gdb/user-regs.c

   1 /* User visible, per-frame registers, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2002-2024 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 "user-regs.h"
  23 #include "gdbtypes.h"
  24 #include "frame.h"
  25 #include "arch-utils.h"
  26 #include "command.h"
  27 #include "cli/cli-cmds.h"
  28
  29 /* A table of user registers.
  30
  31    User registers have regnum's that live above of the range [0
  32    .. gdbarch_num_regs + gdbarch_num_pseudo_regs)
  33    (which is controlled by the target).
  34    The target should never see a user register's regnum value.
  35
  36    Always append, never delete.  By doing this, the relative regnum
  37    (offset from gdbarch_num_regs + gdbarch_num_pseudo_regs)
  38     assigned to each user  register never changes.  */
  39
  40 struct user_reg
  41 {
  42   const char *name;
  43   /* Avoid the "read" symbol name as it conflicts with a preprocessor symbol
  44      in the NetBSD header for Stack Smashing Protection, that wraps the read(2)
  45      syscall.  */
  46   struct value *(*xread) (const frame_info_ptr &frame, const void *baton);
  47   const void *baton;
  48   struct user_reg *next;
  49 };
  50
  51 /* This structure is named gdb_user_regs instead of user_regs to avoid
  52    conflicts with any "struct user_regs" in system headers.  For instance,
  53    on ARM GNU/Linux native builds, nm-linux.h includes <signal.h> includes
  54    <sys/ucontext.h> includes <sys/procfs.h> includes <sys/user.h>, which
  55    declares "struct user_regs".  */
  56
  57 struct gdb_user_regs
  58 {
  59   struct user_reg *first = nullptr;
  60   struct user_reg **last = nullptr;
  61 };
  62
  63 static void
  64 append_user_reg (struct gdb_user_regs *regs, const char *name,
  65                  user_reg_read_ftype *xread, const void *baton,
  66                  struct user_reg *reg)
  67 {
  68   /* The caller is responsible for allocating memory needed to store
  69      the register.  By doing this, the function can operate on a
  70      register list stored in the common heap or a specific obstack.  */
  71   gdb_assert (reg != NULL);
  72   reg->name = name;
  73   reg->xread = xread;
  74   reg->baton = baton;
  75   reg->next = NULL;
  76   if (regs->last == nullptr)
  77     regs->last = &regs->first;
  78   (*regs->last) = reg;
  79   regs->last = &(*regs->last)->next;
  80 }
  81
  82 /* An array of the builtin user registers.  */
  83
  84 static struct gdb_user_regs builtin_user_regs;
  85
  86 void
  87 user_reg_add_builtin (const char *name, user_reg_read_ftype *xread,
  88                       const void *baton)
  89 {
  90   append_user_reg (&builtin_user_regs, name, xread, baton,
  91                    XNEW (struct user_reg));
  92 }
  93
  94 /* Per-architecture user registers.  Start with the builtin user
  95    registers and then, again, append.  */
  96
  97 static const registry<gdbarch>::key<gdb_user_regs> user_regs_data;
  98
  99 static gdb_user_regs *
 100 get_user_regs (struct gdbarch *gdbarch)
 101 {
 102   struct gdb_user_regs *regs = user_regs_data.get (gdbarch);
 103   if (regs == nullptr)
 104     {
 105       regs = new struct gdb_user_regs;
 106
 107       struct obstack *obstack = gdbarch_obstack (gdbarch);
 108       regs->last = &regs->first;
 109       for (user_reg *reg = builtin_user_regs.first;
 110            reg != NULL;
 111            reg = reg->next)
 112         append_user_reg (regs, reg->name, reg->xread, reg->baton,
 113                          OBSTACK_ZALLOC (obstack, struct user_reg));
 114       user_regs_data.set (gdbarch, regs);
 115     }
 116
 117   return regs;
 118 }
 119
 120 void
 121 user_reg_add (struct gdbarch *gdbarch, const char *name,
 122               user_reg_read_ftype *xread, const void *baton)
 123 {
 124   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 125   gdb_assert (regs != NULL);
 126   append_user_reg (regs, name, xread, baton,
 127                    GDBARCH_OBSTACK_ZALLOC (gdbarch, struct user_reg));
 128 }
 129
 130 int
 131 user_reg_map_name_to_regnum (struct gdbarch *gdbarch, const char *name,
 132                              int len)
 133 {
 134   /* Make life easy, set the len to something reasonable.  */
 135   if (len < 0)
 136     len = strlen (name);
 137
 138   /* Search register name space first - always let an architecture
 139      specific register override the user registers.  */
 140   {
 141     int maxregs = gdbarch_num_cooked_regs (gdbarch);
 142
 143     for (int i = 0; i < maxregs; i++)
 144       {
 145         const char *regname = gdbarch_register_name (gdbarch, i);
 146
 147         if (len == strlen (regname) && strncmp (regname, name, len) == 0)
 148           return i;
 149       }
 150   }
 151
 152   /* Search the user name space.  */
 153   {
 154     struct gdb_user_regs *regs = get_user_regs (gdbarch);
 155     struct user_reg *reg;
 156     int nr;
 157
 158     for (nr = 0, reg = regs->first; reg != NULL; reg = reg->next, nr++)
 159       {
 160         if ((len < 0 && strcmp (reg->name, name))
 161             || (len == strlen (reg->name)
 162                 && strncmp (reg->name, name, len) == 0))
 163           return gdbarch_num_cooked_regs (gdbarch) + nr;
 164       }
 165   }
 166
 167   return -1;
 168 }
 169
 170 static struct user_reg *
 171 usernum_to_user_reg (struct gdbarch *gdbarch, int usernum)
 172 {
 173   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 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, const frame_info_ptr &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 user_reg *reg;
 220   int regnum;
 221
 222   struct gdb_user_regs *regs = get_user_regs (gdbarch);
 223   regnum = gdbarch_num_cooked_regs (gdbarch);
 224
 225   gdb_printf (" %-11s %3s\n", "Name", "Nr");
 226   for (reg = regs->first; reg != NULL; reg = reg->next, ++regnum)
 227     gdb_printf (" %-11s %3d\n", reg->name, regnum);
 228 }
 229
 230 void _initialize_user_regs ();
 231 void
 232 _initialize_user_regs ()
 233 {
 234   add_cmd ("user-registers", class_maintenance,
 235            maintenance_print_user_registers,
 236            _("List the names of the current user registers."),
 237            &maintenanceprintlist);
 238 }