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3 Commits

Author SHA1 Message Date
Pedro Alves
3207396b95 Fix Python frame unwinder issue caught by Valgrind 
Valgrind shows:

 ==17026== Invalid write of size 8
 ==17026==    at 0x54AA80: pending_frame_invalidate (py-unwind.c:477)
 ==17026==    by 0x5AB934: do_my_cleanups (cleanups.c:155)
 ==17026==    by 0x5AB9AF: do_cleanups (cleanups.c:177)
 ==17026==    by 0x54B009: pyuw_sniffer (py-unwind.c:606)
 ==17026==    by 0x755DAC: frame_unwind_try_unwinder (frame-unwind.c:105)
 ==17026==    by 0x755EEE: frame_unwind_find_by_frame (frame-unwind.c:160)
 ==17026==    by 0x750FFA: compute_frame_id (frame.c:454)
 ==17026==    by 0x753BD6: get_prev_frame_if_no_cycle (frame.c:1781)
 ==17026==    by 0x754292: get_prev_frame_always_1 (frame.c:1955)
 ==17026==    by 0x7542DA: get_prev_frame_always (frame.c:1971)
 ==17026==    by 0x7547BE: get_prev_frame (frame.c:2213)
 ==17026==    by 0x7532BD: unwind_to_current_frame (frame.c:1450)
 ==17026==  Address 0xd27b570 is 16 bytes inside a block of size 32 free'd
 ==17026==    at 0x4A07577: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
 ==17026==    by 0x54B276: gdb_Py_DECREF (python-internal.h:185)
 ==17026==    by 0x54B298: py_decref (py-utils.c:34)
 ==17026==    by 0x5AB934: do_my_cleanups (cleanups.c:155)
 ==17026==    by 0x5AB9AF: do_cleanups (cleanups.c:177)
 ==17026==    by 0x54B009: pyuw_sniffer (py-unwind.c:606)
 ==17026==    by 0x755DAC: frame_unwind_try_unwinder (frame-unwind.c:105)
 ==17026==    by 0x755EEE: frame_unwind_find_by_frame (frame-unwind.c:160)
 ==17026==    by 0x750FFA: compute_frame_id (frame.c:454)
 ==17026==    by 0x753BD6: get_prev_frame_if_no_cycle (frame.c:1781)
 ==17026==    by 0x754292: get_prev_frame_always_1 (frame.c:1955)
 ==17026==    by 0x7542DA: get_prev_frame_always (frame.c:1971)
 ==17026==

Simply invalidate the object before releasing it.

gdb/ChangeLog:
2015-08-13  Pedro Alves  <palves@redhat.com>

	* python/py-unwind.c (pyuw_sniffer): Install the invalidate
	cleanup after the decref cleanup, not before.
 2015-08-13 18:56:42 +01:00
Yuanhui Zhang
13fa0398d7 Fix a couple C++ build issues 
Building mingw GDB with --enable-build-with-cxx shows:

../../binutils-gdb/gdb/python/py-unwind.c:500:45: error: cannot convert 'cached_frame_info::reg_info*' to 'pyuw_prev_register(frame_info*, void**, int)::reg_info*' in initialization
   struct reg_info *reg_info = cached_frame->reg;
                                             ^
../../binutils-gdb/gdb/python/py-unwind.c:501:60: error: invalid use of incomplete type 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
   struct reg_info *reg_info_end = reg_info + cached_frame->reg_count;
                                                            ^
../../binutils-gdb/gdb/python/py-unwind.c:500:10: error: forward declaration of 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
   struct reg_info *reg_info = cached_frame->reg;
          ^
../../binutils-gdb/gdb/python/py-unwind.c:505:37: error: cannot increment a pointer to incomplete type 'pyuw_prev_register(frame_info*, void**, int)::reg_info'
   for (; reg_info < reg_info_end; ++reg_info)
                                     ^
../../binutils-gdb/gdb/python/py-unwind.c:507:29: error: invalid use of incomplete type 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
       if (regnum == reg_info->number)
                             ^
../../binutils-gdb/gdb/python/py-unwind.c:500:10: error: forward declaration of 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
   struct reg_info *reg_info = cached_frame->reg;
          ^
../../binutils-gdb/gdb/python/py-unwind.c:508:68: error: invalid use of incomplete type 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
         return frame_unwind_got_bytes (this_frame, regnum, reg_info->data);
                                                                    ^
../../binutils-gdb/gdb/python/py-unwind.c:500:10: error: forward declaration of 'struct pyuw_prev_register(frame_info*, void**, int)::reg_info'
   struct reg_info *reg_info = cached_frame->reg;
          ^
../../binutils-gdb/gdb/python/py-unwind.c: In function 'int pyuw_sniffer(const frame_unwind*, frame_info*, void**)':
../../binutils-gdb/gdb/python/py-unwind.c:574:70: warning: invalid conversion from 'void*' to 'cached_frame_info*' [-fpermissive]
                             reg_count * sizeof (cached_frame->reg[0]));
                                                                      ^
../../binutils-gdb/gdb/python/py-unwind.c: In function 'void pyuw_on_new_gdbarch(gdbarch*)':
../../binutils-gdb/gdb/python/py-unwind.c:636:47: warning: invalid conversion from 'void*' to 'pyuw_gdbarch_data_type*' [-fpermissive]
       gdbarch_data (newarch, pyuw_gdbarch_data);
                                               ^
../../binutils-gdb/gdb/python/py-unwind.c:647:29: warning: invalid conversion from 'void*' to 'const frame_data*' [-fpermissive]
       unwinder->unwind_data = (void *) newarch;
                             ^
../../binutils-gdb/gdb/python/py-unwind.c: At global scope:
../../binutils-gdb/gdb/python/py-unwind.c:699:21: error: redefinition of 'PyTypeObject pending_frame_object_type'
 static PyTypeObject pending_frame_object_type =
                     ^
../../binutils-gdb/gdb/python/py-unwind.c:96:21: error: 'PyTypeObject pending_frame_object_type' previously declared here
 static PyTypeObject pending_frame_object_type
                     ^
../../binutils-gdb/gdb/python/py-unwind.c:749:21: error: redefinition of 'PyTypeObject unwind_info_object_type'
 static PyTypeObject unwind_info_object_type =
                     ^
../../binutils-gdb/gdb/python/py-unwind.c:99:21: error: 'PyTypeObject unwind_info_object_type' previously declared here
 static PyTypeObject unwind_info_object_type
                     ^

