gdb/alphanbsd-tdep.c

   1 /* Target-dependent code for NetBSD/alpha.
   2
   3    Copyright (C) 2002, 2003, 2004, 2006 Free Software Foundation, Inc.
   4
   5    Contributed by Wasabi Systems, 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 "gdbcore.h"
  26 #include "frame.h"
  27 #include "regcache.h"
  28 #include "value.h"
  29 #include "osabi.h"
  30
  31 #include "gdb_string.h"
  32
  33 #include "alpha-tdep.h"
  34 #include "alphabsd-tdep.h"
  35 #include "nbsd-tdep.h"
  36 #include "solib-svr4.h"
  37
  38 static void
  39 fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  40                       CORE_ADDR ignore)
  41 {
  42   char *regs, *fpregs;
  43   int regno;
  44
  45   /* Table to map a gdb register number to a trapframe register index.  */
  46   static const int regmap[] =
  47   {
  48      0,   1,   2,   3,
  49      4,   5,   6,   7,
  50      8,   9,  10,  11,
  51     12,  13,  14,  15,
  52     30,  31,  32,  16,
  53     17,  18,  19,  20,
  54     21,  22,  23,  24,
  55     25,  29,  26
  56   };
  57 #define SIZEOF_TRAPFRAME (33 * 8)
  58
  59   /* We get everything from one section.  */
  60   if (which != 0)
  61     return;
  62
  63   regs = core_reg_sect;
  64   fpregs = core_reg_sect + SIZEOF_TRAPFRAME;
  65
  66   if (core_reg_size < (SIZEOF_TRAPFRAME + SIZEOF_STRUCT_FPREG))
  67     {
  68       warning (_("Wrong size register set in core file."));
  69       return;
  70     }
  71
  72   /* Integer registers.  */
  73   for (regno = 0; regno < ALPHA_ZERO_REGNUM; regno++)
  74     regcache_raw_supply (current_regcache, regno, regs + (regmap[regno] * 8));
  75   regcache_raw_supply (current_regcache, ALPHA_ZERO_REGNUM, NULL);
  76   regcache_raw_supply (current_regcache, PC_REGNUM, regs + (28 * 8));
  77
  78   /* Floating point registers.  */
  79   alphabsd_supply_fpreg (fpregs, -1);
  80 }
  81
  82 static void
  83 fetch_elfcore_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  84                          CORE_ADDR ignore)
  85 {
  86   switch (which)
  87     {
  88     case 0:  /* Integer registers.  */
  89       if (core_reg_size != SIZEOF_STRUCT_REG)
  90         warning (_("Wrong size register set in core file."));
  91       else
  92         alphabsd_supply_reg (core_reg_sect, -1);
  93       break;
  94
  95     case 2:  /* Floating point registers.  */
  96       if (core_reg_size != SIZEOF_STRUCT_FPREG)
  97         warning (_("Wrong size FP register set in core file."));
  98       else
  99         alphabsd_supply_fpreg (core_reg_sect, -1);
 100       break;
 101
 102     default:
 103       /* Don't know what kind of register request this is; just ignore it.  */
 104       break;
 105     }
 106 }
 107
 108 static struct core_fns alphanbsd_core_fns =
 109 {
 110   bfd_target_unknown_flavour,           /* core_flavour */
 111   default_check_format,                 /* check_format */
 112   default_core_sniffer,                 /* core_sniffer */
 113   fetch_core_registers,                 /* core_read_registers */
 114   NULL                                  /* next */
 115 };
 116
 117 static struct core_fns alphanbsd_elfcore_fns =
 118 {
 119   bfd_target_elf_flavour,               /* core_flavour */
 120   default_check_format,                 /* check_format */
 121   default_core_sniffer,                 /* core_sniffer */
 122   fetch_elfcore_registers,              /* core_read_registers */
 123   NULL                                  /* next */
 124 };
 125
 126 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 127    designated code sequence that is used to return from a signal handler.
 128    In particular, the return address of a signal handler points to the
 129    following code sequence:
 130
 131         ldq     a0, 0(sp)
 132         lda     sp, 16(sp)
 133         lda     v0, 295(zero)   # __sigreturn14
 134         call_pal callsys
 135
 136    Each instruction has a unique encoding, so we simply attempt to match
 137    the instruction the PC is pointing to with any of the above instructions.
 138    If there is a hit, we know the offset to the start of the designated
 139    sequence and can then check whether we really are executing in the
 140    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 141    start of the return sequence is returned.  */
 142 static const unsigned char sigtramp_retcode[] =
 143 {
 144   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 145   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 146   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 147   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 148 };
 149 #define RETCODE_NWORDS          4
 150 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 151
 152 LONGEST
 153 alphanbsd_sigtramp_offset (CORE_ADDR pc)
 154 {
 155   unsigned char ret[RETCODE_SIZE], w[4];
 156   LONGEST off;
 157   int i;
 158
 159   if (deprecated_read_memory_nobpt (pc, (char *) w, 4) != 0)
 160     return -1;
 161
 162   for (i = 0; i < RETCODE_NWORDS; i++)
 163     {
 164       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 165         break;
 166     }
 167   if (i == RETCODE_NWORDS)
 168     return (-1);
 169
 170   off = i * 4;
 171   pc -= off;
 172
 173   if (deprecated_read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 174     return -1;
 175
 176   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 177     return off;
 178
 179   return -1;
 180 }
 181
 182 static int
 183 alphanbsd_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
 184 {
 185   return (nbsd_pc_in_sigtramp (pc, func_name)
 186           || alphanbsd_sigtramp_offset (pc) >= 0);
 187 }
 188
 189 static CORE_ADDR
 190 alphanbsd_sigcontext_addr (struct frame_info *frame)
 191 {
 192   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 193      We will probably need to disassemble the trampoline to figure
 194      out which trampoline frame type we have.  */
 195   return get_frame_base (frame);
 196 }
 197
 198 static void
 199 alphanbsd_init_abi (struct gdbarch_info info,
 200                     struct gdbarch *gdbarch)
 201 {
 202   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 203
 204   /* Hook into the DWARF CFI frame unwinder.  */
 205   alpha_dwarf2_init_abi (info, gdbarch);
 206
 207   /* Hook into the MDEBUG frame unwinder.  */
 208   alpha_mdebug_init_abi (info, gdbarch);
 209
 210   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 211      must use software single-stepping.  */
 212   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 213
 214   /* NetBSD/alpha has SVR4-style shared libraries.  */
 215   set_solib_svr4_fetch_link_map_offsets
 216     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 217
 218   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 219   tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;
 220   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 221
 222   tdep->jb_pc = 2;
 223   tdep->jb_elt_size = 8;
 224 }
 225
 226 void
 227 _initialize_alphanbsd_tdep (void)
 228 {
 229   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
 230                           alphanbsd_init_abi);
 231   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,
 232                           alphanbsd_init_abi);
 233
 234   deprecated_add_core_fns (&alphanbsd_core_fns);
 235   deprecated_add_core_fns (&alphanbsd_elfcore_fns);
 236 }