyninfo_sect == NULL) |
| goto set_addr; |
| |
| dynaddr = bfd_section_vma (abfd, dyninfo_sect); |
| |
| if (dynaddr + l_addr != l_dynaddr) |
| { |
| 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; |
| } |
| |
| /* 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. */ |
| if ((l_addr & align) == ((l_dynaddr - dynaddr) & align)) |
| { |
| l_addr = l_dynaddr - dynaddr; |
| |
| warning (_(".dynamic section for \"%s\" " |
| "is not at the expected address"), so->so_name); |
| warning (_("difference appears to be caused by prelink, " |
| "adjusting expectations")); |
| } |
| else |
| warning (_(".dynamic section for \"%s\" " |
| "is not at the expected address " |
| "(wrong library or version mismatch?)"), so->so_name); |
| } |
| |
| set_addr: |
| so->lm_info->l_addr = l_addr; |
| } |
| |
| return so->lm_info->l_addr; |
| } |
| |
| static CORE_ADDR |
| LM_NEXT (struct so_list *so) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return extract_typed_address (so->lm_info->lm + lmo->l_next_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| static CORE_ADDR |
| LM_NAME (struct so_list *so) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return extract_typed_address (so->lm_info->lm + lmo->l_name_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| static int |
| IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| /* Assume that everything is a library if the dynamic loader was loaded |
| late by a static executable. */ |
| if (bfd_get_section_by_name (exec_bfd, ".dynamic") == NULL) |
| return 0; |
| |
| return extract_typed_address (so->lm_info->lm + lmo->l_prev_offset, |
| builtin_type_void_data_ptr) == 0; |
| } |
| |
| static CORE_ADDR debug_base; /* Base of dynamic linker structures */ |
| |
| /* Validity flag for debug_loader_offset. */ |
| static int debug_loader_offset_p; |
| |
| /* Load address for the dynamic linker, inferred. */ |
| static CORE_ADDR debug_loader_offset; |
| |
| /* Name of the dynamic linker, valid if debug_loader_offset_p. */ |
| static char *debug_loader_name; |
| |
| /* Local function prototypes */ |
| |
| static int match_main (char *); |
| |
| static CORE_ADDR bfd_lookup_symbol (bfd *, char *); |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| bfd_lookup_symbol -- lookup the value for a specific symbol |
| |
| SYNOPSIS |
| |
| CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname) |
| |
| DESCRIPTION |
| |
| An expensive way to lookup the value of a single symbol for |
| bfd's that are only temporary anyway. This is used by the |
| shared library support to find the address of the debugger |
| notification routine in the shared library. |
| |
| The returned symbol may be in a code or data section; functions |
| will normally be in a code section, but may be in a data section |
| if this architecture uses function descriptors. |
| |
| Note that 0 is specifically allowed as an error return (no |
| such symbol). |
| */ |
| |
| static CORE_ADDR |
| bfd_lookup_symbol (bfd *abfd, char *symname) |
| { |
| long storage_needed; |
| asymbol *sym; |
| asymbol **symbol_table; |
| unsigned int number_of_symbols; |
| unsigned int i; |
| struct cleanup *back_to; |
| CORE_ADDR symaddr = 0; |
| |
| storage_needed = bfd_get_symtab_upper_bound (abfd); |
| |
| if (storage_needed > 0) |
| { |
| symbol_table = (asymbol **) xmalloc (storage_needed); |
| back_to = make_cleanup (xfree, symbol_table); |
| number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); |
| |
| for (i = 0; i < number_of_symbols; i++) |
| { |
| sym = *symbol_table++; |
| if (strcmp (sym->name, symname) == 0 |
| && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0) |
| { |
| /* BFD symbols are section relative. */ |
| symaddr = sym->value + sym->section->vma; |
| break; |
| } |
| } |
| do_cleanups (back_to); |
| } |
| |
| if (symaddr) |
| return symaddr; |
| |
| /* On FreeBSD, the dynamic linker is stripped by default. So we'll |
| have to check the dynamic string table too. */ |
| |
| storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); |
| |
| if (storage_needed > 0) |
| { |
| symbol_table = (asymbol **) xmalloc (storage_needed); |
| back_to = make_cleanup (xfree, symbol_table); |
| number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); |
| |
| for (i = 0; i < number_of_symbols; i++) |
| { |
| sym = *symbol_table++; |
| |
| if (strcmp (sym->name, symname) == 0 |
| && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0) |
| { |
| /* BFD symbols are section relative. */ |
| symaddr = sym->value + sym->section->vma; |
| break; |
| } |
| } |
