src/target/arm_semihosting.c

   1 /***************************************************************************
   2  *   Copyright (C) 2009 by Marvell Technology Group Ltd.                   *
   3  *   Written by Nicolas Pitre <nico@marvell.com>                           *
   4  *                                                                         *
   5  *   Copyright (C) 2010 by Spencer Oliver                                  *
   6  *   spen@spen-soft.co.uk                                                  *
   7  *                                                                         *
   8  *   This program is free software; you can redistribute it and/or modify  *
   9  *   it under the terms of the GNU General Public License as published by  *
  10  *   the Free Software Foundation; either version 2 of the License, or     *
  11  *   (at your option) any later version.                                   *
  12  *                                                                         *
  13  *   This program is distributed in the hope that it will be useful,       *
  14  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  15  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  16  *   GNU General Public License for more details.                          *
  17  *                                                                         *
  18  *   You should have received a copy of the GNU General Public License     *
  19  *   along with this program; if not, write to the                         *
  20  *   Free Software Foundation, Inc.,                                       *
  21  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
  22  ***************************************************************************/
  23
  24 /**
  25  * @file
  26  * Hold ARM semihosting support.
  27  *
  28  * Semihosting enables code running on an ARM target to use the I/O
  29  * facilities on the host computer. The target application must be linked
  30  * against a library that forwards operation requests by using the SVC
  31  * instruction trapped at the Supervisor Call vector by the debugger.
  32  * Details can be found in chapter 8 of DUI0203I_rvct_developer_guide.pdf
  33  * from ARM Ltd.
  34  */
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include "config.h"
  38 #endif
  39
  40 #include "arm.h"
  41 #include "armv4_5.h"
  42 #include "arm7_9_common.h"
  43 #include "armv7m.h"
  44 #include "cortex_m.h"
  45 #include "register.h"
  46 #include "arm_semihosting.h"
  47 #include <helper/binarybuffer.h>
  48 #include <helper/log.h>
  49 #include <sys/stat.h>
  50
  51 static int open_modeflags[12] = {
  52         O_RDONLY,
  53         O_RDONLY | O_BINARY,
  54         O_RDWR,
  55         O_RDWR | O_BINARY,
  56         O_WRONLY | O_CREAT | O_TRUNC,
  57         O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
  58         O_RDWR | O_CREAT | O_TRUNC,
  59         O_RDWR | O_CREAT | O_TRUNC | O_BINARY,
  60         O_WRONLY | O_CREAT | O_APPEND,
  61         O_WRONLY | O_CREAT | O_APPEND | O_BINARY,
  62         O_RDWR | O_CREAT | O_APPEND,
  63         O_RDWR | O_CREAT | O_APPEND | O_BINARY
  64 };
  65
  66 static int do_semihosting(struct target *target)
  67 {
  68         struct arm *arm = target_to_arm(target);
  69         uint32_t r0 = buf_get_u32(arm->core_cache->reg_list[0].value, 0, 32);
  70         uint32_t r1 = buf_get_u32(arm->core_cache->reg_list[1].value, 0, 32);
  71         uint8_t params[16];
  72         int retval, result;
  73
  74         /*
  75          * TODO: lots of security issues are not considered yet, such as:
  76          * - no validation on target provided file descriptors
  77          * - no safety checks on opened/deleted/renamed file paths
  78          * Beware the target app you use this support with.
  79          *
  80          * TODO: explore mapping requests to GDB's "File-I/O Remote
  81          * Protocol Extension" ... when GDB is active.
