gdb/dwarf2-frame.h

   1 /* Frame unwinder for frames with DWARF Call Frame Information.
   2
   3    Copyright (C) 2003-2018 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 struct objfile;
  27 struct frame_info;
  28 struct dwarf2_per_cu_data;
  29 struct agent_expr;
  30 struct axs_value;
  31
  32 /* Register rule.  */
  33
  34 enum dwarf2_frame_reg_rule
  35 {
  36   /* Make certain that 0 maps onto the correct enum value; the
  37      corresponding structure is being initialized using memset zero.
  38      This indicates that CFI didn't provide any information at all
  39      about a register, leaving how to obtain its value totally
  40      unspecified.  */
  41   DWARF2_FRAME_REG_UNSPECIFIED = 0,
  42
  43   /* The term "undefined" comes from the DWARF2 CFI spec which this
  44      code is moddeling; it indicates that the register's value is
  45      "undefined".  GCC uses the less formal term "unsaved".  Its
  46      definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
  47      The failure to differentiate the two helps explain a few problems
  48      with the CFI generated by GCC.  */
  49   DWARF2_FRAME_REG_UNDEFINED,
  50   DWARF2_FRAME_REG_SAVED_OFFSET,
  51   DWARF2_FRAME_REG_SAVED_REG,
  52   DWARF2_FRAME_REG_SAVED_EXP,
  53   DWARF2_FRAME_REG_SAME_VALUE,
  54
  55   /* These are defined in Dwarf3.  */
  56   DWARF2_FRAME_REG_SAVED_VAL_OFFSET,
  57   DWARF2_FRAME_REG_SAVED_VAL_EXP,
  58
  59   /* These aren't defined by the DWARF2 CFI specification, but are
  60      used internally by GDB.  */
  61   DWARF2_FRAME_REG_FN,          /* Call a registered function.  */
  62   DWARF2_FRAME_REG_RA,          /* Return Address.  */
  63   DWARF2_FRAME_REG_RA_OFFSET,   /* Return Address with offset.  */
  64   DWARF2_FRAME_REG_CFA,         /* Call Frame Address.  */
  65   DWARF2_FRAME_REG_CFA_OFFSET   /* Call Frame Address with offset.  */
  66 };
  67
  68 /* Register state.  */
  69
  70 struct dwarf2_frame_state_reg
  71 {
  72   /* Each register save state can be described in terms of a CFA slot,
  73      another register, or a location expression.  */
  74   union {
  75     LONGEST offset;
  76     ULONGEST reg;
  77     struct
  78     {
  79       const gdb_byte *start;
  80       ULONGEST len;
  81     } exp;
  82     struct value *(*fn) (struct frame_info *this_frame, void **this_cache,
  83                          int regnum);
  84   } loc;
  85   enum dwarf2_frame_reg_rule how;
  86 };
  87
  88 enum cfa_how_kind
  89 {
  90   CFA_UNSET,
  91   CFA_REG_OFFSET,
  92   CFA_EXP
  93 };
  94
  95 struct dwarf2_frame_state_reg_info
  96 {
  97   dwarf2_frame_state_reg_info () = default;
  98   ~dwarf2_frame_state_reg_info ()
  99   {
 100     delete prev;
 101     xfree (reg);
 102   }
 103
 104   /* Copy constructor.  */
 105   dwarf2_frame_state_reg_info (const dwarf2_frame_state_reg_info &src)
 106     : num_regs (src.num_regs), 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     size_t size = src.num_regs * sizeof (struct dwarf2_frame_state_reg);
 111
 112     reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
 113     memcpy (reg, src.reg, size);
 114   }
 115
 116   /* Assignment operator for both move-assignment and copy-assignment.  */
 117   dwarf2_frame_state_reg_info&
 118   operator= (dwarf2_frame_state_reg_info rhs)
 119   {
 120     swap (*this, rhs);
 121     return *this;
 122   }
 123
 124   /* Move constructor.  */
 125   dwarf2_frame_state_reg_info (dwarf2_frame_state_reg_info &&rhs) noexcept
 126     : reg (rhs.reg), num_regs (rhs.num_regs), cfa_offset (rhs.cfa_offset),
 127       cfa_reg (rhs.cfa_reg), cfa_how (rhs.cfa_how), cfa_exp (rhs.cfa_exp),
 128       prev (rhs.prev)
 129   {
 130     rhs.prev = nullptr;
 131     rhs.reg = nullptr;
 132   }
 133
 134 /* Assert that the register set RS is large enough to store gdbarch_num_regs
 135    columns.  If necessary, enlarge the register set.  */
 136   void alloc_regs (int num_regs_requested)
 137   {
 138     if (num_regs_requested <= num_regs)
 139       return;
 140
 141     size_t size = sizeof (struct dwarf2_frame_state_reg);
 142
 143     reg = (struct dwarf2_frame_state_reg *)
 144       xrealloc (reg, num_regs_requested * size);
 145
 146     /* Initialize newly allocated registers.  */
 147     memset (reg + num_regs, 0, (num_regs_requested - num_regs) * size);
 148     num_regs = num_regs_requested;
 149   }
 150
 151   struct dwarf2_frame_state_reg *reg = NULL;
 152   int num_regs = 0;
 153
 154   LONGEST cfa_offset = 0;
 155   ULONGEST cfa_reg = 0;
