arch/mn10300/kernel/gdb-stub.c

   1 /* MN10300 GDB stub
   2  *
   3  * Originally written by Glenn Engel, Lake Stevens Instrument Division
   4  *
   5  * Contributed by HP Systems
   6  *
   7  * Modified for SPARC by Stu Grossman, Cygnus Support.
   8  *
   9  * Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
  10  * Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
  11  *
  12  * Copyright (C) 1995 Andreas Busse
  13  *
  14  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  15  * Modified for Linux/mn10300 by David Howells <dhowells@redhat.com>
  16  */
  17
  18 /*
  19  *  To enable debugger support, two things need to happen.  One, a
  20  *  call to set_debug_traps() is necessary in order to allow any breakpoints
  21  *  or error conditions to be properly intercepted and reported to gdb.
  22  *  Two, a breakpoint needs to be generated to begin communication.  This
  23  *  is most easily accomplished by a call to breakpoint().  Breakpoint()
  24  *  simulates a breakpoint by executing a BREAK instruction.
  25  *
  26  *
  27  *    The following gdb commands are supported:
  28  *
  29  * command          function                               Return value
  30  *
  31  *    g             return the value of the CPU registers  hex data or ENN
  32  *    G             set the value of the CPU registers     OK or ENN
  33  *
  34  *    mAA..AA,LLLL  Read LLLL bytes at address AA..AA      hex data or ENN
  35  *    MAA..AA,LLLL: Write LLLL bytes at address AA.AA      OK or ENN
  36  *
  37  *    c             Resume at current address              SNN   ( signal NN)
  38  *    cAA..AA       Continue at address AA..AA             SNN
  39  *
  40  *    s             Step one instruction                   SNN
  41  *    sAA..AA       Step one instruction from AA..AA       SNN
  42  *
  43  *    k             kill
  44  *
  45  *    ?             What was the last sigval ?             SNN   (signal NN)
  46  *
  47  *    bBB..BB       Set baud rate to BB..BB                OK or BNN, then sets
  48  *                                                         baud rate
  49  *
  50  * All commands and responses are sent with a packet which includes a
  51  * checksum.  A packet consists of
  52  *
  53  * $<packet info>#<checksum>.
  54  *
  55  * where
  56  * <packet info> :: <characters representing the command or response>
  57  * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
  58  *
  59  * When a packet is received, it is first acknowledged with either '+' or '-'.
  60  * '+' indicates a successful transfer.  '-' indicates a failed transfer.
  61  *
  62  * Example:
  63  *
  64  * Host:                  Reply:
  65  * $m0,10#2a               +$00010203040506070809101112131415#42
  66  *
  67  *
  68  *  ==============
  69  *  MORE EXAMPLES:
  70  *  ==============
  71  *
  72  *  For reference -- the following are the steps that one
  73  *  company took (RidgeRun Inc) to get remote gdb debugging
  74  *  going. In this scenario the host machine was a PC and the
  75  *  target platform was a Galileo EVB64120A MIPS evaluation
  76  *  board.
  77  *
  78  *  Step 1:
  79  *  First download gdb-5.0.tar.gz from the internet.
  80  *  and then build/install the package.
  81  *
  82  *  Example:
  83  *    $ tar zxf gdb-5.0.tar.gz
  84  *    $ cd gdb-5.0
  85  *    $ ./configure --target=am33_2.0-linux-gnu
  86  *    $ make
  87  *    $ install
  88  *    am33_2.0-linux-gnu-gdb
  89  *
  90  *  Step 2:
  91  *  Configure linux for remote debugging and build it.
  92  *
  93  *  Example:
  94  *    $ cd ~/linux
  95  *    $ make menuconfig <go to "Kernel Hacking" and turn on remote debugging>
  96  *    $ make dep; make vmlinux
  97  *
  98  *  Step 3:
  99  *  Download the kernel to the remote target and start
 100  *  the kernel running. It will promptly halt and wait
 101  *  for the host gdb session to connect. It does this
 102  *  since the "Kernel Hacking" option has defined
 103  *  CONFIG_REMOTE_DEBUG which in turn enables your calls
 104  *  to:
 105  *     set_debug_traps();
 106  *     breakpoint();
 107  *
 108  *  Step 4:
 109  *  Start the gdb session on the host.
 110  *
 111  *  Example:
 112  *    $ am33_2.0-linux-gnu-gdb vmlinux
 113  *    (gdb) set remotebaud 115200
 114  *    (gdb) target remote /dev/ttyS1
 115  *    ...at this point you are connected to
 116  *       the remote target and can use gdb
 117  *       in the normal fasion. Setting
 118  *       breakpoints, single stepping,
 119  *       printing variables, etc.
 120  *
 121  */
 122
 123 #include <linux/string.h>
 124 #include <linux/kernel.h>
 125 #include <linux/signal.h>
 126 #include <linux/sched.h>
 127 #include <linux/mm.h>
 128 #include <linux/console.h>
 129 #include <linux/init.h>
 130 #include <linux/bug.h>
 131
 132 #include <asm/pgtable.h>
 133 #include <asm/system.h>
 134 #include <asm/gdb-stub.h>
 135 #include <asm/exceptions.h>
 136 #include <asm/cacheflush.h>
 137 #include <asm/serial-regs.h>
 138 #include <asm/busctl-regs.h>
 139 #include <unit/leds.h>
 140 #include <unit/serial.h>
 141
 142 /* define to use F7F7 rather than FF which is subverted by JTAG debugger */
 143 #undef GDBSTUB_USE_F7F7_AS_BREAKPOINT
 144
 145 /*
 146  * BUFMAX defines the maximum number of characters in inbound/outbound buffers
 147  * at least NUMREGBYTES*2 are needed for register packets
 148  */
 149 #define BUFMAX 2048
 150
 151 static const char gdbstub_banner[] =
 152         "Linux/MN10300 GDB Stub (c) RedHat 2007\n";
 153
 154 u8      gdbstub_rx_buffer[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
 155 u32     gdbstub_rx_inp;
 156 u32     gdbstub_rx_outp;
 157 u8      gdbstub_busy;
 158 u8      gdbstub_rx_overflow;
 159 u8      gdbstub_rx_unget;
 160
 161 static u8       gdbstub_flush_caches;
 162 static char     input_buffer[BUFMAX];
 163 static char     output_buffer[BUFMAX];
 164 static char     trans_buffer[BUFMAX];
 165
 166 struct gdbstub_bkpt {
 167         u8      *addr;          /* address of breakpoint */
 168         u8      len;            /* size of breakpoint */
 169         u8      origbytes[7];   /* original bytes */
 170 };
 171
 172 static struct gdbstub_bkpt gdbstub_bkpts[256];
 173
 174 /*
 175  * local prototypes
 176  */
 177 static void getpacket(char *buffer);
 178 static int putpacket(char *buffer);
 179 static int computeSignal(enum exception_code excep);
 180 static int hex(unsigned char ch);
 181 static int hexToInt(char **ptr, int *intValue);
 182 static unsigned char *mem2hex(const void *mem, char *buf, int count,
 183                               int may_fault);
 184 static const char *hex2mem(const char *buf, void *_mem, int count,
 185                            int may_fault);
 186
 187 /*
 188  * Convert ch from a hex digit to an int
 189  */
 190 static int hex(unsigned char ch)
 191 {
 192         if (ch >= 'a' && ch <= 'f')
 193                 return ch - 'a' + 10;
 194         if (ch >= '0' && ch <= '9')
 195                 return ch - '0';
 196         if (ch >= 'A' && ch <= 'F')
 197                 return ch - 'A' + 10;
 198         return -1;
 199 }
 200
 201 #ifdef CONFIG_GDBSTUB_DEBUGGING
 202
 203 void debug_to_serial(const char *p, int n)
 204 {
 205         __debug_to_serial(p, n);
 206         /* gdbstub_console_write(NULL, p, n); */
 207 }
 208
 209 void gdbstub_printk(const char *fmt, ...)
