gdb/ia64-hpux-tdep.c

   1 /* Target-dependent code for the IA-64 for GDB, the GNU debugger.
   2
   3    Copyright (C) 2010 Free Software Foundation, 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "ia64-tdep.h"
  22 #include "ia64-hpux-tdep.h"
  23 #include "osabi.h"
  24 #include "gdbtypes.h"
  25 #include "solib.h"
  26 #include "target.h"
  27 #include "frame.h"
  28 #include "regcache.h"
  29 #include "gdbcore.h"
  30 #include "inferior.h"
  31
  32 /* A sequence of instructions pushed on the stack when we want to perform
  33    an inferior function call.  The main purpose of this code is to save
  34    the output region of the register frame belonging to the function
  35    from which we are making the call.  Normally, all registers are saved
  36    prior to the call, but this does not include stacked registers because
  37    they are seen by GDB as pseudo registers.
  38
  39    With Linux kernels, these stacked registers can be saved by simply
  40    creating a new register frame, or in other words by moving the BSP.
  41    But the HP/UX kernel does not allow this.  So we rely on this code
  42    instead, that makes functions calls whose only purpose is to create
  43    new register frames.
  44
  45    The array below is the result obtained after assembling the code
  46    shown below. It's an array of bytes in order to make it independent
  47    of the host endianess, in case it ends up being used on more than
  48    one target.
  49
  50    start:
  51         // Save b0 before using it (into preserved reg: r4).
  52         mov r4 = b0
  53         ;;
  54
  55         br.call.dptk.few b0 = stub#
  56         ;;
  57
  58         // Add a nop bundle where we can insert our dummy breakpoint.
  59         nop.m 0
  60         nop.i 0
  61         nop.i 0
  62         ;;
  63
  64    stub:
  65         // Alloc a new register stack frame.  Here, we set the size
  66         // of all regions to zero.  Eventually, GDB will manually
  67         // change the instruction to set the size of the local region
  68         // to match size of the output region of the function from
  69         // which we are making the function call.  This is to protect
  70         // the value of the output registers of the function from
  71         // which we are making the call.
  72         alloc r6 = ar.pfs, 0, 0, 0, 0
  73
  74         // Save b0 before using it again (into preserved reg: r5).
  75         mov r5 = b0
  76         ;;
  77
  78         //  Now that we have protected the entire output region of the
  79         //  register stack frame, we can call our function that will
  80         //  setup the arguments, and call our target function.
  81         br.call.dptk.few b0 = call_dummy#
  82         ;;
  83
  84         //  Restore b0, ar.pfs, and return
  85         mov b0 = r5
  86         mov.i ar.pfs = r6
  87         ;;
  88         br.ret.dptk.few b0
  89         ;;
  90
  91    call_dummy:
  92         //  Alloc a new frame, with 2 local registers, and 8 output registers
  93         //  (8 output registers for the maximum of 8 slots passed by register).
  94         alloc r32 = ar.pfs, 2, 0, 8, 0
  95
  96         //  Save b0 before using it to call our target function.
  97         mov r33 = b0
  98
  99         // Load the argument values placed by GDB inside r14-r21 in their
 100         // proper registers.
