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   1 /***************************************************************************
   2  *   Copyright (C) 2009 by Marvell Technology Group Ltd.                   *
   3  *   Written by Nicolas Pitre <nico@marvell.com>                           *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20
  21 /**
  22  * @file
  23  * Hold ARM semihosting support.
  24  *
  25  * Semihosting enables code running on an ARM target to use the I/O
  26  * facilities on the host computer. The target application must be linked
  27  * against a library that forwards operation requests by using the SVC
  28  * instruction trapped at the Supervisor Call vector by the debugger.
  29  * Details can be found in chapter 8 of DUI0203I_rvct_developer_guide.pdf
  30  * from ARM Ltd.
  31  */
  32
  33 #ifdef HAVE_CONFIG_H
  34 #include "config.h"
  35 #endif
  36
  37 #include "armv4_5.h"
  38 #include "register.h"
  39 #include "arm_semihosting.h"
  40 #include <helper/binarybuffer.h>
  41 #include <helper/log.h>
  42
  43
  44 static int do_semihosting(struct target *target)
  45 {
  46         struct arm *armv4_5 = target_to_armv4_5(target);
  47         uint32_t r0 = buf_get_u32(armv4_5->core_cache->reg_list[0].value, 0, 32);
  48         uint32_t r1 = buf_get_u32(armv4_5->core_cache->reg_list[1].value, 0, 32);
  49         uint32_t lr = buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, ARMV4_5_MODE_SVC, 14).value, 0, 32);
  50         uint32_t spsr = buf_get_u32(armv4_5->spsr->value, 0, 32);;
  51         uint8_t params[16];
  52         int retval, result;
  53
  54         /*
  55          * TODO: lots of security issues are not considered yet, such as:
  56          * - no validation on target provided file descriptors
  57          * - no safety checks on opened/deleted/renamed file paths
  58          * Beware the target app you use this support with.
  59          */
  60         switch (r0) {
  61         case 0x01:      /* SYS_OPEN */
  62                 retval = target_read_memory(target, r1, 4, 3, params);
  63                 if (retval != ERROR_OK)
  64                         return retval;
  65                 else {
  66                         uint32_t a = target_buffer_get_u32(target, params+0);
  67                         uint32_t m = target_buffer_get_u32(target, params+4);
  68                         uint32_t l = target_buffer_get_u32(target, params+8);
  69                         if (l <= 255 && m <= 11) {
  70                                 uint8_t fn[256];
  71                                 int mode;
  72                                 retval = target_read_memory(target, a, 1, l, fn);
  73                                 if (retval != ERROR_OK)
  74                                         return retval;
  75                                 fn[l] = 0;
  76                                 if (m & 0x2)
  77                                         mode = O_RDWR;
  78                                 else if (m & 0xc)
  79                                         mode = O_WRONLY;
  80                                 else
  81                                         mode = O_RDONLY;
  82                                 if (m >= 8)
  83                                         mode |= O_CREAT|O_APPEND;
  84                                 else if (m >= 4)
  85                                         mode |= O_CREAT|O_TRUNC;
  86                                 if (strcmp((char *)fn, ":tt") == 0) {
  87                                         if ((mode & 3) == 0)
  88                                                 result = dup(0);
  89                                         else
  90                                                 result = dup(1);
  91                                 } else
  92                                         result = open((char *)fn, mode);
  93                                 armv4_5->semihosting_errno =  errno;
  94                         } else {
  95                                 result = -1;
  96                                 armv4_5->semihosting_errno = EINVAL;
  97                         }
  98                 }
  99                 break;
 100
 101         case 0x02:      /* SYS_CLOSE */
 102                 retval = target_read_memory(target, r1, 4, 1, params);
 103                 if (retval != ERROR_OK)
 104                         return retval;
 105                 else {
 106                         int fd = target_buffer_get_u32(target, params+0);
 107                         result = close(fd);
 108                         armv4_5->semihosting_errno = errno;
 109                 }
 110                 break;
 111
 112         case 0x03:      /* SYS_WRITEC */
 113                 {
 114                         unsigned char c;
 115                         retval = target_read_memory(target, r1, 1, 1, &c);
 116                         if (retval != ERROR_OK)
 117                                 return retval;
 118                         putchar(c);
 119                         result = 0;
 120                 }
 121                 break;
 122
 123         case 0x04:      /* SYS_WRITE0 */
 124                 do {
 125                         unsigned char c;
