gdb/i386nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/i386.
   2
   3    Copyright 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "arch-utils.h"
  25 #include "gdbcore.h"
  26 #include "regcache.h"
  27 #include "regset.h"
  28 #include "osabi.h"
  29
  30 #include "gdb_assert.h"
  31 #include "gdb_string.h"
  32
  33 #include "i386-tdep.h"
  34 #include "i387-tdep.h"
  35 #include "nbsd-tdep.h"
  36
  37 #include "solib-svr4.h"
  38
  39 /* From <machine/reg.h>.  */
  40 static int i386nbsd_r_reg_offset[] =
  41 {
  42   0 * 4,                        /* %eax */
  43   1 * 4,                        /* %ecx */
  44   2 * 4,                        /* %edx */
  45   3 * 4,                        /* %ebx */
  46   4 * 4,                        /* %esp */
  47   5 * 4,                        /* %ebp */
  48   6 * 4,                        /* %esi */
  49   7 * 4,                        /* %edi */
  50   8 * 4,                        /* %eip */
  51   9 * 4,                        /* %eflags */
  52   10 * 4,                       /* %cs */
  53   11 * 4,                       /* %ss */
  54   12 * 4,                       /* %ds */
  55   13 * 4,                       /* %es */
  56   14 * 4,                       /* %fs */
  57   15 * 4                        /* %gs */
  58 };
  59
  60 static void
  61 i386nbsd_aout_supply_regset (const struct regset *regset,
  62                              struct regcache *regcache, int regnum,
  63                              const void *regs, size_t len)
  64 {
  65   const struct gdbarch_tdep *tdep = regset->descr;
  66
  67   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
  68
  69   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  70   i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
  71 }
  72
  73 static const struct regset *
  74 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
  75                                         const char *sect_name,
  76                                         size_t sect_size)
  77 {
  78   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  79
  80   /* NetBSD a.out core dumps don't use seperate register sets for the
  81      general-purpose and floating-point registers.  */
  82
  83   if (strcmp (sect_name, ".reg") == 0
  84       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
  85     {
  86       if (tdep->gregset == NULL)
  87         {
  88           tdep->gregset = XMALLOC (struct regset);
  89           tdep->gregset->descr = tdep;
  90           tdep->gregset->supply_regset = i386nbsd_aout_supply_regset;
  91         }
  92       return tdep->gregset;
  93     }
  94
  95   return NULL;
  96 }
  97
  98 /* Under NetBSD/i386, signal handler invocations can be identified by the
  99    designated code sequence that is used to return from a signal handler.
 100    In particular, the return address of a signal handler points to the
 101    following code sequence:
 102
 103         leal    0x10(%esp), %eax
 104         pushl   %eax
 105         pushl   %eax
 106         movl    $0x127, %eax            # __sigreturn14
 107         int     $0x80
 108
 109    Each instruction has a unique encoding, so we simply attempt to match
 110    the instruction the PC is pointing to with any of the above instructions.
 111    If there is a hit, we know the offset to the start of the designated
 112    sequence and can then check whether we really are executing in the
 113    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 114    start of the return sequence is returned.  */
 115 #define RETCODE_INSN1           0x8d
 116 #define RETCODE_INSN2           0x50
 117 #define RETCODE_INSN3           0x50
 118 #define RETCODE_INSN4           0xb8
 119 #define RETCODE_INSN5           0xcd
 120
 121 #define RETCODE_INSN2_OFF       4
 122 #define RETCODE_INSN3_OFF       5
 123 #define RETCODE_INSN4_OFF       6
 124 #define RETCODE_INSN5_OFF       11
 125
 126 static const unsigned char sigtramp_retcode[] =
 127 {
 128   RETCODE_INSN1, 0x44, 0x24, 0x10,
 129   RETCODE_INSN2,
 130   RETCODE_INSN3,
 131   RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
 132   RETCODE_INSN5, 0x80,
 133 };
 134
 135 static LONGEST
 136 i386nbsd_sigtramp_offset (CORE_ADDR pc)
 137 {
 138   unsigned char ret[sizeof(sigtramp_retcode)], insn;
 139   LONGEST off;
 140   int i;
 141
 142   if (read_memory_nobpt (pc, &insn, 1) != 0)
 143     return -1;
 144
 145   switch (insn)
 146     {
 147     case RETCODE_INSN1:
 148       off = 0;
 149       break;
 150
 151     case RETCODE_INSN2:
 152       /* INSN2 and INSN3 are the same.  Read at the location of PC+1
 153          to determine if we're actually looking at INSN2 or INSN3.  */
 154       if (read_memory_nobpt (pc + 1, &insn, 1) != 0)
 155         return -1;
 156
 157       if (insn == RETCODE_INSN3)
 158         off = RETCODE_INSN2_OFF;
 159       else
 160         off = RETCODE_INSN3_OFF;
 161       break;
 162
 163     case RETCODE_INSN4:
 164       off = RETCODE_INSN4_OFF;
 165       break;
 166
 167     case RETCODE_INSN5:
 168       off = RETCODE_INSN5_OFF;
 169       break;
 170
 171     default:
 172       return -1;
 173     }
 174
 175   pc -= off;
 176
 177   if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 178     return -1;
 179
 180   if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
 181     return off;
 182
 183   return -1;
 184 }
 185
 186 static int
 187 i386nbsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
 188 {
 189   return (nbsd_pc_in_sigtramp (pc, name)
 190           || i386nbsd_sigtramp_offset (pc) >= 0);
 191 }
 192
 193 /* From <machine/signal.h>.  */
 194 int i386nbsd_sc_reg_offset[] =
 195 {
 196   10 * 4,                       /* %eax */
 197   9 * 4,                        /* %ecx */
 198   8 * 4,                        /* %edx */
 199   7 * 4,                        /* %ebx */
 200   14 * 4,                       /* %esp */
 201   6 * 4,                        /* %ebp */
 202   5 * 4,                        /* %esi */
 203   4 * 4,                        /* %edi */
 204   11 * 4,                       /* %eip */
 205   13 * 4,                       /* %eflags */
 206   12 * 4,                       /* %cs */
 207   15 * 4,                       /* %ss */
 208   3 * 4,                        /* %ds */
 209   2 * 4,                        /* %es */
 210   1 * 4,                        /* %fs */
 211   0 * 4                         /* %gs */
 212 };
 213
 214 static void
 215 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 216 {
 217   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 218
 219   /* Obviously NetBSD is BSD-based.  */
 220   i386bsd_init_abi (info, gdbarch);
 221
 222   /* NetBSD has a different `struct reg'.  */
 223   tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
 224   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
 225   tdep->sizeof_gregset = 16 * 4;
 226
 227   /* NetBSD has different signal trampoline conventions.  */
 228   set_gdbarch_pc_in_sigtramp (gdbarch, i386nbsd_pc_in_sigtramp);
 229   /* FIXME: kettenis/20020906: We should probably provide
 230      NetBSD-specific versions of these functions if we want to
 231      recognize signal trampolines that live on the stack.  */
 232   set_gdbarch_sigtramp_start (gdbarch, NULL);
 233   set_gdbarch_sigtramp_end (gdbarch, NULL);
 234
 235   /* NetBSD uses -freg-struct-return by default.  */
 236   tdep->struct_return = reg_struct_return;
 237
 238   /* NetBSD has a `struct sigcontext' that's different from the
 239      origional 4.3 BSD.  */
 240   tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
 241   tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
 242 }
 243
 244 /* NetBSD a.out.  */
 245
 246 static void
 247 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 248 {
 249   i386nbsd_init_abi (info, gdbarch);
 250
 251   /* NetBSD a.out has a single register set.  */
 252   set_gdbarch_regset_from_core_section
 253     (gdbarch, i386nbsd_aout_regset_from_core_section);
 254 }
 255
 256 /* NetBSD ELF.  */
 257
 258 static void
 259 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 260 {
 261   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 262
 263   /* It's still NetBSD.  */
 264   i386nbsd_init_abi (info, gdbarch);
 265
 266   /* But ELF-based.  */
 267   i386_elf_init_abi (info, gdbarch);
 268
 269   /* NetBSD ELF uses SVR4-style shared libraries.  */
 270   set_gdbarch_in_solib_call_trampoline (gdbarch,
 271                                         generic_in_solib_call_trampoline);
 272   set_solib_svr4_fetch_link_map_offsets
 273     (gdbarch, nbsd_ilp32_solib_svr4_fetch_link_map_offsets);
 274
 275   /* NetBSD ELF uses -fpcc-struct-return by default.  */
 276   tdep->struct_return = pcc_struct_return;
 277 }
 278
 279 void
 280 _initialize_i386nbsd_tdep (void)
 281 {
 282   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
 283                           i386nbsdaout_init_abi);
 284   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
 285                           i386nbsdelf_init_abi);
 286 }