 210 {
 211         va_list args;
 212         int len;
 213
 214         /* Emit the output into the temporary buffer */
 215         va_start(args, fmt);
 216         len = vsnprintf(trans_buffer, sizeof(trans_buffer), fmt, args);
 217         va_end(args);
 218         debug_to_serial(trans_buffer, len);
 219 }
 220
 221 #endif
 222
 223 static inline char *gdbstub_strcpy(char *dst, const char *src)
 224 {
 225         int loop = 0;
 226         while ((dst[loop] = src[loop]))
 227                loop++;
 228         return dst;
 229 }
 230
 231 /*
 232  * scan for the sequence $<data>#<checksum>
 233  */
 234 static void getpacket(char *buffer)
 235 {
 236         unsigned char checksum;
 237         unsigned char xmitcsum;
 238         unsigned char ch;
 239         int count, i, ret, error;
 240
 241         for (;;) {
 242                 /*
 243                  * wait around for the start character,
 244                  * ignore all other characters
 245                  */
 246                 do {
 247                         gdbstub_io_rx_char(&ch, 0);
 248                 } while (ch != '$');
 249
 250                 checksum = 0;
 251                 xmitcsum = -1;
 252                 count = 0;
 253                 error = 0;
 254
 255                 /*
 256                  * now, read until a # or end of buffer is found
 257                  */
 258                 while (count < BUFMAX) {
 259                         ret = gdbstub_io_rx_char(&ch, 0);
 260                         if (ret < 0)
 261                                 error = ret;
 262
 263                         if (ch == '#')
 264                                 break;
 265                         checksum += ch;
 266                         buffer[count] = ch;
 267                         count++;
 268                 }
 269
 270                 if (error == -EIO) {
 271                         gdbstub_proto("### GDB Rx Error - Skipping packet"
 272                                       " ###\n");
 273                         gdbstub_proto("### GDB Tx NAK\n");
 274                         gdbstub_io_tx_char('-');
 275                         continue;
 276                 }
 277
 278                 if (count >= BUFMAX || error)
 279                         continue;
 280
 281                 buffer[count] = 0;
 282
 283                 /* read the checksum */
 284                 ret = gdbstub_io_rx_char(&ch, 0);
 285                 if (ret < 0)
 286                         error = ret;
 287                 xmitcsum = hex(ch) << 4;
 288
 289                 ret = gdbstub_io_rx_char(&ch, 0);
 290                 if (ret < 0)
 291                         error = ret;
 292                 xmitcsum |= hex(ch);
 293
 294                 if (error) {
 295                         if (error == -EIO)
 296                                 gdbstub_io("### GDB Rx Error -"
 297                                            " Skipping packet\n");
 298                         gdbstub_io("### GDB Tx NAK\n");
 299                         gdbstub_io_tx_char('-');
 300                         continue;
 301                 }
 302
 303                 /* check the checksum */
 304                 if (checksum != xmitcsum) {
 305                         gdbstub_io("### GDB Tx NAK\n");
 306                         gdbstub_io_tx_char('-');        /* failed checksum */
 307                         continue;
 308                 }
 309
 310                 gdbstub_proto("### GDB Rx '$%s#%02x' ###\n", buffer, checksum);
 311                 gdbstub_io("### GDB Tx ACK\n");
 312                 gdbstub_io_tx_char('+'); /* successful transfer */
 313
 314                 /*
 315                  * if a sequence char is present,
 316                  * reply the sequence ID
 317                  */
 318                 if (buffer[2] == ':') {
 319                         gdbstub_io_tx_char(buffer[0]);
 320                         gdbstub_io_tx_char(buffer[1]);
 321
 322                         /*
 323                          * remove sequence chars from buffer
 324                          */
 325                         count = 0;
 326                         while (buffer[count])
 327                                 count++;
 328                         for (i = 3; i <= count; i++)
 329                                 buffer[i - 3] = buffer[i];
 330                 }
 331
 332                 break;
 333         }
 334 }
 335
 336 /*
 337  * send the packet in buffer.
 338  * - return 0 if successfully ACK'd
 339  * - return 1 if abandoned due to new incoming packet
 340  */
 341 static int putpacket(char *buffer)
 342 {
 343         unsigned char checksum;
 344         unsigned char ch;
 345         int count;
 346
 347         /*
 348          * $<packet info>#<checksum>.
 349          */
 350         gdbstub_proto("### GDB Tx $'%s'#?? ###\n", buffer);
 351
 352         do {
 353                 gdbstub_io_tx_char('$');
 354                 checksum = 0;
 355                 count = 0;
 356
 357                 while ((ch = buffer[count]) != 0) {
 358                         gdbstub_io_tx_char(ch);
 359                         checksum += ch;
 360                         count += 1;
 361                 }
 362
 363                 gdbstub_io_tx_char('#');
 364                 gdbstub_io_tx_char(hex_asc_hi(checksum));
 365                 gdbstub_io_tx_char(hex_asc_lo(checksum));
 366
 367         } while (gdbstub_io_rx_char(&ch, 0),
 368                  ch == '-' && (gdbstub_io("### GDB Rx NAK\n"), 0),
 369                  ch != '-' && ch != '+' &&
 370                  (gdbstub_io("### GDB Rx ??? %02x\n", ch), 0),
 371                  ch != '+' && ch != '$');
 372
 373         if (ch == '+') {
 374                 gdbstub_io("### GDB Rx ACK\n");
 375                 return 0;
 376         }
 377
 378         gdbstub_io("### GDB Tx Abandoned\n");
 379         gdbstub_rx_unget = ch;
 380         return 1;
 381 }
 382
 383 /*
 384  * While we find nice hex chars, build an int.
 385  * Return number of chars processed.