| do_cleanups (back_to); |
| } |
| |
| return symaddr; |
| } |
| |
| /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is |
| returned and the corresponding PTR is set. */ |
| |
| static int |
| scan_dyntag (int dyntag, bfd *abfd, CORE_ADDR *ptr) |
| { |
| int arch_size, step, sect_size; |
| long dyn_tag; |
| CORE_ADDR dyn_ptr, dyn_addr; |
| gdb_byte *bufend, *bufstart, *buf; |
| Elf32_External_Dyn *x_dynp_32; |
| Elf64_External_Dyn *x_dynp_64; |
| struct bfd_section *sect; |
| |
| if (abfd == NULL) |
| return 0; |
| arch_size = bfd_get_arch_size (abfd); |
| if (arch_size == -1) |
| return 0; |
| |
| /* Find the start address of the .dynamic section. */ |
| sect = bfd_get_section_by_name (abfd, ".dynamic"); |
| if (sect == NULL) |
| return 0; |
| dyn_addr = bfd_section_vma (abfd, sect); |
| |
| /* Read in .dynamic from the BFD. We will get the actual value |
| from memory later. */ |
| sect_size = bfd_section_size (abfd, sect); |
| buf = bufstart = alloca (sect_size); |
| if (!bfd_get_section_contents (abfd, sect, |
| buf, 0, sect_size)) |
| 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 (bufend = buf + sect_size; |
| buf < bufend; |
| buf += step) |
| { |
| if (arch_size == 32) |
| { |
| x_dynp_32 = (Elf32_External_Dyn *) buf; |
| dyn_tag = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp_32->d_tag); |
| dyn_ptr = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp_32->d_un.d_ptr); |
| } |
| else |
| { |
| x_dynp_64 = (Elf64_External_Dyn *) buf; |
| dyn_tag = bfd_h_get_64 (abfd, (bfd_byte *) x_dynp_64->d_tag); |
| dyn_ptr = bfd_h_get_64 (abfd, (bfd_byte *) x_dynp_64->d_un.d_ptr); |
| } |
| if (dyn_tag == DT_NULL) |
| return 0; |
| if (dyn_tag == dyntag) |
| { |
| /* If requested, try to read the runtime value of this .dynamic |
| entry. */ |
| if (ptr) |
| { |
| gdb_byte ptr_buf[8]; |
| CORE_ADDR ptr_addr; |
| |
| ptr_addr = dyn_addr + (buf - bufstart) + arch_size / 8; |
| if (target_read_memory (ptr_addr, ptr_buf, arch_size / 8) == 0) |
| dyn_ptr = extract_typed_address (ptr_buf, |
| builtin_type_void_data_ptr); |
| *ptr = dyn_ptr; |
| } |
| return 1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| elf_locate_base -- locate the base address of dynamic linker structs |
| for SVR4 elf targets. |
| |
| SYNOPSIS |
| |
| CORE_ADDR elf_locate_base (void) |
| |
| DESCRIPTION |
| |
| 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) |
| { |
| struct minimal_symbol *msymbol; |
| CORE_ADDR dyn_ptr; |
| |
| /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this |
| instead of DT_DEBUG, although they sometimes contain an unused |
| DT_DEBUG. */ |
| if (scan_dyntag (DT_MIPS_RLD_MAP, exec_bfd, &dyn_ptr)) |
| { |
| gdb_byte *pbuf; |
| int pbuf_size = TYPE_LENGTH (builtin_type_void_data_ptr); |
| pbuf = 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, builtin_type_void_data_ptr); |
| } |
| |
| /* Find DT_DEBUG. */ |
| if (scan_dyntag (DT_DEBUG, exec_bfd, &dyn_ptr)) |
| return dyn_ptr; |
| |
| /* This may be a static executable. Look for the symbol |
| conventionally named _r_debug, as a last resort. */ |
| msymbol = lookup_minimal_symbol ("_r_debug", NULL, symfile_objfile); |
| if (msymbol != NULL) |
| return SYMBOL_VALUE_ADDRESS (msymbol); |
| |
| /* DT_DEBUG entry not found. */ |
| return 0; |
| } |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| locate_base -- locate the base address of dynamic linker structs |
| |
| SYNOPSIS |
| |
| CORE_ADDR locate_base (void) |
| |
| DESCRIPTION |
| |
| For both the SunOS and SVR4 shared library implementations, if the |
| inferior executable has been linked dynamically, there is a single |
| address somewhere in the inferior's data space which is the key to |
| locating all of the dynamic linker's runtime structures. This |
| address is the value of the debug base symbol. The job of this |
| function is to find and return that address, or to return 0 if there |
| is no such address (the executable is statically linked for example). |
| |
| For SunOS, the job is almost trivial, since the dynamic linker and |
| all of it's structures are statically linked to the executable at |
| link time. Thus the symbol for the address we are looking for has |
| already been added to the minimal symbol table for the executable's |
| objfile at the time the symbol file's symbols were read, and all we |
| have to do is look it up there. Note that we explicitly do NOT want |
| to find the copies in the shared library. |
| |
| The SVR4 version is a bit more complicated because the address |
