gdb/i386nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/i386.
   2
   3    Copyright 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002,
   4    2003, 2004
   5    Free Software Foundation, Inc.
   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 2 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, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "arch-utils.h"
  26 #include "frame.h"
  27 #include "gdbcore.h"
  28 #include "regcache.h"
  29 #include "regset.h"
  30 #include "osabi.h"
  31 #include "symtab.h"
  32
  33 #include "gdb_assert.h"
  34 #include "gdb_string.h"
  35
  36 #include "i386-tdep.h"
  37 #include "i387-tdep.h"
  38 #include "nbsd-tdep.h"
  39 #include "solib-svr4.h"
  40
  41 /* From <machine/reg.h>.  */
  42 static int i386nbsd_r_reg_offset[] =
  43 {
  44   0 * 4,                        /* %eax */
  45   1 * 4,                        /* %ecx */
  46   2 * 4,                        /* %edx */
  47   3 * 4,                        /* %ebx */
  48   4 * 4,                        /* %esp */
  49   5 * 4,                        /* %ebp */
  50   6 * 4,                        /* %esi */
  51   7 * 4,                        /* %edi */
  52   8 * 4,                        /* %eip */
  53   9 * 4,                        /* %eflags */
  54   10 * 4,                       /* %cs */
  55   11 * 4,                       /* %ss */
  56   12 * 4,                       /* %ds */
  57   13 * 4,                       /* %es */
  58   14 * 4,                       /* %fs */
  59   15 * 4                        /* %gs */
  60 };
  61
  62 static void
  63 i386nbsd_aout_supply_regset (const struct regset *regset,
  64                              struct regcache *regcache, int regnum,
  65                              const void *regs, size_t len)
  66 {
  67   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  68
  69   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
  70
  71   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  72   i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
  73 }
  74
  75 static const struct regset *
  76 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
  77                                         const char *sect_name,
  78                                         size_t sect_size)
  79 {
  80   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  81
  82   /* NetBSD a.out core dumps don't use seperate register sets for the
  83      general-purpose and floating-point registers.  */
  84
  85   if (strcmp (sect_name, ".reg") == 0
  86       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
  87     {
  88       if (tdep->gregset == NULL)
  89         tdep->gregset =
  90           regset_alloc (gdbarch, i386nbsd_aout_supply_regset, NULL);
  91       return tdep->gregset;
  92     }
  93
  94   return NULL;
  95 }
  96
  97 /* Under NetBSD/i386, signal handler invocations can be identified by the
  98    designated code sequence that is used to return from a signal handler.
  99    In particular, the return address of a signal handler points to the
 100    following code sequence:
 101
 102         leal    0x10(%esp), %eax
 103         pushl   %eax
 104         pushl   %eax
 105         movl    $0x127, %eax            # __sigreturn14
 106         int     $0x80
 107
 108    Each instruction has a unique encoding, so we simply attempt to match
 109    the instruction the PC is pointing to with any of the above instructions.
 110    If there is a hit, we know the offset to the start of the designated
 111    sequence and can then check whether we really are executing in the
 112    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 113    start of the return sequence is returned.  */
 114 #define RETCODE_INSN1           0x8d
 115 #define RETCODE_INSN2           0x50
 116 #define RETCODE_INSN3           0x50
 117 #define RETCODE_INSN4           0xb8
 118 #define RETCODE_INSN5           0xcd
 119
 120 #define RETCODE_INSN2_OFF       4
 121 #define RETCODE_INSN3_OFF       5
 122 #define RETCODE_INSN4_OFF       6
 123 #define RETCODE_INSN5_OFF       11
 124
 125 static const unsigned char sigtramp_retcode[] =
 126 {
 127   RETCODE_INSN1, 0x44, 0x24, 0x10,
 128   RETCODE_INSN2,
 129   RETCODE_INSN3,
 130   RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
 131   RETCODE_INSN5, 0x80,
 132 };
 133
 134 static LONGEST
 135 i386nbsd_sigtramp_offset (CORE_ADDR pc)
 136 {
 137   unsigned char ret[sizeof(sigtramp_retcode)], insn;
 138   LONGEST off;
 139   int i;
 140
 141   if (deprecated_read_memory_nobpt (pc, &insn, 1) != 0)
 142     return -1;
 143
 144   switch (insn)