 386  */
 387 static int hexToInt(char **ptr, int *intValue)
 388 {
 389         int numChars = 0;
 390         int hexValue;
 391
 392         *intValue = 0;
 393
 394         while (**ptr) {
 395                 hexValue = hex(**ptr);
 396                 if (hexValue < 0)
 397                         break;
 398
 399                 *intValue = (*intValue << 4) | hexValue;
 400                 numChars++;
 401
 402                 (*ptr)++;
 403         }
 404
 405         return (numChars);
 406 }
 407
 408 /*
 409  * We single-step by setting breakpoints. When an exception
 410  * is handled, we need to restore the instructions hoisted
 411  * when the breakpoints were set.
 412  *
 413  * This is where we save the original instructions.
 414  */
 415 static struct gdb_bp_save {
 416         u8      *addr;
 417         u8      opcode[2];
 418 } step_bp[2];
 419
 420 static const unsigned char gdbstub_insn_sizes[256] =
 421 {
 422         /* 1  2  3  4  5  6  7  8  9  a  b  c  d  e  f */
 423         1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, /* 0 */
 424         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 1 */
 425         2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, /* 2 */
 426         3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, /* 3 */
 427         1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, /* 4 */
 428         1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, /* 5 */
 429         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6 */
 430         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 7 */
 431         2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 8 */
 432         2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 9 */
 433         2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* a */
 434         2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* b */
 435         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 2, /* c */
 436         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* d */
 437         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* e */
 438         0, 2, 2, 2, 2, 2, 2, 4, 0, 3, 0, 4, 0, 6, 7, 1  /* f */
 439 };
 440
 441 static int __gdbstub_mark_bp(u8 *addr, int ix)
 442 {
 443         if (addr < (u8 *) 0x70000000UL)
 444                 return 0;
 445         /* 70000000-7fffffff: vmalloc area */
 446         if (addr < (u8 *) 0x80000000UL)
 447                 goto okay;
 448         if (addr < (u8 *) 0x8c000000UL)
 449                 return 0;
 450         /* 8c000000-93ffffff: SRAM, SDRAM */
 451         if (addr < (u8 *) 0x94000000UL)
 452                 goto okay;
 453         return 0;
 454
 455 okay:
 456         if (gdbstub_read_byte(addr + 0, &step_bp[ix].opcode[0]) < 0 ||
 457             gdbstub_read_byte(addr + 1, &step_bp[ix].opcode[1]) < 0)
 458                 return 0;
 459
 460         step_bp[ix].addr = addr;
 461         return 1;
 462 }
 463
 464 static inline void __gdbstub_restore_bp(void)
 465 {
 466 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
 467         if (step_bp[0].addr) {
 468                 gdbstub_write_byte(step_bp[0].opcode[0], step_bp[0].addr + 0);
 469                 gdbstub_write_byte(step_bp[0].opcode[1], step_bp[0].addr + 1);
 470         }
 471         if (step_bp[1].addr) {
 472                 gdbstub_write_byte(step_bp[1].opcode[0], step_bp[1].addr + 0);
 473                 gdbstub_write_byte(step_bp[1].opcode[1], step_bp[1].addr + 1);
 474         }
 475 #else
 476         if (step_bp[0].addr)
 477                 gdbstub_write_byte(step_bp[0].opcode[0], step_bp[0].addr + 0);
 478         if (step_bp[1].addr)
 479                 gdbstub_write_byte(step_bp[1].opcode[0], step_bp[1].addr + 0);
 480 #endif
 481
 482         gdbstub_flush_caches = 1;
 483
 484         step_bp[0].addr         = NULL;
 485         step_bp[0].opcode[0]    = 0;
 486         step_bp[0].opcode[1]    = 0;
 487         step_bp[1].addr         = NULL;
 488         step_bp[1].opcode[0]    = 0;
 489         step_bp[1].opcode[1]    = 0;
 490 }
 491
 492 /*
 493  * emulate single stepping by means of breakpoint instructions
 494  */
 495 static int gdbstub_single_step(struct pt_regs *regs)
 496 {
 497         unsigned size;
 498         uint32_t x;
 499         uint8_t cur, *pc, *sp;
 500
 501         step_bp[0].addr         = NULL;
 502         step_bp[0].opcode[0]    = 0;
 503         step_bp[0].opcode[1]    = 0;
 504         step_bp[1].addr         = NULL;
 505         step_bp[1].opcode[0]    = 0;
 506         step_bp[1].opcode[1]    = 0;
 507         x = 0;
 508
 509         pc = (u8 *) regs->pc;
 510         sp = (u8 *) (regs + 1);
 511         if (gdbstub_read_byte(pc, &cur) < 0)
 512                 return -EFAULT;
 513
 514         gdbstub_bkpt("Single Step from %p { %02x }\n", pc, cur);
 515
 516         gdbstub_flush_caches = 1;
 517
 518         size = gdbstub_insn_sizes[cur];
 519         if (size > 0) {
 520                 if (!__gdbstub_mark_bp(pc + size, 0))
 521                         goto fault;
 522         } else {
 523                 switch (cur) {
 524                         /* Bxx (d8,PC) */
 525                 case 0xc0 ... 0xca:
 526                         if (gdbstub_read_byte(pc + 1, (u8 *) &x) < 0)
 527                                 goto fault;
 528                         if (!__gdbstub_mark_bp(pc + 2, 0))
 529                                 goto fault;
 530                         if ((x < 0 || x > 2) &&
 531                             !__gdbstub_mark_bp(pc + (s8) x, 1))
 532                                 goto fault;
 533                         break;
 534
 535                         /* LXX (d8,PC) */
 536                 case 0xd0 ... 0xda:
 537                         if (!__gdbstub_mark_bp(pc + 1, 0))
 538                                 goto fault;
 539                         if (regs->pc != regs->lar &&
 540                             !__gdbstub_mark_bp((u8 *) regs->lar, 1))
 541                                 goto fault;
 542                         break;
 543
 544                         /* SETLB - loads the next for bytes into the LIR
 545                          * register */
 546                 case 0xdb:
 547                         if (!__gdbstub_mark_bp(pc + 1, 0))
 548                                 goto fault;
 549                         break;
 550
 551                         /* JMP (d16,PC) or CALL (d16,PC) */
 552                 case 0xcc:
 553                 case 0xcd:
 554                         if (gdbstub_read_byte(pc + 1, ((u8 *) &x) + 0) < 0 ||
 555                             gdbstub_read_byte(pc + 2, ((u8 *) &x) + 1) < 0)
 556                                 goto fault;
 557                         if (!__gdbstub_mark_bp(pc + (s16) x, 0))
 558                                 goto fault;
 559                         break;
 560
 561                         /* JMP (d32,PC) or CALL (d32,PC) */
 562                 case 0xdc:
 563                 case 0xdd:
 564                         if (gdbstub_read_byte(pc + 1, ((u8 *) &x) + 0) < 0 ||
 565                             gdbstub_read_byte(pc + 2, ((u8 *) &x) + 1) < 0 ||
 566                             gdbstub_read_byte(pc + 3, ((u8 *) &x) + 2) < 0 ||
 567                             gdbstub_read_byte(pc + 4, ((u8 *) &x) + 3) < 0)
 568                                 goto fault;
 569                         if (!__gdbstub_mark_bp(pc + (s32) x, 0))
 570                                 goto fault;
 571                         break;
 572
 573                         /* RETF */
 574                 case 0xde:
 575                         if (!__gdbstub_mark_bp((u8 *) regs->mdr, 0))
 576                                 goto fault;
 577                         break;
 578
 579                         /* RET */
 580                 case 0xdf:
 581                         if (gdbstub_read_byte(pc + 2, (u8 *) &x) < 0)
 582                                 goto fault;
 583                         sp += (s8)x;
 584                         if (gdbstub_read_byte(sp + 0, ((u8 *) &x) + 0) < 0 ||
 585                             gdbstub_read_byte(sp + 1, ((u8 *) &x) + 1) < 0 ||
 586                             gdbstub_read_byte(sp + 2, ((u8 *) &x) + 2) < 0 ||
 587                             gdbstub_read_byte(sp + 3, ((u8 *) &x) + 3) < 0)
 588                                 goto fault;
 589                         if (!__gdbstub_mark_bp((u8 *) x, 0))
 590                                 goto fault;
 591                         break;
 592
 593                 case 0xf0:
 594                         if (gdbstub_read_byte(pc + 1, &cur) < 0)
