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   /* 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) (struct frame_info * 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;
  61   struct user_reg **last;
  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   (*regs->last) = reg;
  78   regs->last = &(*regs->last)->next;
  79 }
  80
  81 /* An array of the builtin user registers.  */
  82
  83 static struct gdb_user_regs builtin_user_regs = {
  84   NULL, &builtin_user_regs.first
  85 };
  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 struct gdbarch_data *user_regs_data;
  99
 100 static void *
 101 user_regs_init (struct obstack *obstack)
 102 {
 103   struct user_reg *reg;
 104   struct gdb_user_regs *regs = OBSTACK_ZALLOC (obstack, struct gdb_user_regs);
 105
 106   regs->last = &regs->first;
 107   for (reg = builtin_user_regs.first; reg != NULL; reg = reg->next)
 108     append_user_reg (regs, reg->name, reg->xread, reg->baton,
 109                      OBSTACK_ZALLOC (obstack, struct user_reg));
 110   return regs;
 111 }
 112
 113 void
 114 user_reg_add (struct gdbarch *gdbarch, const char *name,
 115               user_reg_read_ftype *xread, const void *baton)
 116 {
 117   struct gdb_user_regs *regs
 118     = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 119   gdb_assert (regs != NULL);
 120   append_user_reg (regs, name, xread, baton,
 121                    GDBARCH_OBSTACK_ZALLOC (gdbarch, struct user_reg));
 122 }
 123
 124 int
 125 user_reg_map_name_to_regnum (struct gdbarch *gdbarch, const char *name,
 126                              int len)
 127 {
 128   /* Make life easy, set the len to something reasonable.  */
 129   if (len < 0)
 130     len = strlen (name);
 131
 132   /* Search register name space first - always let an architecture
 133      specific register override the user registers.  */
 134   {
 135     int i;
 136     int maxregs = gdbarch_num_cooked_regs (gdbarch);
 137
 138     for (i = 0; i < maxregs; i++)
 139       {
 140         const char *regname = gdbarch_register_name (gdbarch, i);
 141
 142         if (regname != NULL && len == strlen (regname)
 143             && strncmp (regname, name, len) == 0)
 144           {
 145             return i;
 146           }
 147       }
 148   }
 149
 150   /* Search the user name space.  */
 151   {
 152     struct gdb_user_regs *regs
 153       = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 154     struct user_reg *reg;
 155     int nr;
 156
 157     for (nr = 0, reg = regs->first; reg != NULL; reg = reg->next, nr++)
 158       {
 159         if ((len < 0 && strcmp (reg->name, name))
 160             || (len == strlen (reg->name)
 161                 && strncmp (reg->name, name, len) == 0))
 162           return gdbarch_num_cooked_regs (gdbarch) + nr;
 163       }
 164   }
 165
 166   return -1;
 167 }
 168
 169 static struct user_reg *
 170 usernum_to_user_reg (struct gdbarch *gdbarch, int usernum)
 171 {
 172   struct gdb_user_regs *regs
 173     = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 174   struct user_reg *reg;
 175
 176   for (reg = regs->first; reg != NULL; reg = reg->next)
 177     {
 178       if (usernum == 0)
 179         return reg;
 180       usernum--;
 181     }
 182   return NULL;
 183 }
 184
 185 const char *
 186 user_reg_map_regnum_to_name (struct gdbarch *gdbarch, int regnum)
 187 {
 188   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 189
 190   if (regnum < 0)
 191     return NULL;
 192   else if (regnum < maxregs)
 193     return gdbarch_register_name (gdbarch, regnum);
 194   else
 195     {
 196       struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 197       if (reg == NULL)
 198         return NULL;
 199       else
 200         return reg->name;
 201     }
 202 }
 203
 204 struct value *
 205 value_of_user_reg (int regnum, struct frame_info *frame)
 206 {
 207   struct gdbarch *gdbarch = get_frame_arch (frame);
 208   int maxregs = gdbarch_num_cooked_regs (gdbarch);
 209   struct user_reg *reg = usernum_to_user_reg (gdbarch, regnum - maxregs);
 210
 211   gdb_assert (reg != NULL);
 212   return reg->xread (frame, reg->baton);
 213 }
 214
 215 static void
 216 maintenance_print_user_registers (const char *args, int from_tty)
 217 {
 218   struct gdbarch *gdbarch = get_current_arch ();
 219   struct gdb_user_regs *regs;
 220   struct user_reg *reg;
 221   int regnum;
 222
 223   regs = (struct gdb_user_regs *) gdbarch_data (gdbarch, user_regs_data);
 224   regnum = gdbarch_num_cooked_regs (gdbarch);
 225
 226   fprintf_unfiltered (gdb_stdout, " %-11s %3s\n", "Name", "Nr");
 227   for (reg = regs->first; reg != NULL; reg = reg->next, ++regnum)
 228     fprintf_unfiltered (gdb_stdout, " %-11s %3d\n", reg->name, regnum);
 229 }
 230
 231 void _initialize_user_regs ();
 232 void
 233 _initialize_user_regs ()
 234 {
 235   user_regs_data = gdbarch_data_register_pre_init (user_regs_init);
 236
 237   add_cmd ("user-registers", class_maintenance,
 238            maintenance_print_user_registers,
 239            _("List the names of the current user registers."),
 240            &maintenanceprintlist);
 241 }