 156   enum cfa_how_kind cfa_how = CFA_UNSET;
 157   const gdb_byte *cfa_exp = NULL;
 158
 159   /* Used to implement DW_CFA_remember_state.  */
 160   struct dwarf2_frame_state_reg_info *prev = NULL;
 161
 162 private:
 163   friend void swap (dwarf2_frame_state_reg_info& lhs,
 164                     dwarf2_frame_state_reg_info& rhs)
 165   {
 166     using std::swap;
 167
 168     swap (lhs.reg, rhs.reg);
 169     swap (lhs.num_regs, rhs.num_regs);
 170     swap (lhs.cfa_offset, rhs.cfa_offset);
 171     swap (lhs.cfa_reg, rhs.cfa_reg);
 172     swap (lhs.cfa_how, rhs.cfa_how);
 173     swap (lhs.cfa_exp, rhs.cfa_exp);
 174     swap (lhs.prev, rhs.prev);
 175   }
 176 };
 177
 178 struct dwarf2_cie;
 179
 180 /* Structure describing a frame state.  */
 181
 182 struct dwarf2_frame_state
 183 {
 184   dwarf2_frame_state (CORE_ADDR pc, struct dwarf2_cie *cie);
 185
 186   /* Each register save state can be described in terms of a CFA slot,
 187      another register, or a location expression.  */
 188   struct dwarf2_frame_state_reg_info regs {};
 189
 190   /* The PC described by the current frame state.  */
 191   CORE_ADDR pc;
 192
 193   /* Initial register set from the CIE.
 194      Used to implement DW_CFA_restore.  */
 195   struct dwarf2_frame_state_reg_info initial {};
 196
 197   /* The information we care about from the CIE.  */
 198   const LONGEST data_align;
 199   const ULONGEST code_align;
 200   const ULONGEST retaddr_column;
 201
 202   /* Flags for known producer quirks.  */
 203
 204   /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
 205      and DW_CFA_def_cfa_offset takes a factored offset.  */
 206   bool armcc_cfa_offsets_sf = false;
 207
 208   /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
 209      the CFA is defined as REG - OFFSET rather than REG + OFFSET.  */
 210   bool armcc_cfa_offsets_reversed = false;
 211 };
 212
 213 /* Set the architecture-specific register state initialization
 214    function for GDBARCH to INIT_REG.  */
 215
 216 extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
 217                                        void (*init_reg) (struct gdbarch *, int,
 218                                              struct dwarf2_frame_state_reg *,
 219                                              struct frame_info *));
 220
 221 /* Set the architecture-specific signal trampoline recognition
 222    function for GDBARCH to SIGNAL_FRAME_P.  */
 223
 224 extern void
 225   dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
 226                                    int (*signal_frame_p) (struct gdbarch *,
 227                                                           struct frame_info *));
 228
 229 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
 230    register numbers.  */
 231
 232 extern void
 233   dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
 234                                   int (*adjust_regnum) (struct gdbarch *,
 235                                                         int, int));
 236
 237 /* Append the DWARF-2 frame unwinders to GDBARCH's list.  */
 238
 239 void dwarf2_append_unwinders (struct gdbarch *gdbarch);
 240
 241 /* Return the frame base methods for the function that contains PC, or
 242    NULL if it can't be handled by the DWARF CFI frame unwinder.  */
 243
 244 extern const struct frame_base *
 245   dwarf2_frame_base_sniffer (struct frame_info *this_frame);
 246
 247 /* Compute the DWARF CFA for a frame.  */
 248
 249 CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame);
 250
 251 /* Find the CFA information for PC.
 252
 253    Return 1 if a register is used for the CFA, or 0 if another
 254    expression is used.  Throw an exception on error.
 255
 256    GDBARCH is the architecture to use.
 257    DATA is the per-CU data.
 258
 259    REGNUM_OUT is an out parameter that is set to the register number.
 260    OFFSET_OUT is the offset to use from this register.
 261    These are only filled in when 1 is returned.
 262
 263    TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA
 264    in other cases.  These are only used when 0 is returned.  */
 265
 266 extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
 267                                   struct dwarf2_per_cu_data *data,
 268                                   int *regnum_out, LONGEST *offset_out,
 269                                   CORE_ADDR *text_offset_out,
 270                                   const gdb_byte **cfa_start_out,
 271                                   const gdb_byte **cfa_end_out);
 272
 273 #endif /* dwarf2-frame.h */