gdb/minsyms.h

   1 /* Minimal symbol table definitions for GDB.
   2
   3    Copyright (C) 2011-2022 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 #ifndef MINSYMS_H
  21 #define MINSYMS_H
  22
  23 struct type;
  24
  25 /* Several lookup functions return both a minimal symbol and the
  26    objfile in which it is found.  This structure is used in these
  27    cases.  */
  28
  29 struct bound_minimal_symbol
  30 {
  31   bound_minimal_symbol (struct minimal_symbol *msym, struct objfile *objf)
  32     : minsym (msym),
  33       objfile (objf)
  34   {
  35   }
  36
  37   bound_minimal_symbol () = default;
  38
  39   /* The minimal symbol that was found, or NULL if no minimal symbol
  40      was found.  */
  41
  42   struct minimal_symbol *minsym = nullptr;
  43
  44   /* If MINSYM is not NULL, then this is the objfile in which the
  45      symbol is defined.  */
  46
  47   struct objfile *objfile = nullptr;
  48
  49   /* Return the obj_section from OBJFILE for MINSYM.  */
  50
  51   struct obj_section *obj_section () const
  52   {
  53     return minsym->obj_section (objfile);
  54   }
  55 };
  56
  57 /* This header declares most of the API for dealing with minimal
  58    symbols and minimal symbol tables.  A few things are declared
  59    elsewhere; see below.
  60
  61    A minimal symbol is a symbol for which there is no direct debug
  62    information.  For example, for an ELF binary, minimal symbols are
  63    created from the ELF symbol table.
  64
  65    For the definition of the minimal symbol structure, see struct
  66    minimal_symbol in symtab.h.
  67
  68    Minimal symbols are stored in tables attached to an objfile; see
  69    objfiles.h for details.  Code should generally treat these tables
  70    as opaque and use functions provided by minsyms.c to inspect them.
  71 */
  72
  73 struct msym_bunch;
  74
  75 /* An RAII-based object that is used to record minimal symbols while
  76    they are being read.  */
  77 class minimal_symbol_reader
  78 {
  79  public:
  80
  81   /* Prepare to start collecting minimal symbols.  This should be
  82      called by a symbol reader to initialize the minimal symbol
  83      module.  */
  84
  85   explicit minimal_symbol_reader (struct objfile *);
  86
  87   ~minimal_symbol_reader ();
  88
  89   /* Install the minimal symbols that have been collected into the
  90      given objfile.  */
  91
  92   void install ();
  93
  94   /* Record a new minimal symbol.  This is the "full" entry point;
  95      simpler convenience entry points are also provided below.
  96
  97      This returns a new minimal symbol.  It is ok to modify the returned
  98      minimal symbol (though generally not necessary).  It is not ok,
  99      though, to stash the pointer anywhere; as minimal symbols may be
 100      moved after creation.  The memory for the returned minimal symbol
 101      is still owned by the minsyms.c code, and should not be freed.
 102
 103      Arguments are:
 104
 105      NAME - the symbol's name
 106      COPY_NAME - if true, the minsym code must make a copy of NAME.  If
 107      false, then NAME must be NUL-terminated, and must have a lifetime
 108      that is at least as long as OBJFILE's lifetime.
 109      ADDRESS - the address of the symbol
 110      MS_TYPE - the type of the symbol
 111      SECTION - the symbol's section
 112   */
 113
 114   struct minimal_symbol *record_full (gdb::string_view name,
 115                                       bool copy_name,
 116                                       CORE_ADDR address,
 117                                       enum minimal_symbol_type ms_type,
 118                                       int section);
 119
 120   /* Like record_full, but:
 121      - computes the length of NAME
 122      - passes COPY_NAME = true,
 123      - and passes a default SECTION, depending on the type
 124
 125      This variant does not return the new symbol.  */
 126
 127   void record (const char *name, CORE_ADDR address,
 128                enum minimal_symbol_type ms_type);
 129
 130   /* Like record_full, but:
 131      - computes the length of NAME
 132      - passes COPY_NAME = true.
