1 /* Frame unwinder for frames with DWARF Call Frame Information. 2 3 Copyright (C) 2003-2023 Free Software Foundation, Inc. 4 5 Contributed by Mark Kettenis. 6 7 This file is part of GDB. 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 21 22 #ifndef DWARF2_FRAME_H 23 #define DWARF2_FRAME_H 1 24 25 struct gdbarch; 26 class frame_info_ptr; 27 struct dwarf2_per_cu_data; 28 struct agent_expr; 29 struct axs_value; 30 31 /* Register rule. */ 32 33 enum dwarf2_frame_reg_rule 34 { 35 /* Make certain that 0 maps onto the correct enum value; the 36 corresponding structure is being initialized using memset zero. 37 This indicates that CFI didn't provide any information at all 38 about a register, leaving how to obtain its value totally 39 unspecified. */ 40 DWARF2_FRAME_REG_UNSPECIFIED = 0, 41 42 /* The term "undefined" comes from the DWARF2 CFI spec which this 43 code is modeling; it indicates that the register's value is 44 "undefined". GCC uses the less formal term "unsaved". Its 45 definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED. 46 The failure to differentiate the two helps explain a few problems 47 with the CFI generated by GCC. */ 48 DWARF2_FRAME_REG_UNDEFINED, 49 DWARF2_FRAME_REG_SAVED_OFFSET, 50 DWARF2_FRAME_REG_SAVED_REG, 51 DWARF2_FRAME_REG_SAVED_EXP, 52 DWARF2_FRAME_REG_SAME_VALUE, 53 54 /* These are defined in Dwarf3. */ 55 DWARF2_FRAME_REG_SAVED_VAL_OFFSET, 56 DWARF2_FRAME_REG_SAVED_VAL_EXP, 57 58 /* These aren't defined by the DWARF2 CFI specification, but are 59 used internally by GDB. */ 60 DWARF2_FRAME_REG_FN, /* Call a registered function. */ 61 DWARF2_FRAME_REG_RA, /* Return Address. */ 62 DWARF2_FRAME_REG_RA_OFFSET, /* Return Address with offset. */ 63 DWARF2_FRAME_REG_CFA, /* Call Frame Address. */ 64 DWARF2_FRAME_REG_CFA_OFFSET /* Call Frame Address with offset. */ 65 }; 66 67 /* Register state. */ 68 69 typedef struct value *(*fn_prev_register) (frame_info_ptr this_frame, 70 void **this_cache, int regnum); 71 72 struct dwarf2_frame_state_reg 73 { 74 /* Each register save state can be described in terms of a CFA slot, 75 another register, or a location expression. */ 76 union { 77 LONGEST offset; 78 ULONGEST reg; 79 struct 80 { 81 const gdb_byte *start; 82 ULONGEST len; 83 } exp; 84 fn_prev_register fn; 85 } loc; 86 enum dwarf2_frame_reg_rule how; 87 }; 88 89 enum cfa_how_kind 90 { 91 CFA_UNSET, 92 CFA_REG_OFFSET, 93 CFA_EXP 94 }; 95 96 struct dwarf2_frame_state_reg_info 97 { 98 dwarf2_frame_state_reg_info () = default; 99 ~dwarf2_frame_state_reg_info () 100 { 101 delete prev; 102 } 103 104 /* Copy constructor. */ 105 dwarf2_frame_state_reg_info (const dwarf2_frame_state_reg_info &src) 106 : reg (src.reg), cfa_offset (src.cfa_offset), 107 cfa_reg (src.cfa_reg), cfa_how (src.cfa_how), cfa_exp (src.cfa_exp), 108 prev (src.prev) 109 { 110 } 111 112 /* Assignment operator for both move-assignment and copy-assignment. */ 113 dwarf2_frame_state_reg_info& 114 operator= (dwarf2_frame_state_reg_info rhs) 115 { 116 swap (*this, rhs); 117 return *this; 118 } 119 120 /* Move constructor. */ 121 dwarf2_frame_state_reg_info (dwarf2_frame_state_reg_info &&rhs) noexcept 122 : reg (std::move (rhs.reg)), cfa_offset (rhs.cfa_offset), 123 cfa_reg (rhs.cfa_reg), cfa_how (rhs.cfa_how), cfa_exp (rhs.cfa_exp), 124 prev (rhs.prev) 125 { 126 rhs.prev = nullptr; 127 } 128 129 /* If necessary, enlarge the register set to hold NUM_REGS_REQUESTED 130 registers. */ 131 void alloc_regs (int num_regs_requested) 132 { 133 gdb_assert (num_regs_requested > 0); 134 135 if (num_regs_requested <= reg.size ()) 136 return; 137 138 reg.resize (num_regs_requested); 139 } 140 141 std::vector<struct dwarf2_frame_state_reg> reg; 142 143 LONGEST cfa_offset = 0; 144 ULONGEST cfa_reg = 0; 145 enum cfa_how_kind cfa_how = CFA_UNSET; 146 const gdb_byte *cfa_exp = NULL; 147 148 /* Used to implement DW_CFA_remember_state. */ 149 struct dwarf2_frame_state_reg_info *prev = NULL; 150 151 private: 152 friend void swap (dwarf2_frame_state_reg_info& lhs, 153 dwarf2_frame_state_reg_info& rhs) 154 { 155 using std::swap; 156 157 swap (lhs.reg, rhs.reg); 158 swap (lhs.cfa_offset, rhs.cfa_offset); 159 swap (lhs.cfa_reg, rhs.cfa_reg); 160 swap (lhs.cfa_how, rhs.cfa_how); 161 swap (lhs.cfa_exp, rhs.cfa_exp); 162 swap (lhs.prev, rhs.prev); 163 } 164 }; 165 166 struct dwarf2_cie; 167 168 /* Structure describing a frame state. */ 169 170 struct dwarf2_frame_state 171 { 172 dwarf2_frame_state (CORE_ADDR pc, struct dwarf2_cie *cie); 173 174 /* Each register save state can be described in terms of a CFA