  82          */
  83         switch (r0) {
  84         case 0x01:      /* SYS_OPEN */
  85                 retval = target_read_memory(target, r1, 4, 3, params);
  86                 if (retval != ERROR_OK)
  87                         return retval;
  88                 else {
  89                         uint32_t a = target_buffer_get_u32(target, params+0);
  90                         uint32_t m = target_buffer_get_u32(target, params+4);
  91                         uint32_t l = target_buffer_get_u32(target, params+8);
  92                         if (l <= 255 && m <= 11) {
  93                                 uint8_t fn[256];
  94                                 retval = target_read_memory(target, a, 1, l, fn);
  95                                 if (retval != ERROR_OK)
  96                                         return retval;
  97                                 fn[l] = 0;
  98                                 if (strcmp((char *)fn, ":tt") == 0) {
  99                                         if (m < 4)
 100                                                 result = dup(STDIN_FILENO);
 101                                         else
 102                                                 result = dup(STDOUT_FILENO);
 103                                 } else {
 104                                         /* cygwin requires the permission setting
 105                                          * otherwise it will fail to reopen a previously
 106                                          * written file */
 107                                         result = open((char *)fn, open_modeflags[m], 0644);
 108                                 }
 109                                 arm->semihosting_errno =  errno;
 110                         } else {
 111                                 result = -1;
 112                                 arm->semihosting_errno = EINVAL;
 113                         }
 114                 }
 115                 break;
 116
 117         case 0x02:      /* SYS_CLOSE */
 118                 retval = target_read_memory(target, r1, 4, 1, params);
 119                 if (retval != ERROR_OK)
 120                         return retval;
 121                 else {
 122                         int fd = target_buffer_get_u32(target, params+0);
 123                         result = close(fd);
 124                         arm->semihosting_errno = errno;
 125                 }
 126                 break;
 127
 128         case 0x03:      /* SYS_WRITEC */
 129                 {
 130                         unsigned char c;
 131                         retval = target_read_memory(target, r1, 1, 1, &c);
 132                         if (retval != ERROR_OK)
 133                                 return retval;
 134                         putchar(c);
 135                         result = 0;
 136                 }
 137                 break;
 138
 139         case 0x04:      /* SYS_WRITE0 */
 140                 do {
 141                         unsigned char c;
 142                         retval = target_read_memory(target, r1++, 1, 1, &c);
 143                         if (retval != ERROR_OK)
 144                                 return retval;
 145                         if (!c)
 146                                 break;
 147                         putchar(c);
 148                 } while (1);
 149                 result = 0;
 150                 break;
 151
 152         case 0x05:      /* SYS_WRITE */
 153                 retval = target_read_memory(target, r1, 4, 3, params);
 154                 if (retval != ERROR_OK)
 155                         return retval;
 156                 else {
 157                         int fd = target_buffer_get_u32(target, params+0);
 158                         uint32_t a = target_buffer_get_u32(target, params+4);
 159                         size_t l = target_buffer_get_u32(target, params+8);
 160                         uint8_t *buf = malloc(l);
 161                         if (!buf) {
 162                                 result = -1;
 163                                 arm->semihosting_errno = ENOMEM;
 164                         } else {
 165                                 retval = target_read_buffer(target, a, l, buf);
 166                                 if (retval != ERROR_OK) {
 167                                         free(buf);
 168                                         return retval;
 169                                 }
 170                                 result = write(fd, buf, l);
 171                                 arm->semihosting_errno = errno;
 172                                 if (result >= 0)
 173                                         result = l - result;
 174                                 free(buf);
 175                         }
 176                 }
 177                 break;
 178
 179         case 0x06:      /* SYS_READ */
 180                 retval = target_read_memory(target, r1, 4, 3, params);
 181                 if (retval != ERROR_OK)
 182                         return retval;
 183                 else {
 184                         int fd = target_buffer_get_u32(target, params+0);
 185                         uint32_t a = target_buffer_get_u32(target, params+4);
 186                         ssize_t l = target_buffer_get_u32(target, params+8);
 187                         uint8_t *buf = malloc(l);
 188                         if (!buf) {
 189                                 result = -1;
 190                                 arm->semihosting_errno = ENOMEM;
 191                         } else {
 192                                 result = read(fd, buf, l);
 193                                 arm->semihosting_errno = errno;
 194                                 if (result >= 0) {
 195                                         retval = target_write_buffer(target, a, result, buf);
 196                                         if (retval != ERROR_OK) {
 197                                                 free(buf);