 126                         retval = target_read_memory(target, r1, 1, 1, &c);
 127                         if (retval != ERROR_OK)
 128                                 return retval;
 129                         if (!c)
 130                                 break;
 131                         putchar(c);
 132                 } while (1);
 133                 result = 0;
 134                 break;
 135
 136         case 0x05:      /* SYS_WRITE */
 137                 retval = target_read_memory(target, r1, 4, 3, params);
 138                 if (retval != ERROR_OK)
 139                         return retval;
 140                 else {
 141                         int fd = target_buffer_get_u32(target, params+0);
 142                         uint32_t a = target_buffer_get_u32(target, params+4);
 143                         size_t l = target_buffer_get_u32(target, params+8);
 144                         uint8_t *buf = malloc(l);
 145                         if (!buf) {
 146                                 result = -1;
 147                                 armv4_5->semihosting_errno = ENOMEM;
 148                         } else {
 149                                 retval = target_read_buffer(target, a, l, buf);
 150                                 if (retval != ERROR_OK) {
 151                                         free(buf);
 152                                         return retval;
 153                                 }
 154                                 result = write(fd, buf, l);
 155                                 armv4_5->semihosting_errno = errno;
 156                                 if (result >= 0)
 157                                         result = l - result;
 158                                 free(buf);
 159                         }
 160                 }
 161                 break;
 162
 163         case 0x06:      /* SYS_READ */
 164                 retval = target_read_memory(target, r1, 4, 3, params);
 165                 if (retval != ERROR_OK)
 166                         return retval;
 167                 else {
 168                         int fd = target_buffer_get_u32(target, params+0);
 169                         uint32_t a = target_buffer_get_u32(target, params+4);
 170                         ssize_t l = target_buffer_get_u32(target, params+8);
 171                         uint8_t *buf = malloc(l);
 172                         if (!buf) {
 173                                 result = -1;
 174                                 armv4_5->semihosting_errno = ENOMEM;
 175                         } else {
 176                                 result = read(fd, buf, l);
 177                                 armv4_5->semihosting_errno = errno;
 178                                 if (result > 0) {
 179                                         retval = target_write_buffer(target, a, result, buf);
 180                                         if (retval != ERROR_OK) {
 181                                                 free(buf);
 182                                                 return retval;
 183                                         }
 184                                         result = l - result;
 185                                 }
 186                                 free(buf);
 187                         }
 188                 }
 189                 break;
 190
 191         case 0x07:      /* SYS_READC */
 192                 result = getchar();
 193                 break;
 194
 195         case 0x08:      /* SYS_ISERROR */
 196                 retval = target_read_memory(target, r1, 4, 1, params);
 197                 if (retval != ERROR_OK)
 198                         return retval;
 199                 result = (target_buffer_get_u32(target, params+0) != 0);
 200                 break;
 201
 202         case 0x09:      /* SYS_ISTTY */
 203                 retval = target_read_memory(target, r1, 4, 1, params);
 204                 if (retval != ERROR_OK)
 205                         return retval;
 206                 result = isatty(target_buffer_get_u32(target, params+0));
 207                 break;
 208
 209         case 0x0a:      /* SYS_SEEK */
 210                 retval = target_read_memory(target, r1, 4, 2, params);
 211                 if (retval != ERROR_OK)
 212                         return retval;
 213                 else {
 214                         int fd = target_buffer_get_u32(target, params+0);
 215                         off_t pos = target_buffer_get_u32(target, params+4);
 216                         result = lseek(fd, pos, SEEK_SET);
 217                         armv4_5->semihosting_errno = errno;
 218                         if (result == pos)
 219                                 result = 0;
 220                 }
 221                 break;
 222
 223         case 0x0c:      /* SYS_FLEN */
 224                 retval = target_read_memory(target, r1, 4, 1, params);
 225                 if (retval != ERROR_OK)
 226                         return retval;
 227                 else {
 228                         int fd = target_buffer_get_u32(target, params+0);
 229                         off_t cur = lseek(fd, 0, SEEK_CUR);
 230                         if (cur == (off_t)-1) {
 231                                 armv4_5->semihosting_errno = errno;