slot, 175 another register, or a location expression. */ 176 struct dwarf2_frame_state_reg_info regs {}; 177 178 /* The PC described by the current frame state. */ 179 CORE_ADDR pc; 180 181 /* Initial register set from the CIE. 182 Used to implement DW_CFA_restore. */ 183 struct dwarf2_frame_state_reg_info initial {}; 184 185 /* The information we care about from the CIE. */ 186 const LONGEST data_align; 187 const ULONGEST code_align; 188 const ULONGEST retaddr_column; 189 190 /* Flags for known producer quirks. */ 191 192 /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa 193 and DW_CFA_def_cfa_offset takes a factored offset. */ 194 bool armcc_cfa_offsets_sf = false; 195 196 /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that 197 the CFA is defined as REG - OFFSET rather than REG + OFFSET. */ 198 bool armcc_cfa_offsets_reversed = false; 199 }; 200 201 /* When this is true the DWARF frame unwinders can be used if they are 202 registered with the gdbarch. Not all architectures can or do use the 203 DWARF unwinders. Setting this to true on a target that does not 204 otherwise support the DWARF unwinders has no effect. */ 205 extern bool dwarf2_frame_unwinders_enabled_p; 206 207 /* Set the architecture-specific register state initialization 208 function for GDBARCH to INIT_REG. */ 209 210 extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch, 211 void (*init_reg) (struct gdbarch *, int, 212 struct dwarf2_frame_state_reg *, 213 frame_info_ptr)); 214 215 /* Set the architecture-specific signal trampoline recognition 216 function for GDBARCH to SIGNAL_FRAME_P. */ 217 218 extern void 219 dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch, 220 int (*signal_frame_p) (struct gdbarch *, 221 frame_info_ptr)); 222 223 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame 224 register numbers. */ 225 226 extern void 227 dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch, 228 int (*adjust_regnum) (struct gdbarch *, 229 int, int)); 230 231 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */ 232 233 void dwarf2_append_unwinders (struct gdbarch *gdbarch); 234 235 /* Return the frame base methods for the function that contains PC, or 236 NULL if it can't be handled by the DWARF CFI frame unwinder. */ 237 238 extern const struct frame_base * 239 dwarf2_frame_base_sniffer (frame_info_ptr this_frame); 240 241 /* Compute the DWARF CFA for a frame. */ 242 243 CORE_ADDR dwarf2_frame_cfa (frame_info_ptr this_frame); 244 245 /* Find the CFA information for PC. 246 247 Return 1 if a register is used for the CFA, or 0 if another 248 expression is used. Throw an exception on error. 249 250 GDBARCH is the architecture to use. 251 DATA is the per-CU data. 252 253 REGNUM_OUT is an out parameter that is set to the register number. 254 OFFSET_OUT is the offset to use from this register. 255 These are only filled in when 1 is returned. 256 257 TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA 258 in other cases. These are only used when 0 is returned. */ 259 260 extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc, 261 struct dwarf2_per_cu_data *data, 262 int *regnum_out, LONGEST *offset_out, 263 CORE_ADDR *text_offset_out, 264 const gdb_byte **cfa_start_out, 265 const gdb_byte **cfa_end_out); 266 267 268 /* Allocate a new instance of the function unique data. 269 270 The main purpose of this custom function data object is to allow caching the 271 value of expensive lookups in the prev_register implementation. 272 273 THIS_FRAME is the frame that the custom data object should be associated 274 with. 275 THIS_CACHE is the dwarf2 cache object to store the pointer on. 276 COOKIE is the key for the prev_function implementation. 277 SIZE is the size of the custom data object to allocate. */ 278 279 extern void *dwarf2_frame_allocate_fn_data (frame_info_ptr this_frame, 280 void **this_cache, 281 fn_prev_register cookie, 282 unsigned long size); 283 284 /* Retrieve the function unique data for this frame or NULL if none exists. 285 286 The main purpose of this custom function data object is to allow caching the 287 value of expensive lookups in the prev_register implementation. 288 289 THIS_FRAME is the frame that the custom data object should be associated 290 with. 291 THIS_CACHE is the dwarf2 cache object to store the pointer on. 292 COOKIE is the key for the prev_function implementation. */ 293 294 extern void *dwarf2_frame_get_fn_data (frame_info_ptr this_frame, 295 void **this_cache, 296 fn_prev_register cookie); 297 298 #endif /* dwarf2-frame.h */ 299