 198                                                 return retval;
 199                                         }
 200                                         result = l - result;
 201                                 }
 202                                 free(buf);
 203                         }
 204                 }
 205                 break;
 206
 207         case 0x07:      /* SYS_READC */
 208                 result = getchar();
 209                 break;
 210
 211         case 0x08:      /* SYS_ISERROR */
 212                 retval = target_read_memory(target, r1, 4, 1, params);
 213                 if (retval != ERROR_OK)
 214                         return retval;
 215                 result = (target_buffer_get_u32(target, params+0) != 0);
 216                 break;
 217
 218         case 0x09:      /* SYS_ISTTY */
 219                 retval = target_read_memory(target, r1, 4, 1, params);
 220                 if (retval != ERROR_OK)
 221                         return retval;
 222                 result = isatty(target_buffer_get_u32(target, params+0));
 223                 break;
 224
 225         case 0x0a:      /* SYS_SEEK */
 226                 retval = target_read_memory(target, r1, 4, 2, params);
 227                 if (retval != ERROR_OK)
 228                         return retval;
 229                 else {
 230                         int fd = target_buffer_get_u32(target, params+0);
 231                         off_t pos = target_buffer_get_u32(target, params+4);
 232                         result = lseek(fd, pos, SEEK_SET);
 233                         arm->semihosting_errno = errno;
 234                         if (result == pos)
 235                                 result = 0;
 236                 }
 237                 break;
 238
 239         case 0x0c:      /* SYS_FLEN */
 240                 retval = target_read_memory(target, r1, 4, 1, params);
 241                 if (retval != ERROR_OK)
 242                         return retval;
 243                 else {
 244                         int fd = target_buffer_get_u32(target, params+0);
 245                         struct stat buf;
 246                         result = fstat(fd, &buf);
 247                         if (result == -1) {
 248                                 arm->semihosting_errno = errno;
 249                                 result = -1;
 250                                 break;
 251                         }
 252                         result = buf.st_size;
 253                 }
 254                 break;
 255
 256         case 0x0e:      /* SYS_REMOVE */
 257                 retval = target_read_memory(target, r1, 4, 2, params);
 258                 if (retval != ERROR_OK)
 259                         return retval;
 260                 else {
 261                         uint32_t a = target_buffer_get_u32(target, params+0);
 262                         uint32_t l = target_buffer_get_u32(target, params+4);
 263                         if (l <= 255) {
 264                                 uint8_t fn[256];
 265                                 retval = target_read_memory(target, a, 1, l, fn);
 266                                 if (retval != ERROR_OK)
 267                                         return retval;
 268                                 fn[l] = 0;
 269                                 result = remove((char *)fn);
 270                                 arm->semihosting_errno =  errno;
 271                         } else {
 272                                 result = -1;
 273                                 arm->semihosting_errno = EINVAL;
 274                         }
 275                 }
 276                 break;
 277
 278         case 0x0f:      /* SYS_RENAME */
 279                 retval = target_read_memory(target, r1, 4, 4, params);
 280                 if (retval != ERROR_OK)
 281                         return retval;
 282                 else {
 283                         uint32_t a1 = target_buffer_get_u32(target, params+0);
 284                         uint32_t l1 = target_buffer_get_u32(target, params+4);
 285                         uint32_t a2 = target_buffer_get_u32(target, params+8);
 286                         uint32_t l2 = target_buffer_get_u32(target, params+12);
 287                         if (l1 <= 255 && l2 <= 255) {
 288                                 uint8_t fn1[256], fn2[256];
 289                                 retval = target_read_memory(target, a1, 1, l1, fn1);
 290                                 if (retval != ERROR_OK)
 291                                         return retval;
 292                                 retval = target_read_memory(target, a2, 1, l2, fn2);
 293                                 if (retval != ERROR_OK)
 294                                         return retval;
 295                                 fn1[l1] = 0;
 296                                 fn2[l2] = 0;
 297                                 result = rename((char *)fn1, (char *)fn2);
 298                                 arm->semihosting_errno =  errno;
 299                         } else {
 300                                 result = -1;
 301                                 arm->semihosting_errno = EINVAL;
 302                         }
 303                 }
 304                 break;
 305
 306         case 0x11:      /* SYS_TIME */
 307                 result = time(NULL);
 308                 break;
 309
 310         case 0x13:      /* SYS_ERRNO */
 311                 result = arm->semihosting_errno;
 312                 break;
 313
 314         case 0x15:      /* SYS_GET_CMDLINE */
 315                 retval = target_read_memory(target, r1, 4, 2, params);
 316                 if (retval != ERROR_OK)
 317                         return retval;
 318                 else {
 319                         uint32_t a = target_buffer_get_u32(target, params+0);
 320                         uint32_t l = target_buffer_get_u32(target, params+4);