| is contained somewhere in the dynamic info section. We have to go |
| to a lot more work to discover the address of the debug base symbol. |
| Because of this complexity, we cache the value we find and return that |
| value on subsequent invocations. Note there is no copy in the |
| executable symbol tables. |
| |
| */ |
| |
| static CORE_ADDR |
| locate_base (void) |
| { |
| /* Check to see if we have a currently valid address, and if so, avoid |
| doing all this work again and just return the cached address. If |
| we have no cached address, try to locate it in the dynamic info |
| section for ELF executables. There's no point in doing any of this |
| though if we don't have some link map offsets to work with. */ |
| |
| if (debug_base == 0 && svr4_have_link_map_offsets ()) |
| { |
| if (exec_bfd != NULL |
| && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) |
| debug_base = elf_locate_base (); |
| } |
| return (debug_base); |
| } |
| |
| /* Find the first element in the inferior's dynamic link map, and |
| return its address in the inferior. |
| |
| 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 (void) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return read_memory_typed_address (debug_base + lmo->r_map_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| /* Find r_brk from the inferior's debug base. */ |
| |
| static CORE_ADDR |
| solib_svr4_r_brk (void) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| |
| return read_memory_typed_address (debug_base + lmo->r_brk_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| /* 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 (void) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| ULONGEST version; |
| |
| /* Check version, and return zero if `struct r_debug' doesn't have |
| the r_ldsomap member. */ |
| version = read_memory_unsigned_integer (debug_base + lmo->r_version_offset, |
| lmo->r_version_size); |
| if (version < 2 || lmo->r_ldsomap_offset == -1) |
| return 0; |
| |
| return read_memory_typed_address (debug_base + lmo->r_ldsomap_offset, |
| builtin_type_void_data_ptr); |
| } |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| open_symbol_file_object |
| |
| SYNOPSIS |
| |
| void open_symbol_file_object (void *from_tty) |
| |
| DESCRIPTION |
| |
| If no open symbol file, attempt to locate and open the main symbol |
| file. On SVR4 systems, this is the first link map entry. If its |
| name is here, we can open it. Useful when attaching to a process |
| without first loading its symbol file. |
| |
| If FROM_TTYP dereferences to a non-zero integer, allow messages to |
| be printed. This parameter is a pointer rather than an int because |
| open_symbol_file_object() is called via catch_errors() and |
| catch_errors() requires a pointer argument. */ |
| |
| static int |
| open_symbol_file_object (void *from_ttyp) |
| { |
| CORE_ADDR lm, l_name; |
| char *filename; |
| int errcode; |
| int from_tty = *(int *)from_ttyp; |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| int l_name_size = TYPE_LENGTH (builtin_type_void_data_ptr); |
| gdb_byte *l_name_buf = xmalloc (l_name_size); |
| struct cleanup *cleanups = make_cleanup (xfree, l_name_buf); |
| |
| if (symfile_objfile) |
| if (!query ("Attempt to reload symbols from process? ")) |
| return 0; |
| |
| /* Always locate the debug struct, in case it has moved. */ |
| debug_base = 0; |
| if (locate_base () == 0) |
| return 0; /* failed somehow... */ |
| |
| /* First link map member should be the executable. */ |
| lm = solib_svr4_r_map (); |
| 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, l_name_size); |
| |
| /* Convert the address to host format. */ |
| l_name = extract_typed_address (l_name_buf, builtin_type_void_data_ptr); |
| |
| /* Free l_name_buf. */ |
| do_cleanups (cleanups); |
| |
| if (l_name == 0) |
| return 0; /* No filename. */ |
| |
| /* Now fetch the filename from target memory. */ |
| target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| make_cleanup (xfree, filename); |
| |
| if (errcode) |
| { |
| warning (_("failed to read exec filename from attached file: %s"), |
| safe_strerror (errcode)); |
| return 0; |
| } |
| |
| /* Have a pathname: read the symbol file. */ |
| symbol_file_add_main (filename, from_tty); |
| |
| return 1; |
| } |
| |
| /* If no shared library information is available from the dynamic |
| linker, build a fallback list from other sources. */ |
| |
| static struct so_list * |
| svr4_default_sos (void) |
| { |
| struct so_list *head = NULL; |
| struct so_list **link_ptr = &head; |
| |
| if (debug_loader_offset_p) |
