229 lines
7.4 KiB
C
229 lines
7.4 KiB
C
/* Reading symbol files from memory.
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Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001,
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2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010
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Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* This file defines functions (and commands to exercise those
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functions) for reading debugging information from object files
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whose images are mapped directly into the inferior's memory. For
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example, the Linux kernel maps a "syscall DSO" into each process's
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address space; this DSO provides kernel-specific code for some
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system calls.
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At the moment, BFD only has functions for parsing object files from
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memory for the ELF format, even though the general idea isn't
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ELF-specific. This means that BFD only provides the functions GDB
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needs when configured for ELF-based targets. So these functions
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may only be compiled on ELF-based targets.
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GDB has no idea whether it has been configured for an ELF-based
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target or not: it just tries to handle whatever files it is given.
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But this means there are no preprocessor symbols on which we could
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make these functions' compilation conditional.
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So, for the time being, we put these functions alone in this file,
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and have .mt files reference them as appropriate. In the future, I
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hope BFD will provide a format-independent bfd_from_remote_memory
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entry point. */
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#include "defs.h"
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#include "symtab.h"
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#include "gdbcore.h"
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#include "objfiles.h"
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#include "exceptions.h"
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#include "gdbcmd.h"
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#include "target.h"
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#include "value.h"
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#include "symfile.h"
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#include "observer.h"
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#include "auxv.h"
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#include "elf/common.h"
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/* Read inferior memory at ADDR to find the header of a loaded object file
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and read its in-core symbols out of inferior memory. TEMPL is a bfd
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representing the target's format. NAME is the name to use for this
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symbol file in messages; it can be NULL or a malloc-allocated string
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which will be attached to the BFD. */
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static struct objfile *
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symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, char *name,
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int from_tty)
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{
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struct objfile *objf;
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struct bfd *nbfd;
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struct bfd_section *sec;
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bfd_vma loadbase;
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struct section_addr_info *sai;
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unsigned int i;
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if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
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error (_("add-symbol-file-from-memory not supported for this target"));
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nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase,
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target_read_memory);
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if (nbfd == NULL)
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error (_("Failed to read a valid object file image from memory."));
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if (name == NULL)
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nbfd->filename = xstrdup ("shared object read from target memory");
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else
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nbfd->filename = name;
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if (!bfd_check_format (nbfd, bfd_object))
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{
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/* FIXME: should be checking for errors from bfd_close (for one thing,
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on error it does not free all the storage associated with the
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bfd). */
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bfd_close (nbfd);
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error (_("Got object file from memory but can't read symbols: %s."),
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bfd_errmsg (bfd_get_error ()));
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}
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sai = alloc_section_addr_info (bfd_count_sections (nbfd));
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make_cleanup (xfree, sai);
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i = 0;
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for (sec = nbfd->sections; sec != NULL; sec = sec->next)
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if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
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{
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sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase;
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sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec);
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sai->other[i].sectindex = sec->index;
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++i;
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}
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objf = symbol_file_add_from_bfd (nbfd, from_tty ? SYMFILE_VERBOSE : 0,
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sai, OBJF_SHARED);
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/* This might change our ideas about frames already looked at. */
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reinit_frame_cache ();
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return objf;
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}
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static void
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add_symbol_file_from_memory_command (char *args, int from_tty)
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{
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CORE_ADDR addr;
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struct bfd *templ;
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if (args == NULL)
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error (_("add-symbol-file-from-memory requires an expression argument"));
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addr = parse_and_eval_address (args);
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/* We need some representative bfd to know the target we are looking at. */
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if (symfile_objfile != NULL)
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templ = symfile_objfile->obfd;
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else
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templ = exec_bfd;
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if (templ == NULL)
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error (_("\
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Must use symbol-file or exec-file before add-symbol-file-from-memory."));
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symbol_file_add_from_memory (templ, addr, NULL, from_tty);
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}
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/* Arguments for symbol_file_add_from_memory_wrapper. */
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struct symbol_file_add_from_memory_args
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{
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struct bfd *bfd;
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CORE_ADDR sysinfo_ehdr;
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char *name;
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int from_tty;
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};
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/* Wrapper function for symbol_file_add_from_memory, for
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catch_exceptions. */
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static int
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symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data)
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{
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struct symbol_file_add_from_memory_args *args = data;
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symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->name,
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args->from_tty);
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return 0;
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}
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/* Try to add the symbols for the vsyscall page, if there is one. This function
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is called via the inferior_created observer. */
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static void
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add_vsyscall_page (struct target_ops *target, int from_tty)
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{
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CORE_ADDR sysinfo_ehdr;
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if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
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&& sysinfo_ehdr != (CORE_ADDR) 0)
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{
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struct bfd *bfd;
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struct symbol_file_add_from_memory_args args;
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if (core_bfd != NULL)
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bfd = core_bfd;
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else if (exec_bfd != NULL)
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bfd = exec_bfd;
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else
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/* FIXME: cagney/2004-05-06: Should not require an existing
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BFD when trying to create a run-time BFD of the VSYSCALL
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page in the inferior. Unfortunately that's the current
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interface so for the moment bail. Introducing a
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``bfd_runtime'' (a BFD created using the loaded image) file
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format should fix this. */
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{
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warning (_("\
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Could not load vsyscall page because no executable was specified\n\
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try using the \"file\" command first."));
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return;
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}
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args.bfd = bfd;
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args.sysinfo_ehdr = sysinfo_ehdr;
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args.name = xstrprintf ("system-supplied DSO at %s",
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paddress (target_gdbarch, sysinfo_ehdr));
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/* Pass zero for FROM_TTY, because the action of loading the
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vsyscall DSO was not triggered by the user, even if the user
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typed "run" at the TTY. */
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args.from_tty = 0;
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catch_exceptions (uiout, symbol_file_add_from_memory_wrapper,
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&args, RETURN_MASK_ALL);
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}
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}
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/* Provide a prototype to silence -Wmissing-prototypes. */
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extern initialize_file_ftype _initialize_symfile_mem;
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void
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_initialize_symfile_mem (void)
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{
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add_cmd ("add-symbol-file-from-memory", class_files,
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add_symbol_file_from_memory_command, _("\
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Load the symbols out of memory from a dynamically loaded object file.\n\
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Give an expression for the address of the file's shared object file header."),
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&cmdlist);
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/* Want to know of each new inferior so that its vsyscall info can
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be extracted. */
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observer_attach_inferior_created (add_vsyscall_page);
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}
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