gdb/i386-nto-tdep.c

   1 /* Target-dependent code for QNX Neutrino x86.
   2
   3    Copyright (C) 2003-2020 Free Software Foundation, Inc.
   4
   5    Contributed by QNX Software Systems Ltd.
   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 "osabi.h"
  25 #include "regcache.h"
  26 #include "target.h"
  27
  28 #include "i386-tdep.h"
  29 #include "i387-tdep.h"
  30 #include "nto-tdep.h"
  31 #include "solib.h"
  32 #include "solib-svr4.h"
  33
  34 #ifndef X86_CPU_FXSR
  35 #define X86_CPU_FXSR (1L << 12)
  36 #endif
  37
  38 /* Why 13?  Look in our /usr/include/x86/context.h header at the
  39    x86_cpu_registers structure and you'll see an 'exx' junk register
  40    that is just filler.  Don't ask me, ask the kernel guys.  */
  41 #define NUM_GPREGS 13
  42
  43 /* Mapping between the general-purpose registers in `struct xxx'
  44    format and GDB's register cache layout.  */
  45
  46 /* From <x86/context.h>.  */
  47 static int i386nto_gregset_reg_offset[] =
  48 {
  49   7 * 4,                        /* %eax */
  50   6 * 4,                        /* %ecx */
  51   5 * 4,                        /* %edx */
  52   4 * 4,                        /* %ebx */
  53   11 * 4,                       /* %esp */
  54   2 * 4,                        /* %epb */
  55   1 * 4,                        /* %esi */
  56   0 * 4,                        /* %edi */
  57   8 * 4,                        /* %eip */
  58   10 * 4,                       /* %eflags */
  59   9 * 4,                        /* %cs */
  60   12 * 4,                       /* %ss */
  61   -1                            /* filler */
  62 };
  63
  64 /* Given a GDB register number REGNUM, return the offset into
  65    Neutrino's register structure or -1 if the register is unknown.  */
  66
  67 static int
  68 nto_reg_offset (int regnum)
  69 {
  70   if (regnum >= 0 && regnum < ARRAY_SIZE (i386nto_gregset_reg_offset))
  71     return i386nto_gregset_reg_offset[regnum];
  72
  73   return -1;
  74 }
  75
  76 static void
  77 i386nto_supply_gregset (struct regcache *regcache, char *gpregs)
  78 {
  79   struct gdbarch *gdbarch = regcache->arch ();
  80   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  81
  82   gdb_assert (tdep->gregset_reg_offset == i386nto_gregset_reg_offset);
  83   i386_gregset.supply_regset (&i386_gregset, regcache, -1,
  84                               gpregs, NUM_GPREGS * 4);
  85 }
  86
  87 static void
  88 i386nto_supply_fpregset (struct regcache *regcache, char *fpregs)
  89 {
  90   if (nto_cpuinfo_valid && nto_cpuinfo_flags | X86_CPU_FXSR)
  91     i387_supply_fxsave (regcache, -1, fpregs);
  92   else
  93     i387_supply_fsave (regcache, -1, fpregs);
  94 }
  95
  96 static void
  97 i386nto_supply_regset (struct regcache *regcache, int regset, char *data)
  98 {
  99   switch (regset)
 100     {
 101     case NTO_REG_GENERAL:
 102       i386nto_supply_gregset (regcache, data);
 103       break;
 104     case NTO_REG_FLOAT:
 105       i386nto_supply_fpregset (regcache, data);
 106       break;
 107     }
 108 }
 109
 110 static int
 111 i386nto_regset_id (int regno)
 112 {
 113   if (regno == -1)
 114     return NTO_REG_END;
 115   else if (regno < I386_NUM_GREGS)
 116     return NTO_REG_GENERAL;
 117   else if (regno < I386_NUM_GREGS + I387_NUM_REGS)
 118     return NTO_REG_FLOAT;
 119   else if (regno < I386_SSE_NUM_REGS)
 120     return NTO_REG_FLOAT; /* We store xmm registers in fxsave_area.  */
 121
 122   return -1;                    /* Error.  */
 123 }
 124
 125 static int
 126 i386nto_register_area (struct gdbarch *gdbarch,
 127                        int regno, int regset, unsigned *off)
 128 {
 129   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 130
 131   *off = 0;
 132   if (regset == NTO_REG_GENERAL)
 133     {
 134       if (regno == -1)
 135         return NUM_GPREGS * 4;
 136
 137       *off = nto_reg_offset (regno);
 138       if (*off == -1)
 139         return 0;
 140       return 4;
 141     }
 142   else if (regset == NTO_REG_FLOAT)
 143     {
 144       unsigned off_adjust, regsize, regset_size, regno_base;
