gdb/m68k-linux-nat.c

   1 /* Motorola m68k native support for GNU/Linux.
   2
   3    Copyright (C) 1996-2021 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 "frame.h"
  22 #include "inferior.h"
  23 #include "language.h"
  24 #include "gdbcore.h"
  25 #include "regcache.h"
  26 #include "target.h"
  27 #include "linux-nat.h"
  28 #include "gdbarch.h"
  29
  30 #include "m68k-tdep.h"
  31
  32 #include <sys/dir.h>
  33 #include <signal.h>
  34 #include "nat/gdb_ptrace.h"
  35 #include <sys/user.h>
  36 #include <sys/ioctl.h>
  37 #include <fcntl.h>
  38 #include <sys/procfs.h>
  39
  40 #ifdef HAVE_SYS_REG_H
  41 #include <sys/reg.h>
  42 #endif
  43
  44 #include <sys/file.h>
  45 #include <sys/stat.h>
  46
  47 #include "floatformat.h"
  48
  49 /* Prototypes for supply_gregset etc.  */
  50 #include "gregset.h"
  51
  52 /* Defines ps_err_e, struct ps_prochandle.  */
  53 #include "gdb_proc_service.h"
  54
  55 #include "inf-ptrace.h"
  56
  57 #ifndef PTRACE_GET_THREAD_AREA
  58 #define PTRACE_GET_THREAD_AREA 25
  59 #endif
  60 \f
  61
  62 class m68k_linux_nat_target final : public linux_nat_target
  63 {
  64 public:
  65   /* Add our register access methods.  */
  66   void fetch_registers (struct regcache *, int) override;
  67   void store_registers (struct regcache *, int) override;
  68 };
  69
  70 static m68k_linux_nat_target the_m68k_linux_nat_target;
  71
  72 /* This table must line up with gdbarch_register_name in "m68k-tdep.c".  */
  73 static const int regmap[] =
  74 {
  75   PT_D0, PT_D1, PT_D2, PT_D3, PT_D4, PT_D5, PT_D6, PT_D7,
  76   PT_A0, PT_A1, PT_A2, PT_A3, PT_A4, PT_A5, PT_A6, PT_USP,
  77   PT_SR, PT_PC,
  78   /* PT_FP0, ..., PT_FP7 */
  79   21, 24, 27, 30, 33, 36, 39, 42,
  80   /* PT_FPCR, PT_FPSR, PT_FPIAR */
  81   45, 46, 47
  82 };
  83
  84 /* Which ptrace request retrieves which registers?
  85    These apply to the corresponding SET requests as well.  */
  86 #define NUM_GREGS (18)
  87 #define MAX_NUM_REGS (NUM_GREGS + 11)
  88
  89 static int
  90 getregs_supplies (int regno)
  91 {
  92   return 0 <= regno && regno < NUM_GREGS;
  93 }
  94
  95 static int
  96 getfpregs_supplies (int regno)
  97 {
  98   return M68K_FP0_REGNUM <= regno && regno <= M68K_FPI_REGNUM;
  99 }
 100
 101 /* Does the current host support the GETREGS request?  */
 102 static int have_ptrace_getregs =
 103 #ifdef HAVE_PTRACE_GETREGS
 104   1
 105 #else
 106   0
 107 #endif
 108 ;
 109
 110 \f
 111
 112 /* Fetching registers directly from the U area, one at a time.  */
 113
 114 /* Fetch one register.  */
 115
 116 static void
 117 fetch_register (struct regcache *regcache, int regno)
 118 {
 119   struct gdbarch *gdbarch = regcache->arch ();
 120   long regaddr, val;
 121   int i;
 122   gdb_byte buf[M68K_MAX_REGISTER_SIZE];
 123   pid_t tid = get_ptrace_pid (regcache->ptid ());
 124
 125   regaddr = 4 * regmap[regno];
 126   for (i = 0; i < register_size (gdbarch, regno); i += sizeof (long))
 127     {
 128       errno = 0;
 129       val = ptrace (PTRACE_PEEKUSER, tid, regaddr, 0);
 130       memcpy (&buf[i], &val, sizeof (long));
 131       regaddr += sizeof (long);
 132       if (errno != 0)
 133         error (_("Couldn't read register %s (#%d): %s."),
 134                gdbarch_register_name (gdbarch, regno),
 135                regno, safe_strerror (errno));
 136     }
 137   regcache->raw_supply (regno, buf);
 138 }
 139
 140 /* Fetch register values from the inferior.
