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binutils-gdb/gdb/gcore.c
Pedro Alves 492d29ea1c Split TRY_CATCH into TRY + CATCH 
This patch splits the TRY_CATCH macro into three, so that we go from
this:

~~~
  volatile gdb_exception ex;

  TRY_CATCH (ex, RETURN_MASK_ERROR)
    {
    }
  if (ex.reason < 0)
    {
    }
~~~

to this:

~~~
  TRY
    {
    }
  CATCH (ex, RETURN_MASK_ERROR)
    {
    }
  END_CATCH
~~~

Thus, we'll be getting rid of the local volatile exception object, and
declaring the caught exception in the catch block.

This allows reimplementing TRY/CATCH in terms of C++ exceptions when
building in C++ mode, while still allowing to build GDB in C mode
(using setjmp/longjmp), as a transition step.

TBC, after this patch, is it _not_ valid to have code between the TRY
and the CATCH blocks, like:

  TRY
    {
    }

  // some code here.

  CATCH (ex, RETURN_MASK_ERROR)
    {
    }
  END_CATCH

Just like it isn't valid to do that with C++'s native try/catch.

By switching to creating the exception object inside the CATCH block
scope, we can get rid of all the explicitly allocated volatile
exception objects all over the tree, and map the CATCH block more
directly to C++'s catch blocks.

The majority of the TRY_CATCH -> TRY+CATCH+END_CATCH conversion was
done with a script, rerun from scratch at every rebase, no manual
editing involved.  After the mechanical conversion, a few places
needed manual intervention, to fix preexisting cases where we were
using the exception object outside of the TRY_CATCH block, and cases
where we were using "else" after a 'if (ex.reason) < 0)' [a CATCH
after this patch].  The result was folded into this patch so that GDB
still builds at each incremental step.

END_CATCH is necessary for two reasons:

First, because we name the exception object in the CATCH block, which
requires creating a scope, which in turn must be closed somewhere.
Declaring the exception variable in the initializer field of a for
block, like:

  #define CATCH(EXCEPTION, mask) \
    for (struct gdb_exception EXCEPTION; \
         exceptions_state_mc_catch (&EXCEPTION, MASK); \
	 EXCEPTION = exception_none)

would avoid needing END_CATCH, but alas, in C mode, we build with C90,
which doesn't allow mixed declarations and code.

Second, because when TRY/CATCH are wired to real C++ try/catch, as
long as we need to handle cleanup chains, even if there's no CATCH
block that wants to catch the exception, we need for stop at every
frame in the unwind chain and run cleanups, then rethrow.  That will
be done in END_CATCH.

After we require C++, we'll still need TRY/CATCH/END_CATCH until
cleanups are completely phased out -- TRY/CATCH in C++ mode will
save/restore the current cleanup chain, like in C mode, and END_CATCH
catches otherwise uncaugh exceptions, runs cleanups and rethrows, so
that C++ cleanups and exceptions can coexist.

IMO, this still makes the TRY/CATCH code look a bit more like a
newcomer would expect, so IMO worth it even if we weren't considering
C++.

gdb/ChangeLog.
2015-03-07  Pedro Alves  <palves@redhat.com>

	* common/common-exceptions.c (struct catcher) <exception>: No
	longer a pointer to volatile exception.  Now an exception value.
	<mask>: Delete field.
	(exceptions_state_mc_init): Remove all parameters.  Adjust.
	(exceptions_state_mc): No longer pop the catcher here.
	(exceptions_state_mc_catch): New function.
	(throw_exception): Adjust.
	* common/common-exceptions.h (exceptions_state_mc_init): Remove
	all parameters.
	(exceptions_state_mc_catch): Declare.
	(TRY_CATCH): Rename to ...
	(TRY): ... this.  Remove EXCEPTION and MASK parameters.
	(CATCH, END_CATCH): New.
	All callers adjusted.

gdb/gdbserver/ChangeLog:
2015-03-07  Pedro Alves  <palves@redhat.com>

	Adjust all callers of TRY_CATCH to use TRY/CATCH/END_CATCH
	instead.
2015-03-07 15:14:14 +00:00

640 lines
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/* Generate a core file for the inferior process.
Copyright (C) 2001-2015 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"
/* 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 (const char *filename)
{
bfd *obfd = gdb_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_1 -- do the actual work of write_gcore_file. */
static void
write_gcore_file_1 (bfd *obfd)
{
struct cleanup *cleanup;
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, &note_size);
else
note_data = gdbarch_make_corefile_notes (target_gdbarch (), obfd, &note_size);
cleanup = make_cleanup (xfree, note_data);
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 ()));
do_cleanups (cleanup);
}
/* 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);
}
static void
do_bfd_delete_cleanup (void *arg)
{
bfd *obfd = arg;
const char *filename = obfd->filename;
gdb_bfd_unref (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 *filename_chain;
struct cleanup *bfd_chain;
char *corefilename;
bfd *obfd;
/* No use generating a corefile without a target process. */
if (!target_has_execution)
noprocess ();
if (args && *args)
corefilename = tilde_expand (args);
else
{
/* Default corefile name is "core.PID". */
corefilename = xstrprintf ("core.%d", ptid_get_pid (inferior_ptid));
}
filename_chain = make_cleanup (xfree, corefilename);
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. */
bfd_chain = make_cleanup (do_bfd_delete_cleanup, obfd);
/* Call worker function. */
write_gcore_file (obfd);
/* Succeeded. */
discard_cleanups (bfd_chain);
gdb_bfd_unref (obfd);
fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename);
do_cleanups (filename_chain);
}
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, 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 = 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;
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 (!startswith (bfd_section_name (obfd, osec), "load"))
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);
}
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