1 /* Definitions for frame unwinder, for GDB, the GNU debugger.
3 Copyright (C) 2003-2020 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/>. */
22 #include "frame-unwind.h"
23 #include "dummy-frame.h"
24 #include "inline-frame.h"
27 #include "gdb_obstack.h"
30 #include "dwarf2/frame-tailcall.h"
32 static struct gdbarch_data
*frame_unwind_data
;
34 struct frame_unwind_table_entry
36 const struct frame_unwind
*unwinder
;
37 struct frame_unwind_table_entry
*next
;
40 struct frame_unwind_table
42 struct frame_unwind_table_entry
*list
;
43 /* The head of the OSABI part of the search list. */
44 struct frame_unwind_table_entry
**osabi_head
;
47 /* A helper function to add an unwinder to a list. LINK says where to
48 install the new unwinder. The new link is returned. */
50 static struct frame_unwind_table_entry
**
51 add_unwinder (struct obstack
*obstack
, const struct frame_unwind
*unwinder
,
52 struct frame_unwind_table_entry
**link
)
54 *link
= OBSTACK_ZALLOC (obstack
, struct frame_unwind_table_entry
);
55 (*link
)->unwinder
= unwinder
;
56 return &(*link
)->next
;
60 frame_unwind_init (struct obstack
*obstack
)
62 struct frame_unwind_table
*table
63 = OBSTACK_ZALLOC (obstack
, struct frame_unwind_table
);
65 /* Start the table out with a few default sniffers. OSABI code
66 can't override this. */
67 struct frame_unwind_table_entry
**link
= &table
->list
;
69 link
= add_unwinder (obstack
, &dummy_frame_unwind
, link
);
70 /* The DWARF tailcall sniffer must come before the inline sniffer.
71 Otherwise, we can end up in a situation where a DWARF frame finds
72 tailcall information, but then the inline sniffer claims a frame
73 before the tailcall sniffer, resulting in confusion. This is
74 safe to do always because the tailcall sniffer can only ever be
75 activated if the newer frame was created using the DWARF
76 unwinder, and it also found tailcall information. */
77 link
= add_unwinder (obstack
, &dwarf2_tailcall_frame_unwind
, link
);
78 link
= add_unwinder (obstack
, &inline_frame_unwind
, link
);
80 /* The insertion point for OSABI sniffers. */
81 table
->osabi_head
= link
;
86 frame_unwind_prepend_unwinder (struct gdbarch
*gdbarch
,
87 const struct frame_unwind
*unwinder
)
89 struct frame_unwind_table
*table
90 = (struct frame_unwind_table
*) gdbarch_data (gdbarch
, frame_unwind_data
);
91 struct frame_unwind_table_entry
*entry
;
93 /* Insert the new entry at the start of the list. */
94 entry
= GDBARCH_OBSTACK_ZALLOC (gdbarch
, struct frame_unwind_table_entry
);
95 entry
->unwinder
= unwinder
;
96 entry
->next
= (*table
->osabi_head
);
97 (*table
->osabi_head
) = entry
;
101 frame_unwind_append_unwinder (struct gdbarch
*gdbarch
,
102 const struct frame_unwind
*unwinder
)
104 struct frame_unwind_table
*table
105 = (struct frame_unwind_table
*) gdbarch_data (gdbarch
, frame_unwind_data
);
106 struct frame_unwind_table_entry
**ip
;
108 /* Find the end of the list and insert the new entry there. */
109 for (ip
= table
->osabi_head
; (*ip
) != NULL
; ip
= &(*ip
)->next
);
110 (*ip
) = GDBARCH_OBSTACK_ZALLOC (gdbarch
, struct frame_unwind_table_entry
);
111 (*ip
)->unwinder
= unwinder
;
114 /* Call SNIFFER from UNWINDER. If it succeeded set UNWINDER for
115 THIS_FRAME and return 1. Otherwise the function keeps THIS_FRAME
116 unchanged and returns 0. */
119 frame_unwind_try_unwinder (struct frame_info
*this_frame
, void **this_cache
,
120 const struct frame_unwind
*unwinder
)
124 frame_prepare_for_sniffer (this_frame
, unwinder
);
128 res
= unwinder
->sniffer (unwinder
, this_frame
, this_cache
);
130 catch (const gdb_exception
&ex
)
132 /* Catch all exceptions, caused by either interrupt or error.
