gdb/alphanbsd-tdep.c

   1 /* Target-dependent code for NetBSD/Alpha.
   2
   3    Copyright 2002, 2003, 2004 Free Software Foundation, Inc.
   4    Contributed by Wasabi Systems, 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., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "gdbcore.h"
  25 #include "frame.h"
  26 #include "regcache.h"
  27 #include "value.h"
  28 #include "osabi.h"
  29
  30 #include "solib-svr4.h"
  31
  32 #include "alpha-tdep.h"
  33 #include "alphabsd-tdep.h"
  34 #include "nbsd-tdep.h"
  35
  36 static void
  37 fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  38                       CORE_ADDR ignore)
  39 {
  40   char *regs, *fpregs;
  41   int regno;
  42
  43   /* Table to map a gdb register number to a trapframe register index.  */
  44   static const int regmap[] =
  45   {
  46      0,   1,   2,   3,
  47      4,   5,   6,   7,
  48      8,   9,  10,  11,
  49     12,  13,  14,  15,
  50     30,  31,  32,  16,
  51     17,  18,  19,  20,
  52     21,  22,  23,  24,
  53     25,  29,  26
  54   };
  55 #define SIZEOF_TRAPFRAME (33 * 8)
  56
  57   /* We get everything from one section.  */
  58   if (which != 0)
  59     return;
  60
  61   regs = core_reg_sect;
  62   fpregs = core_reg_sect + SIZEOF_TRAPFRAME;
  63
  64   if (core_reg_size < (SIZEOF_TRAPFRAME + SIZEOF_STRUCT_FPREG))
  65     {
  66       warning ("Wrong size register set in core file.");
  67       return;
  68     }
  69
  70   /* Integer registers.  */
  71   for (regno = 0; regno < ALPHA_ZERO_REGNUM; regno++)
  72     supply_register (regno, regs + (regmap[regno] * 8));
  73   supply_register (ALPHA_ZERO_REGNUM, NULL);
  74   supply_register (PC_REGNUM, regs + (28 * 8));
  75
  76   /* Floating point registers.  */
  77   alphabsd_supply_fpreg (fpregs, -1);
  78 }
  79
  80 static void
  81 fetch_elfcore_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  82                          CORE_ADDR ignore)
  83 {
  84   switch (which)
  85     {
  86     case 0:  /* Integer registers.  */
  87       if (core_reg_size != SIZEOF_STRUCT_REG)
  88         warning ("Wrong size register set in core file.");
  89       else
  90         alphabsd_supply_reg (core_reg_sect, -1);
  91       break;
  92
  93     case 2:  /* Floating point registers.  */
  94       if (core_reg_size != SIZEOF_STRUCT_FPREG)
  95         warning ("Wrong size FP register set in core file.");
  96       else
  97         alphabsd_supply_fpreg (core_reg_sect, -1);
  98       break;
  99
 100     default:
 101       /* Don't know what kind of register request this is; just ignore it.  */
 102       break;
 103     }
 104 }
 105
 106 static struct core_fns alphanbsd_core_fns =
 107 {
 108   bfd_target_unknown_flavour,           /* core_flavour */
 109   default_check_format,                 /* check_format */
 110   default_core_sniffer,                 /* core_sniffer */
 111   fetch_core_registers,                 /* core_read_registers */
 112   NULL                                  /* next */
 113 };
 114
 115 static struct core_fns alphanbsd_elfcore_fns =
 116 {
 117   bfd_target_elf_flavour,               /* core_flavour */
 118   default_check_format,                 /* check_format */
 119   default_core_sniffer,                 /* core_sniffer */
 120   fetch_elfcore_registers,              /* core_read_registers */
 121   NULL                                  /* next */
 122 };
 123
 124 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 125    designated code sequence that is used to return from a signal handler.
 126    In particular, the return address of a signal handler points to the
 127    following code sequence:
 128
 129         ldq     a0, 0(sp)
 130         lda     sp, 16(sp)
 131         lda     v0, 295(zero)   # __sigreturn14
 132         call_pal callsys
 133
 134    Each instruction has a unique encoding, so we simply attempt to match
 135    the instruction the PC is pointing to with any of the above instructions.
 136    If there is a hit, we know the offset to the start of the designated
 137    sequence and can then check whether we really are executing in the
 138    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 139    start of the return sequence is returned.  */
 140 static const unsigned char sigtramp_retcode[] =
 141 {
 142   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 143   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 144   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 145   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 146 };
 147 #define RETCODE_NWORDS          4
 148 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 149
 150 LONGEST
 151 alphanbsd_sigtramp_offset (CORE_ADDR pc)
 152 {
 153   unsigned char ret[RETCODE_SIZE], w[4];
 154   LONGEST off;
 155   int i;
 156
 157   if (read_memory_nobpt (pc, (char *) w, 4) != 0)
 158     return -1;
 159
 160   for (i = 0; i < RETCODE_NWORDS; i++)
 161     {
 162       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 163         break;
 164     }
 165   if (i == RETCODE_NWORDS)
 166     return (-1);
 167
 168   off = i * 4;
 169   pc -= off;
 170
 171   if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 172     return -1;
 173
 174   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 175     return off;
 176
 177   return -1;
 178 }
 179
 180 static int
 181 alphanbsd_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
 182 {
 183   return (nbsd_pc_in_sigtramp (pc, func_name)
 184           || alphanbsd_sigtramp_offset (pc) >= 0);
 185 }
 186
 187 static CORE_ADDR
 188 alphanbsd_sigcontext_addr (struct frame_info *frame)
 189 {
 190   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 191      We will probably need to disassemble the trampoline to figure
 192      out which trampoline frame type we have.  */
 193   return get_frame_base (frame);
 194 }
 195
 196 static void
 197 alphanbsd_init_abi (struct gdbarch_info info,
 198                     struct gdbarch *gdbarch)
 199 {
 200   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 201
 202   /* Hook into the DWARF CFI frame unwinder.  */
 203   alpha_dwarf2_init_abi (info, gdbarch);
 204
 205   /* Hook into the MDEBUG frame unwinder.  */
 206   alpha_mdebug_init_abi (info, gdbarch);
 207
 208   set_gdbarch_pc_in_sigtramp (gdbarch, alphanbsd_pc_in_sigtramp);
 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   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 215                                  nbsd_lp64_solib_svr4_fetch_link_map_offsets);
 216
 217   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 218   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 219
 220   tdep->jb_pc = 2;
 221   tdep->jb_elt_size = 8;
 222 }
 223
 224 void
 225 _initialize_alphanbsd_tdep (void)
 226 {
 227   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
 228                           alphanbsd_init_abi);
 229   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,
 230                           alphanbsd_init_abi);
 231
 232   add_core_fns (&alphanbsd_core_fns);
 233   add_core_fns (&alphanbsd_elfcore_fns);
 234 }