gdb/user-regs.c

   1 /* User visible, per-frame registers, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2002-2020 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   struct value *(*read) (struct frame_info * frame, const void *baton);
  45   const void *baton;
  46   struct user_reg *next;
  47 };
  48
  49 /* This structure is named gdb_user_regs instead of user_regs to avoid
  50    conflicts with any "struct user_regs" in system headers.  For instance,
  51    on ARM GNU/Linux native builds, nm-linux.h includes <signal.h> includes
  52    <sys/ucontext.h> includes <sys/procfs.h> includes <sys/user.h>, which
  53    declares "struct user_regs".  */
  54
  55 struct gdb_user_regs
  56 {
  57   struct user_reg *first;
  58   struct user_reg **last;
  59 };
  60
  61 static void
  62 append_user_reg (struct gdb_user_regs *regs, const char *name,
  63                  user_reg_read_ftype *read, const void *baton,
  64                  struct user_reg *reg)
  65 {
  66   /* The caller is responsible for allocating memory needed to store
  67      the register.  By doing this, the function can operate on a
  68      register list stored in the common heap or a specific obstack.  */
  69   gdb_assert (reg != NULL);
  70   reg->name = name;
  71   reg->read = read;
  72   reg->baton = baton;
  73   reg->next = NULL;
  74   (*regs->last) = reg;
  75   regs->last = &(*regs->last)->next;
  76 }
  77
  78 /* An array of the builtin user registers.  */
  79
  80 static struct gdb_user_regs builtin_user_regs = {
  81   NULL, &builtin_user_regs.first
  82 };
  83
  84 void
  85 user_reg_add_builtin (const char *name, user_reg_read_ftype *read,
  86                       const void *baton)
  87 {
  88   append_user_reg (&builtin_user_regs, name, read, baton,
  89                    XNEW (struct user_reg));
  90 }
  91
  92 /* Per-architecture user registers.  Start with the builtin user
  93    registers and then, again, append.  */
  94
  95 static struct gdbarch_data *user_regs_data;
  96
  97 static void *
  98 user_regs_init (struct gdbarch *gdbarch)
  99 {
 100   struct user_reg *reg;
 101   struct gdb_user_regs *regs
 102     = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct gdb_user_regs);
 103
 104   regs->last = &regs->first;
 105   for (reg = builtin_user_regs.first; reg != NULL; reg = reg->next)
 106     append_user_reg (regs, reg->name, reg->read, reg->baton,
 107                      GDBARCH_OBSTACK_ZALLOC (gdbarch, struct user_reg));
 108   return regs;
 109 }
 110
 111 void
 112 user_reg_add (struct gdbarch *gdbarch, const char *name,
 113               user_reg_read_ftype *read, const void *baton)
 114 {
 115   struct gdb_user_regs *regs
 116     = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 117
 118   if (regs == NULL)
 119     {
 120       /* ULGH, called during architecture initialization.  Patch
 121          things up.  */
 122       regs = (struct gdb_user_regs *) user_regs_init (gdbarch);
 123       deprecated_set_gdbarch_data (gdbarch, user_regs_data, regs);
 124     }
 125   append_user_reg (regs, name, read, baton,
 126                    GDBARCH_OBSTACK_ZALLOC (gdbarch, struct user_reg));
 127 }
 128
 129 int
 130 user_reg_map_name_to_regnum (struct gdbarch *gdbarch, const char *name,
 131                              int len)
 132 {
 133   /* Make life easy, set the len to something reasonable.  */
 134   if (len < 0)
 135     len = strlen (name);
 136
 137   /* Search register name space first - always let an architecture
 138      specific register override the user registers.  */
 139   {
 140     int i;
 141     int maxregs = gdbarch_num_cooked_regs (gdbarch);
 142
 143     for (i = 0; i < maxregs; i++)
 144       {
 145         const char *regname = gdbarch_register_name (gdbarch, i);
 146
 147         if (regname != NULL && len == strlen (regname)
 148             && strncmp (regname, name, len) == 0)
 149           {
 150             return i;
 151           }
 152       }
 153   }
 154
 155   /* Search the user name space.  */
 156   {
 157     struct gdb_user_regs *regs
 158       = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 159     struct user_reg *reg;
 160     int nr;
 161
 162     for (nr = 0, reg = regs->first; reg != NULL; reg = reg->next, nr++)
 163       {
 164         if ((len < 0 && strcmp (reg->name, name))
 165             || (len == strlen (reg->name)
 166                 && strncmp (reg->name, name, len) == 0))
 167           return gdbarch_num_cooked_regs (gdbarch) + nr;
 168       }
 169   }
 170
 171   return -1;
 172 }
 173
 174 static struct user_reg *
 175 usernum_to_user_reg (struct gdbarch *gdbarch, int usernum)
 176 {
 177   struct gdb_user_regs *regs
 178     = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 179   struct user_reg *reg;
 180
 181   for (reg = regs->first; reg != NULL; reg = reg->next)
 182     {
 183       if (usernum == 0)
 184         return reg;
 185       usernum--;
 186     }
 187   return NULL;
 188 }
 189
 190 const char *
 191 user_reg_map_regnum_to_name (struct gdbarch *gdbarch, int regnum)
 192 {
 193   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 194
 195   if (regnum < 0)
 196     return NULL;
 197   else if (regnum < maxregs)
 198     return gdbarch_register_name (gdbarch, regnum);
 199   else
 200     {
 201       struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 202       if (reg == NULL)
 203         return NULL;
 204       else
 205         return reg->name;
 206     }
 207 }
 208
 209 struct value *
 210 value_of_user_reg (int regnum, struct frame_info *frame)
 211 {
 212   struct gdbarch *gdbarch = get_frame_arch (frame);
 213   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 214   struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 215
 216   gdb_assert (reg != NULL);
 217   return reg->read (frame, reg->baton);
 218 }
 219
 220 static void
 221 maintenance_print_user_registers (const char *args, int from_tty)
 222 {
 223   struct gdbarch *gdbarch = get_current_arch ();
 224   struct gdb_user_regs *regs;
 225   struct user_reg *reg;
 226   int regnum;
 227
 228   regs = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 229   regnum = gdbarch_num_cooked_regs (gdbarch);
 230
 231   fprintf_unfiltered (gdb_stdout, " %-11s %3s\n", "Name", "Nr");
 232   for (reg = regs->first; reg != NULL; reg = reg->next, ++regnum)
 233     fprintf_unfiltered (gdb_stdout, " %-11s %3d\n", reg->name, regnum);
 234 }
 235
 236 void
 237 _initialize_user_regs (void)
 238 {
 239   user_regs_data = gdbarch_data_register_post_init (user_regs_init);
 240
 241   add_cmd ("user-registers", class_maintenance,
 242            maintenance_print_user_registers,
 243            _("List the names of the current user registers."),
 244            &maintenanceprintlist);
 245 }