 101         or r34 = r14, r0
 102         or r35 = r15, r0
 103         or r36 = r16, r0
 104         or r37 = r17, r0
 105         or r38 = r18, r0
 106         or r39 = r19, r0
 107         or r40 = r20, r0
 108         or r41 = r21, r0
 109         ;;
 110
 111         // actual call
 112         br.call.dptk.few b0 = b1
 113         ;;
 114
 115         mov.i ar.pfs=r32
 116         mov b0=r33
 117         ;;
 118
 119         br.ret.dptk.few b0
 120         ;;
 121
 122 */
 123
 124 static const gdb_byte ia64_hpux_dummy_code[] =
 125 {
 126   0x02, 0x00, 0x00, 0x00, 0x01, 0x00, 0x40, 0x00,
 127   0x00, 0x62, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
 128   0x1d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 129   0x00, 0x02, 0x00, 0x00, 0x20, 0x00, 0x00, 0x52,
 130   0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 131   0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
 132   0x02, 0x30, 0x00, 0x00, 0x80, 0x05, 0x50, 0x00,
 133   0x00, 0x62, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
 134   0x1d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 135   0x00, 0x02, 0x00, 0x00, 0x30, 0x00, 0x00, 0x52,
 136   0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x28,
 137   0x04, 0x80, 0x03, 0x00, 0x60, 0x00, 0xaa, 0x00,
 138   0x1d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 139   0x00, 0x02, 0x00, 0x80, 0x00, 0x00, 0x84, 0x02,
 140   0x00, 0x00, 0x29, 0x04, 0x80, 0x05, 0x10, 0x02,
 141   0x00, 0x62, 0x00, 0x40, 0xe4, 0x00, 0x38, 0x80,
 142   0x00, 0x18, 0x3d, 0x00, 0x0e, 0x20, 0x40, 0x82,
 143   0x00, 0x1c, 0x40, 0xa0, 0x14, 0x01, 0x38, 0x80,
 144   0x00, 0x30, 0x49, 0x00, 0x0e, 0x20, 0x70, 0x9a,
 145   0x00, 0x1c, 0x40, 0x00, 0x45, 0x01, 0x38, 0x80,
 146   0x0a, 0x48, 0x55, 0x00, 0x0e, 0x20, 0x00, 0x00,
 147   0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
 148   0x1d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 149   0x00, 0x02, 0x00, 0x00, 0x10, 0x00, 0x80, 0x12,
 150   0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 151   0x01, 0x55, 0x00, 0x00, 0x10, 0x0a, 0x00, 0x07,
 152   0x1d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 153   0x00, 0x02, 0x00, 0x80, 0x00, 0x00, 0x84, 0x02
 154 };
 155
 156 /* The offset to be used in order to get the __reason pseudo-register
 157    when using one of the *UREGS ttrace requests (see system header file
 158    /usr/include/ia64/sys/uregs.h for more details).
 159
 160    The documentation for this pseudo-register says that a nonzero value
 161    indicates that the thread stopped due to a fault, trap, or interrupt.
 162    A null value indicates a stop inside a syscall.  */
 163 #define IA64_HPUX_UREG_REASON 0x00070000
 164
 165 /* Return nonzero if the value of the register identified by REGNUM
 166    can be modified.  */
 167
 168 static int
 169 ia64_hpux_can_store_ar_register (int regnum)
 170 {
 171   switch (regnum)
 172     {
 173       case IA64_RSC_REGNUM:
 174       case IA64_RNAT_REGNUM:
 175       case IA64_CSD_REGNUM:
 176       case IA64_SSD_REGNUM:
 177       case IA64_CCV_REGNUM:
 178       case IA64_UNAT_REGNUM:
 179       case IA64_FPSR_REGNUM:
 180       case IA64_PFS_REGNUM:
 181       case IA64_LC_REGNUM:
 182       case IA64_EC_REGNUM:
 183          return 1;
 184          break;
 185
 186       default:
 187          return 0;
 188          break;
 189     }
 190 }
 191
 192 /* The "cannot_store_register" target_ops method.  */
 193
 194 static int
 195 ia64_hpux_cannot_store_register (struct gdbarch *gdbarch, int regnum)
 196 {
 197   /* General registers.  */
 198
 199   if (regnum == IA64_GR0_REGNUM)
 200     return 1;
 201
 202   /* FP register.  */
 203
 204   if (regnum == IA64_FR0_REGNUM || regnum == IA64_FR1_REGNUM)
 205     return 1;
 206
 207   /* Application registers.  */
 208   if (regnum >= IA64_AR0_REGNUM && regnum <= IA64_AR0_REGNUM + 127)
 209     return (!ia64_hpux_can_store_ar_register (regnum));
 210
 211   /* We can store all other registers.  */
 212   return 0;
 213 }
 214
 215 /* Return nonzero if the inferior is stopped inside a system call.  */
 216
 217 static int
 218 ia64_hpux_stopped_in_syscall (struct gdbarch *gdbarch)
 219 {
 220   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 221   struct target_ops *ops = &current_target;
 222   gdb_byte buf[8];
 223   int len;
 224
 225   len = target_read (ops, TARGET_OBJECT_HPUX_UREGS, NULL,
 226                      buf, IA64_HPUX_UREG_REASON, sizeof (buf));
 227   if (len == -1)
 228     /* The target wasn't able to tell us.  Assume we are not stopped
 229        in a system call, which is the normal situation.  */
 230     return 0;
 231   gdb_assert (len == 8);
 232
 233   return (extract_unsigned_integer (buf, len, byte_order) == 0);
 234 }
 235
 236 /* The "size_of_register_frame" gdbarch_tdep routine for ia64-hpux.  */
 237
 238 static int
 239 ia64_hpux_size_of_register_frame (struct frame_info *this_frame,
 240                                   ULONGEST cfm)
 241 {
 242   int sof;
 243
 244   if (frame_relative_level (this_frame) == 0
 245       && ia64_hpux_stopped_in_syscall (get_frame_arch (this_frame)))
 246     /* If the inferior stopped in a system call, the base address
 247        of the register frame is at BSP - SOL instead of BSP - SOF.
