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binutils-gdb/gdb/gcore.c

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/* Generate a core file for the inferior process.
Copyright (C) 2001-2018 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 <fcntl.h>
#include "regcache.h"
#include "regset.h"
#include "gdb_bfd.h"
#include "readline/tilde.h"
#include <algorithm>
#include "common/gdb_unlinker.h"
#include "byte-vector.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. */
gdb_bfd_ref_ptr
create_gcore_bfd (const char *filename)
{
gdb_bfd_ref_ptr obfd (gdb_bfd_openw (filename, default_gcore_target ()));
if (obfd == NULL)
error (_("Failed to open '%s' for output."), filename);
bfd_set_format (obfd.get (), bfd_core);
bfd_set_arch_mach (obfd.get (), default_gcore_arch (), default_gcore_mach ());
return obfd;
}
/* write_gcore_file_1 -- do the actual work of write_gcore_file. */
static void
write_gcore_file_1 (bfd *obfd)
{
gdb::unique_xmalloc_ptr<char> note_data;
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.reset (target_make_corefile_notes (obfd, &note_size));
else
note_data.reset (gdbarch_make_corefile_notes (target_gdbarch (), obfd,
&note_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.get (), 0,
note_size))
warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
}
/* write_gcore_file -- helper for gcore_command (exported).
Compose and write the corefile data to the core file. */
void
write_gcore_file (bfd *obfd)
{
struct gdb_exception except = exception_none;
target_prepare_to_generate_core ();
TRY
{
write_gcore_file_1 (obfd);
}
CATCH (e, RETURN_MASK_ALL)
{
except = e;
}
END_CATCH
target_done_generating_core ();
if (except.reason < 0)
throw_exception (except);
}
/* gcore_command -- implements the 'gcore' command.
Generate a core file from the inferior process. */
static void
gcore_command (const char *args, int from_tty)
{
gdb::unique_xmalloc_ptr<char> corefilename;
/* No use generating a corefile without a target process. */
if (!target_has_execution)
noprocess ();
if (args && *args)
corefilename.reset (tilde_expand (args));
else
{
/* Default corefile name is "core.PID". */
corefilename.reset (xstrprintf ("core.%d", ptid_get_pid (inferior_ptid)));
}
if (info_verbose)
fprintf_filtered (gdb_stdout,
"Opening corefile '%s' for output.\n",
corefilename.get ());
/* Open the output file. */
gdb_bfd_ref_ptr obfd (create_gcore_bfd (corefilename.get ()));
/* Arrange to unlink the file on failure. */
gdb::unlinker unlink_file (corefilename.get ());
/* Call worker function. */
write_gcore_file (obfd.get ());
/* Succeeded. */
unlink_file.keep ();
fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename.get ());
}
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).minsym != 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).minsym != 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, NULL, 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 (startswith (bfd_section_name (obfd, osec), "load"))
p_type = PT_LOAD;
else if (startswith (bfd_section_name (obfd, osec), "note"))
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);
}
/* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
GDB is creating. */
static int
gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read,
int write, int exec, int modified, void *data)
{
bfd *obfd = (bfd *) 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 && modified == 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 && modified == 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 (objfile->separate_debug_objfile_backlink == NULL
&& ((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:;
}
if (write == 0)
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;
}
int
objfile_find_memory_regions (struct target_ops *self,
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);
/* Separate debug info files are irrelevant for gcore. */
if (objfile->separate_debug_objfile_backlink != NULL)
continue;
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. */
1, /* MODIFIED is unknown, pass it as true. */
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. */
1, /* Stack section will be modified. */
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. */
1, /* Heap section will be modified. */
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;
/* 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 (!startswith (bfd_section_name (obfd, osec), "load"))
return;
size = std::min (total_size, (bfd_size_type) MAX_COPY_BYTES);
gdb::byte_vector memhunk (size);
while (total_size > 0)
{
if (size > total_size)
size = total_size;
if (target_read_memory (bfd_section_vma (obfd, osec) + offset,
memhunk.data (), 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.data (),
offset, size))
{
warning (_("Failed to write corefile contents (%s)."),
bfd_errmsg (bfd_get_error ()));
break;
}
total_size -= size;
offset += size;
}
}
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;
}
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);
}
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