gdb/i386nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/i386.
   2
   3    Copyright (C) 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003,
   4    2004, 2007 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., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include "defs.h"
  24 #include "arch-utils.h"
  25 #include "frame.h"
  26 #include "gdbcore.h"
  27 #include "regcache.h"
  28 #include "regset.h"
  29 #include "osabi.h"
  30 #include "symtab.h"
  31
  32 #include "gdb_assert.h"
  33 #include "gdb_string.h"
  34
  35 #include "i386-tdep.h"
  36 #include "i387-tdep.h"
  37 #include "nbsd-tdep.h"
  38 #include "solib-svr4.h"
  39
  40 /* From <machine/reg.h>.  */
  41 static int i386nbsd_r_reg_offset[] =
  42 {
  43   0 * 4,                        /* %eax */
  44   1 * 4,                        /* %ecx */
  45   2 * 4,                        /* %edx */
  46   3 * 4,                        /* %ebx */
  47   4 * 4,                        /* %esp */
  48   5 * 4,                        /* %ebp */
  49   6 * 4,                        /* %esi */
  50   7 * 4,                        /* %edi */
  51   8 * 4,                        /* %eip */
  52   9 * 4,                        /* %eflags */
  53   10 * 4,                       /* %cs */
  54   11 * 4,                       /* %ss */
  55   12 * 4,                       /* %ds */
  56   13 * 4,                       /* %es */
  57   14 * 4,                       /* %fs */
  58   15 * 4                        /* %gs */
  59 };
  60
  61 static void
  62 i386nbsd_aout_supply_regset (const struct regset *regset,
  63                              struct regcache *regcache, int regnum,
  64                              const void *regs, size_t len)
  65 {
  66   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  67
  68   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
  69
  70   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  71   i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
  72 }
  73
  74 static const struct regset *
  75 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
  76                                         const char *sect_name,
  77                                         size_t sect_size)
  78 {
  79   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  80
  81   /* NetBSD a.out core dumps don't use seperate register sets for the
  82      general-purpose and floating-point registers.  */
  83
  84   if (strcmp (sect_name, ".reg") == 0
  85       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
  86     {
  87       if (tdep->gregset == NULL)
  88         tdep->gregset =
  89           regset_alloc (gdbarch, i386nbsd_aout_supply_regset, NULL);
  90       return tdep->gregset;
  91     }
  92
  93   return NULL;
  94 }
  95
  96 /* Under NetBSD/i386, signal handler invocations can be identified by the
  97    designated code sequence that is used to return from a signal handler.
  98    In particular, the return address of a signal handler points to the
  99    following code sequence:
 100
 101         leal    0x10(%esp), %eax
 102         pushl   %eax
 103         pushl   %eax
 104         movl    $0x127, %eax            # __sigreturn14
 105         int     $0x80
 106
 107    Each instruction has a unique encoding, so we simply attempt to match
 108    the instruction the PC is pointing to with any of the above instructions.
 109    If there is a hit, we know the offset to the start of the designated
 110    sequence and can then check whether we really are executing in the
 111    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 112    start of the return sequence is returned.  */
 113 #define RETCODE_INSN1           0x8d
 114 #define RETCODE_INSN2           0x50
 115 #define RETCODE_INSN3           0x50
 116 #define RETCODE_INSN4           0xb8
 117 #define RETCODE_INSN5           0xcd
 118
 119 #define RETCODE_INSN2_OFF       4
 120 #define RETCODE_INSN3_OFF       5
 121 #define RETCODE_INSN4_OFF       6
 122 #define RETCODE_INSN5_OFF       11
 123
 124 static const unsigned char sigtramp_retcode[] =
 125 {
 126   RETCODE_INSN1, 0x44, 0x24, 0x10,
 127   RETCODE_INSN2,
 128   RETCODE_INSN3,
 129   RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
 130   RETCODE_INSN5, 0x80,
 131 };
 132
 133 static LONGEST
 134 i386nbsd_sigtramp_offset (struct frame_info *next_frame)
 135 {
 136   CORE_ADDR pc = frame_pc_unwind (next_frame);
 137   unsigned char ret[sizeof(sigtramp_retcode)], insn;
 138   LONGEST off;
 139   int i;
 140
 141   if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
 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 (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
 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 (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 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 (next_frame) >= 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_solib_svr4_fetch_link_map_offsets
 274     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 275
 276   /* NetBSD ELF uses -fpcc-struct-return by default.  */
 277   tdep->struct_return = pcc_struct_return;
 278 }
 279
 280 void
 281 _initialize_i386nbsd_tdep (void)
 282 {
 283   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
 284                           i386nbsdaout_init_abi);
 285   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
 286                           i386nbsdelf_init_abi);
 287 }