1 /* Definitions for frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003-2019 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 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. 11 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. 16 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/>. */ 19 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" 29 30 static struct gdbarch_data *frame_unwind_data; 31 32 struct frame_unwind_table_entry 33 { 34 const struct frame_unwind *unwinder; 35 struct frame_unwind_table_entry *next; 36 }; 37 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 }; 44 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); 50 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 } 62 63 void 64 frame_unwind_prepend_unwinder (struct gdbarch *gdbarch, 65 const struct frame_unwind *unwinder) 66 { 67 struct frame_unwind_table *table 68 = (struct frame_unwind_table *) gdbarch_data (gdbarch, frame_unwind_data); 69 struct frame_unwind_table_entry *entry; 70 71 /* Insert the new entry at the start of the list. */ 72 entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry); 73 entry->unwinder = unwinder; 74 entry->next = (*table->osabi_head); 75 (*table->osabi_head) = entry; 76 } 77 78 void 79 frame_unwind_append_unwinder (struct gdbarch *gdbarch, 80 const struct frame_unwind *unwinder) 81 { 82 struct frame_unwind_table *table 83 = (struct frame_unwind_table *) gdbarch_data (gdbarch, frame_unwind_data); 84 struct frame_unwind_table_entry **ip; 85 86 /* Find the end of the list and insert the new entry there. */ 87 for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next); 88 (*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry); 89 (*ip)->unwinder = unwinder; 90 } 91 92 /* Call SNIFFER from UNWINDER. If it succeeded set UNWINDER for 93 THIS_FRAME and return 1. Otherwise the function keeps THIS_FRAME 94 unchanged and returns 0. */ 95 96 static int 97 frame_unwind_try_unwinder (struct frame_info *this_frame, void **this_cache, 98 const struct frame_unwind *unwinder) 99 { 100 int res = 0; 101 102 frame_prepare_for_sniffer (this_frame, unwinder); 103 104 TRY 105 { 106 res = unwinder->sniffer (unwinder, this_frame, this_cache); 107 } 108 CATCH (ex, RETURN_MASK_ALL) 109 { 110 /* Catch all exceptions, caused by either interrupt or error. 111 Reset *THIS_CACHE. */ 112 *this_cache = NULL; 113 frame_cleanup_after_sniffer (this_frame); 114 115 if (ex.error == NOT_AVAILABLE_ERROR) 116 { 117 /* This usually means that not even the PC is available, 118 thus most unwinders aren't able to determine if they're 119 the best fit. Keep trying. Fallback prologue unwinders 120 should always accept the frame. */ 121 return 0; 122 } 123 throw_exception (ex); 124 } 125 END_CATCH 126 127 if (res) 128 return 1; 129 else 130 { 131 /* Don't set *THIS_CACHE to NULL here, because sniffer has to do 132 so. */ 133 frame_cleanup_after_sniffer (this_frame); 134 return 0; 135 } 136 gdb_assert_not_reached ("frame_unwind_try_unwinder"); 137 } 138 139 /* Iterate through sniffers for THIS_FRAME frame until one returns with an 140 unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set 141 by this function. Possibly initialize THIS_CACHE. */ 142 143 void 144 frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache) 145 { 146 struct gdbarch *gdbarch = get_frame_arch (this_frame); 147 struct frame_unwind_table *table 148 = (struct frame_unwind_table *) gdbarch_data (gdbarch, frame_unwind_data); 149 struct frame_unwind_table_entry *entry; 150 const struct frame_unwind *unwinder_from_target; 151 152 unwinder_from_target = target_get_unwinder (); 153 if (unwinder_from_target != NULL 154 && frame_unwind_try_unwinder (this_frame, this_cache, 155 unwinder_from_target)) 156 return; 157 158 unwinder_from_target = target_get_tailcall_unwinder (); 159 if (unwinder_from_target != NULL 160 && frame_unwind_try_unwinder (this_frame, this_cache, 161 unwinder_from_target)) 162 return; 163 164 for (entry = table->list; entry != NULL; entry = entry->next) 165 if (frame_unwind_try_unwinder (this_frame, this_cache, entry->unwinder)) 166 return; 167 168 internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed")); 169 } 170 171 /* A default frame sniffer which always accepts the frame. Used