1/* Frame unwinder for frames with DWARF Call Frame Information. 2 3 Copyright (C) 2003-2020 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 25struct gdbarch; 26struct frame_info; 27struct dwarf2_per_cu_data; 28struct agent_expr; 29struct axs_value; 30 31/* Register rule. */ 32 33enum 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 69struct dwarf2_frame_state_reg 70{ 71 /* Each register save state can be described in terms of a CFA slot, 72 another register, or a location expression. */ 73 union { 74 LONGEST offset; 75 ULONGEST reg; 76 struct 77 { 78 const gdb_byte *start; 79 ULONGEST len; 80 } exp; 81 struct value *(*fn) (struct frame_info *this_frame, void **this_cache, 82 int regnum); 83 } loc; 84 enum dwarf2_frame_reg_rule how; 85}; 86 87enum cfa_how_kind 88{ 89 CFA_UNSET, 90 CFA_REG_OFFSET, 91 CFA_EXP 92}; 93 94struct dwarf2_frame_state_reg_info 95{ 96 dwarf2_frame_state_reg_info () = default; 97 ~dwarf2_frame_state_reg_info () 98 { 99 delete prev; 100 } 101 102 /* Copy constructor. */ 103 dwarf2_frame_state_reg_info (const dwarf2_frame_state_reg_info &src) 104 : reg (src.reg), cfa_offset (src.cfa_offset), 105 cfa_reg (src.cfa_reg), cfa_how (src.cfa_how), cfa_exp (src.cfa_exp), 106 prev (src.prev) 107 { 108 } 109 110 /* Assignment operator for both move-assignment and copy-assignment. */ 111 dwarf2_frame_state_reg_info& 112 operator= (dwarf2_frame_state_reg_info rhs) 113 { 114 swap (*this, rhs); 115 return *this; 116 } 117 118 /* Move constructor. */ 119 dwarf2_frame_state_reg_info (dwarf2_frame_state_reg_info &&rhs) noexcept 120 : reg (std::move (rhs.reg)), cfa_offset (rhs.cfa_offset), 121 cfa_reg (rhs.cfa_reg), cfa_how (rhs.cfa_how), cfa_exp (rhs.cfa_exp), 122 prev (rhs.prev) 123 { 124 rhs.prev = nullptr; 125 } 126 127 /* If necessary, enlarge the register set to hold NUM_REGS_REQUESTED 128 registers. */ 129 void alloc_regs (int num_regs_requested) 130 { 131 gdb_assert (num_regs_requested > 0); 132 133 if (num_regs_requested <= reg.size ()) 134 return; 135 136 reg.resize (num_regs_requested); 137 } 138 139 std::vector<struct dwarf2_frame_state_reg> reg; 140 141 LONGEST cfa_offset = 0; 142 ULONGEST cfa_reg = 0; 143 enum cfa_how_kind cfa_how = CFA_UNSET; 144 const gdb_byte *cfa_exp = NULL; 145 146 /* Used to implement DW_CFA_remember_state. */ 147 struct dwarf2_frame_state_reg_info *prev = NULL; 148 149private: 150 friend void swap (dwarf2_frame_state_reg_info& lhs, 151 dwarf2_frame_state_reg_info& rhs) 152 { 153 using std::swap; 154 155 swap (lhs.reg, rhs.reg); 156 swap (lhs.cfa_offset, rhs.cfa_offset); 157 swap (lhs.cfa_reg, rhs.cfa_reg); 158 swap (lhs.cfa_how, rhs.cfa_how); 159 swap (lhs.cfa_exp, rhs.cfa_exp); 160 swap (lhs.prev, rhs.prev); 161 } 162}; 163 164struct dwarf2_cie; 165 166/* Structure describing a frame state. */ 167 168struct dwarf2_frame_state 169{ 170 dwarf2_frame_state (CORE_ADDR pc, struct dwarf2_cie *cie); 171 172 /* Each register save state can be described in terms of a CFA slot, 173 another register, or a location expression. */ 174 struct dwarf2_frame_state_reg_info regs {}; 175 176 /* The PC described by the current frame state. */ 177 CORE_ADDR pc; 178 179 /* Initial register set from the CIE. 180 Used to implement DW_CFA_restore. */ 181 struct dwarf2_frame_state_reg_info initial {}; 182 183 /* The information we care about from the CIE. */ 184 const LONGEST data_align; 185 const ULONGEST code_align; 186 const ULONGEST retaddr_column; 187 188 /* Flags for known producer quirks. */ 189 190 /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa 191 and DW_CFA_def_cfa_offset takes a factored offset. */ 192 bool armcc_cfa_offsets_sf = false; 193 194 /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that 195 the CFA is defined as REG - OFFSET rather than REG + OFFSET. */ 196 bool armcc_cfa_offsets_reversed = false; 197}; 198 199/* When this is true the DWARF frame unwinders can be used if they are 200 registered with the gdbarch. Not all architectures can or do use the 201 DWARF unwinders. Setting this to true on a target that does not 202 otherwise support the DWARF unwinders has no effect. */ 203extern bool dwarf2_frame_unwinders_enabled_p; 204 205/* Set the architecture-specific register state initialization 206 function for GDBARCH to INIT_REG. */ 207 208extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch, 209 void (*init_reg) (struct gdbarch *, int, 210 struct dwarf2_frame_state_reg *, 211 struct frame_info *)); 212 213/* Set the architecture-specific signal trampoline recognition 214 function for GDBARCH to SIGNAL_FRAME_P. */ 215 216extern void 217 dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch, 218 int (*signal_frame_p) (struct gdbarch *, 219 struct frame_info *)); 220 221/* Set the architecture-specific adjustment of .eh_frame and .debug_frame 222 register numbers. */ 223 224extern void 225 dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch, 226 int (*adjust_regnum) (struct gdbarch *, 227 int, int)); 228 229/* Append the DWARF-2 frame unwinders to GDBARCH's list. */ 230 231void dwarf2_append_unwinders (struct gdbarch *gdbarch); 232 233/* Return the frame base methods for the function that contains PC, or 234 NULL if it can't be handled by the DWARF CFI frame unwinder. */ 235 236extern const struct frame_base * 237 dwarf2_frame_base_sniffer (struct frame_info *this_frame); 238 239/* Compute the DWARF CFA for a frame. */ 240 241CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame); 242 243/* Find the CFA information for PC. 244 245 Return 1 if a register is used for the CFA, or 0 if another 246 expression is used. Throw an exception on error. 247 248 GDBARCH is the architecture to use. 249 DATA is the per-CU data. 250 251 REGNUM_OUT is an out parameter that is set to the register number. 252 OFFSET_OUT is the offset to use from this register. 253 These are only filled in when 1 is returned. 254 255 TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA 256 in other cases. These are only used when 0 is returned. */ 257 258extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc, 259 struct dwarf2_per_cu_data *data, 260 int *regnum_out, LONGEST *offset_out, 261 CORE_ADDR *text_offset_out, 262 const gdb_byte **cfa_start_out, 263 const gdb_byte **cfa_end_out); 264 265#endif /* dwarf2-frame.h */ 266