 232                                 result = -1;
 233                                 break;
 234                         }
 235                         result = lseek(fd, 0, SEEK_END);
 236                         armv4_5->semihosting_errno = errno;
 237                         if (lseek(fd, cur, SEEK_SET) == (off_t)-1) {
 238                                 armv4_5->semihosting_errno = errno;
 239                                 result = -1;
 240                         }
 241                 }
 242                 break;
 243
 244         case 0x0e:      /* SYS_REMOVE */
 245                 retval = target_read_memory(target, r1, 4, 2, params);
 246                 if (retval != ERROR_OK)
 247                         return retval;
 248                 else {
 249                         uint32_t a = target_buffer_get_u32(target, params+0);
 250                         uint32_t l = target_buffer_get_u32(target, params+4);
 251                         if (l <= 255) {
 252                                 uint8_t fn[256];
 253                                 retval = target_read_memory(target, a, 1, l, fn);
 254                                 if (retval != ERROR_OK)
 255                                         return retval;
 256                                 fn[l] = 0;
 257                                 result = remove((char *)fn);
 258                                 armv4_5->semihosting_errno =  errno;
 259                         } else {
 260                                 result = -1;
 261                                 armv4_5->semihosting_errno = EINVAL;
 262                         }
 263                 }
 264                 break;
 265
 266         case 0x0f:      /* SYS_RENAME */
 267                 retval = target_read_memory(target, r1, 4, 4, params);
 268                 if (retval != ERROR_OK)
 269                         return retval;
 270                 else {
 271                         uint32_t a1 = target_buffer_get_u32(target, params+0);
 272                         uint32_t l1 = target_buffer_get_u32(target, params+4);
 273                         uint32_t a2 = target_buffer_get_u32(target, params+8);
 274                         uint32_t l2 = target_buffer_get_u32(target, params+12);
 275                         if (l1 <= 255 && l2 <= 255) {
 276                                 uint8_t fn1[256], fn2[256];
 277                                 retval = target_read_memory(target, a1, 1, l1, fn1);
 278                                 if (retval != ERROR_OK)
 279                                         return retval;
 280                                 retval = target_read_memory(target, a2, 1, l2, fn2);
 281                                 if (retval != ERROR_OK)
 282                                         return retval;
 283                                 fn1[l1] = 0;
 284                                 fn2[l2] = 0;
 285                                 result = rename((char *)fn1, (char *)fn2);
 286                                 armv4_5->semihosting_errno =  errno;
 287                         } else {
 288                                 result = -1;
 289                                 armv4_5->semihosting_errno = EINVAL;
 290                         }
 291                 }
 292                 break;
 293
 294         case 0x11:      /* SYS_TIME */
 295                 result = time(NULL);
 296                 break;
 297
 298         case 0x13:      /* SYS_ERRNO */
 299                 result = armv4_5->semihosting_errno;
 300                 break;
 301
 302         case 0x15:      /* SYS_GET_CMDLINE */
 303                 retval = target_read_memory(target, r1, 4, 2, params);
 304                 if (retval != ERROR_OK)
 305                         return retval;
 306                 else {
 307                         uint32_t a = target_buffer_get_u32(target, params+0);
 308                         uint32_t l = target_buffer_get_u32(target, params+4);
 309                         char *arg = "foobar";
 310                         uint32_t s = strlen(arg) + 1;
 311                         if (l < s)
 312                                 result = -1;
 313                         else {
 314                                 retval = target_write_buffer(target, a, s, (void*)arg);
 315                                 if (retval != ERROR_OK)
 316                                         return retval;
 317                                 result = 0;
 318                         }
 319                 }
 320                 break;
 321
 322         case 0x16:      /* SYS_HEAPINFO */
 323                 retval = target_read_memory(target, r1, 4, 1, params);
 324                 if (retval != ERROR_OK)
 325                         return retval;
 326                 else {
 327                         uint32_t a = target_buffer_get_u32(target, params+0);
 328                         /* tell the remote we have no idea */
 329                         memset(params, 0, 4*4);
 330                         retval = target_write_memory(target, a, 4, 4, params);
 331                         if (retval != ERROR_OK)
 332                                 return retval;
 333                         result = 0;
 334                 }
 335                 break;
 336
