gdb/alpha-nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/alpha.
   2
   3    Copyright (C) 2002-2020 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 3 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, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "gdbcore.h"
  25 #include "osabi.h"
  26 #include "regcache.h"
  27 #include "regset.h"
  28 #include "value.h"
  29
  30 #include "alpha-tdep.h"
  31 #include "alpha-bsd-tdep.h"
  32 #include "nbsd-tdep.h"
  33 #include "solib-svr4.h"
  34 #include "target.h"
  35
  36 /* Core file support.  */
  37
  38 /* Sizeof `struct reg' in <machine/reg.h>.  */
  39 #define ALPHANBSD_SIZEOF_GREGS  (32 * 8)
  40
  41 /* Sizeof `struct fpreg' in <machine/reg.h.  */
  42 #define ALPHANBSD_SIZEOF_FPREGS ((32 * 8) + 8)
  43
  44 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  45    in the floating-point register set REGSET to register cache
  46    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  47
  48 static void
  49 alphanbsd_supply_fpregset (const struct regset *regset,
  50                            struct regcache *regcache,
  51                            int regnum, const void *fpregs, size_t len)
  52 {
  53   const gdb_byte *regs = (const gdb_byte *) fpregs;
  54   int i;
  55
  56   gdb_assert (len >= ALPHANBSD_SIZEOF_FPREGS);
  57
  58   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
  59     {
  60       if (regnum == i || regnum == -1)
  61         regcache->raw_supply (i, regs + (i - ALPHA_FP0_REGNUM) * 8);
  62     }
  63
  64   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
  65     regcache->raw_supply (ALPHA_FPCR_REGNUM, regs + 32 * 8);
  66 }
  67
  68 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  69    in the general-purpose register set REGSET to register cache
  70    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  71
  72 static void
  73 alphanbsd_aout_supply_gregset (const struct regset *regset,
  74                                struct regcache *regcache,
  75                                int regnum, const void *gregs, size_t len)
  76 {
  77   const gdb_byte *regs = (const gdb_byte *) gregs;
  78   int i;
  79
  80   /* Table to map a GDB register number to a trapframe register index.  */
  81   static const int regmap[] =
  82   {
  83      0,   1,   2,   3,
  84      4,   5,   6,   7,
  85      8,   9,  10,  11,
  86     12,  13,  14,  15,
  87     30,  31,  32,  16,
  88     17,  18,  19,  20,
  89     21,  22,  23,  24,
  90     25,  29,  26
  91   };
  92
  93   gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);
  94
  95   for (i = 0; i < ARRAY_SIZE(regmap); i++)
  96     {
  97       if (regnum == i || regnum == -1)
  98         regcache->raw_supply (i, regs + regmap[i] * 8);
  99     }
 100
 101   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 102     regcache->raw_supply (ALPHA_PC_REGNUM, regs + 31 * 8);
 103
 104   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 105     {
 106       regs += ALPHANBSD_SIZEOF_GREGS;
 107       len -= ALPHANBSD_SIZEOF_GREGS;
 108       alphanbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 109     }
 110 }
 111
 112 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 113    in the general-purpose register set REGSET to register cache
 114    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 115
 116 static void
 117 alphanbsd_supply_gregset (const struct regset *regset,
 118                           struct regcache *regcache,
 119                           int regnum, const void *gregs, size_t len)
 120 {
 121   const gdb_byte *regs = (const gdb_byte *) gregs;
 122   int i;
 123
 124   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 125     {
 126       alphanbsd_aout_supply_gregset (regset, regcache, regnum, gregs, len);
 127       return;
 128     }
 129
 130   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 131     {
 132       if (regnum == i || regnum == -1)
 133         regcache->raw_supply (i, regs + i * 8);
 134     }
 135
 136   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 137     regcache->raw_supply (ALPHA_PC_REGNUM, regs + 31 * 8);
 138 }
 139
 140 /* NetBSD/alpha register sets.  */
 141
 142 static const struct regset alphanbsd_gregset =
 143 {
 144   NULL,
 145   alphanbsd_supply_gregset,
 146   NULL,
 147   REGSET_VARIABLE_SIZE
 148 };
 149
 150 static const struct regset alphanbsd_fpregset =
 151 {
 152   NULL,
 153   alphanbsd_supply_fpregset
 154 };
 155
 156 /* Iterate over supported core file register note sections. */
 157
 158 void
 159 alphanbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 160                                         iterate_over_regset_sections_cb *cb,
 161                                         void *cb_data,
 162                                         const struct regcache *regcache)
 163 {
 164   cb (".reg", ALPHANBSD_SIZEOF_GREGS, ALPHANBSD_SIZEOF_GREGS,
 165       &alphanbsd_gregset, NULL, cb_data);
 166   cb (".reg2", ALPHANBSD_SIZEOF_FPREGS, ALPHANBSD_SIZEOF_FPREGS,
 167       &alphanbsd_fpregset, NULL, cb_data);
 168 }
 169 \f
 170
 171 /* Signal trampolines.  */
 172
 173 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 174    designated code sequence that is used to return from a signal handler.
