| 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 | } |