1 /* Frame unwinder for frames using the libunwind library.
2
3 Copyright 2003, 2004 Free Software Foundation, Inc.
4
5 Written by Jeff Johnston, contributed by Red Hat Inc.
6
7 This file is part of GDB.
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
23
24 #include "defs.h"
25
26 #include "inferior.h"
27 #include "frame.h"
28 #include "frame-base.h"
29 #include "frame-unwind.h"
30 #include "gdbcore.h"
31 #include "gdbtypes.h"
32 #include "symtab.h"
33 #include "objfiles.h"
34 #include "regcache.h"
35
36 #include <dlfcn.h>
37
38 #include "gdb_assert.h"
39 #include "gdb_string.h"
40
41 #include "libunwind-frame.h"
42
43 #include "complaints.h"
44
45 static int libunwind_initialized;
46 static struct gdbarch_data *libunwind_descr_handle;
47
48 /* Required function pointers from libunwind. */
49 static int (*unw_get_reg_p) (unw_cursor_t *, unw_regnum_t, unw_word_t *);
50 static int (*unw_get_fpreg_p) (unw_cursor_t *, unw_regnum_t, unw_fpreg_t *);
51 static int (*unw_get_saveloc_p) (unw_cursor_t *, unw_regnum_t, unw_save_loc_t *);
52 static int (*unw_step_p) (unw_cursor_t *);
53 static int (*unw_init_remote_p) (unw_cursor_t *, unw_addr_space_t, void *);
54 static unw_addr_space_t (*unw_create_addr_space_p) (unw_accessors_t *, int);
55 static int (*unw_search_unwind_table_p) (unw_addr_space_t, unw_word_t, unw_dyn_info_t *,
56 unw_proc_info_t *, int, void *);
57 static unw_word_t (*unw_find_dyn_list_p) (unw_addr_space_t, unw_dyn_info_t *,
58 void *);
59
60
61 struct libunwind_frame_cache
62 {
63 CORE_ADDR base;
64 CORE_ADDR func_addr;
65 unw_cursor_t cursor;
66 };
67
68 /* We need to qualify the function names with a platform-specific prefix to match
69 the names used by the libunwind library. The UNW_OBJ macro is provided by the
70 libunwind.h header file. */
71 #define STRINGIFY2(name) #name
72 #define STRINGIFY(name) STRINGIFY2(name)
73
74 #ifndef LIBUNWIND_SO
75 #define LIBUNWIND_SO "libunwind-" STRINGIFY(UNW_TARGET) ".so"
76 #endif
77
78 static char *get_reg_name = STRINGIFY(UNW_OBJ(get_reg));
79 static char *get_fpreg_name = STRINGIFY(UNW_OBJ(get_fpreg));
80 static char *get_saveloc_name = STRINGIFY(UNW_OBJ(get_save_loc));
81 static char *step_name = STRINGIFY(UNW_OBJ(step));
82 static char *init_remote_name = STRINGIFY(UNW_OBJ(init_remote));
83 static char *create_addr_space_name = STRINGIFY(UNW_OBJ(create_addr_space));
84 static char *search_unwind_table_name = STRINGIFY(UNW_OBJ(search_unwind_table));
85 static char *find_dyn_list_name = STRINGIFY(UNW_OBJ(find_dyn_list));
86
87 static struct libunwind_descr *
libunwind_descr(struct gdbarch * gdbarch)88 libunwind_descr (struct gdbarch *gdbarch)
89 {
90 return gdbarch_data (gdbarch, libunwind_descr_handle);
91 }
92
93 static void *
libunwind_descr_init(struct gdbarch * gdbarch)94 libunwind_descr_init (struct gdbarch *gdbarch)
95 {
96 struct libunwind_descr *descr = GDBARCH_OBSTACK_ZALLOC (gdbarch,
97 struct libunwind_descr);
98 return descr;
99 }
100
101 void
libunwind_frame_set_descr(struct gdbarch * gdbarch,struct libunwind_descr * descr)102 libunwind_frame_set_descr (struct gdbarch *gdbarch, struct libunwind_descr *descr)
103 {
104 struct libunwind_descr *arch_descr;
105
106 gdb_assert (gdbarch != NULL);
107
108 arch_descr = gdbarch_data (gdbarch, libunwind_descr_handle);
109
110 if (arch_descr == NULL)
111 {
112 /* First time here. Must initialize data area. */
113 arch_descr = libunwind_descr_init (gdbarch);
114 deprecated_set_gdbarch_data (gdbarch, libunwind_descr_handle, arch_descr);
115 }
116
117 /* Copy new descriptor info into arch descriptor. */
118 arch_descr->gdb2uw = descr->gdb2uw;
119 arch_descr->uw2gdb = descr->uw2gdb;
120 arch_descr->is_fpreg = descr->is_fpreg;
121 arch_descr->accessors = descr->accessors;
122 }
123
124 static struct libunwind_frame_cache *
libunwind_frame_cache(struct frame_info * next_frame,void ** this_cache)125 libunwind_frame_cache (struct frame_info *next_frame, void **this_cache)
126 {
127 unw_accessors_t *acc;
128 unw_addr_space_t as;
129 unw_word_t fp;
130 unw_regnum_t uw_sp_regnum;