 595                                 goto fault;
 596
 597                         if (cur >= 0xf0 && cur <= 0xf7) {
 598                                 /* JMP (An) / CALLS (An) */
 599                                 switch (cur & 3) {
 600                                 case 0: x = regs->a0; break;
 601                                 case 1: x = regs->a1; break;
 602                                 case 2: x = regs->a2; break;
 603                                 case 3: x = regs->a3; break;
 604                                 }
 605                                 if (!__gdbstub_mark_bp((u8 *) x, 0))
 606                                         goto fault;
 607                         } else if (cur == 0xfc) {
 608                                 /* RETS */
 609                                 if (gdbstub_read_byte(
 610                                             sp + 0, ((u8 *) &x) + 0) < 0 ||
 611                                     gdbstub_read_byte(
 612                                             sp + 1, ((u8 *) &x) + 1) < 0 ||
 613                                     gdbstub_read_byte(
 614                                             sp + 2, ((u8 *) &x) + 2) < 0 ||
 615                                     gdbstub_read_byte(
 616                                             sp + 3, ((u8 *) &x) + 3) < 0)
 617                                         goto fault;
 618                                 if (!__gdbstub_mark_bp((u8 *) x, 0))
 619                                         goto fault;
 620                         } else if (cur == 0xfd) {
 621                                 /* RTI */
 622                                 if (gdbstub_read_byte(
 623                                             sp + 4, ((u8 *) &x) + 0) < 0 ||
 624                                     gdbstub_read_byte(
 625                                             sp + 5, ((u8 *) &x) + 1) < 0 ||
 626                                     gdbstub_read_byte(
 627                                             sp + 6, ((u8 *) &x) + 2) < 0 ||
 628                                     gdbstub_read_byte(
 629                                             sp + 7, ((u8 *) &x) + 3) < 0)
 630                                         goto fault;
 631                                 if (!__gdbstub_mark_bp((u8 *) x, 0))
 632                                         goto fault;
 633                         } else {
 634                                 if (!__gdbstub_mark_bp(pc + 2, 0))
 635                                         goto fault;
 636                         }
 637
 638                         break;
 639
 640                         /* potential 3-byte conditional branches */
 641                 case 0xf8:
 642                         if (gdbstub_read_byte(pc + 1, &cur) < 0)
 643                                 goto fault;
 644                         if (!__gdbstub_mark_bp(pc + 3, 0))
 645                                 goto fault;
 646
 647                         if (cur >= 0xe8 && cur <= 0xeb) {
 648                                 if (gdbstub_read_byte(
 649                                             pc + 2, ((u8 *) &x) + 0) < 0)
 650                                         goto fault;
 651                                 if ((x < 0 || x > 3) &&
 652                                     !__gdbstub_mark_bp(pc + (s8) x, 1))
 653                                         goto fault;
 654                         }
 655                         break;
 656
 657                 case 0xfa:
 658                         if (gdbstub_read_byte(pc + 1, &cur) < 0)
 659                                 goto fault;
 660
 661                         if (cur == 0xff) {
 662                                 /* CALLS (d16,PC) */
 663                                 if (gdbstub_read_byte(
 664                                             pc + 2, ((u8 *) &x) + 0) < 0 ||
 665                                     gdbstub_read_byte(
 666                                             pc + 3, ((u8 *) &x) + 1) < 0)
 667                                         goto fault;
 668                                 if (!__gdbstub_mark_bp(pc + (s16) x, 0))
 669                                         goto fault;
 670                         } else {
 671                                 if (!__gdbstub_mark_bp(pc + 4, 0))
 672                                         goto fault;
 673                         }
 674                         break;
 675
 676                 case 0xfc:
 677                         if (gdbstub_read_byte(pc + 1, &cur) < 0)
 678                                 goto fault;
 679                         if (cur == 0xff) {
 680                                 /* CALLS (d32,PC) */
 681                                 if (gdbstub_read_byte(
 682                                             pc + 2, ((u8 *) &x) + 0) < 0 ||
 683                                     gdbstub_read_byte(
 684                                             pc + 3, ((u8 *) &x) + 1) < 0 ||
 685                                     gdbstub_read_byte(
 686                                             pc + 4, ((u8 *) &x) + 2) < 0 ||
 687                                     gdbstub_read_byte(
 688                                             pc + 5, ((u8 *) &x) + 3) < 0)
 689                                         goto fault;
 690                                 if (!__gdbstub_mark_bp(
 691                                             pc + (s32) x, 0))
 692                                         goto fault;
 693                         } else {
 694                                 if (!__gdbstub_mark_bp(
 695                                             pc + 6, 0))
 696                                         goto fault;
 697                         }
 698                         break;
 699
 700                 }
 701         }
 702
 703         gdbstub_bkpt("Step: %02x at %p; %02x at %p\n",
 704                      step_bp[0].opcode[0], step_bp[0].addr,
 705                      step_bp[1].opcode[0], step_bp[1].addr);
 706
 707         if (step_bp[0].addr) {
 708 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
 709                 if (gdbstub_write_byte(0xF7, step_bp[0].addr + 0) < 0 ||
 710                     gdbstub_write_byte(0xF7, step_bp[0].addr + 1) < 0)
 711                         goto fault;
 712 #else
 713                 if (gdbstub_write_byte(0xFF, step_bp[0].addr + 0) < 0)
 714                         goto fault;
 715 #endif
 716         }
 717
 718         if (step_bp[1].addr) {
 719 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
 720                 if (gdbstub_write_byte(0xF7, step_bp[1].addr + 0) < 0 ||
 721                     gdbstub_write_byte(0xF7, step_bp[1].addr + 1) < 0)
 722                         goto fault;
 723 #else
 724                 if (gdbstub_write_byte(0xFF, step_bp[1].addr + 0) < 0)
 725                         goto fault;
 726 #endif
 727         }
 728
 729         return 0;
 730
 731  fault:
 732         /* uh-oh - silly address alert, try and restore things */
 733         __gdbstub_restore_bp();
 734         return -EFAULT;
 735 }
 736
 737 #ifdef CONFIG_GDBSTUB_CONSOLE
 738
 739 void gdbstub_console_write(struct console *con, const char *p, unsigned n)
 740 {
 741         static const char gdbstub_cr[] = { 0x0d };
 742         char outbuf[26];
 743         int qty;
 744         u8 busy;
 745
 746         busy = gdbstub_busy;
 747         gdbstub_busy = 1;
 748
 749         outbuf[0] = 'O';
 750
 751         while (n > 0) {
 752                 qty = 1;
 753
 754                 while (n > 0 && qty < 20) {
 755                         mem2hex(p, outbuf + qty, 2, 0);
 756                         qty += 2;
 757                         if (*p == 0x0a) {
 758                                 mem2hex(gdbstub_cr, outbuf + qty, 2, 0);
 759                                 qty += 2;
 760                         }
 761                         p++;
 762                         n--;
 763                 }
 764
 765                 outbuf[qty] = 0;
 766                 putpacket(outbuf);
 767         }
 768
 769         gdbstub_busy = busy;
 770 }
 771
 772 static kdev_t gdbstub_console_dev(struct console *con)
 773 {
 774         return MKDEV(1, 3); /* /dev/null */
 775 }
 776
 777 static struct console gdbstub_console = {
 778         .name   = "gdb",
 779         .write  = gdbstub_console_write,
 780         .device = gdbstub_console_dev,
 781         .flags  = CON_PRINTBUFFER,
 782         .index  = -1,
 783 };
 784
 785 #endif
 786
 787 /*
 788  * Convert the memory pointed to by mem into hex, placing result in buf.