 133
 134      This variant does not return the new symbol.  */
 135
 136   void record_with_info (const char *name, CORE_ADDR address,
 137                          enum minimal_symbol_type ms_type,
 138                          int section)
 139   {
 140     record_full (name, true, address, ms_type, section);
 141   }
 142
 143  private:
 144
 145   DISABLE_COPY_AND_ASSIGN (minimal_symbol_reader);
 146
 147   struct objfile *m_objfile;
 148
 149   /* Bunch currently being filled up.
 150      The next field points to chain of filled bunches.  */
 151
 152   struct msym_bunch *m_msym_bunch;
 153
 154   /* Number of slots filled in current bunch.  */
 155
 156   int m_msym_bunch_index;
 157
 158   /* Total number of minimal symbols recorded so far for the
 159      objfile.  */
 160
 161   int m_msym_count;
 162 };
 163
 164 \f
 165
 166 /* Return whether MSYMBOL is a function/method.  If FUNC_ADDRESS_P is
 167    non-NULL, and the MSYMBOL is a function, then *FUNC_ADDRESS_P is
 168    set to the function's address, already resolved if MINSYM points to
 169    a function descriptor.  */
 170
 171 bool msymbol_is_function (struct objfile *objfile,
 172                           minimal_symbol *minsym,
 173                           CORE_ADDR *func_address_p = NULL);
 174
 175 /* Compute a hash code for the string argument.  Unlike htab_hash_string,
 176    this is a case-insensitive hash to support "set case-sensitive off".  */
 177
 178 unsigned int msymbol_hash (const char *);
 179
 180 /* Like msymbol_hash, but compute a hash code that is compatible with
 181    strcmp_iw.  */
 182
 183 unsigned int msymbol_hash_iw (const char *);
 184
 185 /* Compute the next hash value from previous HASH and the character C.  This
 186    is only a GDB in-memory computed value with no external files compatibility
 187    requirements.  */
 188
 189 #define SYMBOL_HASH_NEXT(hash, c)                       \
 190   ((hash) * 67 + TOLOWER ((unsigned char) (c)) - 113)
 191
 192 \f
 193
 194 /* Look through all the current minimal symbol tables and find the
 195    first minimal symbol that matches NAME.  If OBJF is non-NULL, limit
 196    the search to that objfile.  If SFILE is non-NULL, the only
 197    file-scope symbols considered will be from that source file (global
 198    symbols are still preferred).  Returns a bound minimal symbol that
 199    matches, or an empty bound minimal symbol if no match is found.  */
 200
 201 struct bound_minimal_symbol lookup_minimal_symbol (const char *,
 202                                                    const char *,
 203                                                    struct objfile *);
 204
 205 /* Like lookup_minimal_symbol, but searches all files and
 206    objfiles.  */
 207
 208 struct bound_minimal_symbol lookup_bound_minimal_symbol (const char *);
 209
 210 /* Look through all the current minimal symbol tables and find the
 211    first minimal symbol that matches NAME and has text type.  If OBJF
 212    is non-NULL, limit the search to that objfile.  Returns a bound
 213    minimal symbol that matches, or an "empty" bound minimal symbol
 214    otherwise.
