/* Generate a core file for the inferior process. Copyright (C) 2001-2012 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-bfd.h" #include "infcall.h" #include "inferior.h" #include "gdbcore.h" #include "objfiles.h" #include "solib.h" #include "symfile.h" #include "arch-utils.h" #include "completer.h" #include "gcore.h" #include "cli/cli-decode.h" #include "gdb_assert.h" #include <fcntl.h> #include "regcache.h" #include "regset.h" /* The largest amount of memory to read from the target at once. We must throttle it to limit the amount of memory used by GDB during generate-core-file for programs with large resident data. */ #define MAX_COPY_BYTES (1024 * 1024) static const char *default_gcore_target (void); static enum bfd_architecture default_gcore_arch (void); static unsigned long default_gcore_mach (void); static int gcore_memory_sections (bfd *); /* create_gcore_bfd -- helper for gcore_command (exported). Open a new bfd core file for output, and return the handle. */ bfd * create_gcore_bfd (char *filename) { bfd *obfd = bfd_openw (filename, default_gcore_target ()); if (!obfd) error (_("Failed to open '%s' for output."), filename); bfd_set_format (obfd, bfd_core); bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ()); return obfd; } /* write_gcore_file -- helper for gcore_command (exported). Compose and write the corefile data to the core file. */ void write_gcore_file (bfd *obfd) { void *note_data = NULL; int note_size = 0; asection *note_sec = NULL; /* An external target method must build the notes section. */ /* FIXME: uweigand/2011-10-06: All architectures that support core file generation should be converted to gdbarch_make_corefile_notes; at that point, the target vector method can be removed. */ if (!gdbarch_make_corefile_notes_p (target_gdbarch)) note_data = target_make_corefile_notes (obfd, ¬e_size); else note_data = gdbarch_make_corefile_notes (target_gdbarch, obfd, ¬e_size); if (note_data == NULL || note_size == 0) error (_("Target does not support core file generation.")); /* Create the note section. */ note_sec = bfd_make_section_anyway_with_flags (obfd, "note0", SEC_HAS_CONTENTS | SEC_READONLY | SEC_ALLOC); if (note_sec == NULL) error (_("Failed to create 'note' section for corefile: %s"), bfd_errmsg (bfd_get_error ())); bfd_set_section_vma (obfd, note_sec, 0); bfd_set_section_alignment (obfd, note_sec, 0); bfd_set_section_size (obfd, note_sec, note_size); /* Now create the memory/load sections. */ if (gcore_memory_sections (obfd) == 0) error (_("gcore: failed to get corefile memory sections from target.")); /* Write out the contents of the note section. */ if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size)) warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ())); } static void do_bfd_delete_cleanup (void *arg) { bfd *obfd = arg; const char *filename = obfd->filename; bfd_close (arg); unlink (filename); } /* gcore_command -- implements the 'gcore' command. Generate a core file from the inferior process. */ static void gcore_command (char *args, int from_tty) { struct cleanup *old_chain; char *corefilename, corefilename_buffer[40]; bfd *obfd; /* No use generating a corefile without a target process. */ if (!target_has_execution) noprocess (); if (args && *args) corefilename = args; else { /* Default corefile name is "core.PID". */ sprintf (corefilename_buffer, "core.%d", PIDGET (inferior_ptid)); corefilename = corefilename_buffer; } if (info_verbose) fprintf_filtered (gdb_stdout, "Opening corefile '%s' for output.\n", corefilename); /* Open the output file. */ obfd = create_gcore_bfd (corefilename); /* Need a cleanup that will close and delete the file. */ old_chain = make_cleanup (do_bfd_delete_cleanup, obfd); /* Call worker function. */ write_gcore_file (obfd); /* Succeeded. */ fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); discard_cleanups (old_chain); bfd_close (obfd); } static unsigned long default_gcore_mach (void) { #if 1 /* See if this even matters... */ return 0; #else const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); if (bfdarch != NULL) return bfdarch->mach; if (exec_bfd == NULL) error (_("Can't find default bfd machine type (need execfile).")); return bfd_get_mach (exec_bfd); #endif /* 1 */ } static enum bfd_architecture default_gcore_arch (void) { const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); if (bfdarch != NULL) return bfdarch->arch; if (exec_bfd == NULL) error (_("Can't find bfd architecture for corefile (need execfile).")); return bfd_get_arch (exec_bfd); } static const char * default_gcore_target (void) { /* The gdbarch may define a target to use for core files. */ if (gdbarch_gcore_bfd_target_p (target_gdbarch)) return gdbarch_gcore_bfd_target (target_gdbarch); /* Otherwise, try to fall back to the exec_bfd target. This will probably not work for non-ELF targets. */ if (exec_bfd == NULL) return NULL; else