133 Reset *THIS_CACHE. */
135 frame_cleanup_after_sniffer (this_frame
);
137 if (ex
.error
== NOT_AVAILABLE_ERROR
)
139 /* This usually means that not even the PC is available,
140 thus most unwinders aren't able to determine if they're
141 the best fit. Keep trying. Fallback prologue unwinders
142 should always accept the frame. */
152 /* Don't set *THIS_CACHE to NULL here, because sniffer has to do
154 frame_cleanup_after_sniffer (this_frame
);
157 gdb_assert_not_reached ("frame_unwind_try_unwinder");
160 /* Iterate through sniffers for THIS_FRAME frame until one returns with an
161 unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set
162 by this function. Possibly initialize THIS_CACHE. */
165 frame_unwind_find_by_frame (struct frame_info
*this_frame
, void **this_cache
)
167 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
168 struct frame_unwind_table
*table
169 = (struct frame_unwind_table
*) gdbarch_data (gdbarch
, frame_unwind_data
);
170 struct frame_unwind_table_entry
*entry
;
171 const struct frame_unwind
*unwinder_from_target
;
173 unwinder_from_target
= target_get_unwinder ();
174 if (unwinder_from_target
!= NULL
175 && frame_unwind_try_unwinder (this_frame
, this_cache
,
176 unwinder_from_target
))
179 unwinder_from_target
= target_get_tailcall_unwinder ();
180 if (unwinder_from_target
!= NULL
181 && frame_unwind_try_unwinder (this_frame
, this_cache
,
182 unwinder_from_target
))
185 for (entry
= table
->list
; entry
!= NULL
; entry
= entry
->next
)
186 if (frame_unwind_try_unwinder (this_frame
, this_cache
, entry
->unwinder
))
189 internal_error (__FILE__
, __LINE__
, _("frame_unwind_find_by_frame failed"));
192 /* A default frame sniffer which always accepts the frame. Used by
193 fallback prologue unwinders. */
196 default_frame_sniffer (const struct frame_unwind
*self
,
197 struct frame_info
*this_frame
,
198 void **this_prologue_cache
)
203 /* The default frame unwinder stop_reason callback. */
205 enum unwind_stop_reason
206 default_frame_unwind_stop_reason (struct frame_info
*this_frame
,
209 struct frame_id this_id
= get_frame_id (this_frame
);
211 if (frame_id_eq (this_id
, outer_frame_id
))
212 return UNWIND_OUTERMOST
;
214 return UNWIND_NO_REASON
;
217 /* See frame-unwind.h. */
220 default_unwind_pc (struct gdbarch
*gdbarch
, struct frame_info
*next_frame
)
222 int pc_regnum
= gdbarch_pc_regnum (gdbarch
);
223 CORE_ADDR pc
= frame_unwind_register_unsigned (next_frame
, pc_regnum
);
224 pc
= gdbarch_addr_bits_remove (gdbarch
, pc
);
228 /* See frame-unwind.h. */
231 default_unwind_sp (struct gdbarch
*gdbarch
, struct frame_info
*next_frame
)
233 int sp_regnum
= gdbarch_sp_regnum (gdbarch
);
234 return frame_unwind_register_unsigned (next_frame
, sp_regnum
);
237 /* Helper functions for value-based register unwinding. These return
238 a (possibly lazy) value of the appropriate type. */
240 /* Return a value which indicates that FRAME did not save REGNUM. */
243 frame_unwind_got_optimized (struct frame_info
*frame
, int regnum
)
245 struct gdbarch
*gdbarch
= frame_unwind_arch (frame
);
246 struct type
*type
= register_type (gdbarch
, regnum
);
249 /* Return an lval_register value, so that we print it as
251 val
= allocate_value_lazy (type
);
252 set_value_lazy (val
, 0);
253 mark_value_bytes_optimized_out (val
, 0, TYPE_LENGTH (type
));
254 VALUE_LVAL (val
) = lval_register
;
255 VALUE_REGNUM (val
) = regnum
;
256 VALUE_NEXT_FRAME_ID (val
)
257 = get_frame_id (get_next_frame_sentinel_okay (frame
));
261 /* Return a value which indicates that FRAME copied REGNUM into
262 register NEW_REGNUM. */
265 frame_unwind_got_register (struct frame_info
*frame
,
266 int regnum
, int new_regnum
)
268 return value_of_register_lazy (frame
, new_regnum
);
271 /* Return a value which indicates that FRAME saved REGNUM in memory at
275 frame_unwind_got_memory (struct frame_info
*frame
, int regnum
, CORE_ADDR addr
)
277 struct gdbarch
*gdbarch
= frame_unwind_arch (frame
);
278 struct value
*v
= value_at_lazy (register_type (gdbarch
, regnum
), addr
);
280 set_value_stack (v
, 1);
284 /* Return a value which indicates that FRAME's saved version of
285 REGNUM has a known constant (computed) value of VAL. */
288 frame_unwind_got_constant (struct frame_info
*frame
, int regnum
,
291 struct gdbarch
*gdbarch
= frame_unwind_arch (frame
);
292 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
293 struct value
*reg_val
;
295 reg_val
= value_zero (register_type (gdbarch
, regnum
), not_lval
);
296 store_unsigned_integer (value_contents_writeable (reg_val
),
297 register_size (gdbarch
, regnum
), byte_order
, val
);
302 frame_unwind_got_bytes (struct frame_info
*frame
, int regnum
, gdb_byte
*buf
)
304 struct gdbarch
*gdbarch
= frame_unwind_arch (frame
);
305 struct value
*reg_val
;
307 reg_val
= value_zero (register_type (gdbarch
, regnum
), not_lval
);
308 memcpy (value_contents_raw (reg_val
), buf
, register_size (gdbarch
, regnum
));
312 /* Return a value which indicates that FRAME's saved version of REGNUM
313 has a known constant (computed) value of ADDR. Convert the
314 CORE_ADDR to a target address if necessary. */
317 frame_unwind_got_address (struct frame_info
*frame
, int regnum
,
320 struct gdbarch
*gdbarch
= frame_unwind_arch (frame
);
321 struct value
*reg_val
;
323 reg_val
= value_zero (register_type (gdbarch
, regnum
), not_lval
);
324 pack_long (value_contents_writeable (reg_val
),
325 register_type (gdbarch
, regnum
), addr
);
329 void _initialize_frame_unwind ();
331 _initialize_frame_unwind ()
333 frame_unwind_data
= gdbarch_data_register_pre_init (frame_unwind_init
);