by 172 fallback prologue unwinders. */ 173 174 int 175 default_frame_sniffer (const struct frame_unwind *self, 176 struct frame_info *this_frame, 177 void **this_prologue_cache) 178 { 179 return 1; 180 } 181 182 /* The default frame unwinder stop_reason callback. */ 183 184 enum unwind_stop_reason 185 default_frame_unwind_stop_reason (struct frame_info *this_frame, 186 void **this_cache) 187 { 188 struct frame_id this_id = get_frame_id (this_frame); 189 190 if (frame_id_eq (this_id, outer_frame_id)) 191 return UNWIND_OUTERMOST; 192 else 193 return UNWIND_NO_REASON; 194 } 195 196 /* See frame-unwind.h. */ 197 198 CORE_ADDR 199 default_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame) 200 { 201 int pc_regnum = gdbarch_pc_regnum (gdbarch); 202 CORE_ADDR pc = frame_unwind_register_unsigned (next_frame, pc_regnum); 203 pc = gdbarch_addr_bits_remove (gdbarch, pc); 204 return pc; 205 } 206 207 /* See frame-unwind.h. */ 208 209 CORE_ADDR 210 default_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame) 211 { 212 int sp_regnum = gdbarch_sp_regnum (gdbarch); 213 return frame_unwind_register_unsigned (next_frame, sp_regnum); 214 } 215 216 /* Helper functions for value-based register unwinding. These return 217 a (possibly lazy) value of the appropriate type. */ 218 219 /* Return a value which indicates that FRAME did not save REGNUM. */ 220 221 struct value * 222 frame_unwind_got_optimized (struct frame_info *frame, int regnum) 223 { 224 struct gdbarch *gdbarch = frame_unwind_arch (frame); 225 struct type *type = register_type (gdbarch, regnum); 226 struct value *val; 227 228 /* Return an lval_register value, so that we print it as 229 "<not saved>". */ 230 val = allocate_value_lazy (type); 231 set_value_lazy (val, 0); 232 mark_value_bytes_optimized_out (val, 0, TYPE_LENGTH (type)); 233 VALUE_LVAL (val) = lval_register; 234 VALUE_REGNUM (val) = regnum; 235 VALUE_NEXT_FRAME_ID (val) 236 = get_frame_id (get_next_frame_sentinel_okay (frame)); 237 return val; 238 } 239 240 /* Return a value which indicates that FRAME copied REGNUM into 241 register NEW_REGNUM. */ 242 243 struct value * 244 frame_unwind_got_register (struct frame_info *frame, 245 int regnum, int new_regnum) 246 { 247 return value_of_register_lazy (frame, new_regnum); 248 } 249 250 /* Return a value which indicates that FRAME saved REGNUM in memory at 251 ADDR. */ 252 253 struct value * 254 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr) 255 { 256 struct gdbarch *gdbarch = frame_unwind_arch (frame); 257 struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr); 258 259 set_value_stack (v, 1); 260 return v; 261 } 262 263 /* Return a value which indicates that FRAME's saved version of 264 REGNUM has a known constant (computed) value of VAL. */ 265 266 struct value * 267 frame_unwind_got_constant (struct frame_info *frame, int regnum, 268 ULONGEST val) 269 { 270 struct gdbarch *gdbarch = frame_unwind_arch (frame); 271 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 272 struct value *reg_val; 273 274 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 275 store_unsigned_integer (value_contents_writeable (reg_val), 276 register_size (gdbarch, regnum), byte_order, val); 277 return reg_val; 278 } 279 280 struct value * 281 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf) 282 { 283 struct gdbarch *gdbarch = frame_unwind_arch (frame); 284 struct value *reg_val; 285 286 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 287 memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum)); 288 return reg_val; 289 } 290 291 /* Return a value which indicates that FRAME's saved version of REGNUM 292 has a known constant (computed) value of ADDR. Convert the 293 CORE_ADDR to a target address if necessary. */ 294 295 struct value * 296 frame_unwind_got_address (struct frame_info *frame, int regnum, 297 CORE_ADDR addr) 298 { 299 struct gdbarch *gdbarch = frame_unwind_arch (frame); 300 struct value *reg_val; 301 302 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 303 pack_long (value_contents_writeable (reg_val), 304 register_type (gdbarch, regnum), addr); 305 return reg_val; 306 } 307 308 void 309 _initialize_frame_unwind (void) 310 { 311 frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init); 312 } 313