 141    If REGNO is negative, do this for all registers.
 142    Otherwise, REGNO specifies which register (so we can save time).  */
 143
 144 static void
 145 old_fetch_inferior_registers (struct regcache *regcache, int regno)
 146 {
 147   if (regno >= 0)
 148     {
 149       fetch_register (regcache, regno);
 150     }
 151   else
 152     {
 153       for (regno = 0;
 154            regno < gdbarch_num_regs (regcache->arch ());
 155            regno++)
 156         {
 157           fetch_register (regcache, regno);
 158         }
 159     }
 160 }
 161
 162 /* Store one register.  */
 163
 164 static void
 165 store_register (const struct regcache *regcache, int regno)
 166 {
 167   struct gdbarch *gdbarch = regcache->arch ();
 168   long regaddr, val;
 169   int i;
 170   gdb_byte buf[M68K_MAX_REGISTER_SIZE];
 171   pid_t tid = get_ptrace_pid (regcache->ptid ());
 172
 173   regaddr = 4 * regmap[regno];
 174
 175   /* Put the contents of regno into a local buffer.  */
 176   regcache->raw_collect (regno, buf);
 177
 178   /* Store the local buffer into the inferior a chunk at the time.  */
 179   for (i = 0; i < register_size (gdbarch, regno); i += sizeof (long))
 180     {
 181       errno = 0;
 182       memcpy (&val, &buf[i], sizeof (long));
 183       ptrace (PTRACE_POKEUSER, tid, regaddr, val);
 184       regaddr += sizeof (long);
 185       if (errno != 0)
 186         error (_("Couldn't write register %s (#%d): %s."),
 187                gdbarch_register_name (gdbarch, regno),
 188                regno, safe_strerror (errno));
 189     }
 190 }
 191
 192 /* Store our register values back into the inferior.
 193    If REGNO is negative, do this for all registers.
 194    Otherwise, REGNO specifies which register (so we can save time).  */
 195
 196 static void
 197 old_store_inferior_registers (const struct regcache *regcache, int regno)
 198 {
 199   if (regno >= 0)
 200     {
 201       store_register (regcache, regno);
 202     }
 203   else
 204     {
 205       for (regno = 0;
 206            regno < gdbarch_num_regs (regcache->arch ());
 207            regno++)
 208         {
 209           store_register (regcache, regno);
 210         }
 211     }
 212 }
 213 \f
 214 /*  Given a pointer to a general register set in /proc format
 215    (elf_gregset_t *), unpack the register contents and supply
 216    them as gdb's idea of the current register values.  */
 217
 218 void
 219 supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
 220 {
 221   struct gdbarch *gdbarch = regcache->arch ();
 222   const elf_greg_t *regp = (const elf_greg_t *) gregsetp;
 223   int regi;
 224
 225   for (regi = M68K_D0_REGNUM;
 226        regi <= gdbarch_sp_regnum (gdbarch);
 227        regi++)
 228     regcache->raw_supply (regi, &regp[regmap[regi]]);
 229   regcache->raw_supply (gdbarch_ps_regnum (gdbarch), &regp[PT_SR]);
 230   regcache->raw_supply (gdbarch_pc_regnum (gdbarch), &regp[PT_PC]);
 231 }
 232
 233 /* Fill register REGNO (if it is a general-purpose register) in
 234    *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
 235    do this for all registers.  */
 236 void
 237 fill_gregset (const struct regcache *regcache,
 238               elf_gregset_t *gregsetp, int regno)
 239 {
 240   elf_greg_t *regp = (elf_greg_t *) gregsetp;
 241   int i;
 242
 243   for (i = 0; i < NUM_GREGS; i++)
 244     if (regno == -1 || regno == i)
 245       regcache->raw_collect (i, regp + regmap[i]);
 246 }
 247
 248 #ifdef HAVE_PTRACE_GETREGS
 249
 250 /* Fetch all general-purpose registers from process/thread TID and
 251    store their values in GDB's register array.  */
 252
 253 static void
 254 fetch_regs (struct regcache *regcache, int tid)
 255 {
 256   elf_gregset_t regs;
 257
 258   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 259     {
 260       if (errno == EIO)
 261         {
 262           /* The kernel we're running on doesn't support the GETREGS
 263              request.  Reset `have_ptrace_getregs'.  */
 264           have_ptrace_getregs = 0;