 175    In particular, the return address of a signal handler points to the
 176    following code sequence:
 177
 178         ldq     a0, 0(sp)
 179         lda     sp, 16(sp)
 180         lda     v0, 295(zero)   # __sigreturn14
 181         call_pal callsys
 182
 183    Each instruction has a unique encoding, so we simply attempt to match
 184    the instruction the PC is pointing to with any of the above instructions.
 185    If there is a hit, we know the offset to the start of the designated
 186    sequence and can then check whether we really are executing in the
 187    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 188    start of the return sequence is returned.  */
 189 static const gdb_byte sigtramp_retcode[] =
 190 {
 191   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 192   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 193   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 194   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 195 };
 196 #define RETCODE_NWORDS          4
 197 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 198
 199 static LONGEST
 200 alphanbsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
 201 {
 202   gdb_byte ret[RETCODE_SIZE], w[4];
 203   LONGEST off;
 204   int i;
 205
 206   if (target_read_memory (pc, w, 4) != 0)
 207     return -1;
 208
 209   for (i = 0; i < RETCODE_NWORDS; i++)
 210     {
 211       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 212         break;
 213     }
 214   if (i == RETCODE_NWORDS)
 215     return (-1);
 216
 217   off = i * 4;
 218   pc -= off;
 219
 220   if (target_read_memory (pc, ret, sizeof (ret)) != 0)
 221     return -1;
 222
 223   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 224     return off;
 225
 226   return -1;
 227 }
 228
 229 static int
 230 alphanbsd_pc_in_sigtramp (struct gdbarch *gdbarch,
 231                           CORE_ADDR pc, const char *func_name)
 232 {
 233   return (nbsd_pc_in_sigtramp (pc, func_name)
 234           || alphanbsd_sigtramp_offset (gdbarch, pc) >= 0);
 235 }
 236
 237 static CORE_ADDR
 238 alphanbsd_sigcontext_addr (struct frame_info *frame)
 239 {
 240   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 241      We will probably need to disassemble the trampoline to figure
 242      out which trampoline frame type we have.  */
 243   if (!get_next_frame (frame))
 244     return 0;
 245   return get_frame_base (get_next_frame (frame));
 246 }
 247 \f
 248
 249 static void
 250 alphanbsd_init_abi (struct gdbarch_info info,
 251                     struct gdbarch *gdbarch)
 252 {
 253   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 254
 255   /* Hook into the DWARF CFI frame unwinder.  */
 256   alpha_dwarf2_init_abi (info, gdbarch);
 257
 258   /* Hook into the MDEBUG frame unwinder.  */
 259   alpha_mdebug_init_abi (info, gdbarch);
 260
 261   nbsd_init_abi (info, gdbarch);
 262
 263   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 264      must use software single-stepping.  */
 265   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 266
 267   /* NetBSD/alpha has SVR4-style shared libraries.  */
 268   set_solib_svr4_fetch_link_map_offsets
 269     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 270
 271   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 272   tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;
 273   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 274
 275   tdep->jb_pc = 2;
 276   tdep->jb_elt_size = 8;
 277
 278   set_gdbarch_iterate_over_regset_sections
 279     (gdbarch, alphanbsd_iterate_over_regset_sections);
 280 }
 281 \f
 282
 283 void _initialize_alphanbsd_tdep ();
 284 void
 285 _initialize_alphanbsd_tdep ()
 286 {
 287   /* Even though NetBSD/alpha used ELF since day one, it used the
 288      traditional a.out-style core dump format before NetBSD 1.6, but
 289      we don't support those.  */
 290   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD,
 291                           alphanbsd_init_abi);
 292 }