gdb/user-regs.c

   1 /* User visible, per-frame registers, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2002-2023 Free Software Foundation, Inc.
   4
   5    Contributed by Red Hat.
   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 #include "defs.h"
  23 #include "user-regs.h"
  24 #include "gdbtypes.h"
  25 #include "frame.h"
  26 #include "arch-utils.h"
  27 #include "command.h"
  28 #include "cli/cli-cmds.h"
  29
  30 /* A table of user registers.
  31
  32    User registers have regnum's that live above of the range [0
  33    .. gdbarch_num_regs + gdbarch_num_pseudo_regs)
  34    (which is controlled by the target).
  35    The target should never see a user register's regnum value.
  36
  37    Always append, never delete.  By doing this, the relative regnum
  38    (offset from gdbarch_num_regs + gdbarch_num_pseudo_regs)
  39     assigned to each user  register never changes.  */
  40
  41 struct user_reg
  42 {
  43   const char *name;
  44   /* Avoid the "read" symbol name as it conflicts with a preprocessor symbol
  45      in the NetBSD header for Stack Smashing Protection, that wraps the read(2)
  46      syscall.  */
  47   struct value *(*xread) (frame_info_ptr frame, const void *baton);
  48   const void *baton;
  49   struct user_reg *next;
  50 };
  51
  52 /* This structure is named gdb_user_regs instead of user_regs to avoid
  53    conflicts with any "struct user_regs" in system headers.  For instance,
  54    on ARM GNU/Linux native builds, nm-linux.h includes <signal.h> includes
  55    <sys/ucontext.h> includes <sys/procfs.h> includes <sys/user.h>, which
  56    declares "struct user_regs".  */
  57
  58 struct gdb_user_regs
  59 {
  60   struct user_reg *first = nullptr;
  61   struct user_reg **last = nullptr;
  62 };
  63
  64 static void
  65 append_user_reg (struct gdb_user_regs *regs, const char *name,
  66                  user_reg_read_ftype *xread, const void *baton,
  67                  struct user_reg *reg)
  68 {
  69   /* The caller is responsible for allocating memory needed to store
  70      the register.  By doing this, the function can operate on a
  71      register list stored in the common heap or a specific obstack.  */
  72   gdb_assert (reg != NULL);
  73   reg->name = name;
  74   reg->xread = xread;
  75   reg->baton = baton;
  76   reg->next = NULL;
  77   if (regs->last == nullptr)
  78     regs->last = &regs->first;
  79   (*regs->last) = reg;
  80   regs->last = &(*regs->last)->next;
  81 }
  82
  83 /* An array of the builtin user registers.  */
  84
  85 static struct gdb_user_regs builtin_user_regs;
  86
  87 void
  88 user_reg_add_builtin (const char *name, user_reg_read_ftype *xread,
  89                       const void *baton)
  90 {
  91   append_user_reg (&builtin_user_regs, name, xread, baton,
  92                    XNEW (struct user_reg));
  93 }
  94
  95 /* Per-architecture user registers.  Start with the builtin user
  96    registers and then, again, append.  */
  97
  98 static const registry<gdbarch>::key<gdb_user_regs> user_regs_data;
  99
 100 static gdb_user_regs *
 101 get_user_regs (struct gdbarch *gdbarch)
 102 {
 103   struct gdb_user_regs *regs = user_regs_data.get (gdbarch);
 104   if (regs == nullptr)
 105     {
 106       regs = new struct gdb_user_regs;
 107
 108       struct obstack *obstack = gdbarch_obstack (gdbarch);
 109       regs->last = &regs->first;
 110       for (user_reg *reg = builtin_user_regs.first;
 111            reg != NULL;
 112            reg = reg->next)
 113         append_user_reg (regs, reg->name, reg->xread, reg->baton,
 114                          OBSTACK_ZALLOC (obstack, struct user_reg));
 115       user_regs_data.set (gdbarch, regs);
 116     }
 117
