| /* Reading symbol files from memory. |
| |
| Copyright (C) 1986-2024 Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| /* This file defines functions (and commands to exercise those |
| functions) for reading debugging information from object files |
| whose images are mapped directly into the inferior's memory. For |
| example, the Linux kernel maps a "syscall DSO" into each process's |
| address space; this DSO provides kernel-specific code for some |
| system calls. |
| |
| At the moment, BFD only has functions for parsing object files from |
| memory for the ELF format, even though the general idea isn't |
| ELF-specific. This means that BFD only provides the functions GDB |
| needs when configured for ELF-based targets. So these functions |
| may only be compiled on ELF-based targets. |
| |
| GDB has no idea whether it has been configured for an ELF-based |
| target or not: it just tries to handle whatever files it is given. |
| But this means there are no preprocessor symbols on which we could |
| make these functions' compilation conditional. |
| |
| So, for the time being, we put these functions alone in this file, |
| and have .mt files reference them as appropriate. In the future, I |
| hope BFD will provide a format-independent bfd_from_remote_memory |
| entry point. */ |
| |
| |
| #include "exceptions.h" |
| #include "symtab.h" |
| #include "gdbcore.h" |
| #include "objfiles.h" |
| #include "cli/cli-cmds.h" |
| #include "target.h" |
| #include "value.h" |
| #include "symfile.h" |
| #include "observable.h" |
| #include "auxv.h" |
| #include "elf/common.h" |
| #include "gdb_bfd.h" |
| #include "inferior.h" |
| |
| /* Verify parameters of target_read_memory_bfd and target_read_memory are |
| compatible. */ |
| |
| static_assert (sizeof (CORE_ADDR) >= sizeof (bfd_vma)); |
| static_assert (sizeof (gdb_byte) == sizeof (bfd_byte)); |
| static_assert (sizeof (ssize_t) <= sizeof (bfd_size_type)); |
| |
| /* Provide bfd/ compatible prototype for target_read_memory. Casting would not |
| be enough as LEN width may differ. */ |
| |
| static int |
| target_read_memory_bfd (bfd_vma memaddr, bfd_byte *myaddr, bfd_size_type len) |
| { |
| /* MYADDR must be already allocated for the LEN size so it has to fit in |
| ssize_t. */ |
| gdb_assert ((ssize_t) len == len); |
| |
| return target_read_memory (memaddr, myaddr, len); |
| } |
| |
| /* Read inferior memory at ADDR to find the header of a loaded object file |
| and read its in-core symbols out of inferior memory. SIZE, if |
| non-zero, is the known size of the object. TEMPL is a bfd |
| representing the target's format. NAME is the name to use for this |
| symbol file in messages; it can be NULL. */ |
| static struct objfile * |
| symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, |
| size_t size, const char *name, int from_tty) |
| { |
| struct objfile *objf; |
| struct bfd *nbfd; |
| struct bfd_section *sec; |
| bfd_vma loadbase; |
| symfile_add_flags add_flags = SYMFILE_NOT_FILENAME; |
| |
| if (bfd_get_flavour (templ) != bfd_target_elf_flavour) |
| error (_("add-symbol-file-from-memory not supported for this target")); |
| |
| nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, size, &loadbase, |
| target_read_memory_bfd); |
| if (nbfd == NULL) |
| error (_("Failed to read a valid object file image from memory.")); |
| |
| /* Manage the new reference for the duration of this function. */ |
| gdb_bfd_ref_ptr nbfd_holder = gdb_bfd_ref_ptr::new_reference (nbfd); |
| |
| if (name == NULL) |
| name = "shared object read from target memory"; |
| bfd_set_filename (nbfd, name); |
| |