| { |
| struct so_list *new = XZALLOC (struct so_list); |
| |
| new->lm_info = xmalloc (sizeof (struct lm_info)); |
| |
| /* Nothing will ever check the cached copy of the link |
| map if we set l_addr. */ |
| new->lm_info->l_addr = debug_loader_offset; |
| new->lm_info->lm = NULL; |
| |
| strncpy (new->so_name, debug_loader_name, SO_NAME_MAX_PATH_SIZE - 1); |
| new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; |
| strcpy (new->so_original_name, new->so_name); |
| |
| *link_ptr = new; |
| link_ptr = &new->next; |
| } |
| |
| return head; |
| } |
| |
| /* LOCAL FUNCTION |
| |
| current_sos -- build a list of currently loaded shared objects |
| |
| SYNOPSIS |
| |
| struct so_list *current_sos () |
| |
| DESCRIPTION |
| |
| Build a list of `struct so_list' objects describing the shared |
| objects currently loaded in the inferior. This list does not |
| include an entry for the main executable file. |
| |
| Note that we only gather information directly available from the |
| inferior --- we don't examine any of the shared library files |
| themselves. The declaration of `struct so_list' says which fields |
| we provide values for. */ |
| |
| static struct so_list * |
| svr4_current_sos (void) |
| { |
| CORE_ADDR lm; |
| struct so_list *head = 0; |
| struct so_list **link_ptr = &head; |
| CORE_ADDR ldsomap = 0; |
| |
| /* Always locate the debug struct, in case it has moved. */ |
| debug_base = 0; |
| locate_base (); |
| |
| /* If we can't find the dynamic linker's base structure, this |
| must not be a dynamically linked executable. Hmm. */ |
| if (! debug_base) |
| return svr4_default_sos (); |
| |
| /* Walk the inferior's link map list, and build our list of |
| `struct so_list' nodes. */ |
| lm = solib_svr4_r_map (); |
| |
| while (lm) |
| { |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| struct so_list *new = XZALLOC (struct so_list); |
| struct cleanup *old_chain = make_cleanup (xfree, new); |
| |
| new->lm_info = xmalloc (sizeof (struct lm_info)); |
| make_cleanup (xfree, new->lm_info); |
| |
| new->lm_info->l_addr = (CORE_ADDR)-1; |
| new->lm_info->lm = xzalloc (lmo->link_map_size); |
| make_cleanup (xfree, new->lm_info->lm); |
| |
| read_memory (lm, new->lm_info->lm, lmo->link_map_size); |
| |
| lm = LM_NEXT (new); |
| |
| /* 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_LINK_MAP_ENTRY (new) && ldsomap == 0) |
| free_so (new); |
| else |
| { |
| int errcode; |
| char *buffer; |
| |
| /* Extract this shared object's name. */ |
| target_read_string (LM_NAME (new), &buffer, |
| SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| if (errcode != 0) |
| warning (_("Can't read pathname for load map: %s."), |
| safe_strerror (errcode)); |
| else |
| { |
| strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); |
| new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; |
| strcpy (new->so_original_name, new->so_name); |
| } |
| xfree (buffer); |
| |
| /* If this entry has no name, or its name matches the name |
| for the main executable, don't include it in the list. */ |
| if (! new->so_name[0] |
| || match_main (new->so_name)) |
| free_so (new); |
| else |
| { |
| new->next = 0; |
| *link_ptr = new; |
| link_ptr = &new->next; |
| } |
| } |
| |
| /* 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. */ |
| if (lm == 0 && ldsomap == 0) |
| lm = ldsomap = solib_svr4_r_ldsomap (); |
| |
| discard_cleanups (old_chain); |
| } |
| |
| if (head == NULL) |
| return svr4_default_sos (); |
| |
| return head; |
| } |
| |
| /* Get the address of the link_map for a given OBJFILE. Loop through |
| the link maps, and return the address of the one corresponding to |
| the given objfile. Note that this function takes into account that |
| objfile can be the main executable, not just a shared library. The |
| main executable has always an empty name field in the linkmap. */ |
| |
| CORE_ADDR |
| svr4_fetch_objfile_link_map (struct objfile *objfile) |
| { |
| CORE_ADDR lm; |
| |
| if (locate_base () == 0) |
| return 0; /* failed somehow... */ |
| |
| /* Position ourselves on the first link map. */ |
| lm = solib_svr4_r_map (); |
| while (lm) |
| { |
| /* Get info on the layout of the r_debug and link_map structures. */ |
| struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| int errcode; |
| char *buffer; |
| struct lm_info objfile_lm_info; |
| struct cleanup *old_chain; |
| CORE_ADDR name_address; |
| int l_name_size = TYPE_LENGTH (builtin_type_void_data_ptr); |
| gdb_byte *l_name_buf = xmalloc (l_name_size); |
| old_chain = make_cleanup (xfree, l_name_buf); |