 145       /* The following are flags indicating number in our fxsave_area.  */
 146       int first_four = (regno >= I387_FCTRL_REGNUM (tdep)
 147                         && regno <= I387_FISEG_REGNUM (tdep));
 148       int second_four = (regno > I387_FISEG_REGNUM (tdep)
 149                          && regno <= I387_FOP_REGNUM (tdep));
 150       int st_reg = (regno >= I387_ST0_REGNUM (tdep)
 151                     && regno < I387_ST0_REGNUM (tdep) + 8);
 152       int xmm_reg = (regno >= I387_XMM0_REGNUM (tdep)
 153                      && regno < I387_MXCSR_REGNUM (tdep));
 154
 155       if (nto_cpuinfo_valid && nto_cpuinfo_flags | X86_CPU_FXSR)
 156         {
 157           off_adjust = 32;
 158           regsize = 16;
 159           regset_size = 512;
 160           /* fxsave_area structure.  */
 161           if (first_four)
 162             {
 163               /* fpu_control_word, fpu_status_word, fpu_tag_word, fpu_operand
 164                  registers.  */
 165               regsize = 2; /* Two bytes each.  */
 166               off_adjust = 0;
 167               regno_base = I387_FCTRL_REGNUM (tdep);
 168             }
 169           else if (second_four)
 170             {
 171               /* fpu_ip, fpu_cs, fpu_op, fpu_ds registers.  */
 172               regsize = 4;
 173               off_adjust = 8;
 174               regno_base = I387_FISEG_REGNUM (tdep) + 1;
 175             }
 176           else if (st_reg)
 177             {
 178               /* ST registers.  */
 179               regsize = 16;
 180               off_adjust = 32;
 181               regno_base = I387_ST0_REGNUM (tdep);
 182             }
 183           else if (xmm_reg)
 184             {
 185               /* XMM registers.  */
 186               regsize = 16;
 187               off_adjust = 160;
 188               regno_base = I387_XMM0_REGNUM (tdep);
 189             }
 190           else if (regno == I387_MXCSR_REGNUM (tdep))
 191             {
 192               regsize = 4;
 193               off_adjust = 24;
 194               regno_base = I387_MXCSR_REGNUM (tdep);
 195             }
 196           else
 197             {
 198               /* Whole regset.  */
 199               gdb_assert (regno == -1);
 200               off_adjust = 0;
 201               regno_base = 0;
 202               regsize = regset_size;
 203             }
 204         }
 205       else
 206         {
 207           regset_size = 108;
 208           /* fsave_area structure.  */
 209           if (first_four || second_four)
 210             {
 211               /* fpu_control_word, ... , fpu_ds registers.  */
 212               regsize = 4;
 213               off_adjust = 0;
 214               regno_base = I387_FCTRL_REGNUM (tdep);
 215             }
 216           else if (st_reg)
 217             {
 218               /* One of ST registers.  */
 219               regsize = 10;
 220               off_adjust = 7 * 4;
 221               regno_base = I387_ST0_REGNUM (tdep);
 222             }
 223           else
 224             {
 225               /* Whole regset.  */
 226               gdb_assert (regno == -1);
 227               off_adjust = 0;
 228               regno_base = 0;
 229               regsize = regset_size;
 230             }
 231         }
 232
 233       if (regno != -1)
 234         *off = off_adjust + (regno - regno_base) * regsize;
 235       else
 236         *off = 0;
 237       return regsize;
 238     }
 239   return -1;
 240 }
 241
 242 static int
 243 i386nto_regset_fill (const struct regcache *regcache, int regset, char *data)
 244 {
 245   if (regset == NTO_REG_GENERAL)
 246     {
 247       int regno;
 248
 249       for (regno = 0; regno < NUM_GPREGS; regno++)
 250         {
 251           int offset = nto_reg_offset (regno);
 252           if (offset != -1)
 253             regcache->raw_collect (regno, data + offset);
 254         }
 255     }
 256   else if (regset == NTO_REG_FLOAT)
 257     {
 258       if (nto_cpuinfo_valid && nto_cpuinfo_flags | X86_CPU_FXSR)
 259         i387_collect_fxsave (regcache, -1, data);
 260       else
 261         i387_collect_fsave (regcache, -1, data);