 789  * - if successful, return a pointer to the last char put in buf (NUL)
 790  * - in case of mem fault, return NULL
 791  * may_fault is non-zero if we are reading from arbitrary memory, but is
 792  * currently not used.
 793  */
 794 static
 795 unsigned char *mem2hex(const void *_mem, char *buf, int count, int may_fault)
 796 {
 797         const u8 *mem = _mem;
 798         u8 ch[4];
 799
 800         if ((u32) mem & 1 && count >= 1) {
 801                 if (gdbstub_read_byte(mem, ch) != 0)
 802                         return 0;
 803                 buf = pack_hex_byte(buf, ch[0]);
 804                 mem++;
 805                 count--;
 806         }
 807
 808         if ((u32) mem & 3 && count >= 2) {
 809                 if (gdbstub_read_word(mem, ch) != 0)
 810                         return 0;
 811                 buf = pack_hex_byte(buf, ch[0]);
 812                 buf = pack_hex_byte(buf, ch[1]);
 813                 mem += 2;
 814                 count -= 2;
 815         }
 816
 817         while (count >= 4) {
 818                 if (gdbstub_read_dword(mem, ch) != 0)
 819                         return 0;
 820                 buf = pack_hex_byte(buf, ch[0]);
 821                 buf = pack_hex_byte(buf, ch[1]);
 822                 buf = pack_hex_byte(buf, ch[2]);
 823                 buf = pack_hex_byte(buf, ch[3]);
 824                 mem += 4;
 825                 count -= 4;
 826         }
 827
 828         if (count >= 2) {
 829                 if (gdbstub_read_word(mem, ch) != 0)
 830                         return 0;
 831                 buf = pack_hex_byte(buf, ch[0]);
 832                 buf = pack_hex_byte(buf, ch[1]);
 833                 mem += 2;
 834                 count -= 2;
 835         }
 836
 837         if (count >= 1) {
 838                 if (gdbstub_read_byte(mem, ch) != 0)
 839                         return 0;
 840                 buf = pack_hex_byte(buf, ch[0]);
 841         }
 842
 843         *buf = 0;
 844         return buf;
 845 }
 846
 847 /*
 848  * convert the hex array pointed to by buf into binary to be placed in mem
 849  * return a pointer to the character AFTER the last byte written
 850  * may_fault is non-zero if we are reading from arbitrary memory, but is
 851  * currently not used.
 852  */
 853 static
 854 const char *hex2mem(const char *buf, void *_mem, int count, int may_fault)
 855 {
 856         u8 *mem = _mem;
 857         union {
 858                 u32 val;
 859                 u8 b[4];
 860         } ch;
 861
 862         if ((u32) mem & 1 && count >= 1) {
 863                 ch.b[0]  = hex(*buf++) << 4;
 864                 ch.b[0] |= hex(*buf++);
 865                 if (gdbstub_write_byte(ch.val, mem) != 0)
 866                         return 0;
 867                 mem++;
 868                 count--;
 869         }
 870
 871         if ((u32) mem & 3 && count >= 2) {
 872                 ch.b[0]  = hex(*buf++) << 4;
 873                 ch.b[0] |= hex(*buf++);
 874                 ch.b[1]  = hex(*buf++) << 4;
 875                 ch.b[1] |= hex(*buf++);
 876                 if (gdbstub_write_word(ch.val, mem) != 0)
 877                         return 0;
 878                 mem += 2;
 879                 count -= 2;
 880         }
 881
 882         while (count >= 4) {
 883                 ch.b[0]  = hex(*buf++) << 4;
 884                 ch.b[0] |= hex(*buf++);
 885                 ch.b[1]  = hex(*buf++) << 4;
 886                 ch.b[1] |= hex(*buf++);
 887                 ch.b[2]  = hex(*buf++) << 4;
 888                 ch.b[2] |= hex(*buf++);
 889                 ch.b[3]  = hex(*buf++) << 4;
 890                 ch.b[3] |= hex(*buf++);
 891                 if (gdbstub_write_dword(ch.val, mem) != 0)
 892                         return 0;
 893                 mem += 4;
 894                 count -= 4;
 895         }
 896
 897         if (count >= 2) {
 898                 ch.b[0]  = hex(*buf++) << 4;
 899                 ch.b[0] |= hex(*buf++);
 900                 ch.b[1]  = hex(*buf++) << 4;
 901                 ch.b[1] |= hex(*buf++);
 902                 if (gdbstub_write_word(ch.val, mem) != 0)
 903                         return 0;
 904                 mem += 2;
 905                 count -= 2;
 906         }
 907
 908         if (count >= 1) {
 909                 ch.b[0]  = hex(*buf++) << 4;
 910                 ch.b[0] |= hex(*buf++);
 911                 if (gdbstub_write_byte(ch.val, mem) != 0)
 912                         return 0;
 913         }
 914
 915         return buf;
 916 }
 917
 918 /*
 919  * This table contains the mapping between MN10300 exception codes, and
 920  * signals, which are primarily what GDB understands.  It also indicates
 921  * which hardware traps we need to commandeer when initializing the stub.
