1 /* Traditional frame unwind support, for GDB the GNU Debugger. 2 3 Copyright (C) 2003-2020 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 "trad-frame.h" 23 #include "regcache.h" 24 #include "frame-unwind.h" 25 #include "target.h" 26 #include "value.h" 27 #include "gdbarch.h" 28 29 struct trad_frame_cache 30 { 31 struct frame_info *this_frame; 32 CORE_ADDR this_base; 33 struct trad_frame_saved_reg *prev_regs; 34 struct frame_id this_id; 35 }; 36 37 struct trad_frame_cache * 38 trad_frame_cache_zalloc (struct frame_info *this_frame) 39 { 40 struct trad_frame_cache *this_trad_cache; 41 42 this_trad_cache = FRAME_OBSTACK_ZALLOC (struct trad_frame_cache); 43 this_trad_cache->prev_regs = trad_frame_alloc_saved_regs (this_frame); 44 this_trad_cache->this_frame = this_frame; 45 return this_trad_cache; 46 } 47 48 /* See trad-frame.h. */ 49 50 void 51 trad_frame_reset_saved_regs (struct gdbarch *gdbarch, 52 struct trad_frame_saved_reg *regs) 53 { 54 int numregs = gdbarch_num_cooked_regs (gdbarch); 55 for (int regnum = 0; regnum < numregs; regnum++) 56 { 57 regs[regnum].realreg = regnum; 58 regs[regnum].addr = -1; 59 } 60 } 61 62 struct trad_frame_saved_reg * 63 trad_frame_alloc_saved_regs (struct gdbarch *gdbarch) 64 { 65 int numregs = gdbarch_num_cooked_regs (gdbarch); 66 struct trad_frame_saved_reg *this_saved_regs 67 = FRAME_OBSTACK_CALLOC (numregs, struct trad_frame_saved_reg); 68 69 trad_frame_reset_saved_regs (gdbarch, this_saved_regs); 70 return this_saved_regs; 71 } 72 73 /* A traditional frame is unwound by analysing the function prologue 74 and using the information gathered to track registers. For 75 non-optimized frames, the technique is reliable (just need to check 76 for all potential instruction sequences). */ 77 78 struct trad_frame_saved_reg * 79 trad_frame_alloc_saved_regs (struct frame_info *this_frame) 80 { 81 struct gdbarch *gdbarch = get_frame_arch (this_frame); 82 83 return trad_frame_alloc_saved_regs (gdbarch); 84 } 85 86 enum { TF_REG_VALUE = -1, TF_REG_UNKNOWN = -2 }; 87 88 int 89 trad_frame_value_p (struct trad_frame_saved_reg this_saved_regs[], int regnum) 90 { 91 return (this_saved_regs[regnum].realreg == TF_REG_VALUE); 92 } 93 94 int 95 trad_frame_addr_p (struct trad_frame_saved_reg this_saved_regs[], int regnum) 96 { 97 return (this_saved_regs[regnum].realreg >= 0 98 && this_saved_regs[regnum].addr != -1); 99 } 100 101 int 102 trad_frame_realreg_p (struct trad_frame_saved_reg this_saved_regs[], 103 int regnum) 104 { 105 return (this_saved_regs[regnum].realreg >= 0 106 && this_saved_regs[regnum].addr == -1); 107 } 108 109 void 110 trad_frame_set_value (struct trad_frame_saved_reg this_saved_regs[], 111 int regnum, LONGEST val) 112 { 113 /* Make the REALREG invalid, indicating that the ADDR contains the 114 register's value. */ 115 this_saved_regs[regnum].realreg = TF_REG_VALUE; 116 this_saved_regs[regnum].addr = val; 117 } 118 119 /* See trad-frame.h. */ 120 121 void 122 trad_frame_set_realreg (struct trad_frame_saved_reg this_saved_regs[], 123 int regnum, int realreg) 124 { 125 this_saved_regs[regnum].realreg = realreg; 126 this_saved_regs[regnum].addr = -1; 127 } 128 129 /* See trad-frame.h. */ 130 131 void 132 trad_frame_set_addr (struct trad_frame_saved_reg this_saved_regs[], 133 int regnum, CORE_ADDR addr) 134 { 135 this_saved_regs[regnum].realreg = regnum; 136 this_saved_regs[regnum].addr = addr; 137 } 138 139 void 140 trad_frame_set_reg_value (struct trad_frame_cache *this_trad_cache, 141 int regnum, LONGEST val) 142 { 143 /* External interface for users of trad_frame_cache 144 (who cannot access the prev_regs object directly). */ 145 trad_frame_set_value (this_trad_cache->prev_regs, regnum, val); 146 } 147 148 void 149 trad_frame_set_reg_realreg (struct trad_frame_cache *this_trad_cache, 150 int regnum, int realreg) 151 { 152 trad_frame_set_realreg (this_trad_cache->prev_regs, regnum, realreg); 153 } 154 155 void 156 trad_frame_set_reg_addr (struct trad_frame_cache *this_trad_cache, 157 int regnum, CORE_ADDR addr) 158 { 159 trad_frame_set_addr (this_trad_cache->prev_regs, regnum, addr); 160 } 161 162 void 163 trad_frame_set_reg_regmap (struct trad_frame_cache *this_trad_cache, 164 const struct regcache_map_entry *regmap, 165 CORE_ADDR addr, size_t size) 166 { 167 struct gdbarch *gdbarch = get_frame_arch (this_trad_cache->this_frame); 168 int offs = 0, count; 169 170 for (; (count = regmap->count) != 0; regmap++) 171 { 172 int regno = regmap->regno; 173 int slot_size = regmap->size; 174 175 if (slot_size == 0 && regno != REGCACHE_MAP_SKIP) 176 slot_size = register_size (gdbarch, regno); 177 178 if (offs + slot_size > size) 179 break; 180 181 if (regno == REGCACHE_MAP_SKIP) 182 offs += count * slot_size; 183 else 184 for (; count--; regno++, offs += slot_size) 185 { 186 /* Mimic the semantics of regcache::transfer_regset if a 187 register slot's size does not match the size of a 188 register. 189 190 If a register slot is larger than a register, assume 191 the register's value is stored in the first N bytes of 192 the slot and ignore the remaining bytes. 193 194 If the register slot is smaller than the register, 195 assume that the slot contains the low N bytes of the 196 register's value. Since trad_frame assumes that 197 registers stored by address are sized according to the 198 register, read the low N bytes and zero-extend them to 199 generate a register value. */ 200 if (slot_size >= register_size (gdbarch, regno)) 201 trad_frame_set_reg_addr (this_trad_cache, regno, addr + offs); 202 else 203 { 204 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 205 gdb_byte buf[slot_size]; 206 207 if (target_read_memory (addr + offs, buf, sizeof buf) == 0) 208 { 209 LONGEST val 210 = extract_unsigned_integer (buf, sizeof buf, byte_order); 211 trad_frame_set_reg_value (this_trad_cache, regno, val); 212 } 213 } 214 } 215 } 216 } 217 218 void 219 trad_frame_set_unknown (struct trad_frame_saved_reg this_saved_regs[], 220 int regnum) 221 { 222 /* Make the REALREG invalid, indicating that the value is not known. */ 223 this_saved_regs[regnum].realreg = TF_REG_UNKNOWN; 224 this_saved_regs[regnum].addr = -1; 225 } 226 227 struct value * 228 trad_frame_get_prev_register (struct frame_info *this_frame, 229 struct trad_frame_saved_reg this_saved_regs[], 230 int regnum) 231 { 232 if (trad_frame_addr_p (this_saved_regs, regnum)) 233 /* The register was saved in memory. */ 234 return frame_unwind_got_memory (this_frame, regnum, 235 this_saved_regs[regnum].addr); 236 else if (trad_frame_realreg_p (this_saved_regs, regnum)) 237 return frame_unwind_got_register (this_frame, regnum, 238 this_saved_regs[regnum].realreg); 239 else if (trad_frame_value_p (this_saved_regs, regnum)) 240 /* The register's value is available. */ 241 return frame_unwind_got_constant (this_frame, regnum, 242 this_saved_regs[regnum].addr); 243 else 244 return frame_unwind_got_optimized (this_frame, regnum); 245 } 246 247 struct value * 248 trad_frame_get_register (struct trad_frame_cache *this_trad_cache, 249 struct frame_info *this_frame, 250 int regnum) 251 { 252 return trad_frame_get_prev_register (this_frame, this_trad_cache->prev_regs, 253 regnum); 254 } 255 256 void 257 trad_frame_set_id (struct trad_frame_cache *this_trad_cache, 258 struct frame_id this_id) 259 { 260 this_trad_cache->this_id = this_id; 261 } 262 263 void 264 trad_frame_get_id (struct trad_frame_cache *this_trad_cache, 265 struct frame_id *this_id) 266 { 267 (*this_id) = this_trad_cache->this_id; 268 } 269 270 void 271 trad_frame_set_this_base (struct trad_frame_cache *this_trad_cache, 272 CORE_ADDR this_base) 273 { 274 this_trad_cache->this_base = this_base; 275 } 276 277 CORE_ADDR 278 trad_frame_get_this_base (struct trad_frame_cache *this_trad_cache) 279 { 280 return this_trad_cache->this_base; 281 } 282