1 /* Definitions for frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003-2013 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 "exceptions.h" 28 #include "gdb_assert.h" 29 #include "gdb_obstack.h" 30 31 static struct gdbarch_data *frame_unwind_data; 32 33 struct frame_unwind_table_entry 34 { 35 const struct frame_unwind *unwinder; 36 struct frame_unwind_table_entry *next; 37 }; 38 39 struct frame_unwind_table 40 { 41 struct frame_unwind_table_entry *list; 42 /* The head of the OSABI part of the search list. */ 43 struct frame_unwind_table_entry **osabi_head; 44 }; 45 46 static void * 47 frame_unwind_init (struct obstack *obstack) 48 { 49 struct frame_unwind_table *table 50 = OBSTACK_ZALLOC (obstack, struct frame_unwind_table); 51 52 /* Start the table out with a few default sniffers. OSABI code 53 can't override this. */ 54 table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry); 55 table->list->unwinder = &dummy_frame_unwind; 56 table->list->next = OBSTACK_ZALLOC (obstack, 57 struct frame_unwind_table_entry); 58 table->list->next->unwinder = &inline_frame_unwind; 59 /* The insertion point for OSABI sniffers. */ 60 table->osabi_head = &table->list->next->next; 61 return table; 62 } 63 64 void 65 frame_unwind_prepend_unwinder (struct gdbarch *gdbarch, 66 const struct frame_unwind *unwinder) 67 { 68 struct frame_unwind_table *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 = gdbarch_data (gdbarch, frame_unwind_data); 83 struct frame_unwind_table_entry **ip; 84 85 /* Find the end of the list and insert the new entry there. */ 86 for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next); 87 (*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry); 88 (*ip)->unwinder = unwinder; 89 } 90 91 /* Iterate through sniffers for THIS_FRAME frame until one returns with an 92 unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set 93 by this function. Possibly initialize THIS_CACHE. */ 94 95 void 96 frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache) 97 { 98 struct gdbarch *gdbarch = get_frame_arch (this_frame); 99 struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data); 100 struct frame_unwind_table_entry *entry; 101 102 for (entry = table->list; entry != NULL; entry = entry->next) 103 { 104 struct cleanup *old_cleanup; 105 volatile struct gdb_exception ex; 106 int res = 0; 107 108 old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder); 109 110 TRY_CATCH (ex, RETURN_MASK_ERROR) 111 { 112 res = entry->unwinder->sniffer (entry->unwinder, this_frame, 113 this_cache); 114 } 115 if (ex.reason < 0 && 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 } 122 else if (ex.reason < 0) 123 throw_exception (ex); 124 else if (res) 125 { 126 discard_cleanups (old_cleanup); 127 return; 128 } 129 130 do_cleanups (old_cleanup); 131 } 132 internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed")); 133 } 134 135 /* A default frame sniffer which always accepts the frame. Used by 136 fallback prologue unwinders. */ 137 138 int 139 default_frame_sniffer (const struct frame_unwind *self, 140 struct frame_info *this_frame, 141 void **this_prologue_cache) 142 { 143 return 1; 144 } 145 146 /* A default frame unwinder stop_reason callback that always claims 147 the frame is unwindable. */ 148 149 enum unwind_stop_reason 150 default_frame_unwind_stop_reason (struct frame_info *this_frame, 151 void **this_cache) 152 { 153 return UNWIND_NO_REASON; 154 } 155 156 /* Helper functions for value-based register unwinding. These return 157 a (possibly lazy) value of the appropriate type. */ 158 159 /* Return a value which indicates that FRAME did not save REGNUM. */ 160 161 struct value * 162 frame_unwind_got_optimized (struct frame_info *frame, int regnum) 163 { 164 struct gdbarch *gdbarch = frame_unwind_arch (frame); 165 struct value *reg_val; 166 167 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 168 set_value_optimized_out (reg_val, 1); 169 return reg_val; 170 } 171 172 /* Return a value which indicates that FRAME copied REGNUM into 173 register NEW_REGNUM. */ 174 175 struct value * 176 frame_unwind_got_register (struct frame_info *frame, 177 int regnum, int new_regnum) 178 { 179 return value_of_register_lazy (frame, new_regnum); 180 } 181 182 /* Return a value which indicates that FRAME saved REGNUM in memory at 183 ADDR. */ 184 185 struct value * 186 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr) 187 { 188 struct gdbarch *gdbarch = frame_unwind_arch (frame); 189 struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr); 190 191 set_value_stack (v, 1); 192 return v; 193 } 194 195 /* Return a value which indicates that FRAME's saved version of 196 REGNUM has a known constant (computed) value of VAL. */ 197 198 struct value * 199 frame_unwind_got_constant (struct frame_info *frame, int regnum, 200 ULONGEST val) 201 { 202 struct gdbarch *gdbarch = frame_unwind_arch (frame); 203 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 204 struct value *reg_val; 205 206 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 207 store_unsigned_integer (value_contents_writeable (reg_val), 208 register_size (gdbarch, regnum), byte_order, val); 209 return reg_val; 210 } 211 212 struct value * 213 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf) 214 { 215 struct gdbarch *gdbarch = frame_unwind_arch (frame); 216 struct value *reg_val; 217 218 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 219 memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum)); 220 return reg_val; 221 } 222 223 /* Return a value which indicates that FRAME's saved version of REGNUM 224 has a known constant (computed) value of ADDR. Convert the 225 CORE_ADDR to a target address if necessary. */ 226 227 struct value * 228 frame_unwind_got_address (struct frame_info *frame, int regnum, 229 CORE_ADDR addr) 230 { 231 struct gdbarch *gdbarch = frame_unwind_arch (frame); 232 struct value *reg_val; 233 234 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 235 pack_long (value_contents_writeable (reg_val), 236 register_type (gdbarch, regnum), addr); 237 return reg_val; 238 } 239 240 /* -Wmissing-prototypes */ 241 extern initialize_file_ftype _initialize_frame_unwind; 242 243 void 244 _initialize_frame_unwind (void) 245 { 246 frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init); 247 } 248