 262     }
 263   else
 264     return -1;
 265
 266   return 0;
 267 }
 268
 269 /* Return whether THIS_FRAME corresponds to a QNX Neutrino sigtramp
 270    routine.  */
 271
 272 static int
 273 i386nto_sigtramp_p (struct frame_info *this_frame)
 274 {
 275   CORE_ADDR pc = get_frame_pc (this_frame);
 276   const char *name;
 277
 278   find_pc_partial_function (pc, &name, NULL, NULL);
 279   return name && strcmp ("__signalstub", name) == 0;
 280 }
 281
 282 /* Assuming THIS_FRAME is a QNX Neutrino sigtramp routine, return the
 283    address of the associated sigcontext structure.  */
 284
 285 static CORE_ADDR
 286 i386nto_sigcontext_addr (struct frame_info *this_frame)
 287 {
 288   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 289   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 290   gdb_byte buf[4];
 291   CORE_ADDR ptrctx;
 292
 293   /* We store __ucontext_t addr in EDI register.  */
 294   get_frame_register (this_frame, I386_EDI_REGNUM, buf);
 295   ptrctx = extract_unsigned_integer (buf, 4, byte_order);
 296   ptrctx += 24 /* Context pointer is at this offset.  */;
 297
 298   return ptrctx;
 299 }
 300
 301 static void
 302 init_i386nto_ops (void)
 303 {
 304   nto_regset_id = i386nto_regset_id;
 305   nto_supply_gregset = i386nto_supply_gregset;
 306   nto_supply_fpregset = i386nto_supply_fpregset;
 307   nto_supply_altregset = nto_dummy_supply_regset;
 308   nto_supply_regset = i386nto_supply_regset;
 309   nto_register_area = i386nto_register_area;
 310   nto_regset_fill = i386nto_regset_fill;
 311   nto_fetch_link_map_offsets =
 312     svr4_ilp32_fetch_link_map_offsets;
 313 }
 314
 315 static void
 316 i386nto_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 317 {
 318   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 319   static struct target_so_ops nto_svr4_so_ops;
 320
 321   /* Deal with our strange signals.  */
 322   nto_initialize_signals ();
 323
 324   /* NTO uses ELF.  */
 325   i386_elf_init_abi (info, gdbarch);
 326
 327   /* Neutrino rewinds to look more normal.  Need to override the i386
 328      default which is [unfortunately] to decrement the PC.  */
 329   set_gdbarch_decr_pc_after_break (gdbarch, 0);
 330
 331   tdep->gregset_reg_offset = i386nto_gregset_reg_offset;
 332   tdep->gregset_num_regs = ARRAY_SIZE (i386nto_gregset_reg_offset);
 333   tdep->sizeof_gregset = NUM_GPREGS * 4;
 334
 335   tdep->sigtramp_p = i386nto_sigtramp_p;
 336   tdep->sigcontext_addr = i386nto_sigcontext_addr;
 337   tdep->sc_reg_offset = i386nto_gregset_reg_offset;
 338   tdep->sc_num_regs = ARRAY_SIZE (i386nto_gregset_reg_offset);
 339
 340   /* Setjmp()'s return PC saved in EDX (5).  */
 341   tdep->jb_pc_offset = 20;      /* 5x32 bit ints in.  */
 342
 343   set_solib_svr4_fetch_link_map_offsets
 344     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 345
 346   /* Initialize this lazily, to avoid an initialization order
 347      dependency on solib-svr4.c's _initialize routine.  */
 348   if (nto_svr4_so_ops.in_dynsym_resolve_code == NULL)
 349     {
 350       nto_svr4_so_ops = svr4_so_ops;
 351
 352       /* Our loader handles solib relocations differently than svr4.  */
 353       nto_svr4_so_ops.relocate_section_addresses
 354         = nto_relocate_section_addresses;
 355
 356       /* Supply a nice function to find our solibs.  */
 357       nto_svr4_so_ops.find_and_open_solib
 358         = nto_find_and_open_solib;
 359
 360       /* Our linker code is in libc.  */
 361       nto_svr4_so_ops.in_dynsym_resolve_code
 362         = nto_in_dynsym_resolve_code;
 363     }
 364   set_solib_ops (gdbarch, &nto_svr4_so_ops);
 365
 366   set_gdbarch_wchar_bit (gdbarch, 32);
 367   set_gdbarch_wchar_signed (gdbarch, 0);
 368 }
 369
 370 void _initialize_i386nto_tdep ();
 371 void
 372 _initialize_i386nto_tdep ()
 373 {
 374   init_i386nto_ops ();
 375   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_QNXNTO,
 376                           i386nto_init_abi);
 377   gdbarch_register_osabi_sniffer (bfd_arch_i386, bfd_target_elf_flavour,
 378                                   nto_elf_osabi_sniffer);
 379 }