131 struct libunwind_frame_cache *cache;
132 struct libunwind_descr *descr;
133 int i, ret;
134
135 if (*this_cache)
136 return *this_cache;
137
138 /* Allocate a new cache. */
139 cache = FRAME_OBSTACK_ZALLOC (struct libunwind_frame_cache);
140
141 cache->func_addr = frame_func_unwind (next_frame);
142
143 /* Get a libunwind cursor to the previous frame. We do this by initializing
144 a cursor. Libunwind treats a new cursor as the top of stack and will get
145 the current register set via the libunwind register accessor. Now, we
146 provide the platform-specific accessors and we set up the register accessor to use
147 the frame register unwinding interfaces so that we properly get the registers for
148 the current frame rather than the top. We then use the unw_step function to
149 move the libunwind cursor back one frame. We can later use this cursor to find previous
150 registers via the unw_get_reg interface which will invoke libunwind's special logic. */
151 descr = libunwind_descr (get_frame_arch (next_frame));
152 acc = descr->accessors;
153 as = unw_create_addr_space_p (acc,
154 TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
155 ? __BIG_ENDIAN
156 : __LITTLE_ENDIAN);
157
158 unw_init_remote_p (&cache->cursor, as, next_frame);
159 unw_step_p (&cache->cursor);
160
161 /* To get base address, get sp from previous frame. */
162 uw_sp_regnum = descr->gdb2uw (SP_REGNUM);
163 ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &fp);
164 if (ret < 0)
165 error ("Can't get libunwind sp register.");
166
167 cache->base = (CORE_ADDR)fp;
168
169 *this_cache = cache;
170 return cache;
171 }
172
173 unw_word_t
libunwind_find_dyn_list(unw_addr_space_t as,unw_dyn_info_t * di,void * arg)174 libunwind_find_dyn_list (unw_addr_space_t as, unw_dyn_info_t *di, void *arg)
175 {
176 return unw_find_dyn_list_p (as, di, arg);
177 }
178
179 static const struct frame_unwind libunwind_frame_unwind =
180 {
181 NORMAL_FRAME,
182 libunwind_frame_this_id,
183 libunwind_frame_prev_register
184 };
185
186 /* Verify if there is sufficient libunwind information for the frame to use
187 libunwind frame unwinding. */
188 const struct frame_unwind *
libunwind_frame_sniffer(struct frame_info * next_frame)189 libunwind_frame_sniffer (struct frame_info *next_frame)
190 {
191 unw_cursor_t cursor;
192 unw_accessors_t *acc;
193 unw_addr_space_t as;
194 struct libunwind_descr *descr;
195 int i, ret;
196
197 /* To test for libunwind unwind support, initialize a cursor to the current frame and try to back
198 up. We use this same method when setting up the frame cache (see libunwind_frame_cache()).
199 If libunwind returns success for this operation, it means that it has found sufficient
200 libunwind unwinding information to do so. */
201
202 descr = libunwind_descr (get_frame_arch (next_frame));
203 acc = descr->accessors;
204 as = unw_create_addr_space_p (acc,
205 TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
206 ? __BIG_ENDIAN
207 : __LITTLE_ENDIAN);
208
209 ret = unw_init_remote_p (&cursor, as, next_frame);
210
211 if (ret >= 0)
212 ret = unw_step_p (&cursor);
213
214 if (ret < 0)
215 return NULL;
216
217 return &libunwind_frame_unwind;
218 }
219
220 void
libunwind_frame_this_id(struct frame_info * next_frame,void ** this_cache,struct frame_id * this_id)221 libunwind_frame_this_id (struct frame_info *next_frame, void **this_cache,
222 struct frame_id *this_id)
223 {
224 struct libunwind_frame_cache *cache =
225 libunwind_frame_cache (next_frame, this_cache);
226
227 (*this_id) = frame_id_build (cache->base, cache->func_addr);
228 }
229
230 void
libunwind_frame_prev_register(struct frame_info * next_frame,void ** this_cache,int regnum,int * optimizedp,enum lval_type * lvalp,CORE_ADDR * addrp,int * realnump,void * valuep)231 libunwind_frame_prev_register (struct frame_info *next_frame, void **this_cache,
232 int regnum, int *optimizedp,
233 enum lval_type *lvalp, CORE_ADDR *addrp,
234 int *realnump, void *valuep)
235 {
236 struct libunwind_frame_cache *cache =