| |
| /* Set up the buffer to contain the portion of the link_map |
| structure that gdb cares about. Note that this is not the |
| whole link_map structure. */ |
| objfile_lm_info.lm = xzalloc (lmo->link_map_size); |
| make_cleanup (xfree, objfile_lm_info.lm); |
| |
| /* Read the link map into our internal structure. */ |
| read_memory (lm, objfile_lm_info.lm, lmo->link_map_size); |
| |
| /* Read address of name from target memory to GDB. */ |
| read_memory (lm + lmo->l_name_offset, l_name_buf, l_name_size); |
| |
| /* Extract this object's name. */ |
| name_address = extract_typed_address (l_name_buf, |
| builtin_type_void_data_ptr); |
| target_read_string (name_address, &buffer, |
| SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| make_cleanup (xfree, buffer); |
| if (errcode != 0) |
| warning (_("Can't read pathname for load map: %s."), |
| safe_strerror (errcode)); |
| else |
| { |
| /* Is this the linkmap for the file we want? */ |
| /* If the file is not a shared library and has no name, |
| we are sure it is the main executable, so we return that. */ |
| |
| if (buffer |
| && ((strcmp (buffer, objfile->name) == 0) |
| || (!(objfile->flags & OBJF_SHARED) |
| && (strcmp (buffer, "") == 0)))) |
| { |
| do_cleanups (old_chain); |
| return lm; |
| } |
| } |
| /* Not the file we wanted, continue checking. */ |
| lm = extract_typed_address (objfile_lm_info.lm + lmo->l_next_offset, |
| builtin_type_void_data_ptr); |
| do_cleanups (old_chain); |
| } |
| 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 (char *soname) |
| { |
| char **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. */ |
| static CORE_ADDR interp_text_sect_low; |
| static CORE_ADDR interp_text_sect_high; |
| static CORE_ADDR interp_plt_sect_low; |
| static CORE_ADDR interp_plt_sect_high; |
| |
| int |
| svr4_in_dynsym_resolve_code (CORE_ADDR pc) |
| { |
| return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) |
| || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) |
| || in_plt_section (pc, NULL)); |
| } |
| |
| /* 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) |
| { |
| /* 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. */ |
| return gdbarch_convert_from_func_ptr_addr (current_gdbarch, |
| bfd_get_start_address (abfd), |
| targ); |
| } |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| enable_break -- arrange for dynamic linker to hit breakpoint |
| |
| SYNOPSIS |
| |
| int enable_break (void) |
| |
| DESCRIPTION |
| |
| 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 it's 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 (void) |
| { |
| #ifdef BKPT_AT_SYMBOL |
| |
| struct minimal_symbol *msymbol; |
| char **bkpt_namep; |
| asection *interp_sect; |
| CORE_ADDR sym_addr; |
| |
| /* First, remove all the solib event breakpoints. Their addresses |
| may have changed since the last time we ran the program. */ |
| remove_solib_event_breakpoints (); |
| |
| interp_text_sect_low = interp_text_sect_high = 0; |
| interp_plt_sect_low = 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, 0, ¤t_target, auto_solib_add); |
| sym_addr = 0; |
| if (debug_base && solib_svr4_r_map () != 0) |
| sym_addr = solib_svr4_r_brk (); |
| |
| if (sym_addr != 0) |
| { |
| struct obj_section *os; |
| |
| sym_addr = gdbarch_addr_bits_remove |
| (current_gdbarch, gdbarch_convert_from_func_ptr_addr (current_gdbarch, |
| sym_addr, |
| ¤t_target)); |
| |
| 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; |
| load_addr = ANOFFSET (os->objfile->section_offsets, |
| os->objfile->sect_index_text); |
| |
| interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
| if (interp_sect) |
| { |
| interp_text_sect_low = |
| bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| interp_text_sect_high = |
| interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| } |
| interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); |
| if (interp_sect) |
| { |
| interp_plt_sect_low = |
| bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| interp_plt_sect_high = |
| interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| } |
| |
| create_solib_event_breakpoint (sym_addr); |
| return 1; |
| } |
| } |
| |
| /* Find the .interp section; if not found, warn the user and drop |
| into the old breakpoint at symbol code. */ |
| interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); |
| if (interp_sect) |
| { |
| unsigned int interp_sect_size; |
| char *buf; |
| CORE_ADDR load_addr = 0; |
| int load_addr_found = 0; |
| int loader_found_in_list = 0; |