 922  */
 923 static const struct excep_to_sig_map {
 924         enum exception_code     excep;  /* MN10300 exception code */
 925         unsigned char           signo;  /* Signal that we map this into */
 926 } excep_to_sig_map[] = {
 927         { EXCEP_ITLBMISS,       SIGSEGV         },
 928         { EXCEP_DTLBMISS,       SIGSEGV         },
 929         { EXCEP_TRAP,           SIGTRAP         },
 930         { EXCEP_ISTEP,          SIGTRAP         },
 931         { EXCEP_IBREAK,         SIGTRAP         },
 932         { EXCEP_OBREAK,         SIGTRAP         },
 933         { EXCEP_UNIMPINS,       SIGILL          },
 934         { EXCEP_UNIMPEXINS,     SIGILL          },
 935         { EXCEP_MEMERR,         SIGSEGV         },
 936         { EXCEP_MISALIGN,       SIGSEGV         },
 937         { EXCEP_BUSERROR,       SIGBUS          },
 938         { EXCEP_ILLINSACC,      SIGSEGV         },
 939         { EXCEP_ILLDATACC,      SIGSEGV         },
 940         { EXCEP_IOINSACC,       SIGSEGV         },
 941         { EXCEP_PRIVINSACC,     SIGSEGV         },
 942         { EXCEP_PRIVDATACC,     SIGSEGV         },
 943         { EXCEP_FPU_DISABLED,   SIGFPE          },
 944         { EXCEP_FPU_UNIMPINS,   SIGFPE          },
 945         { EXCEP_FPU_OPERATION,  SIGFPE          },
 946         { EXCEP_WDT,            SIGALRM         },
 947         { EXCEP_NMI,            SIGQUIT         },
 948         { EXCEP_IRQ_LEVEL0,     SIGINT          },
 949         { EXCEP_IRQ_LEVEL1,     SIGINT          },
 950         { EXCEP_IRQ_LEVEL2,     SIGINT          },
 951         { EXCEP_IRQ_LEVEL3,     SIGINT          },
 952         { EXCEP_IRQ_LEVEL4,     SIGINT          },
 953         { EXCEP_IRQ_LEVEL5,     SIGINT          },
 954         { EXCEP_IRQ_LEVEL6,     SIGINT          },
 955         { 0, 0}
 956 };
 957
 958 /*
 959  * convert the MN10300 exception code into a UNIX signal number
 960  */
 961 static int computeSignal(enum exception_code excep)
 962 {
 963         const struct excep_to_sig_map *map;
 964
 965         for (map = excep_to_sig_map; map->signo; map++)
 966                 if (map->excep == excep)
 967                         return map->signo;
 968
 969         return SIGHUP; /* default for things we don't know about */
 970 }
 971
 972 static u32 gdbstub_fpcr, gdbstub_fpufs_array[32];
 973
 974 /*
 975  *
 976  */
 977 static void gdbstub_store_fpu(void)
 978 {
 979 #ifdef CONFIG_FPU
 980
 981         asm volatile(
 982                 "or %2,epsw\n"
 983 #ifdef CONFIG_MN10300_PROC_MN103E010
 984                 "nop\n"
 985                 "nop\n"
 986 #endif
 987                 "mov %1, a1\n"
 988                 "fmov fs0,  (a1+)\n"
 989                 "fmov fs1,  (a1+)\n"
 990                 "fmov fs2,  (a1+)\n"
 991                 "fmov fs3,  (a1+)\n"
 992                 "fmov fs4,  (a1+)\n"
 993                 "fmov fs5,  (a1+)\n"
 994                 "fmov fs6,  (a1+)\n"
 995                 "fmov fs7,  (a1+)\n"
 996                 "fmov fs8,  (a1+)\n"
 997                 "fmov fs9,  (a1+)\n"
 998                 "fmov fs10, (a1+)\n"
 999                 "fmov fs11, (a1+)\n"
1000                 "fmov fs12, (a1+)\n"
1001                 "fmov fs13, (a1+)\n"
1002                 "fmov fs14, (a1+)\n"
1003                 "fmov fs15, (a1+)\n"
1004                 "fmov fs16, (a1+)\n"
1005                 "fmov fs17, (a1+)\n"
1006                 "fmov fs18, (a1+)\n"
1007                 "fmov fs19, (a1+)\n"
1008                 "fmov fs20, (a1+)\n"
1009                 "fmov fs21, (a1+)\n"
1010                 "fmov fs22, (a1+)\n"
1011                 "fmov fs23, (a1+)\n"
1012                 "fmov fs24, (a1+)\n"
1013                 "fmov fs25, (a1+)\n"
1014                 "fmov fs26, (a1+)\n"
1015                 "fmov fs27, (a1+)\n"
1016                 "fmov fs28, (a1+)\n"
1017                 "fmov fs29, (a1+)\n"
1018                 "fmov fs30, (a1+)\n"
1019                 "fmov fs31, (a1+)\n"
1020                 "fmov fpcr, %0\n"
1021                 : "=d"(gdbstub_fpcr)
1022                 : "g" (&gdbstub_fpufs_array), "i"(EPSW_FE)
1023                 : "a1"
1024                 );
1025 #endif
1026 }
1027
1028 /*
1029  *
1030  */
1031 static void gdbstub_load_fpu(void)
1032 {
1033 #ifdef CONFIG_FPU
1034
1035         asm volatile(
1036                 "or %1,epsw\n"
1037 #ifdef CONFIG_MN10300_PROC_MN103E010
1038                 "nop\n"
1039                 "nop\n"
1040 #endif
1041                 "mov %0, a1\n"
1042                 "fmov (a1+), fs0\n"
1043                 "fmov (a1+), fs1\n"
1044                 "fmov (a1+), fs2\n"
1045                 "fmov (a1+), fs3\n"
1046                 "fmov (a1+), fs4\n"
1047                 "fmov (a1+), fs5\n"
1048                 "fmov (a1+), fs6\n"
1049                 "fmov (a1+), fs7\n"
1050                 "fmov (a1+), fs8\n"
1051                 "fmov (a1+), fs9\n"
1052                 "fmov (a1+), fs10\n"
1053                 "fmov (a1+), fs11\n"
1054                 "fmov (a1+), fs12\n"
1055                 "fmov (a1+), fs13\n"
1056                 "fmov (a1+), fs14\n"
1057                 "fmov (a1+), fs15\n"
1058                 "fmov (a1+), fs16\n"
1059                 "fmov (a1+), fs17\n"
1060                 "fmov (a1+), fs18\n"
1061                 "fmov (a1+), fs19\n"
1062                 "fmov (a1+), fs20\n"
1063                 "fmov (a1+), fs21\n"
1064                 "fmov (a1+), fs22\n"
1065                 "fmov (a1+), fs23\n"
1066                 "fmov (a1+), fs24\n"
1067                 "fmov (a1+), fs25\n"
1068                 "fmov (a1+), fs26\n"
1069                 "fmov (a1+), fs27\n"
1070                 "fmov (a1+), fs28\n"
1071                 "fmov (a1+), fs29\n"
1072                 "fmov (a1+), fs30\n"
1073                 "fmov (a1+), fs31\n"
1074                 "fmov %2, fpcr\n"
1075                 :
1076                 : "g" (&gdbstub_fpufs_array), "i"(EPSW_FE), "d"(gdbstub_fpcr)
1077                 : "a1"
1078         );
1079 #endif
1080 }
1081
1082 /*
1083  * set a software breakpoint
1084  */
1085 int gdbstub_set_breakpoint(u8 *addr, int len)
1086 {