 145     {
 146     case RETCODE_INSN1:
 147       off = 0;
 148       break;
 149
 150     case RETCODE_INSN2:
 151       /* INSN2 and INSN3 are the same.  Read at the location of PC+1
 152          to determine if we're actually looking at INSN2 or INSN3.  */
 153       if (deprecated_read_memory_nobpt (pc + 1, &insn, 1) != 0)
 154         return -1;
 155
 156       if (insn == RETCODE_INSN3)
 157         off = RETCODE_INSN2_OFF;
 158       else
 159         off = RETCODE_INSN3_OFF;
 160       break;
 161
 162     case RETCODE_INSN4:
 163       off = RETCODE_INSN4_OFF;
 164       break;
 165
 166     case RETCODE_INSN5:
 167       off = RETCODE_INSN5_OFF;
 168       break;
 169
 170     default:
 171       return -1;
 172     }
 173
 174   pc -= off;
 175
 176   if (deprecated_read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 177     return -1;
 178
 179   if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
 180     return off;
 181
 182   return -1;
 183 }
 184
 185 /* Return whether the frame preceding NEXT_FRAME corresponds to a
 186    NetBSD sigtramp routine.  */
 187
 188 static int
 189 i386nbsd_sigtramp_p (struct frame_info *next_frame)
 190 {
 191   CORE_ADDR pc = frame_pc_unwind (next_frame);
 192   char *name;
 193
 194   find_pc_partial_function (pc, &name, NULL, NULL);
 195   return (nbsd_pc_in_sigtramp (pc, name)
 196           || i386nbsd_sigtramp_offset (pc) >= 0);
 197 }
 198
 199 /* From <machine/signal.h>.  */
 200 int i386nbsd_sc_reg_offset[] =
 201 {
 202   10 * 4,                       /* %eax */
 203   9 * 4,                        /* %ecx */
 204   8 * 4,                        /* %edx */
 205   7 * 4,                        /* %ebx */
 206   14 * 4,                       /* %esp */
 207   6 * 4,                        /* %ebp */
 208   5 * 4,                        /* %esi */
 209   4 * 4,                        /* %edi */
 210   11 * 4,                       /* %eip */
 211   13 * 4,                       /* %eflags */
 212   12 * 4,                       /* %cs */
 213   15 * 4,                       /* %ss */
 214   3 * 4,                        /* %ds */
 215   2 * 4,                        /* %es */
 216   1 * 4,                        /* %fs */
 217   0 * 4                         /* %gs */
 218 };
 219
 220 static void
 221 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 222 {
 223   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 224
 225   /* Obviously NetBSD is BSD-based.  */
 226   i386bsd_init_abi (info, gdbarch);
 227
 228   /* NetBSD has a different `struct reg'.  */
 229   tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
 230   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
 231   tdep->sizeof_gregset = 16 * 4;
 232
 233   /* NetBSD has different signal trampoline conventions.  */
 234   tdep->sigtramp_start = 0;
 235   tdep->sigtramp_end = 0;
 236   tdep->sigtramp_p = i386nbsd_sigtramp_p;
 237
 238   /* NetBSD uses -freg-struct-return by default.  */
 239   tdep->struct_return = reg_struct_return;
 240
 241   /* NetBSD has a `struct sigcontext' that's different from the
 242      original 4.3 BSD.  */
 243   tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
 244   tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
 245 }
 246
 247 /* NetBSD a.out.  */
 248
 249 static void
 250 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 251 {
 252   i386nbsd_init_abi (info, gdbarch);
 253
 254   /* NetBSD a.out has a single register set.  */
 255   set_gdbarch_regset_from_core_section
 256     (gdbarch, i386nbsd_aout_regset_from_core_section);
 257 }
 258
 259 /* NetBSD ELF.  */
 260
 261 static void
 262 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 263 {
 264   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 265
 266   /* It's still NetBSD.  */
 267   i386nbsd_init_abi (info, gdbarch);
 268
 269   /* But ELF-based.  */
 270   i386_elf_init_abi (info, gdbarch);
 271
 272   /* NetBSD ELF uses SVR4-style shared libraries.  */
 273   set_gdbarch_in_solib_call_trampoline
 274     (gdbarch, generic_in_solib_call_trampoline);
 275   set_solib_svr4_fetch_link_map_offsets
 276     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 277
 278   /* NetBSD ELF uses -fpcc-struct-return by default.  */
 279   tdep->struct_return = pcc_struct_return;
 280 }
 281
 282 void
 283 _initialize_i386nbsd_tdep (void)
 284 {
 285   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
 286                           i386nbsdaout_init_abi);
 287   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
 288                           i386nbsdelf_init_abi);
 289 }