 337         case 0x18:      /* angel_SWIreason_ReportException */
 338                 switch (r1) {
 339                 case 0x20026:   /* ADP_Stopped_ApplicationExit */
 340                         fprintf(stderr, "semihosting: *** application exited ***\n");
 341                         break;
 342                 case 0x20000:   /* ADP_Stopped_BranchThroughZero */
 343                 case 0x20001:   /* ADP_Stopped_UndefinedInstr */
 344                 case 0x20002:   /* ADP_Stopped_SoftwareInterrupt */
 345                 case 0x20003:   /* ADP_Stopped_PrefetchAbort */
 346                 case 0x20004:   /* ADP_Stopped_DataAbort */
 347                 case 0x20005:   /* ADP_Stopped_AddressException */
 348                 case 0x20006:   /* ADP_Stopped_IRQ */
 349                 case 0x20007:   /* ADP_Stopped_FIQ */
 350                 case 0x20020:   /* ADP_Stopped_BreakPoint */
 351                 case 0x20021:   /* ADP_Stopped_WatchPoint */
 352                 case 0x20022:   /* ADP_Stopped_StepComplete */
 353                 case 0x20023:   /* ADP_Stopped_RunTimeErrorUnknown */
 354                 case 0x20024:   /* ADP_Stopped_InternalError */
 355                 case 0x20025:   /* ADP_Stopped_UserInterruption */
 356                 case 0x20027:   /* ADP_Stopped_StackOverflow */
 357                 case 0x20028:   /* ADP_Stopped_DivisionByZero */
 358                 case 0x20029:   /* ADP_Stopped_OSSpecific */
 359                 default:
 360                         fprintf(stderr, "semihosting: exception %#x\n",
 361                                         (unsigned) r1);
 362                 }
 363                 return target_call_event_callbacks(target, TARGET_EVENT_HALTED);
 364
 365         case 0x0d:      /* SYS_TMPNAM */
 366         case 0x10:      /* SYS_CLOCK */
 367         case 0x12:      /* SYS_SYSTEM */
 368         case 0x17:      /* angel_SWIreason_EnterSVC */
 369         case 0x30:      /* SYS_ELAPSED */
 370         case 0x31:      /* SYS_TICKFREQ */
 371         default:
 372                 fprintf(stderr, "semihosting: unsupported call %#x\n",
 373                                 (unsigned) r0);
 374                 result = -1;
 375                 armv4_5->semihosting_errno = ENOTSUP;
 376         }
 377
 378         /* resume execution to the original mode */
 379         buf_set_u32(armv4_5->core_cache->reg_list[0].value, 0, 32, result);
 380         armv4_5->core_cache->reg_list[0].dirty = 1;
 381         buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, lr);
 382         armv4_5->core_cache->reg_list[15].dirty = 1;
 383         buf_set_u32(armv4_5->core_cache->reg_list[ARMV4_5_CPSR].value, 0, 32, spsr);
 384         armv4_5->core_cache->reg_list[ARMV4_5_CPSR].dirty = 1;
 385         armv4_5->core_mode = spsr & 0x1f;
 386         if (spsr & 0x20)
 387                 armv4_5->core_state = ARMV4_5_STATE_THUMB;
 388         return target_resume(target, 1, 0, 0, 0);
 389 }
 390
 391 /**
 392  * Checks for and processes an ARM semihosting request.  This is meant
 393  * to be called when the target is stopped due to a debug mode entry.
 394  * If the value 0 is returned then there was nothing to process. A non-zero
 395  * return value signifies that a request was processed and the target resumed,
 396  * or an error was encountered, in which case the caller must return
 397  * immediately.
 398  *
 399  * @param target Pointer to the ARM target to process
 400  * @param retval Pointer to a location where the return code will be stored
 401  * @return non-zero value if a request was processed or an error encountered
 402  */
 403 int arm_semihosting(struct target *target, int *retval)
 404 {
 405         struct arm *armv4_5 = target_to_armv4_5(target);
 406         uint32_t lr, spsr;
 407
 408         if (!armv4_5->is_semihosting ||
 409             armv4_5->core_mode != ARMV4_5_MODE_SVC ||
 410             buf_get_u32(armv4_5->core_cache->reg_list[15].value, 0, 32) != 0x08)
 411                 return 0;
 412
 413         lr = buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, ARMV4_5_MODE_SVC, 14).value, 0, 32);
 414         spsr = buf_get_u32(armv4_5->spsr->value, 0, 32);
 415
 416         /* check instruction that triggered this trap */
 417         if (spsr & (1 << 5)) {
 418                 /* was in Thumb mode */
 419                 uint8_t insn_buf[2];
 420                 uint16_t insn;
 421                 *retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
 422                 if (*retval != ERROR_OK)
 423                         return 1;
 424                 insn = target_buffer_get_u16(target, insn_buf);
 425                 if (insn != 0xDFAB)
 426                         return 0;
 427         } else {
 428                 /* was in ARM mode */
 429                 uint8_t insn_buf[4];
 430                 uint32_t insn;
 431                 *retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
 432                 if (*retval != ERROR_OK)
 433                         return 1;
 434                 insn = target_buffer_get_u32(target, insn_buf);
 435                 if (insn != 0xEF123456)
 436                         return 0;
 437         }
 438
 439         *retval = do_semihosting(target);
 440         return 1;
 441 }