 321                         char *arg = "foobar";
 322                         uint32_t s = strlen(arg) + 1;
 323                         if (l < s)
 324                                 result = -1;
 325                         else {
 326                                 retval = target_write_buffer(target, a, s, (void *)arg);
 327                                 if (retval != ERROR_OK)
 328                                         return retval;
 329                                 result = 0;
 330                         }
 331                 }
 332                 break;
 333
 334         case 0x16:      /* SYS_HEAPINFO */
 335                 retval = target_read_memory(target, r1, 4, 1, params);
 336                 if (retval != ERROR_OK)
 337                         return retval;
 338                 else {
 339                         uint32_t a = target_buffer_get_u32(target, params+0);
 340                         /* tell the remote we have no idea */
 341                         memset(params, 0, 4*4);
 342                         retval = target_write_memory(target, a, 4, 4, params);
 343                         if (retval != ERROR_OK)
 344                                 return retval;
 345                         result = 0;
 346                 }
 347                 break;
 348
 349         case 0x18:      /* angel_SWIreason_ReportException */
 350                 switch (r1) {
 351                 case 0x20026:   /* ADP_Stopped_ApplicationExit */
 352                         fprintf(stderr, "semihosting: *** application exited ***\n");
 353                         break;
 354                 case 0x20000:   /* ADP_Stopped_BranchThroughZero */
 355                 case 0x20001:   /* ADP_Stopped_UndefinedInstr */
 356                 case 0x20002:   /* ADP_Stopped_SoftwareInterrupt */
 357                 case 0x20003:   /* ADP_Stopped_PrefetchAbort */
 358                 case 0x20004:   /* ADP_Stopped_DataAbort */
 359                 case 0x20005:   /* ADP_Stopped_AddressException */
 360                 case 0x20006:   /* ADP_Stopped_IRQ */
 361                 case 0x20007:   /* ADP_Stopped_FIQ */
 362                 case 0x20020:   /* ADP_Stopped_BreakPoint */
 363                 case 0x20021:   /* ADP_Stopped_WatchPoint */
 364                 case 0x20022:   /* ADP_Stopped_StepComplete */
 365                 case 0x20023:   /* ADP_Stopped_RunTimeErrorUnknown */
 366                 case 0x20024:   /* ADP_Stopped_InternalError */
 367                 case 0x20025:   /* ADP_Stopped_UserInterruption */
 368                 case 0x20027:   /* ADP_Stopped_StackOverflow */
 369                 case 0x20028:   /* ADP_Stopped_DivisionByZero */
 370                 case 0x20029:   /* ADP_Stopped_OSSpecific */
 371                 default:
 372                         fprintf(stderr, "semihosting: exception %#x\n",
 373                                         (unsigned) r1);
 374                 }
 375                 return target_call_event_callbacks(target, TARGET_EVENT_HALTED);
 376
 377         case 0x12:      /* SYS_SYSTEM */
 378                 /* Provide SYS_SYSTEM functionality.  Uses the
 379                  * libc system command, there may be a reason *NOT*
 380                  * to use this, but as I can't think of one, I
 381                  * implemented it this way.
 382                  */
 383                 retval = target_read_memory(target, r1, 4, 2, params);
 384                 if (retval != ERROR_OK)
 385                         return retval;
 386                 else {
 387                         uint32_t len = target_buffer_get_u32(target, params+4);
 388                         uint32_t c_ptr = target_buffer_get_u32(target, params);
 389                         uint8_t cmd[256];
 390                         if (len > 255) {
 391                                 result = -1;
 392                                 arm->semihosting_errno = EINVAL;
 393                         } else {
 394                                 memset(cmd, 0x0, 256);
 395                                 retval = target_read_memory(target, c_ptr, 1, len, cmd);
 396                                 if (retval != ERROR_OK)
 397                                         return retval;
 398                                 else
 399                                         result = system((const char *)cmd);
 400                         }
 401                 }
 402                 break;
 403         case 0x0d:      /* SYS_TMPNAM */
 404         case 0x10:      /* SYS_CLOCK */
 405         case 0x17:      /* angel_SWIreason_EnterSVC */
 406         case 0x30:      /* SYS_ELAPSED */
 407         case 0x31:      /* SYS_TICKFREQ */
 408         default:
 409                 fprintf(stderr, "semihosting: unsupported call %#x\n",
 410                                 (unsigned) r0);
 411                 result = -1;
 412                 arm->semihosting_errno = ENOTSUP;
 413         }
 414
 415         /* resume execution to the original mode */
 416
 417         /* REVISIT this looks wrong ... ARM11 and Cortex-A8
 418          * should work this way at least sometimes.
 419          */
 420         if (is_arm7_9(target_to_arm7_9(target))) {
 421                 uint32_t spsr;
 422
 423                 /* return value in R0 */
 424                 buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
 425                 arm->core_cache->reg_list[0].dirty = 1;
 426
 427                 /* LR --> PC */
 428                 buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
 429                         buf_get_u32(arm_reg_current(arm, 14)->value, 0, 32));
 430                 arm->core_cache->reg_list[15].dirty = 1;
 431
 432                 /* saved PSR --> current PSR */
 433                 spsr = buf_get_u32(arm->spsr->value, 0, 32);
 434
 435                 /* REVISIT should this be arm_set_cpsr(arm, spsr)
 436                  * instead of a partially unrolled version?