237 libunwind_frame_cache (next_frame, this_cache);
238
239 void *ptr;
240 unw_cursor_t *c;
241 unw_save_loc_t sl;
242 int i, ret;
243 unw_word_t intval;
244 unw_fpreg_t fpval;
245 unw_regnum_t uw_regnum;
246 struct libunwind_descr *descr;
247
248 /* Convert from gdb register number to libunwind register number. */
249 descr = libunwind_descr (get_frame_arch (next_frame));
250 uw_regnum = descr->gdb2uw (regnum);
251
252 gdb_assert (regnum >= 0);
253
254 if (!target_has_registers)
255 error ("No registers.");
256
257 *optimizedp = 0;
258 *addrp = 0;
259 *lvalp = not_lval;
260 *realnump = -1;
261
262 if (valuep)
263 memset (valuep, 0, register_size (current_gdbarch, regnum));
264
265 if (uw_regnum < 0)
266 return;
267
268 /* To get the previous register, we use the libunwind register APIs with
269 the cursor we have already pushed back to the previous frame. */
270
271 if (descr->is_fpreg (uw_regnum))
272 {
273 ret = unw_get_fpreg_p (&cache->cursor, uw_regnum, &fpval);
274 ptr = &fpval;
275 }
276 else
277 {
278 ret = unw_get_reg_p (&cache->cursor, uw_regnum, &intval);
279 ptr = &intval;
280 }
281
282 if (ret < 0)
283 return;
284
285 if (valuep)
286 memcpy (valuep, ptr, register_size (current_gdbarch, regnum));
287
288 if (unw_get_saveloc_p (&cache->cursor, uw_regnum, &sl) < 0)
289 return;
290
291 switch (sl.type)
292 {
293 case UNW_SLT_NONE:
294 *optimizedp = 1;
295 break;
296
297 case UNW_SLT_MEMORY:
298 *lvalp = lval_memory;
299 *addrp = sl.u.addr;
300 break;
301
302 case UNW_SLT_REG:
303 *lvalp = lval_register;
304 *realnump = regnum;
305 break;
306 }
307 }
308
309 CORE_ADDR
libunwind_frame_base_address(struct frame_info * next_frame,void ** this_cache)310 libunwind_frame_base_address (struct frame_info *next_frame, void **this_cache)
311 {
312 struct libunwind_frame_cache *cache =
313 libunwind_frame_cache (next_frame, this_cache);
314
315 return cache->base;
316 }
317
318 /* The following is a glue routine to call the libunwind unwind table
319 search function to get unwind information for a specified ip address. */
320 int
libunwind_search_unwind_table(void * as,long ip,void * di,void * pi,int need_unwind_info,void * args)321 libunwind_search_unwind_table (void *as, long ip, void *di,
322 void *pi, int need_unwind_info, void *args)
323 {
324 return unw_search_unwind_table_p (*(unw_addr_space_t *)as, (unw_word_t )ip,
325 di, pi, need_unwind_info, args);
326 }
327
328 static int
libunwind_load(void)329 libunwind_load (void)
330 {
331 void *handle;
332
333 handle = dlopen (LIBUNWIND_SO, RTLD_NOW);
334 if (handle == NULL)
335 return 0;
336
337 /* Initialize pointers to the dynamic library functions we will use. */
338
339 unw_get_reg_p = dlsym (handle, get_reg_name);
340 if (unw_get_reg_p == NULL)
341 return 0;
342
343 unw_get_fpreg_p = dlsym (handle, get_fpreg_name);
344 if (unw_get_fpreg_p == NULL)
345 return 0;
346
347 unw_get_saveloc_p = dlsym (handle, get_saveloc_name);
348 if (unw_get_saveloc_p == NULL)
349 return 0;
350
351 unw_step_p = dlsym (handle, step_name);
352 if (unw_step_p == NULL)
353 return 0;
354
355 unw_init_remote_p = dlsym (handle, init_remote_name);
356 if (unw_init_remote_p == NULL)
357 return 0;
358
359 unw_create_addr_space_p = dlsym (handle, create_addr_space_name);
360 if (unw_create_addr_space_p == NULL)
361 return 0;
362
363 unw_search_unwind_table_p = dlsym (handle, search_unwind_table_name);
364 if (unw_search_unwind_table_p == NULL)
365 return 0;
366
367 unw_find_dyn_list_p = dlsym (handle, find_dyn_list_name);
368 if (unw_find_dyn_list_p == NULL)
369 return 0;
370
371 return 1;
372 }
373
374 int
libunwind_is_initialized(void)375 libunwind_is_initialized (void)
376 {
377 return libunwind_initialized;
378 }
379
380 /* Provide a prototype to silence -Wmissing-prototypes. */
381 void _initialize_libunwind_frame (void);
382
383 void
_initialize_libunwind_frame(void)384 _initialize_libunwind_frame (void)
385 {
386 libunwind_descr_handle = gdbarch_data_register_post_init (libunwind_descr_init);
387
388 libunwind_initialized = libunwind_load ();
389 }
390