gdb/alphanbsd-tdep.c

   1 /* Target-dependent code for NetBSD/Alpha.
   2    Copyright 2002 Free Software Foundation, Inc.
   3    Contributed by Wasabi Systems, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25 #include "value.h"
  26
  27 #include "solib-svr4.h"
  28
  29 #include "alpha-tdep.h"
  30 #include "alphabsd-tdep.h"
  31 #include "nbsd-tdep.h"
  32
  33 static void
  34 fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  35                       CORE_ADDR ignore)
  36 {
  37   char *regs, *fpregs;
  38   int regno;
  39
  40   /* Table to map a gdb register number to a trapframe register index.  */
  41   static const int regmap[] =
  42   {
  43      0,   1,   2,   3,
  44      4,   5,   6,   7,
  45      8,   9,  10,  11,
  46     12,  13,  14,  15,
  47     30,  31,  32,  16,
  48     17,  18,  19,  20,
  49     21,  22,  23,  24,
  50     25,  29,  26
  51   };
  52 #define SIZEOF_TRAPFRAME (33 * 8)
  53
  54   /* We get everything from one section.  */
  55   if (which != 0)
  56     return;
  57
  58   regs = core_reg_sect;
  59   fpregs = core_reg_sect + SIZEOF_TRAPFRAME;
  60
  61   if (core_reg_size < (SIZEOF_TRAPFRAME + SIZEOF_STRUCT_FPREG))
  62     {
  63       warning ("Wrong size register set in core file.");
  64       return;
  65     }
  66
  67   /* Integer registers.  */
  68   for (regno = 0; regno < ALPHA_ZERO_REGNUM; regno++)
  69     supply_register (regno, regs + (regmap[regno] * 8));
  70   supply_register (ALPHA_ZERO_REGNUM, NULL);
  71   supply_register (FP_REGNUM, NULL);
  72   supply_register (PC_REGNUM, regs + (28 * 8));
  73
  74   /* Floating point registers.  */
  75   alphabsd_supply_fpreg (fpregs, -1);
  76 }
  77
  78 static void
  79 fetch_elfcore_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  80                          CORE_ADDR ignore)
  81 {
  82   switch (which)
  83     {
  84     case 0:  /* Integer registers.  */
  85       if (core_reg_size != SIZEOF_STRUCT_REG)
  86         warning ("Wrong size register set in core file.");
  87       else
  88         alphabsd_supply_reg (core_reg_sect, -1);
  89       break;
  90
  91     case 2:  /* Floating point registers.  */
  92       if (core_reg_size != SIZEOF_STRUCT_FPREG)
  93         warning ("Wrong size FP register set in core file.");
  94       else
  95         alphabsd_supply_fpreg (core_reg_sect, -1);
  96       break;
  97
  98     default:
  99       /* Don't know what kind of register request this is; just ignore it.  */
 100       break;
 101     }
 102 }
 103
 104 static struct core_fns alphanbsd_core_fns =
 105 {
 106   bfd_target_unknown_flavour,           /* core_flavour */
 107   default_check_format,                 /* check_format */
 108   default_core_sniffer,                 /* core_sniffer */
 109   fetch_core_registers,                 /* core_read_registers */
 110   NULL                                  /* next */
 111 };
 112
 113 static struct core_fns alphanbsd_elfcore_fns =
 114 {
 115   bfd_target_elf_flavour,               /* core_flavour */
 116   default_check_format,                 /* check_format */
 117   default_core_sniffer,                 /* core_sniffer */
 118   fetch_elfcore_registers,              /* core_read_registers */
 119   NULL                                  /* next */
 120 };
 121
 122 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 123    designated code sequence that is used to return from a signal handler.
 124    In particular, the return address of a signal handler points to the
 125    following code sequence:
 126
 127         ldq     a0, 0(sp)
 128         lda     sp, 16(sp)
 129         lda     v0, 295(zero)   # __sigreturn14
 130         call_pal callsys
 131
 132    Each instruction has a unique encoding, so we simply attempt to match
 133    the instruction the PC is pointing to with any of the above instructions.
 134    If there is a hit, we know the offset to the start of the designated
 135    sequence and can then check whether we really are executing in the
 136    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 137    start of the return sequence is returned.  */
 138 static const unsigned char sigtramp_retcode[] =
 139 {
 140   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 141   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 142   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 143   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 144 };
 145 #define RETCODE_NWORDS          4
 146 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 147
 148 LONGEST
 149 alphanbsd_sigtramp_offset (CORE_ADDR pc)
 150 {
 151   unsigned char ret[RETCODE_SIZE], w[4];
 152   LONGEST off;
 153   int i;
 154
 155   if (read_memory_nobpt (pc, (char *) w, 4) != 0)
 156     return -1;
 157
 158   for (i = 0; i < RETCODE_NWORDS; i++)
 159     {
 160       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 161         break;
 162     }
 163   if (i == RETCODE_NWORDS)
 164     return (-1);
 165
 166   off = i * 4;
 167   pc -= off;
 168
 169   if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 170     return -1;
 171
 172   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 173     return off;
 174
 175   return -1;
 176 }
 177
 178 static int
 179 alphanbsd_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
 180 {
 181   return (nbsd_pc_in_sigtramp (pc, func_name)
 182           || alphanbsd_sigtramp_offset (pc) >= 0);
 183 }
 184
 185 static void
 186 alphanbsd_init_abi (struct gdbarch_info info,
 187                     struct gdbarch *gdbarch)
 188 {
 189   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 190
 191   set_gdbarch_pc_in_sigtramp (gdbarch, alphanbsd_pc_in_sigtramp);
 192
 193   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 194      must use software single-stepping.  */
 195   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 196
 197   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 198                                  nbsd_lp64_solib_svr4_fetch_link_map_offsets);
 199
 200   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 201
 202   tdep->jb_pc = 2;
 203   tdep->jb_elt_size = 8;
 204 }
 205
 206 void
 207 _initialize_alphanbsd_tdep (void)
 208 {
 209   gdbarch_register_osabi (bfd_arch_alpha, GDB_OSABI_NETBSD_ELF,
 210                           alphanbsd_init_abi);
 211
 212   add_core_fns (&alphanbsd_core_fns);
 213   add_core_fns (&alphanbsd_elfcore_fns);
 214 }