 248        This is an HP-UX exception.  */
 249     sof = (cfm & 0x3f80) >> 7;
 250   else
 251     sof = (cfm & 0x7f);
 252
 253   return sof;
 254 }
 255
 256 /* Implement the push_dummy_code gdbarch method.
 257
 258    This function assumes that the SP is already 16-byte-aligned.  */
 259
 260 static CORE_ADDR
 261 ia64_hpux_push_dummy_code (struct gdbarch *gdbarch, CORE_ADDR sp,
 262                            CORE_ADDR funaddr, struct value **args, int nargs,
 263                            struct type *value_type, CORE_ADDR *real_pc,
 264                            CORE_ADDR *bp_addr, struct regcache *regcache)
 265 {
 266   ULONGEST cfm;
 267   int sof, sol, sor, soo;
 268   char buf[16];
 269
 270   regcache_cooked_read_unsigned (regcache, IA64_CFM_REGNUM, &cfm);
 271   sof = cfm & 0x7f;
 272   sol = (cfm >> 7) & 0x7f;
 273   sor = (cfm >> 14) & 0xf;
 274   soo = sof - sol - sor;
 275
 276   /* Reserve some space on the stack to hold the dummy code.  */
 277   sp = sp - sizeof (ia64_hpux_dummy_code);
 278
 279   /* Set the breakpoint address at the first instruction of the bundle
 280      in the dummy code that has only nops.  This is where the dummy code
 281      expects us to break.  */
 282   *bp_addr = sp + 0x20;
 283
 284   /* Start the inferior function call from the dummy code.  The dummy
 285      code will then call our function.  */
 286   *real_pc = sp;
 287
 288   /* Transfer the dummy code to the inferior.  */
 289   write_memory (sp, ia64_hpux_dummy_code, sizeof (ia64_hpux_dummy_code));
 290
 291   /* Update the size of the local portion of the register frame allocated
 292      by ``stub'' to match the size of the output region of the current
 293      register frame.  This allows us to save the stacked registers.
 294
 295      The "alloc" instruction is located at slot 0 of the bundle at +0x30.
 296      Update the "sof" and "sol" portion of that instruction which are
 297      respectively at bits 18-24 and 25-31 of the bundle.  */
 298   memcpy (buf, ia64_hpux_dummy_code + 0x30, sizeof (buf));
 299
 300   buf[2] |= ((soo & 0x3f) << 2);
 301   buf[3] |= (soo << 1);
 302   if (soo > 63)
 303     buf[3] |= 1;
 304
 305   write_memory (sp + 0x30, buf, sizeof (buf));
 306
 307   /* Return the new (already properly aligned) SP.  */
 308   return sp;
 309 }
 310
 311 /* The "allocate_new_rse_frame" ia64_infcall_ops routine for ia64-hpux.  */
 312
 313 static void
 314 ia64_hpux_allocate_new_rse_frame (struct regcache *regcache, ULONGEST bsp,
 315                                   int sof)
 316 {
 317   /* We cannot change the value of the BSP register on HP-UX,
 318      so we can't allocate a new RSE frame.  */
 319 }
 320
 321 /* The "store_argument_in_slot" ia64_infcall_ops routine for ia64-hpux.  */
 322
 323 static void
 324 ia64_hpux_store_argument_in_slot (struct regcache *regcache, CORE_ADDR bsp,
 325                                   int slotnum, gdb_byte *buf)
 326 {
 327   /* The call sequence on this target expects us to place the arguments
 328      inside r14 - r21.  */
 329   regcache_cooked_write (regcache, IA64_GR0_REGNUM + 14 + slotnum, buf);
 330 }
 331
 332 /* The "set_function_addr" ia64_infcall_ops routine for ia64-hpux.  */
 333
 334 static void
 335 ia64_hpux_set_function_addr (struct regcache *regcache, CORE_ADDR func_addr)
 336 {
 337   /* The calling sequence calls the function whose address is placed
 338      in register b1.  */
 339   regcache_cooked_write_unsigned (regcache, IA64_BR1_REGNUM, func_addr);
 340 }
 341
 342 /* The ia64_infcall_ops structure for ia64-hpux.  */
 343
 344 static const struct ia64_infcall_ops ia64_hpux_infcall_ops =
 345 {
 346   ia64_hpux_allocate_new_rse_frame,
 347   ia64_hpux_store_argument_in_slot,
 348   ia64_hpux_set_function_addr
 349 };
 350
 351 /* The "dummy_id" gdbarch routine for ia64-hpux.  */
 352
 353 static struct frame_id
 354 ia64_hpux_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
 355 {
 356   CORE_ADDR sp, pc, bp_addr, bsp;
 357
 358   sp = get_frame_register_unsigned (this_frame, IA64_GR12_REGNUM);
 359
 360   /* Just double-check that the frame PC is within a certain region
 361      of the stack that would be plausible for our dummy code (the dummy
 362      code was pushed at SP + 16).  If not, then return a null frame ID.
