1 /* Reading symbol files from memory. 2 3 Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 4 2001, 2002, 2003, 2004 Free Software Foundation, Inc. 5 6 This file is part of GDB. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 2 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program; if not, write to the Free Software 20 Foundation, Inc., 59 Temple Place - Suite 330, 21 Boston, MA 02111-1307, USA. */ 22 23 /* This file defines functions (and commands to exercise those 24 functions) for reading debugging information from object files 25 whose images are mapped directly into the inferior's memory. For 26 example, the Linux kernel maps a "syscall DSO" into each process's 27 address space; this DSO provides kernel-specific code for some 28 system calls. 29 30 At the moment, BFD only has functions for parsing object files from 31 memory for the ELF format, even though the general idea isn't 32 ELF-specific. This means that BFD only provides the functions GDB 33 needs when configured for ELF-based targets. So these functions 34 may only be compiled on ELF-based targets. 35 36 GDB has no idea whether it has been configured for an ELF-based 37 target or not: it just tries to handle whatever files it is given. 38 But this means there are no preprocessor symbols on which we could 39 make these functions' compilation conditional. 40 41 So, for the time being, we put these functions alone in this file, 42 and have .mt files reference them as appropriate. In the future, I 43 hope BFD will provide a format-independent bfd_from_remote_memory 44 entry point. */ 45 46 47 #include "defs.h" 48 #include "symtab.h" 49 #include "gdbcore.h" 50 #include "objfiles.h" 51 #include "gdbcmd.h" 52 #include "target.h" 53 #include "value.h" 54 #include "symfile.h" 55 56 57 /* Read inferior memory at ADDR to find the header of a loaded object file 58 and read its in-core symbols out of inferior memory. TEMPL is a bfd 59 representing the target's format. */ 60 static struct objfile * 61 symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, int from_tty) 62 { 63 struct objfile *objf; 64 struct bfd *nbfd; 65 struct bfd_section *sec; 66 bfd_vma loadbase; 67 struct section_addr_info *sai; 68 unsigned int i; 69 70 if (bfd_get_flavour (templ) != bfd_target_elf_flavour) 71 error ("add-symbol-file-from-memory not supported for this target"); 72 73 nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase, 74 target_read_memory); 75 if (nbfd == NULL) 76 error ("Failed to read a valid object file image from memory."); 77 78 nbfd->filename = xstrdup ("shared object read from target memory"); 79 80 if (!bfd_check_format (nbfd, bfd_object)) 81 { 82 /* FIXME: should be checking for errors from bfd_close (for one thing, 83 on error it does not free all the storage associated with the 84 bfd). */ 85 bfd_close (nbfd); 86 error ("Got object file from memory but can't read symbols: %s.", 87 bfd_errmsg (bfd_get_error ())); 88 } 89 90 sai = alloc_section_addr_info (bfd_count_sections (nbfd)); 91 make_cleanup (xfree, sai); 92 i = 0; 93 for (sec = nbfd->sections; sec != NULL; sec = sec->next) 94 if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0) 95 { 96 sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase; 97 sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec); 98 sai->other[i].sectindex = sec->index; 99 ++i; 100 } 101 102 objf = symbol_file_add_from_bfd (nbfd, from_tty, 103 sai, 2, OBJF_SHARED); 104 105 /* This might change our ideas about frames already looked at. */ 106 reinit_frame_cache (); 107 108 return objf; 109 } 110 111 112 static void 113 add_symbol_file_from_memory_command (char *args, int from_tty) 114 { 115 CORE_ADDR addr; 116 struct bfd *templ; 117 118 if (args == NULL) 119 error ("add-symbol-file-from-memory requires an expression argument"); 120 121 addr = parse_and_eval_address (args); 122 123 /* We need some representative bfd to know the target we are looking at. */ 124 if (symfile_objfile != NULL) 125 templ = symfile_objfile->obfd; 126 else 127 templ = exec_bfd; 128 if (templ == NULL) 129 error ("\ 130 Must use symbol-file or exec-file before add-symbol-file-from-memory."); 131 132 symbol_file_add_from_memory (templ, addr, from_tty); 133 } 134 135 136 void 137 _initialize_symfile_mem (void) 138 { 139 add_cmd ("add-symbol-file-from-memory", class_files, 140 add_symbol_file_from_memory_command, 141 "\ 142 Load the symbols out of memory from a dynamically loaded object file.\n\ 143 Give an expression for the address of the file's shared object file header.", 144 &cmdlist); 145 146 } 147