 265           return;
 266         }
 267
 268       perror_with_name (_("Couldn't get registers"));
 269     }
 270
 271   supply_gregset (regcache, (const elf_gregset_t *) &regs);
 272 }
 273
 274 /* Store all valid general-purpose registers in GDB's register array
 275    into the process/thread specified by TID.  */
 276
 277 static void
 278 store_regs (const struct regcache *regcache, int tid, int regno)
 279 {
 280   elf_gregset_t regs;
 281
 282   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 283     perror_with_name (_("Couldn't get registers"));
 284
 285   fill_gregset (regcache, &regs, regno);
 286
 287   if (ptrace (PTRACE_SETREGS, tid, 0, (int) &regs) < 0)
 288     perror_with_name (_("Couldn't write registers"));
 289 }
 290
 291 #else
 292
 293 static void fetch_regs (struct regcache *regcache, int tid)
 294 {
 295 }
 296
 297 static void store_regs (const struct regcache *regcache, int tid, int regno)
 298 {
 299 }
 300
 301 #endif
 302
 303 \f
 304 /* Transfering floating-point registers between GDB, inferiors and cores.  */
 305
 306 /* What is the address of fpN within the floating-point register set F?  */
 307 #define FPREG_ADDR(f, n) (&(f)->fpregs[(n) * 3])
 308
 309 /* Fill GDB's register array with the floating-point register values in
 310    *FPREGSETP.  */
 311
 312 void
 313 supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
 314 {
 315   struct gdbarch *gdbarch = regcache->arch ();
 316   int regi;
 317
 318   for (regi = gdbarch_fp0_regnum (gdbarch);
 319        regi < gdbarch_fp0_regnum (gdbarch) + 8; regi++)
 320     regcache->raw_supply
 321       (regi, FPREG_ADDR (fpregsetp, regi - gdbarch_fp0_regnum (gdbarch)));
 322   regcache->raw_supply (M68K_FPC_REGNUM, &fpregsetp->fpcntl[0]);
 323   regcache->raw_supply (M68K_FPS_REGNUM, &fpregsetp->fpcntl[1]);
 324   regcache->raw_supply (M68K_FPI_REGNUM, &fpregsetp->fpcntl[2]);
 325 }
 326
 327 /* Fill register REGNO (if it is a floating-point register) in
 328    *FPREGSETP with the value in GDB's register array.  If REGNO is -1,
 329    do this for all registers.  */
 330
 331 void
 332 fill_fpregset (const struct regcache *regcache,
 333                elf_fpregset_t *fpregsetp, int regno)
 334 {
 335   struct gdbarch *gdbarch = regcache->arch ();
 336   int i;
 337
 338   /* Fill in the floating-point registers.  */
 339   for (i = gdbarch_fp0_regnum (gdbarch);
 340        i < gdbarch_fp0_regnum (gdbarch) + 8; i++)
 341     if (regno == -1 || regno == i)
 342       regcache->raw_collect
 343         (i, FPREG_ADDR (fpregsetp, i - gdbarch_fp0_regnum (gdbarch)));
 344
 345   /* Fill in the floating-point control registers.  */
 346   for (i = M68K_FPC_REGNUM; i <= M68K_FPI_REGNUM; i++)
 347     if (regno == -1 || regno == i)
 348       regcache->raw_collect (i, &fpregsetp->fpcntl[i - M68K_FPC_REGNUM]);
 349 }
 350
 351 #ifdef HAVE_PTRACE_GETREGS
 352
 353 /* Fetch all floating-point registers from process/thread TID and store
 354    thier values in GDB's register array.  */
 355
 356 static void
 357 fetch_fpregs (struct regcache *regcache, int tid)
 358 {
 359   elf_fpregset_t fpregs;
 360
 361   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 362     perror_with_name (_("Couldn't get floating point status"));
 363
 364   supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
 365 }
 366
 367 /* Store all valid floating-point registers in GDB's register array
 368    into the process/thread specified by TID.  */
 369
 370 static void
 371 store_fpregs (const struct regcache *regcache, int tid, int regno)
 372 {
 373   elf_fpregset_t fpregs;
 374
 375   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 376     perror_with_name (_("Couldn't get floating point status"));
 377
 378   fill_fpregset (regcache, &fpregs, regno);
 379
 380   if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
 381     perror_with_name (_("Couldn't write floating point status"));
 382 }
 383
 384 #else
 385
 386 static void fetch_fpregs (struct regcache *regcache, int tid)