 363      This is necessary in our case, because it is possible to produce
 364      the same frame ID for a normal frame, if that frame corresponds
 365      to the function called by our dummy code, and the function has not
 366      modified the registers that we use to build the dummy frame ID.  */
 367   pc = get_frame_pc (this_frame);
 368   if (pc < sp + 16 || pc >= sp + 16 + sizeof (ia64_hpux_dummy_code))
 369     return null_frame_id;
 370
 371   /* The call sequence is such that the address of the dummy breakpoint
 372      we inserted is stored in r5.  */
 373   bp_addr = get_frame_register_unsigned (this_frame, IA64_GR5_REGNUM);
 374
 375   bsp = get_frame_register_unsigned (this_frame, IA64_BSP_REGNUM);
 376
 377   return frame_id_build_special (sp, bp_addr, bsp);
 378 }
 379
 380 /* Should be set to non-NULL if the ia64-hpux solib module is linked in.
 381    This may not be the case because the shared library support code can
 382    only be compiled on ia64-hpux.  */
 383
 384 struct target_so_ops *ia64_hpux_so_ops = NULL;
 385
 386 /* The "find_global_pointer_from_solib" gdbarch_tdep routine for
 387    ia64-hpux.  */
 388
 389 static CORE_ADDR
 390 ia64_hpux_find_global_pointer_from_solib (struct gdbarch *gdbarch,
 391                                           CORE_ADDR faddr)
 392 {
 393   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 394   struct target_ops *ops = &current_target;
 395   gdb_byte buf[8];
 396   LONGEST len;
 397
 398   len = target_read (ops, TARGET_OBJECT_HPUX_SOLIB_GOT,
 399                      paddress (gdbarch, faddr), buf, 0, sizeof (buf));
 400
 401   return extract_unsigned_integer (buf, len, byte_order);
 402 }
 403
 404 static void
 405 ia64_hpux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 406 {
 407   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 408
 409   tdep->size_of_register_frame = ia64_hpux_size_of_register_frame;
 410
 411   set_gdbarch_long_double_format (gdbarch, floatformats_ia64_quad);
 412   set_gdbarch_cannot_store_register (gdbarch, ia64_hpux_cannot_store_register);
 413
 414   /* Inferior functions must be called from stack. */
 415   set_gdbarch_call_dummy_location (gdbarch, ON_STACK);
 416   set_gdbarch_push_dummy_code (gdbarch, ia64_hpux_push_dummy_code);
 417   tdep->infcall_ops = ia64_hpux_infcall_ops;
 418   tdep->find_global_pointer_from_solib
 419       = ia64_hpux_find_global_pointer_from_solib;
 420   set_gdbarch_dummy_id (gdbarch, ia64_hpux_dummy_id);
 421
 422   if (ia64_hpux_so_ops)
 423     set_solib_ops (gdbarch, ia64_hpux_so_ops);
 424 }
 425
 426 /* Provide a prototype to silence -Wmissing-prototypes.  */
 427 extern initialize_file_ftype _initialize_ia64_hpux_tdep;
 428
 429 void
 430 _initialize_ia64_hpux_tdep (void)
 431 {
 432   gdbarch_register_osabi (bfd_arch_ia64, 0, GDB_OSABI_HPUX_ELF,
 433                           ia64_hpux_init_abi);
 434 }