 437                  */
 438
 439                 buf_set_u32(arm->cpsr->value, 0, 32, spsr);
 440                 arm->cpsr->dirty = 1;
 441                 arm->core_mode = spsr & 0x1f;
 442                 if (spsr & 0x20)
 443                         arm->core_state = ARM_STATE_THUMB;
 444
 445         } else {
 446                 /* resume execution, this will be pc+2 to skip over the
 447                  * bkpt instruction */
 448
 449                 /* return result in R0 */
 450                 buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
 451                 arm->core_cache->reg_list[0].dirty = 1;
 452         }
 453
 454         return target_resume(target, 1, 0, 0, 0);
 455 }
 456
 457 /**
 458  * Checks for and processes an ARM semihosting request.  This is meant
 459  * to be called when the target is stopped due to a debug mode entry.
 460  * If the value 0 is returned then there was nothing to process. A non-zero
 461  * return value signifies that a request was processed and the target resumed,
 462  * or an error was encountered, in which case the caller must return
 463  * immediately.
 464  *
 465  * @param target Pointer to the ARM target to process.  This target must
 466  *      not represent an ARMv6-M or ARMv7-M processor.
 467  * @param retval Pointer to a location where the return code will be stored
 468  * @return non-zero value if a request was processed or an error encountered
 469  */
 470 int arm_semihosting(struct target *target, int *retval)
 471 {
 472         struct arm *arm = target_to_arm(target);
 473         uint32_t pc, lr, spsr;
 474         struct reg *r;
 475
 476         if (!arm->is_semihosting)
 477                 return 0;
 478
 479         if (is_arm7_9(target_to_arm7_9(target))) {
 480                 if (arm->core_mode != ARM_MODE_SVC)
 481                         return 0;
 482
 483                 /* Check for PC == 0x00000008 or 0xffff0008: Supervisor Call vector. */
 484                 r = arm->pc;
 485                 pc = buf_get_u32(r->value, 0, 32);
 486                 if (pc != 0x00000008 && pc != 0xffff0008)
 487                         return 0;
 488
 489                 r = arm_reg_current(arm, 14);
 490                 lr = buf_get_u32(r->value, 0, 32);
 491
 492                 /* Core-specific code should make sure SPSR is retrieved
 493                  * when the above checks pass...
 494                  */
 495                 if (!arm->spsr->valid) {
 496                         LOG_ERROR("SPSR not valid!");
 497                         *retval = ERROR_FAIL;
 498                         return 1;
 499                 }
 500
 501                 spsr = buf_get_u32(arm->spsr->value, 0, 32);
 502
 503                 /* check instruction that triggered this trap */
 504                 if (spsr & (1 << 5)) {
 505                         /* was in Thumb (or ThumbEE) mode */
 506                         uint8_t insn_buf[2];
 507                         uint16_t insn;
 508
 509                         *retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
 510                         if (*retval != ERROR_OK)
 511                                 return 1;
 512                         insn = target_buffer_get_u16(target, insn_buf);
 513
 514                         /* SVC 0xab */
 515                         if (insn != 0xDFAB)
 516                                 return 0;
 517                 } else if (spsr & (1 << 24)) {
 518                         /* was in Jazelle mode */
 519                         return 0;
 520                 } else {
 521                         /* was in ARM mode */
 522                         uint8_t insn_buf[4];
 523                         uint32_t insn;
 524
 525                         *retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
 526                         if (*retval != ERROR_OK)
 527                                 return 1;
 528                         insn = target_buffer_get_u32(target, insn_buf);
 529
 530                         /* SVC 0x123456 */
 531                         if (insn != 0xEF123456)
 532                                 return 0;
 533                 }
 534         } else if (is_armv7m(target_to_armv7m(target))) {
 535                 uint16_t insn;
 536
 537                 if (target->debug_reason != DBG_REASON_BREAKPOINT)
 538                         return 0;
 539
 540                 r = arm->pc;
 541                 pc = buf_get_u32(r->value, 0, 32);
 542
 543                 pc &= ~1;
 544                 *retval = target_read_u16(target, pc, &insn);
 545                 if (*retval != ERROR_OK)
 546                         return 1;
 547
 548                 /* bkpt 0xAB */
 549                 if (insn != 0xBEAB)
 550                         return 0;
 551         } else {
 552                 LOG_ERROR("Unsupported semi-hosting Target");
 553                 return 0;
 554         }
 555
 556         *retval = do_semihosting(target);
 557         return 1;
 558 }