| if (!bfd_check_format (nbfd, bfd_object)) |
| error (_("Got object file from memory but can't read symbols: %s."), |
| bfd_errmsg (bfd_get_error ())); |
| |
| section_addr_info sai; |
| for (sec = nbfd->sections; sec != NULL; sec = sec->next) |
| if ((bfd_section_flags (sec) & (SEC_ALLOC|SEC_LOAD)) != 0) |
| sai.emplace_back (bfd_section_vma (sec) + loadbase, |
| bfd_section_name (sec), |
| sec->index); |
| |
| if (from_tty) |
| add_flags |= SYMFILE_VERBOSE; |
| |
| objf = symbol_file_add_from_bfd (nbfd_holder, bfd_get_filename (nbfd), |
| add_flags, &sai, OBJF_SHARED, NULL); |
| |
| current_program_space->add_target_sections (objf); |
| |
| /* This might change our ideas about frames already looked at. */ |
| reinit_frame_cache (); |
| |
| return objf; |
| } |
| |
| |
| static void |
| add_symbol_file_from_memory_command (const char *args, int from_tty) |
| { |
| CORE_ADDR addr; |
| struct bfd *templ; |
| |
| if (args == NULL) |
| error (_("add-symbol-file-from-memory requires an expression argument")); |
| |
| addr = parse_and_eval_address (args); |
| |
| /* We need some representative bfd to know the target we are looking at. */ |
| if (current_program_space->symfile_object_file != NULL) |
| templ = current_program_space->symfile_object_file->obfd.get (); |
| else |
| templ = current_program_space->exec_bfd (); |
| if (templ == NULL) |
| error (_("Must use symbol-file or exec-file " |
| "before add-symbol-file-from-memory.")); |
| |
| symbol_file_add_from_memory (templ, addr, 0, NULL, from_tty); |
| } |
| |
| /* Try to add the symbols for the vsyscall page, if there is one. |
| This function is called via the inferior_created observer. */ |
| |
| static void |
| add_vsyscall_page (inferior *inf) |
| { |
| struct mem_range vsyscall_range; |
| |
| if (gdbarch_vsyscall_range (inf->arch (), &vsyscall_range)) |
| { |
| struct bfd *bfd; |
| |
| if (current_program_space->core_bfd () != nullptr) |
| bfd = current_program_space->core_bfd (); |
| else if (current_program_space->exec_bfd () != nullptr) |
| bfd = current_program_space->exec_bfd (); |
| else |
| /* FIXME: cagney/2004-05-06: Should not require an existing |
| BFD when trying to create a run-time BFD of the VSYSCALL |
| page in the inferior. Unfortunately that's the current |
| interface so for the moment bail. Introducing a |
| ``bfd_runtime'' (a BFD created using the loaded image) file |
| format should fix this. */ |
| { |
| warning (_("Could not load vsyscall page " |
| "because no executable was specified")); |
| return; |
| } |
| |
| std::string name = string_printf ("system-supplied DSO at %s", |
| paddress (current_inferior ()->arch (), |
| vsyscall_range.start)); |
| try |
| { |
| /* Pass zero for FROM_TTY, because the action of loading the |
| vsyscall DSO was not triggered by the user, even if the |
| user typed "run" at the TTY. */ |
| symbol_file_add_from_memory (bfd, |
| vsyscall_range.start, |
| vsyscall_range.length, |
| name.c_str (), |
| 0 /* from_tty */); |
| } |
| catch (const gdb_exception_error &ex) |
| { |
| exception_print (gdb_stderr, ex); |
| } |
| } |
| } |
| |
| void _initialize_symfile_mem (); |
| void |
| _initialize_symfile_mem () |
| { |
| add_cmd ("add-symbol-file-from-memory", class_files, |
| add_symbol_file_from_memory_command, |
| _("Load the symbols out of memory from a " |
| "dynamically loaded object file.\n" |
| "Give an expression for the address " |
| "of the file's shared object file header."), |
| &cmdlist); |
| |
| /* Want to know of each new inferior so that its vsyscall info can |
| be extracted. */ |
| gdb::observers::inferior_created.attach (add_vsyscall_page, "symfile-mem"); |
| } |