| struct so_list *so; |
| bfd *tmp_bfd = NULL; |
| struct target_ops *tmp_bfd_target; |
| int tmp_fd = -1; |
| char *tmp_pathname = NULL; |
| |
| /* Read the contents of the .interp section into a local buffer; |
| the contents specify the dynamic linker this program uses. */ |
| sym_addr = 0; |
| interp_sect_size = bfd_section_size (exec_bfd, interp_sect); |
| buf = alloca (interp_sect_size); |
| bfd_get_section_contents (exec_bfd, interp_sect, |
| buf, 0, interp_sect_size); |
| |
| /* 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. */ |
| |
| tmp_fd = solib_open (buf, &tmp_pathname); |
| if (tmp_fd >= 0) |
| tmp_bfd = bfd_fopen (tmp_pathname, gnutarget, FOPEN_RB, tmp_fd); |
| |
| if (tmp_bfd == NULL) |
| goto bkpt_at_symbol; |
| |
| /* Make sure the dynamic linker's really a useful object. */ |
| if (!bfd_check_format (tmp_bfd, bfd_object)) |
| { |
| warning (_("Unable to grok dynamic linker %s as an object file"), buf); |
| bfd_close (tmp_bfd); |
| goto bkpt_at_symbol; |
| } |
| |
| /* Now convert the TMP_BFD into a target. That way target, as |
| well as BFD operations can be used. Note that closing the |
| target will also close the underlying bfd. */ |
| 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. */ |
| so = master_so_list (); |
| while (so) |
| { |
| if (strcmp (buf, so->so_original_name) == 0) |
| { |
| load_addr_found = 1; |
| loader_found_in_list = 1; |
| load_addr = LM_ADDR_CHECK (so, tmp_bfd); |
| break; |
| } |
| so = so->next; |
| } |
| |
| /* 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 (¤t_target, AT_BASE, &load_addr) > 0) |
| 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) |
| load_addr = (read_pc () |
| - exec_entry_point (tmp_bfd, tmp_bfd_target)); |
| |
| if (!loader_found_in_list) |
| { |
| debug_loader_name = xstrdup (buf); |
| debug_loader_offset_p = 1; |
| debug_loader_offset = load_addr; |
| solib_add (NULL, 0, ¤t_target, 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, ".text"); |
| if (interp_sect) |
| { |
| interp_text_sect_low = |
| bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| interp_text_sect_high = |
| interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| } |
| interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); |
| if (interp_sect) |
| { |
| interp_plt_sect_low = |
| bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| interp_plt_sect_high = |
| interp_plt_sect_low + bfd_section_size (tmp_bfd, 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 = bfd_lookup_symbol (tmp_bfd, *bkpt_namep); |
| 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_gdbarch, |
| sym_addr, |
| tmp_bfd_target); |
| |
| /* We're done with both the temporary bfd and target. Remember, |
| closing the target closes the underlying bfd. */ |
| target_close (tmp_bfd_target, 0); |
| |
| if (sym_addr != 0) |
| { |
| create_solib_event_breakpoint (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: |
| xfree (tmp_pathname); |
| 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. */ |
| |
| for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) |
| { |
| msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); |
| if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) |
| { |
| create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); |
| return 1; |
| } |
| } |
| |
| for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) |
| { |
| msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); |
| if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) |
| { |
| create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); |
| return 1; |
| } |
| } |
| #endif /* BKPT_AT_SYMBOL */ |
| |
| return 0; |
| } |
| |
| /* |
| |
| LOCAL FUNCTION |
| |
| special_symbol_handling -- additional shared library symbol handling |
| |
| SYNOPSIS |
| |
| void special_symbol_handling () |
| |
| DESCRIPTION |
| |
| Once the symbols from a shared object have been loaded in the usual |
| way, we are called to do any system specific symbol handling that |
| is needed. |
| |
| For SunOS4, this consisted of grunging around in the dynamic |
| linkers structures to find symbol definitions for "common" symbols |
| and adding them to the minimal symbol table for the runtime common |
| objfile. |
| |
| However, for SVR4, there's nothing to do. |
| |
| */ |
| |
| static void |
| svr4_special_symbol_handling (void) |
| { |
| } |
| |
| /* 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 PC and if they are |
| different, the main executable is relocated by the proper amount. |
| |
| As written it will only attempt to relocate executables which |