return bfd_get_target (exec_bfd); } /* Derive a reasonable stack segment by unwinding the target stack, and store its limits in *BOTTOM and *TOP. Return non-zero if successful. */ static int derive_stack_segment (bfd_vma *bottom, bfd_vma *top) { struct frame_info *fi, *tmp_fi; gdb_assert (bottom); gdb_assert (top); /* Can't succeed without stack and registers. */ if (!target_has_stack || !target_has_registers) return 0; /* Can't succeed without current frame. */ fi = get_current_frame (); if (fi == NULL) return 0; /* Save frame pointer of TOS frame. */ *top = get_frame_base (fi); /* If current stack pointer is more "inner", use that instead. */ if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) *top = get_frame_sp (fi); /* Find prev-most frame. */ while ((tmp_fi = get_prev_frame (fi)) != NULL) fi = tmp_fi; /* Save frame pointer of prev-most frame. */ *bottom = get_frame_base (fi); /* Now canonicalize their order, so that BOTTOM is a lower address (as opposed to a lower stack frame). */ if (*bottom > *top) { bfd_vma tmp_vma; tmp_vma = *top; *top = *bottom; *bottom = tmp_vma; } return 1; } /* call_target_sbrk -- helper function for derive_heap_segment. */ static bfd_vma call_target_sbrk (int sbrk_arg) { struct objfile *sbrk_objf; struct gdbarch *gdbarch; bfd_vma top_of_heap; struct value *target_sbrk_arg; struct value *sbrk_fn, *ret; bfd_vma tmp; if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL) { sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); if (sbrk_fn == NULL) return (bfd_vma) 0; } else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL) { sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); if (sbrk_fn == NULL) return (bfd_vma) 0; } else return (bfd_vma) 0; gdbarch = get_objfile_arch (sbrk_objf); target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, sbrk_arg); gdb_assert (target_sbrk_arg); ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); if (ret == NULL) return (bfd_vma) 0; tmp = value_as_long (ret); if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) return (bfd_vma) 0; top_of_heap = tmp; return top_of_heap; } /* Derive a reasonable heap segment for ABFD by looking at sbrk and the static data sections. Store its limits in *BOTTOM and *TOP. Return non-zero if successful. */ static int derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) { bfd_vma top_of_data_memory = 0; bfd_vma top_of_heap = 0; bfd_size_type sec_size; bfd_vma sec_vaddr; asection *sec; gdb_assert (bottom); gdb_assert (top); /* This function depends on being able to call a function in the inferior. */ if (!target_has_execution) return 0; /* The following code assumes that the link map is arranged as follows (low to high addresses): --------------------------------- | text sections | --------------------------------- | data sections (including bss) | --------------------------------- | heap | --------------------------------- */ for (sec = abfd->sections; sec; sec = sec->next) { if (bfd_get_section_flags (abfd, sec) & SEC_DATA || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) { sec_vaddr = bfd_get_section_vma (abfd, sec); sec_size = bfd_get_section_size (sec); if (sec_vaddr + sec_size > top_of_data_memory) top_of_data_memory = sec_vaddr + sec_size; } } top_of_heap = call_target_sbrk (0); if (top_of_heap == (bfd_vma) 0) return 0; /* Return results. */ if (top_of_heap > top_of_data_memory) { *bottom = top_of_data_memory; *top = top_of_heap; return 1; } /* No additional heap space needs to be saved. */ return 0; } static void make_output_phdrs (bfd *obfd, asection *osec, void *ignored) { int p_flags = 0; int p_type = 0; /* FIXME: these constants may only be applicable for ELF. */ if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0) p_type = PT_LOAD; else if (strncmp (bfd_section_name (obfd, osec), "note", 4) == 0) p_type = PT_NOTE; else p_type = PT_NULL; p_flags |= PF_R; /* Segment is readable. */ if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) p_flags |= PF_W; /* Segment is writable. */ if (bfd_get_section_flags (obfd, osec) & SEC_CODE) p_flags |= PF_X; /* Segment is executable. */ bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); } static int gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read, int write, int exec, void *data) { bfd *obfd = data; asection *osec; flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; /* If the memory segment has no permissions set, ignore it, otherwise when we later try to access it for read/write, we'll get an error or jam the kernel. */ if (read == 0 && write == 0 && exec == 0) { if (info_verbose) { fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", plongest (size), paddress (target_gdbarch, vaddr)); } return 0; } if (write == 0 && !solib_keep_data_in_core (vaddr, size)) { /* See if this region of memory lies inside a known file on disk. If so, we can avoid copying its contents by clearing SEC_LOAD. */ struct objfile *objfile; struct obj_section *objsec; ALL_OBJSECTIONS (objfile, objsec) { bfd *abfd = objfile->obfd; asection *asec = objsec->the_bfd_section; bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, asec); bfd_vma start = obj_section_addr (objsec) & -align; bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; /* Match if either the entire memory region lies inside the section (i.e. a mapping covering some pages of a large segment) or the entire section lies inside the memory region (i.e. a mapping covering multiple small sections). This BFD was synthesized from reading target memory, we don't want to omit that. */ if (((vaddr >= start && vaddr + size <= end) || (start >= vaddr && end <= vaddr + size)) && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) { flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS); goto keep; /* Break out of two nested for loops. */ } } keep: flags |= SEC_READONLY; } if (exec) flags |= SEC_CODE; else flags |= SEC_DATA; osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); if (osec == NULL) { warning (_("Couldn't make gcore segment: %s"), bfd_errmsg (bfd_get_error ())); return 1; } if (info_verbose) { fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", plongest (size), paddress (target_gdbarch, vaddr)); } bfd_set_section_size (obfd, osec, size); bfd_set_section_vma (obfd, osec, vaddr); bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ return 0; } static int objfile_find_memory_regions (find_memory_region_ftype func, void *obfd) { /* Use objfile data to create memory sections. */ struct objfile *objfile; struct obj_section *objsec; bfd_vma temp_bottom, temp_top; /* Call callback function for each objfile section. */ ALL_OBJSECTIONS (objfile, objsec) { bfd *ibfd = objfile->obfd; asection *isec = objsec->the_bfd_section; flagword flags = bfd_get_section_flags (ibfd, isec); if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) { int size = bfd_section_size (ibfd, isec); int ret; ret = (*func) (obj_section_addr (objsec), size, 1, /* All sections will be readable. */ (flags & SEC_READONLY) == 0, /* Writable. */ (flags & SEC_CODE) != 0, /* Executable. */ obfd); if (ret != 0) return ret; } } /* Make a stack segment. */ if (derive_stack_segment (&temp_bottom, &temp_top)) (*func) (temp_bottom, temp_top - temp_bottom, 1, /* Stack section will be readable. */ 1, /* Stack section will be writable. */ 0, /* Stack section will not be executable. */ obfd); /* Make a heap segment. */ if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) (*func) (temp_bottom, temp_top - temp_bottom, 1, /* Heap section will be readable. */ 1, /* Heap section will be writable. */ 0, /* Heap section will not be executable. */ obfd); return 0; } static void gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) { bfd_size_type size, total_size = bfd_section_size (obfd, osec); file_ptr offset = 0; struct cleanup *old_chain = NULL; void *memhunk; /* Read-only sections are marked; we don't have to copy their contents. */ if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) return; /* Only interested in "load" sections. */ if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0) return; size = min (total_size, MAX_COPY_BYTES); memhunk = xmalloc (size); old_chain = make_cleanup (xfree, memhunk); while (total_size > 0) { if (size > total_size) size = total_size; if (target_read_memory (bfd_section_vma (obfd, osec) + offset, memhunk, size) != 0) { warning (_("Memory read failed for corefile " "section, %s bytes at %s."), plongest (size), paddress (target_gdbarch, bfd_section_vma (obfd, osec))); break; } if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) { warning (_("Failed to write corefile contents (%s)."), bfd_errmsg (bfd_get_error ())); break; } total_size -= size; offset += size; } do_cleanups (old_chain); /* Frees MEMHUNK. */ } static int gcore_memory_sections (bfd *obfd) { /* Try gdbarch method first, then fall back to target method. */ if (!gdbarch_find_memory_regions_p (target_gdbarch) || gdbarch_find_memory_regions (target_gdbarch, gcore_create_callback, obfd) != 0) { if (target_find_memory_regions (gcore_create_callback, obfd) != 0) return 0; /* FIXME: error return/msg? */ } /* Record phdrs for section-to-segment mapping. */ bfd_map_over_sections (obfd, make_output_phdrs, NULL); /* Copy memory region contents. */ bfd_map_over_sections (obfd, gcore_copy_callback, NULL); return 1; } /* Provide a prototype to silence -Wmissing-prototypes. */ extern initialize_file_ftype _initialize_gcore; void _initialize_gcore (void) { add_com ("generate-core-file", class_files, gcore_command, _("\ Save a core file with the current state of the debugged process.\n\ Argument is optional filename. Default filename is 'core.<process_id>'.")); add_com_alias ("gcore", "generate-core-file", class_files, 1); exec_set_find_memory_regions (objfile_find_memory_regions); }