gdb/dwarf2-frame.h

   1 /* Frame unwinder for frames with DWARF Call Frame Information.
   2
   3    Copyright (C) 2003-2017 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     const gdb_byte *exp;
  78     struct value *(*fn) (struct frame_info *this_frame, void **this_cache,
  79                          int regnum);
  80   } loc;
  81   ULONGEST exp_len;
  82   enum dwarf2_frame_reg_rule how;
  83 };
  84
  85 enum cfa_how_kind
  86 {
  87   CFA_UNSET,
  88   CFA_REG_OFFSET,
  89   CFA_EXP
  90 };
  91
  92 struct dwarf2_frame_state_reg_info
  93 {
  94   struct dwarf2_frame_state_reg *reg;
  95   int num_regs;
  96
  97   LONGEST cfa_offset;
  98   ULONGEST cfa_reg;
  99   enum cfa_how_kind cfa_how;
 100   const gdb_byte *cfa_exp;
 101
 102   /* Used to implement DW_CFA_remember_state.  */
 103   struct dwarf2_frame_state_reg_info *prev;
 104 };
 105
 106 /* Structure describing a frame state.  */
 107
 108 struct dwarf2_frame_state
 109 {
 110   /* Each register save state can be described in terms of a CFA slot,
 111      another register, or a location expression.  */
 112   struct dwarf2_frame_state_reg_info regs;
 113
 114   /* The PC described by the current frame state.  */
 115   CORE_ADDR pc;
 116
 117   /* Initial register set from the CIE.
 118      Used to implement DW_CFA_restore.  */
 119   struct dwarf2_frame_state_reg_info initial;
 120
 121   /* The information we care about from the CIE.  */
 122   LONGEST data_align;
 123   ULONGEST code_align;
 124   ULONGEST retaddr_column;
 125
 126   /* Flags for known producer quirks.  */
 127
 128   /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
 129      and DW_CFA_def_cfa_offset takes a factored offset.  */
 130   int armcc_cfa_offsets_sf;
 131
 132   /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
 133      the CFA is defined as REG - OFFSET rather than REG + OFFSET.  */
 134   int armcc_cfa_offsets_reversed;
 135 };
 136
 137 /* Set the architecture-specific register state initialization
 138    function for GDBARCH to INIT_REG.  */
 139
 140 extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
 141                                        void (*init_reg) (struct gdbarch *, int,
 142                                              struct dwarf2_frame_state_reg *,
 143                                              struct frame_info *));
 144
 145 /* Set the architecture-specific signal trampoline recognition
 146    function for GDBARCH to SIGNAL_FRAME_P.  */
 147
 148 extern void
 149   dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
 150                                    int (*signal_frame_p) (struct gdbarch *,
 151                                                           struct frame_info *));
 152
 153 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
 154    register numbers.  */
 155
 156 extern void
 157   dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
 158                                   int (*adjust_regnum) (struct gdbarch *,
 159                                                         int, int));
 160
 161 /* Append the DWARF-2 frame unwinders to GDBARCH's list.  */
 162
 163 void dwarf2_append_unwinders (struct gdbarch *gdbarch);
 164
 165 /* Return the frame base methods for the function that contains PC, or
 166    NULL if it can't be handled by the DWARF CFI frame unwinder.  */
 167
 168 extern const struct frame_base *
 169   dwarf2_frame_base_sniffer (struct frame_info *this_frame);
 170
 171 /* Compute the DWARF CFA for a frame.  */
 172
 173 CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame);
 174
 175 /* Assert that the register set RS is large enough to store gdbarch_num_regs
 176    columns.  If necessary, enlarge the register set.  */
 177
 178 void dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
 179                                     int num_regs);
 180
 181 /* Find the CFA information for PC.
 182
 183    Return 1 if a register is used for the CFA, or 0 if another
 184    expression is used.  Throw an exception on error.
 185
 186    GDBARCH is the architecture to use.
 187    DATA is the per-CU data.
 188
 189    REGNUM_OUT is an out parameter that is set to the register number.
 190    OFFSET_OUT is the offset to use from this register.
 191    These are only filled in when 1 is returned.
 192
 193    TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA
 194    in other cases.  These are only used when 0 is returned.  */
 195
 196 extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
 197                                   struct dwarf2_per_cu_data *data,
 198                                   int *regnum_out, LONGEST *offset_out,
 199                                   CORE_ADDR *text_offset_out,
 200                                   const gdb_byte **cfa_start_out,
 201                                   const gdb_byte **cfa_end_out);
 202
 203 #endif /* dwarf2-frame.h */