1087         int bkpt, loop, xloop;
1088
1089 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
1090         len = (len + 1) & ~1;
1091 #endif
1092
1093         gdbstub_bkpt("setbkpt(%p,%d)\n", addr, len);
1094
1095         for (bkpt = 255; bkpt >= 0; bkpt--)
1096                 if (!gdbstub_bkpts[bkpt].addr)
1097                         break;
1098         if (bkpt < 0)
1099                 return -ENOSPC;
1100
1101         for (loop = 0; loop < len; loop++)
1102                 if (gdbstub_read_byte(&addr[loop],
1103                                       &gdbstub_bkpts[bkpt].origbytes[loop]
1104                                       ) < 0)
1105                         return -EFAULT;
1106
1107         gdbstub_flush_caches = 1;
1108
1109 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
1110         for (loop = 0; loop < len; loop++)
1111                 if (gdbstub_write_byte(0xF7, &addr[loop]) < 0)
1112                         goto restore;
1113 #else
1114         for (loop = 0; loop < len; loop++)
1115                 if (gdbstub_write_byte(0xFF, &addr[loop]) < 0)
1116                         goto restore;
1117 #endif
1118
1119         gdbstub_bkpts[bkpt].addr = addr;
1120         gdbstub_bkpts[bkpt].len = len;
1121
1122         gdbstub_bkpt("Set BKPT[%02x]: %p-%p {%02x%02x%02x%02x%02x%02x%02x}\n",
1123                      bkpt,
1124                      gdbstub_bkpts[bkpt].addr,
1125                      gdbstub_bkpts[bkpt].addr + gdbstub_bkpts[bkpt].len - 1,
1126                      gdbstub_bkpts[bkpt].origbytes[0],
1127                      gdbstub_bkpts[bkpt].origbytes[1],
1128                      gdbstub_bkpts[bkpt].origbytes[2],
1129                      gdbstub_bkpts[bkpt].origbytes[3],
1130                      gdbstub_bkpts[bkpt].origbytes[4],
1131                      gdbstub_bkpts[bkpt].origbytes[5],
1132                      gdbstub_bkpts[bkpt].origbytes[6]
1133                      );
1134
1135         return 0;
1136
1137 restore:
1138         for (xloop = 0; xloop < loop; xloop++)
1139                 gdbstub_write_byte(gdbstub_bkpts[bkpt].origbytes[xloop],
1140                                    addr + xloop);
1141         return -EFAULT;
1142 }
1143
1144 /*
1145  * clear a software breakpoint
1146  */
1147 int gdbstub_clear_breakpoint(u8 *addr, int len)
1148 {
1149         int bkpt, loop;
1150
1151 #ifdef GDBSTUB_USE_F7F7_AS_BREAKPOINT
1152         len = (len + 1) & ~1;
1153 #endif
1154
1155         gdbstub_bkpt("clearbkpt(%p,%d)\n", addr, len);
1156
1157         for (bkpt = 255; bkpt >= 0; bkpt--)
1158                 if (gdbstub_bkpts[bkpt].addr == addr &&
1159                     gdbstub_bkpts[bkpt].len == len)
1160                         break;
1161         if (bkpt < 0)
1162                 return -ENOENT;
1163
1164         gdbstub_bkpts[bkpt].addr = NULL;
1165
1166         gdbstub_flush_caches = 1;
1167
1168         for (loop = 0; loop < len; loop++)
1169                 if (gdbstub_write_byte(gdbstub_bkpts[bkpt].origbytes[loop],
1170                                        addr + loop) < 0)
1171                         return -EFAULT;
1172
1173         return 0;
1174 }
1175
1176 /*
1177  * This function does all command processing for interfacing to gdb
1178  * - returns 1 if the exception should be skipped, 0 otherwise.
1179  */
1180 static int gdbstub(struct pt_regs *regs, enum exception_code excep)
1181 {
1182         unsigned long *stack;
1183         unsigned long epsw, mdr;
1184         uint32_t zero, ssp;
1185         uint8_t broke;
1186         char *ptr;
1187         int sigval;
1188         int addr;
1189         int length;
1190         int loop;
1191
1192         if (excep == EXCEP_FPU_DISABLED)
1193                 return 0;
1194
1195         gdbstub_flush_caches = 0;
1196
1197         mn10300_set_gdbleds(1);
1198
1199         asm volatile("mov mdr,%0" : "=d"(mdr));
1200         asm volatile("mov epsw,%0" : "=d"(epsw));
1201         asm volatile("mov %0,epsw"
1202                      :: "d"((epsw & ~EPSW_IM) | EPSW_IE | EPSW_IM_1));
1203
1204         gdbstub_store_fpu();
1205
1206 #ifdef CONFIG_GDBSTUB_IMMEDIATE
1207         /* skip the initial pause loop */
1208         if (regs->pc == (unsigned long) __gdbstub_pause)
1209                 regs->pc = (unsigned long) start_kernel;
1210 #endif
1211
1212         /* if we were single stepping, restore the opcodes hoisted for the
1213          * breakpoint[s] */
1214         broke = 0;
1215         if ((step_bp[0].addr && step_bp[0].addr == (u8 *) regs->pc) ||
1216             (step_bp[1].addr && step_bp[1].addr == (u8 *) regs->pc))
1217                 broke = 1;
1218
1219         __gdbstub_restore_bp();
1220
1221         if (gdbstub_rx_unget) {
1222                 sigval = SIGINT;
1223                 if (gdbstub_rx_unget != 3)
1224                         goto packet_waiting;
1225                 gdbstub_rx_unget = 0;
1226         }
1227
1228         stack = (unsigned long *) regs->sp;
1229         sigval = broke ? SIGTRAP : computeSignal(excep);
1230
1231         /* send information about a BUG() */
1232         if (!user_mode(regs) && excep == EXCEP_SYSCALL15) {
1233                 const struct bug_entry *bug;
1234
1235                 bug = find_bug(regs->pc);
1236                 if (bug)
1237                         goto found_bug;
1238                 length = snprintf(trans_buffer, sizeof(trans_buffer),
1239                                   "BUG() at address %lx\n", regs->pc);
1240                 goto send_bug_pkt;
1241
1242         found_bug:
1243                 length = snprintf(trans_buffer, sizeof(trans_buffer),
1244                                   "BUG() at address %lx (%s:%d)\n",
1245                                   regs->pc, bug->file, bug->line);
1246
1247         send_bug_pkt:
1248                 ptr = output_buffer;
1249                 *ptr++ = 'O';
1250                 ptr = mem2hex(trans_buffer, ptr, length, 0);
1251                 *ptr = 0;
1252                 putpacket(output_buffer);
1253
1254                 regs->pc -= 2;
1255                 sigval = SIGABRT;
1256         } else if (regs->pc == (unsigned long) __gdbstub_bug_trap) {
