gdb/frame-unwind.c - gdb

Global variables defined

Data types defined

Functions defined

Source code

  1. /* Definitions for frame unwinder, for GDB, the GNU debugger.

  3.    Copyright (C) 2003-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.

  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "frame.h"
  22. #include "frame-unwind.h"
  23. #include "dummy-frame.h"
  24. #include "inline-frame.h"
  25. #include "value.h"
  26. #include "regcache.h"
  27. #include "gdb_obstack.h"
  28. #include "target.h"

  30. ‌static struct gdbarch_data *frame_unwind_data;

  32. ‌struct frame_unwind_table_entry
  33. {
  34.   const struct frame_unwind *unwinder;
  35.   struct frame_unwind_table_entry *next;
  36. };

  38. ‌struct frame_unwind_table
  39. {
  40.   struct frame_unwind_table_entry *list;
  41.   /* The head of the OSABI part of the search list.  */
  42.   struct frame_unwind_table_entry **osabi_head;
  43. };

  45. static void *
  46. ‌frame_unwind_init (struct obstack *obstack)
  47. {
  48.   struct frame_unwind_table *table
  49.     = OBSTACK_ZALLOC (obstack, struct frame_unwind_table);

  51.   /* Start the table out with a few default sniffers.  OSABI code
  52.      can't override this.  */
  53.   table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
  54.   table->list->unwinder = &dummy_frame_unwind;
  55.   table->list->next = OBSTACK_ZALLOC (obstack,
  56.                                       struct frame_unwind_table_entry);
  57.   table->list->next->unwinder = &inline_frame_unwind;
  58.   /* The insertion point for OSABI sniffers.  */
  59.   table->osabi_head = &table->list->next->next;
  60.   return table;
  61. }

  63. void
  64. ‌frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
  65.                                 const struct frame_unwind *unwinder)
  66. {
  67.   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  68.   struct frame_unwind_table_entry *entry;

  70.   /* Insert the new entry at the start of the list.  */
  71.   entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  72.   entry->unwinder = unwinder;
  73.   entry->next = (*table->osabi_head);
  74.   (*table->osabi_head) = entry;
  75. }

  77. void
  78. ‌frame_unwind_append_unwinder (struct gdbarch *gdbarch,
  79.                               const struct frame_unwind *unwinder)
  80. {
  81.   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  82.   struct frame_unwind_table_entry **ip;

  84.   /* Find the end of the list and insert the new entry there.  */
  85.   for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next);
  86.   (*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  87.   (*ip)->unwinder = unwinder;
  88. }

  90. /* Call SNIFFER from UNWINDER.  If it succeeded set UNWINDER for
  91.    THIS_FRAME and return 1.  Otherwise the function keeps THIS_FRAME
  92.    unchanged and returns 0.  */

  94. static int
  95. ‌frame_unwind_try_unwinder (struct frame_info *this_frame, void **this_cache,
  96.                           const struct frame_unwind *unwinder)
  97. {
  98.   struct cleanup *old_cleanup;
  99.   volatile struct gdb_exception ex;
  100.   int res = 0;

  102.   old_cleanup = frame_prepare_for_sniffer (this_frame, unwinder);

  104.   TRY_CATCH (ex, RETURN_MASK_ERROR)
  105.     {
  106.       res = unwinder->sniffer (unwinder, this_frame, this_cache);
  107.     }
  108.   if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
  109.     {
  110.       /* This usually means that not even the PC is available,
  111.         thus most unwinders aren't able to determine if they're
  112.         the best fit.  Keep trying.  Fallback prologue unwinders
  113.         should always accept the frame.  */
  114.       do_cleanups (old_cleanup);
  115.       return 0;
  116.     }
  117.   else if (ex.reason < 0)
  118.     throw_exception (ex);
  119.   else if (res)
  120.     {
  121.       discard_cleanups (old_cleanup);
  122.       return 1;
  123.     }
  124.   else
  125.     {
  126.       do_cleanups (old_cleanup);
  127.       return 0;
  128.     }
  129.   gdb_assert_not_reached ("frame_unwind_try_unwinder");
  130. }

  132. /* Iterate through sniffers for THIS_FRAME frame until one returns with an
  133.    unwinder implementation.  THIS_FRAME->UNWIND must be NULL, it will get set
  134.    by this function.  Possibly initialize THIS_CACHE.  */

  136. void
  137. ‌frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache)
  138. {
  139.   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  140.   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  141.   struct frame_unwind_table_entry *entry;
  142.   const struct frame_unwind *unwinder_from_target;

  144.   unwinder_from_target = target_get_unwinder ();
  145.   if (unwinder_from_target != NULL
  146.       && frame_unwind_try_unwinder (this_frame, this_cache,
  147.                                    unwinder_from_target))
  148.     return;