| lack interpreter sections. It seems likely that only dynamic |
| linker executables will get relocated, though it should work |
| properly for a position-independent static executable as well. */ |
| |
| static void |
| svr4_relocate_main_executable (void) |
| { |
| asection *interp_sect; |
| CORE_ADDR pc = read_pc (); |
| |
| /* Decide if the objfile needs to be relocated. As indicated above, |
| we will only be here when execution is stopped at the beginning |
| of the program. Relocation is necessary if the address at which |
| we are presently stopped differs from the start address stored in |
| the executable AND there's no interpreter section. The condition |
| regarding the interpreter section is very important because if |
| there *is* an interpreter section, execution will begin there |
| instead. When there is an interpreter section, the start address |
| is (presumably) used by the interpreter at some point to start |
| execution of the program. |
| |
| If there is an interpreter, it is normal for it to be set to an |
| arbitrary address at the outset. The job of finding it is |
| handled in enable_break(). |
| |
| So, to summarize, relocations are necessary when there is no |
| interpreter section and the start address obtained from the |
| executable is different from the address at which GDB is |
| currently stopped. |
| |
| [ 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 accomodate the new file |
| type. (E.g, an ET_EXEC executable which has been built to be |
| position-independent could safely be relocated by the OS if |
| desired. It is true that this violates the ABI, but the ABI |
| has been known to be bent from time to time.) - Kevin, Nov 2000. ] |
| */ |
| |
| interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); |
| if (interp_sect == NULL |
| && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0 |
| && (exec_entry_point (exec_bfd, &exec_ops) != pc)) |
| { |
| struct cleanup *old_chain; |
| struct section_offsets *new_offsets; |
| int i, changed; |
| CORE_ADDR displacement; |
| |
| /* It is necessary to relocate the objfile. The amount to |
| relocate by is simply the address at which we are stopped |
| minus the starting address from the executable. |
| |
| 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 |
| addressesing 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. */ |
| |
| displacement = pc - exec_entry_point (exec_bfd, &exec_ops); |
| changed = 0; |
| |
| new_offsets = xcalloc (symfile_objfile->num_sections, |
| sizeof (struct section_offsets)); |
| old_chain = make_cleanup (xfree, new_offsets); |
| |
| for (i = 0; i < symfile_objfile->num_sections; i++) |
| { |
| if (displacement != ANOFFSET (symfile_objfile->section_offsets, i)) |
| changed = 1; |
| new_offsets->offsets[i] = displacement; |
| } |
| |
| if (changed) |
| objfile_relocate (symfile_objfile, new_offsets); |
| |
| do_cleanups (old_chain); |
| } |
| } |
| |
| /* |
| |
| GLOBAL FUNCTION |
| |
| svr4_solib_create_inferior_hook -- shared library startup support |
| |
| SYNOPSIS |
| |
| void svr4_solib_create_inferior_hook () |
| |
| DESCRIPTION |
| |
| When gdb starts up the inferior, it nurses it along (through the |
| shell) until it is ready to execute it's first instruction. At this |
| point, this function gets called via expansion of the macro |
| SOLIB_CREATE_INFERIOR_HOOK. |
| |
| For SunOS executables, this first instruction is typically the |
| one at "_start", or a similar text label, regardless of whether |
| the executable is statically or dynamically linked. The runtime |
| startup code takes care of dynamically linking in any shared |
| libraries, once gdb allows the inferior to continue. |
| |
| 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. |
| |
| For both SunOS shared libraries, and SVR4 shared libraries, 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. |
| |
| FIXME |
| |
| Between enable_break() and disable_break(), this code does not |
| properly handle hitting breakpoints which the user might have |
| set in the startup code or in the dynamic linker itself. Proper |
| handling will probably have to wait until the implementation is |
| changed to use the "breakpoint handler function" method. |
| |
| Also, what if child has exit()ed? Must exit loop somehow. |
| */ |
| |
| static void |
| svr4_solib_create_inferior_hook (void) |
| { |
| /* Relocate the main executable if necessary. */ |
| svr4_relocate_main_executable (); |
| |
| if (!svr4_have_link_map_offsets ()) |
| return; |
| |