 118   return regs;
 119 }
 120
 121 void
 122 user_reg_add (struct gdbarch *gdbarch, const char *name,
 123               user_reg_read_ftype *xread, const void *baton)
 124 {
 125   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 126   gdb_assert (regs != NULL);
 127   append_user_reg (regs, name, xread, baton,
 128                    GDBARCH_OBSTACK_ZALLOC (gdbarch, struct user_reg));
 129 }
 130
 131 int
 132 user_reg_map_name_to_regnum (struct gdbarch *gdbarch, const char *name,
 133                              int len)
 134 {
 135   /* Make life easy, set the len to something reasonable.  */
 136   if (len < 0)
 137     len = strlen (name);
 138
 139   /* Search register name space first - always let an architecture
 140      specific register override the user registers.  */
 141   {
 142     int maxregs = gdbarch_num_cooked_regs (gdbarch);
 143
 144     for (int i = 0; i < maxregs; i++)
 145       {
 146         const char *regname = gdbarch_register_name (gdbarch, i);
 147
 148         if (len == strlen (regname) && strncmp (regname, name, len) == 0)
 149           return i;
 150       }
 151   }
 152
 153   /* Search the user name space.  */
 154   {
 155     struct gdb_user_regs *regs = get_user_regs (gdbarch);
 156     struct user_reg *reg;
 157     int nr;
 158
 159     for (nr = 0, reg = regs->first; reg != NULL; reg = reg->next, nr++)
 160       {
 161         if ((len < 0 && strcmp (reg->name, name))
 162             || (len == strlen (reg->name)
 163                 && strncmp (reg->name, name, len) == 0))
 164           return gdbarch_num_cooked_regs (gdbarch) + nr;
 165       }
 166   }
 167
 168   return -1;
 169 }
 170
 171 static struct user_reg *
 172 usernum_to_user_reg (struct gdbarch *gdbarch, int usernum)
 173 {
 174   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 175   struct user_reg *reg;
 176
 177   for (reg = regs->first; reg != NULL; reg = reg->next)
 178     {
 179       if (usernum == 0)
 180         return reg;
 181       usernum--;
 182     }
 183   return NULL;
 184 }
 185
 186 const char *
 187 user_reg_map_regnum_to_name (struct gdbarch *gdbarch, int regnum)
 188 {
 189   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 190
 191   if (regnum < 0)
 192     return NULL;
 193   else if (regnum < maxregs)
 194     return gdbarch_register_name (gdbarch, regnum);
 195   else
 196     {
 197       struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 198       if (reg == NULL)
 199         return NULL;
 200       else
 201         return reg->name;
 202     }
 203 }
 204
 205 struct value *
 206 value_of_user_reg (int regnum, frame_info_ptr frame)
 207 {
 208   struct gdbarch *gdbarch = get_frame_arch (frame);
 209   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 210   struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 211
 212   gdb_assert (reg != NULL);
 213   return reg->xread (frame, reg->baton);
 214 }
 215
 216 static void
 217 maintenance_print_user_registers (const char *args, int from_tty)
 218 {
 219   struct gdbarch *gdbarch = get_current_arch ();
 220   struct user_reg *reg;
 221   int regnum;
 222
 223   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 224   regnum = gdbarch_num_cooked_regs (gdbarch);
 225
 226   gdb_printf (" %-11s %3s\n", "Name", "Nr");
 227   for (reg = regs->first; reg != NULL; reg = reg->next, ++regnum)
 228     gdb_printf (" %-11s %3d\n", reg->name, regnum);
 229 }
 230
 231 void _initialize_user_regs ();
 232 void
 233 _initialize_user_regs ()
 234 {
 235   add_cmd ("user-registers", class_maintenance,
 236            maintenance_print_user_registers,
 237            _("List the names of the current user registers."),
 238            &maintenanceprintlist);
 239 }