  150.   unwinder_from_target = target_get_tailcall_unwinder ();
  151.   if (unwinder_from_target != NULL
  152.       && frame_unwind_try_unwinder (this_frame, this_cache,
  153.                                    unwinder_from_target))
  154.     return;

  156.   for (entry = table->list; entry != NULL; entry = entry->next)
  157.     if (frame_unwind_try_unwinder (this_frame, this_cache, entry->unwinder))
  158.       return;

  160.   internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed"));
  161. }

  163. /* A default frame sniffer which always accepts the frame.  Used by
  164.    fallback prologue unwinders.  */

  166. int
  167. ‌default_frame_sniffer (const struct frame_unwind *self,
  168.                        struct frame_info *this_frame,
  169.                        void **this_prologue_cache)
  170. {
  171.   return 1;
  172. }

  174. /* The default frame unwinder stop_reason callback.  */

  176. enum unwind_stop_reason
  177. ‌default_frame_unwind_stop_reason (struct frame_info *this_frame,
  178.                                   void **this_cache)
  179. {
  180.   struct frame_id this_id = get_frame_id (this_frame);

  182.   if (frame_id_eq (this_id, outer_frame_id))
  183.     return UNWIND_OUTERMOST;
  184.   else
  185.     return UNWIND_NO_REASON;
  186. }

  188. /* Helper functions for value-based register unwinding.  These return
  189.    a (possibly lazy) value of the appropriate type.  */

  191. /* Return a value which indicates that FRAME did not save REGNUM.  */

  193. struct value *
  194. ‌frame_unwind_got_optimized (struct frame_info *frame, int regnum)
  195. {
  196.   struct gdbarch *gdbarch = frame_unwind_arch (frame);
  197.   struct type *type = register_type (gdbarch, regnum);
  198.   struct value *val;

  200.   /* Return an lval_register value, so that we print it as
  201.      "<not saved>".  */
  202.   val = allocate_value_lazy (type);
  203.   set_value_lazy (val, 0);
  204.   mark_value_bytes_optimized_out (val, 0, TYPE_LENGTH (type));
  205.   VALUE_LVAL (val) = lval_register;
  206.   VALUE_REGNUM (val) = regnum;
  207.   VALUE_FRAME_ID (val) = get_frame_id (frame);
  208.   return val;
  209. }

  211. /* Return a value which indicates that FRAME copied REGNUM into
  212.    register NEW_REGNUM.  */

  214. struct value *
  215. ‌frame_unwind_got_register (struct frame_info *frame,
  216.                            int regnum, int new_regnum)
  217. {
  218.   return value_of_register_lazy (frame, new_regnum);
  219. }

  221. /* Return a value which indicates that FRAME saved REGNUM in memory at
  222.    ADDR.  */

  224. struct value *
  225. ‌frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr)
  226. {
  227.   struct gdbarch *gdbarch = frame_unwind_arch (frame);
  228.   struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr);

  230.   set_value_stack (v, 1);
  231.   return v;
  232. }

  234. /* Return a value which indicates that FRAME's saved version of
  235.    REGNUM has a known constant (computed) value of VAL.  */

  237. struct value *
  238. ‌frame_unwind_got_constant (struct frame_info *frame, int regnum,
  239.                            ULONGEST val)
  240. {
  241.   struct gdbarch *gdbarch = frame_unwind_arch (frame);
  242.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  243.   struct value *reg_val;

  245.   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
  246.   store_unsigned_integer (value_contents_writeable (reg_val),
  247.                           register_size (gdbarch, regnum), byte_order, val);
  248.   return reg_val;
  249. }

  251. struct value *
  252. ‌frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf)
  253. {
  254.   struct gdbarch *gdbarch = frame_unwind_arch (frame);
  255.   struct value *reg_val;

  257.   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
  258.   memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum));
  259.   return reg_val;
  260. }

  262. /* Return a value which indicates that FRAME's saved version of REGNUM
  263.    has a known constant (computed) value of ADDR.  Convert the
  264.    CORE_ADDR to a target address if necessary.  */

  266. struct value *
  267. ‌frame_unwind_got_address (struct frame_info *frame, int regnum,
  268.                           CORE_ADDR addr)
  269. {
  270.   struct gdbarch *gdbarch = frame_unwind_arch (frame);
  271.   struct value *reg_val;

  273.   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
  274.   pack_long (value_contents_writeable (reg_val),
  275.              register_type (gdbarch, regnum), addr);
  276.   return reg_val;
  277. }

  279. /* -Wmissing-prototypes */
  280. extern initialize_file_ftype _initialize_frame_unwind;

  282. void
  283. ‌_initialize_frame_unwind (void)
  284. {
  285.   frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init);
  286. }