 215
 216    This function only searches the mangled (linkage) names.  */
 217
 218 struct bound_minimal_symbol lookup_minimal_symbol_text (const char *,
 219                                                         struct objfile *);
 220
 221 /* Look through the minimal symbols in OBJF (and its separate debug
 222    objfiles) for a global (not file-local) minsym whose linkage name
 223    is NAME.  This is somewhat similar to lookup_minimal_symbol_text,
 224    only data symbols (not text symbols) are considered, and a non-NULL
 225    objfile is not accepted.  Returns a bound minimal symbol that
 226    matches, or an "empty" bound minimal symbol otherwise.  */
 227
 228 extern struct bound_minimal_symbol lookup_minimal_symbol_linkage
 229   (const char *name, struct objfile *objf)
 230   ATTRIBUTE_NONNULL (1) ATTRIBUTE_NONNULL (2);
 231
 232 /* Look through all the current minimal symbol tables and find the
 233    first minimal symbol that matches NAME and PC.  If OBJF is non-NULL,
 234    limit the search to that objfile.  Returns a pointer to the minimal
 235    symbol that matches, or NULL if no match is found.  */
 236
 237 struct minimal_symbol *lookup_minimal_symbol_by_pc_name
 238     (CORE_ADDR, const char *, struct objfile *);
 239
 240 enum class lookup_msym_prefer
 241 {
 242   /* Prefer mst_text symbols.  */
 243   TEXT,
 244
 245   /* Prefer mst_solib_trampoline symbols when there are text and
 246      trampoline symbols at the same address.  Otherwise prefer
 247      mst_text symbols.  */
 248   TRAMPOLINE,
 249
 250   /* Prefer mst_text_gnu_ifunc symbols when there are text and ifunc
 251      symbols at the same address.  Otherwise prefer mst_text
 252      symbols.  */
 253   GNU_IFUNC,
 254 };
 255
 256 /* Search through the minimal symbol table for each objfile and find
 257    the symbol whose address is the largest address that is still less
 258    than or equal to PC_IN, and which matches SECTION.  A matching symbol
 259    must either be zero sized and have address PC_IN, or PC_IN must fall
 260    within the range of addresses covered by the matching symbol.
 261
 262    If SECTION is NULL, this uses the result of find_pc_section
 263    instead.
 264
 265    The result has a non-NULL 'minsym' member if such a symbol is
 266    found, or NULL if PC is not in a suitable range.
 267
 268    See definition of lookup_msym_prefer for description of PREFER.  By
 269    default mst_text symbols are preferred.
 270
 271    If the PREVIOUS pointer is non-NULL, and no matching symbol is found,
 272    then the contents will be set to reference the closest symbol before
 273    PC_IN.  */
 274
 275 struct bound_minimal_symbol lookup_minimal_symbol_by_pc_section
 276   (CORE_ADDR pc_in,
 277    struct obj_section *section,
 278    lookup_msym_prefer prefer = lookup_msym_prefer::TEXT,
 279    bound_minimal_symbol *previous = nullptr);
 280
 281 /* Backward compatibility: search through the minimal symbol table
 282    for a matching PC (no section given).
 283
 284    This is a wrapper that calls lookup_minimal_symbol_by_pc_section
 285    with a NULL section argument.  */
 286
 287 struct bound_minimal_symbol lookup_minimal_symbol_by_pc (CORE_ADDR);
 288
 289 /* Iterate over all the minimal symbols in the objfile OBJF which
 290    match NAME.  Both the ordinary and demangled names of each symbol
 291    are considered.  The caller is responsible for canonicalizing NAME,
 292    should that need to be done.
 293
 294    For each matching symbol, CALLBACK is called with the symbol.  */
 295
 296 void iterate_over_minimal_symbols
 297     (struct objfile *objf, const lookup_name_info &name,
 298      gdb::function_view<bool (struct minimal_symbol *)> callback);
 299
 300 /* Compute the upper bound of MINSYM.  The upper bound is the last
 301    address thought to be part of the symbol.  If the symbol has a
 302    size, it is used.  Otherwise use the lesser of the next minimal
 303    symbol in the same section, or the end of the section, as the end
 304    of the function.  */
 305
 306 CORE_ADDR minimal_symbol_upper_bound (struct bound_minimal_symbol minsym);
 307
 308 /* Return the type of MSYMBOL, a minimal symbol of OBJFILE.  If
 309    ADDRESS_P is not NULL, set it to the MSYMBOL's resolved
 310    address.  */
 311
 312 type *find_minsym_type_and_address (minimal_symbol *msymbol, objfile *objf,
 313                                     CORE_ADDR *address_p);
 314
 315 #endif /* MINSYMS_H */