| if (!enable_break ()) |
| return; |
| |
| #if defined(_SCO_DS) |
| /* SCO needs the loop below, other systems should be using the |
| special shared library breakpoints and the shared library breakpoint |
| service routine. |
| |
| Now run the target. It will eventually hit the breakpoint, at |
| which point all of the libraries will have been mapped in and we |
| can go groveling around in the dynamic linker structures to find |
| out what we need to know about them. */ |
| |
| clear_proceed_status (); |
| stop_soon = STOP_QUIETLY; |
| stop_signal = TARGET_SIGNAL_0; |
| do |
| { |
| target_resume (pid_to_ptid (-1), 0, stop_signal); |
| wait_for_inferior (0); |
| } |
| while (stop_signal != TARGET_SIGNAL_TRAP); |
| stop_soon = NO_STOP_QUIETLY; |
| #endif /* defined(_SCO_DS) */ |
| } |
| |
| static void |
| svr4_clear_solib (void) |
| { |
| debug_base = 0; |
| debug_loader_offset_p = 0; |
| debug_loader_offset = 0; |
| xfree (debug_loader_name); |
| debug_loader_name = NULL; |
| } |
| |
| static void |
| svr4_free_so (struct so_list *so) |
| { |
| xfree (so->lm_info->lm); |
| xfree (so->lm_info); |
| } |
| |
| |
| /* 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_gdbarch) == 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_gdbarch)) - 1); |
| } |
| |
| |
| static void |
| svr4_relocate_section_addresses (struct so_list *so, |
| struct section_table *sec) |
| { |
| sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR_CHECK (so, |
| sec->bfd)); |
| sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR_CHECK (so, |
| sec->bfd)); |
| } |
| |
| |
| /* Architecture-specific operations. */ |
| |
| /* Per-architecture data key. */ |
| static struct gdbarch_data *solib_svr4_data; |
| |
| struct solib_svr4_ops |
| { |
| /* Return a description of the layout of `struct link_map'. */ |
| struct link_map_offsets *(*fetch_link_map_offsets)(void); |
| }; |
| |
| /* Return a default for the architecture-specific operations. */ |
| |
| static void * |
| solib_svr4_init (struct obstack *obstack) |
| { |
| struct solib_svr4_ops *ops; |
| |
| ops = OBSTACK_ZALLOC (obstack, struct solib_svr4_ops); |
| ops->fetch_link_map_offsets = NULL; |
| 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 = gdbarch_data (gdbarch, solib_svr4_data); |
| |
| ops->fetch_link_map_offsets = flmo; |
| |
| set_solib_ops (gdbarch, &svr4_so_ops); |
| } |
| |
| /* 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 = gdbarch_data (current_gdbarch, solib_svr4_data); |
| |
| 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 = gdbarch_data (current_gdbarch, solib_svr4_data); |
| 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 origional 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; |
| |
| /* 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; |
| |
| /* 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; |
| } |
| |
| |
| struct target_so_ops svr4_so_ops; |
| |
| /* Lookup global symbol 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. */ |
| |
| static struct symbol * |
| elf_lookup_lib_symbol (const struct objfile *objfile, |
| const char *name, |
| const char *linkage_name, |
| const domain_enum domain, struct symtab **symtab) |
| { |
| if (objfile->obfd == NULL |
| || scan_dyntag (DT_SYMBOLIC, objfile->obfd, NULL) != 1) |
| return NULL; |
| |
| return lookup_global_symbol_from_objfile |
| (objfile, name, linkage_name, domain, symtab); |
| } |
| |
| static int |
| svr4_same (struct so_list *gdb, struct so_list *inferior) |
| { |
| if (! strcmp (gdb->so_original_name, inferior->so_original_name)) |
| 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_original_name, "/usr/lib/ld.so.1") == 0 |
| && strcmp (inferior->so_original_name, "/lib/ld.so.1") == 0) |
| return 1; |
| |
| return 0; |
| } |
| |
| extern initialize_file_ftype _initialize_svr4_solib; /* -Wmissing-prototypes */ |
| |
| void |
| _initialize_svr4_solib (void) |
| { |
| solib_svr4_data = gdbarch_data_register_pre_init (solib_svr4_init); |
| |
| svr4_so_ops.relocate_section_addresses = svr4_relocate_section_addresses; |
| svr4_so_ops.free_so = svr4_free_so; |
| svr4_so_ops.clear_solib = svr4_clear_solib; |
| svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; |
| svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; |
| svr4_so_ops.current_sos = svr4_current_sos; |
| svr4_so_ops.open_symbol_file_object = open_symbol_file_object; |
| svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code; |
| svr4_so_ops.lookup_lib_global_symbol = elf_lookup_lib_symbol; |
| svr4_so_ops.same = svr4_same; |
| } |