1 /* Definitions for frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010, 2011 4 Free Software Foundation, Inc. 5 6 This file is part of GDB. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 20 21 #include "defs.h" 22 #include "frame.h" 23 #include "frame-unwind.h" 24 #include "dummy-frame.h" 25 #include "inline-frame.h" 26 #include "value.h" 27 #include "regcache.h" 28 #include "exceptions.h" 29 #include "gdb_assert.h" 30 #include "gdb_obstack.h" 31 32 static struct gdbarch_data *frame_unwind_data; 33 34 struct frame_unwind_table_entry 35 { 36 const struct frame_unwind *unwinder; 37 struct frame_unwind_table_entry *next; 38 }; 39 40 struct frame_unwind_table 41 { 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; 45 }; 46 47 static void * 48 frame_unwind_init (struct obstack *obstack) 49 { 50 struct frame_unwind_table *table 51 = OBSTACK_ZALLOC (obstack, struct frame_unwind_table); 52 53 /* Start the table out with a few default sniffers. OSABI code 54 can't override this. */ 55 table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry); 56 table->list->unwinder = &dummy_frame_unwind; 57 table->list->next = OBSTACK_ZALLOC (obstack, 58 struct frame_unwind_table_entry); 59 table->list->next->unwinder = &inline_frame_unwind; 60 /* The insertion point for OSABI sniffers. */ 61 table->osabi_head = &table->list->next->next; 62 return table; 63 } 64 65 void 66 frame_unwind_prepend_unwinder (struct gdbarch *gdbarch, 67 const struct frame_unwind *unwinder) 68 { 69 struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data); 70 struct frame_unwind_table_entry *entry; 71 72 /* Insert the new entry at the start of the list. */ 73 entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry); 74 entry->unwinder = unwinder; 75 entry->next = (*table->osabi_head); 76 (*table->osabi_head) = entry; 77 } 78 79 void 80 frame_unwind_append_unwinder (struct gdbarch *gdbarch, 81 const struct frame_unwind *unwinder) 82 { 83 struct frame_unwind_table *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 /* Iterate through sniffers for THIS_FRAME frame until one returns with an 93 unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set 94 by this function. Possibly initialize THIS_CACHE. */ 95 96 void 97 frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache) 98 { 99 struct gdbarch *gdbarch = get_frame_arch (this_frame); 100 struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data); 101 struct frame_unwind_table_entry *entry; 102 103 for (entry = table->list; entry != NULL; entry = entry->next) 104 { 105 struct cleanup *old_cleanup; 106 volatile struct gdb_exception ex; 107 int res = 0; 108 109 old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder); 110 111 TRY_CATCH (ex, RETURN_MASK_ERROR) 112 { 113 res = entry->unwinder->sniffer (entry->unwinder, this_frame, 114 this_cache); 115 } 116 if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR) 117 { 118 /* This usually means that not even the PC is available, 119 thus most unwinders aren't able to determine if they're 120 the best fit. Keep trying. Fallback prologue unwinders 121 should always accept the frame. */ 122 } 123 else if (ex.reason < 0) 124 throw_exception (ex); 125 else if (res) 126 { 127 discard_cleanups (old_cleanup); 128 return; 129 } 130 131 do_cleanups (old_cleanup); 132 } 133 internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed")); 134 } 135 136 /* A default frame sniffer which always accepts the frame. Used by 137 fallback prologue unwinders. */ 138 139 int 140 default_frame_sniffer (const struct frame_unwind *self, 141 struct frame_info *this_frame, 142 void **this_prologue_cache) 143 { 144 return 1; 145 } 146 147 /* A default frame unwinder stop_reason callback that always claims 148 the frame is unwindable. */ 149 150 enum unwind_stop_reason 151 default_frame_unwind_stop_reason (struct frame_info *this_frame, 152 void **this_cache) 153 { 154 return UNWIND_NO_REASON; 155 } 156 157 /* Helper functions for value-based register unwinding. These return 158 a (possibly lazy) value of the appropriate type. */ 159 160 /* Return a value which indicates that FRAME did not save REGNUM. */ 161 162 struct value * 163 frame_unwind_got_optimized (struct frame_info *frame, int regnum) 164 { 165 struct gdbarch *gdbarch = frame_unwind_arch (frame); 166 struct value *reg_val; 167 168 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 169 set_value_optimized_out (reg_val, 1); 170 return reg_val; 171 } 172 173 /* Return a value which indicates that FRAME copied REGNUM into 174 register NEW_REGNUM. */ 175 176 struct value * 177 frame_unwind_got_register (struct frame_info *frame, 178 int regnum, int new_regnum) 179 { 180 return value_of_register_lazy (frame, new_regnum); 181 } 182 183 /* Return a value which indicates that FRAME saved REGNUM in memory at 184 ADDR. */ 185 186 struct value * 187 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr) 188 { 189 struct gdbarch *gdbarch = frame_unwind_arch (frame); 190 struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr); 191 192 set_value_stack (v, 1); 193 return v; 194 } 195 196 /* Return a value which indicates that FRAME's saved version of 197 REGNUM has a known constant (computed) value of VAL. */ 198 199 struct value * 200 frame_unwind_got_constant (struct frame_info *frame, int regnum, 201 ULONGEST val) 202 { 203 struct gdbarch *gdbarch = frame_unwind_arch (frame); 204 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 205 struct value *reg_val; 206 207 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 208 store_unsigned_integer (value_contents_writeable (reg_val), 209 register_size (gdbarch, regnum), byte_order, val); 210 return reg_val; 211 } 212 213 struct value * 214 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf) 215 { 216 struct gdbarch *gdbarch = frame_unwind_arch (frame); 217 struct value *reg_val; 218 219 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 220 memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum)); 221 return reg_val; 222 } 223 224 /* Return a value which indicates that FRAME's saved version of REGNUM 225 has a known constant (computed) value of ADDR. Convert the 226 CORE_ADDR to a target address if necessary. */ 227 228 struct value * 229 frame_unwind_got_address (struct frame_info *frame, int regnum, 230 CORE_ADDR addr) 231 { 232 struct gdbarch *gdbarch = frame_unwind_arch (frame); 233 struct value *reg_val; 234 235 reg_val = value_zero (register_type (gdbarch, regnum), not_lval); 236 pack_long (value_contents_writeable (reg_val), 237 register_type (gdbarch, regnum), addr); 238 return reg_val; 239 } 240 241 /* -Wmissing-prototypes */ 242 extern initialize_file_ftype _initialize_frame_unwind; 243 244 void 245 _initialize_frame_unwind (void) 246 { 247 frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init); 248 } 249