 387 {
 388 }
 389
 390 static void store_fpregs (const struct regcache *regcache, int tid, int regno)
 391 {
 392 }
 393
 394 #endif
 395 \f
 396 /* Transferring arbitrary registers between GDB and inferior.  */
 397
 398 /* Fetch register REGNO from the child process.  If REGNO is -1, do
 399    this for all registers (including the floating point and SSE
 400    registers).  */
 401
 402 void
 403 m68k_linux_nat_target::fetch_registers (struct regcache *regcache, int regno)
 404 {
 405   pid_t tid;
 406
 407   /* Use the old method of peeking around in `struct user' if the
 408      GETREGS request isn't available.  */
 409   if (! have_ptrace_getregs)
 410     {
 411       old_fetch_inferior_registers (regcache, regno);
 412       return;
 413     }
 414
 415   tid = get_ptrace_pid (regcache->ptid ());
 416
 417   /* Use the PTRACE_GETFPXREGS request whenever possible, since it
 418      transfers more registers in one system call, and we'll cache the
 419      results.  But remember that fetch_fpxregs can fail, and return
 420      zero.  */
 421   if (regno == -1)
 422     {
 423       fetch_regs (regcache, tid);
 424
 425       /* The call above might reset `have_ptrace_getregs'.  */
 426       if (! have_ptrace_getregs)
 427         {
 428           old_fetch_inferior_registers (regcache, -1);
 429           return;
 430         }
 431
 432       fetch_fpregs (regcache, tid);
 433       return;
 434     }
 435
 436   if (getregs_supplies (regno))
 437     {
 438       fetch_regs (regcache, tid);
 439       return;
 440     }
 441
 442   if (getfpregs_supplies (regno))
 443     {
 444       fetch_fpregs (regcache, tid);
 445       return;
 446     }
 447
 448   internal_error (__FILE__, __LINE__,
 449                   _("Got request for bad register number %d."), regno);
 450 }
 451
 452 /* Store register REGNO back into the child process.  If REGNO is -1,
 453    do this for all registers (including the floating point and SSE
 454    registers).  */
 455 void
 456 m68k_linux_nat_target::store_registers (struct regcache *regcache, int regno)
 457 {
 458   pid_t tid;
 459
 460   /* Use the old method of poking around in `struct user' if the
 461      SETREGS request isn't available.  */
 462   if (! have_ptrace_getregs)
 463     {
 464       old_store_inferior_registers (regcache, regno);
 465       return;
 466     }
 467
 468   tid = get_ptrace_pid (regcache->ptid ());
 469
 470   /* Use the PTRACE_SETFPREGS requests whenever possible, since it
 471      transfers more registers in one system call.  But remember that
 472      store_fpregs can fail, and return zero.  */
 473   if (regno == -1)
 474     {
 475       store_regs (regcache, tid, regno);
 476       store_fpregs (regcache, tid, regno);
 477       return;
 478     }
 479
 480   if (getregs_supplies (regno))
 481     {
 482       store_regs (regcache, tid, regno);
 483       return;
 484     }
 485
 486   if (getfpregs_supplies (regno))
 487     {
 488       store_fpregs (regcache, tid, regno);
 489       return;
 490     }
 491
 492   internal_error (__FILE__, __LINE__,
 493                   _("Got request to store bad register number %d."), regno);
 494 }
 495 \f
 496
 497 /* Fetch the thread-local storage pointer for libthread_db.  */
 498
 499 ps_err_e
 500 ps_get_thread_area (struct ps_prochandle *ph,
 501                     lwpid_t lwpid, int idx, void **base)
 502 {
 503   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) < 0)
 504     return PS_ERR;
 505
 506   /* IDX is the bias from the thread pointer to the beginning of the
 507      thread descriptor.  It has to be subtracted due to implementation
 508      quirks in libthread_db.  */
 509   *base = (char *) *base - idx;
 510
 511   return PS_OK;
 512 }
 513
 514 void _initialize_m68k_linux_nat ();
 515 void
 516 _initialize_m68k_linux_nat ()
 517 {
 518   /* Register the target.  */
 519   linux_target = &the_m68k_linux_nat_target;
 520   add_inf_child_target (&the_m68k_linux_nat_target);
 521 }