The first kind of error is caused by the embedded struct definition,
so move it out of the parent struct.

The second kind of error is caused by forward declaring a static
global variable, which works in C, but not in C++ (or C with
-fno-common).  Make it using extern instead, like done in other
similar cases.

gdb/ChangeLog:
2015-05-15  Yuanhui Zhang  <asmwarrior@gmail.com>

	* python/py-unwind.c (struct reg_info): Move out of ...
	(struct cached_frame_info): ... this scope.
	(pending_frame_object_type, unwind_info_object_type): Make extern.
 2015-05-15 16:00:40 +01:00
Sasha Smundak
d11916aa89 Add support for writing unwinders in Python. 
gdb/ChangeLog:

	* Makefile.in (SUBDIR_PYTHON_OBJS): Add py-unwind.o.
	(SUBDIR_PYTHON_SRCS): Add py-unwind.c.
	(py-unwind.o): New recipe.
	* NEWS: mention Python frame unwinding.
	* data-directory/Makefile.in (PYTHON_FILE_LIST): Add
	gdb/unwinder.py and gdb/command/unwinder.py
	* python/lib/gdb/__init__.py (packages): Add frame_unwinders
	list.
	(execute_unwinders): New function.
	* python/lib/gdb/command/unwinders.py: New file.
	* python/lib/gdb/unwinder.py: New file.
	* python/py-objfile.c (objfile_object): Add frame_unwinders field.
	(objfpy_dealloc): Decrement frame_unwinders reference count.
	(objfpy_initialize): Create frame_unwinders list.
	(objfpy_get_frame_unwinders): New function.
	(objfpy_set_frame_unwinders): Ditto.
	(objfile_getset): Add frame_unwinders attribute to Objfile.
	* python/py-progspace.c (pspace_object): Add frame_unwinders field.
	(pspy_dealloc): Decrement frame_unwinders reference count.
	(pspy_initialize): Create frame_unwinders list.
	(pspy_get_frame_unwinders): New function.
	(pspy_set_frame_unwinders): Ditto.
	(pspy_getset): Add frame_unwinders attribute to gdb.Progspace.
	* python/py-unwind.c: New file.
	* python/python-internal.h (pspy_get_name_unwinders): New prototype.
	(objpy_get_frame_unwinders): New prototype.
	(gdbpy_initialize_unwind): New prototype.
	* python/python.c (gdbpy_apply_type_printers): Call
	gdbpy_initialize_unwind.

gdb/doc/ChangeLog:

	* doc/python.texi (Writing a Frame Unwinder in Python): Add
	section.

gdb/testsuite/ChangeLog:

	* gdb.python/py-unwind-maint.c: New file.
	* gdb.python/py-unwind-maint.exp: New test.
	* gdb.python/py-unwind-maint.py: New file.
	* gdb.python/py-unwind.c: New file.
	* gdb.python/py-unwind.exp: New test.
	* gdb.python/py-unwind.py: New test.
 2015-04-01 11:49:12 -07:00