gdb/i386nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/i386.
   2
   3    Copyright (C) 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., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, 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 (struct frame_info *next_frame)
 136 {
 137   CORE_ADDR pc = frame_pc_unwind (next_frame);
 138   unsigned char ret[sizeof(sigtramp_retcode)], insn;
 139   LONGEST off;
 140   int i;
 141
 142   if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
 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 (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
 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 (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 178     return -1;
 179
 180   if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
 181     return off;
 182
 183   return -1;
 184 }
 185
 186 /* Return whether the frame preceding NEXT_FRAME corresponds to a
 187    NetBSD sigtramp routine.  */
 188
 189 static int
 190 i386nbsd_sigtramp_p (struct frame_info *next_frame)
 191 {
 192   CORE_ADDR pc = frame_pc_unwind (next_frame);
 193   char *name;
 194
 195   find_pc_partial_function (pc, &name, NULL, NULL);
 196   return (nbsd_pc_in_sigtramp (pc, name)
 197           || i386nbsd_sigtramp_offset (next_frame) >= 0);
 198 }
 199
 200 /* From <machine/signal.h>.  */
 201 int i386nbsd_sc_reg_offset[] =
 202 {
 203   10 * 4,                       /* %eax */
 204   9 * 4,                        /* %ecx */
 205   8 * 4,                        /* %edx */
 206   7 * 4,                        /* %ebx */
 207   14 * 4,                       /* %esp */
 208   6 * 4,                        /* %ebp */
 209   5 * 4,                        /* %esi */
 210   4 * 4,                        /* %edi */
 211   11 * 4,                       /* %eip */
 212   13 * 4,                       /* %eflags */
 213   12 * 4,                       /* %cs */
 214   15 * 4,                       /* %ss */
 215   3 * 4,                        /* %ds */
 216   2 * 4,                        /* %es */
 217   1 * 4,                        /* %fs */
 218   0 * 4                         /* %gs */
 219 };
 220
 221 static void
 222 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 223 {
 224   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 225
 226   /* Obviously NetBSD is BSD-based.  */
 227   i386bsd_init_abi (info, gdbarch);
 228
 229   /* NetBSD has a different `struct reg'.  */
 230   tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
 231   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
 232   tdep->sizeof_gregset = 16 * 4;
 233
 234   /* NetBSD has different signal trampoline conventions.  */
 235   tdep->sigtramp_start = 0;
 236   tdep->sigtramp_end = 0;
 237   tdep->sigtramp_p = i386nbsd_sigtramp_p;
 238
 239   /* NetBSD uses -freg-struct-return by default.  */
 240   tdep->struct_return = reg_struct_return;
 241
 242   /* NetBSD has a `struct sigcontext' that's different from the
 243      original 4.3 BSD.  */
 244   tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
 245   tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
 246 }
 247
 248 /* NetBSD a.out.  */
 249
 250 static void
 251 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 252 {
 253   i386nbsd_init_abi (info, gdbarch);
 254
 255   /* NetBSD a.out has a single register set.  */
 256   set_gdbarch_regset_from_core_section
 257     (gdbarch, i386nbsd_aout_regset_from_core_section);
 258 }
 259
 260 /* NetBSD ELF.  */
 261
 262 static void
 263 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 264 {
 265   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 266
 267   /* It's still NetBSD.  */
 268   i386nbsd_init_abi (info, gdbarch);
 269
 270   /* But ELF-based.  */
 271   i386_elf_init_abi (info, gdbarch);
 272
 273   /* NetBSD ELF uses SVR4-style shared libraries.  */
 274   set_solib_svr4_fetch_link_map_offsets
 275     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 276
 277   /* NetBSD ELF uses -fpcc-struct-return by default.  */
 278   tdep->struct_return = pcc_struct_return;
 279 }
 280
 281 void
 282 _initialize_i386nbsd_tdep (void)
 283 {
 284   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
 285                           i386nbsdaout_init_abi);
 286   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
 287                           i386nbsdelf_init_abi);
 288 }