1257                 regs->pc = regs->mdr;
1258                 sigval = SIGABRT;
1259         }
1260
1261         /*
1262          * send a message to the debugger's user saying what happened if it may
1263          * not be clear cut (we can't map exceptions onto signals properly)
1264          */
1265         if (sigval != SIGINT && sigval != SIGTRAP && sigval != SIGILL) {
1266                 static const char title[] = "Excep ", tbcberr[] = "BCBERR ";
1267                 static const char crlf[] = "\r\n";
1268                 char hx;
1269                 u32 bcberr = BCBERR;
1270
1271                 ptr = output_buffer;
1272                 *ptr++ = 'O';
1273                 ptr = mem2hex(title, ptr, sizeof(title) - 1, 0);
1274
1275                 hx = hex_asc_hi(excep >> 8);
1276                 ptr = pack_hex_byte(ptr, hx);
1277                 hx = hex_asc_lo(excep >> 8);
1278                 ptr = pack_hex_byte(ptr, hx);
1279                 hx = hex_asc_hi(excep);
1280                 ptr = pack_hex_byte(ptr, hx);
1281                 hx = hex_asc_lo(excep);
1282                 ptr = pack_hex_byte(ptr, hx);
1283
1284                 ptr = mem2hex(crlf, ptr, sizeof(crlf) - 1, 0);
1285                 *ptr = 0;
1286                 putpacket(output_buffer);       /* send it off... */
1287
1288                 /* BCBERR */
1289                 ptr = output_buffer;
1290                 *ptr++ = 'O';
1291                 ptr = mem2hex(tbcberr, ptr, sizeof(tbcberr) - 1, 0);
1292
1293                 hx = hex_asc_hi(bcberr >> 24);
1294                 ptr = pack_hex_byte(ptr, hx);
1295                 hx = hex_asc_lo(bcberr >> 24);
1296                 ptr = pack_hex_byte(ptr, hx);
1297                 hx = hex_asc_hi(bcberr >> 16);
1298                 ptr = pack_hex_byte(ptr, hx);
1299                 hx = hex_asc_lo(bcberr >> 16);
1300                 ptr = pack_hex_byte(ptr, hx);
1301                 hx = hex_asc_hi(bcberr >> 8);
1302                 ptr = pack_hex_byte(ptr, hx);
1303                 hx = hex_asc_lo(bcberr >> 8);
1304                 ptr = pack_hex_byte(ptr, hx);
1305                 hx = hex_asc_hi(bcberr);
1306                 ptr = pack_hex_byte(ptr, hx);
1307                 hx = hex_asc_lo(bcberr);
1308                 ptr = pack_hex_byte(ptr, hx);
1309
1310                 ptr = mem2hex(crlf, ptr, sizeof(crlf) - 1, 0);
1311                 *ptr = 0;
1312                 putpacket(output_buffer);       /* send it off... */
1313         }
1314
1315         /*
1316          * tell the debugger that an exception has occurred
1317          */
1318         ptr = output_buffer;
1319
1320         /*
1321          * Send trap type (converted to signal)
1322          */
1323         *ptr++ = 'T';
1324         ptr = pack_hex_byte(ptr, sigval);
1325
1326         /*
1327          * Send Error PC
1328          */
1329         ptr = pack_hex_byte(ptr, GDB_REGID_PC);
1330         *ptr++ = ':';
1331         ptr = mem2hex(&regs->pc, ptr, 4, 0);
1332         *ptr++ = ';';
1333
1334         /*
1335          * Send frame pointer
1336          */
1337         ptr = pack_hex_byte(ptr, GDB_REGID_FP);
1338         *ptr++ = ':';
1339         ptr = mem2hex(&regs->a3, ptr, 4, 0);
1340         *ptr++ = ';';
1341
1342         /*
1343          * Send stack pointer
1344          */
1345         ssp = (unsigned long) (regs + 1);
1346         ptr = pack_hex_byte(ptr, GDB_REGID_SP);
1347         *ptr++ = ':';
1348         ptr = mem2hex(&ssp, ptr, 4, 0);
1349         *ptr++ = ';';
1350
1351         *ptr++ = 0;
1352         putpacket(output_buffer);       /* send it off... */
1353
1354 packet_waiting:
1355         /*
1356          * Wait for input from remote GDB
1357          */
1358         while (1) {
1359                 output_buffer[0] = 0;
1360                 getpacket(input_buffer);
1361
1362                 switch (input_buffer[0]) {
1363                         /* request repeat of last signal number */
1364                 case '?':
1365                         output_buffer[0] = 'S';
1366                         output_buffer[1] = hex_asc_hi(sigval);
1367                         output_buffer[2] = hex_asc_lo(sigval);
1368                         output_buffer[3] = 0;
1369                         break;
1370
1371                 case 'd':
1372                         /* toggle debug flag */
1373                         break;
1374
1375                         /*
1376                          * Return the value of the CPU registers
1377                          */
1378                 case 'g':
1379                         zero = 0;
1380                         ssp = (u32) (regs + 1);
1381                         ptr = output_buffer;
1382                         ptr = mem2hex(&regs->d0, ptr, 4, 0);
1383                         ptr = mem2hex(&regs->d1, ptr, 4, 0);
1384                         ptr = mem2hex(&regs->d2, ptr, 4, 0);
1385                         ptr = mem2hex(&regs->d3, ptr, 4, 0);
1386                         ptr = mem2hex(&regs->a0, ptr, 4, 0);
1387                         ptr = mem2hex(&regs->a1, ptr, 4, 0);
1388                         ptr = mem2hex(&regs->a2, ptr, 4, 0);
1389                         ptr = mem2hex(&regs->a3, ptr, 4, 0);
1390
1391                         ptr = mem2hex(&ssp, ptr, 4, 0);         /* 8 */
1392                         ptr = mem2hex(&regs->pc, ptr, 4, 0);
1393                         ptr = mem2hex(&regs->mdr, ptr, 4, 0);
1394                         ptr = mem2hex(&regs->epsw, ptr, 4, 0);
1395                         ptr = mem2hex(&regs->lir, ptr, 4, 0);
1396                         ptr = mem2hex(&regs->lar, ptr, 4, 0);
1397                         ptr = mem2hex(&regs->mdrq, ptr, 4, 0);
1398
1399                         ptr = mem2hex(&regs->e0, ptr, 4, 0);    /* 15 */
1400                         ptr = mem2hex(&regs->e1, ptr, 4, 0);
1401                         ptr = mem2hex(&regs->e2, ptr, 4, 0);
1402                         ptr = mem2hex(&regs->e3, ptr, 4, 0);
1403                         ptr = mem2hex(&regs->e4, ptr, 4, 0);
1404                         ptr = mem2hex(&regs->e5, ptr, 4, 0);
1405                         ptr = mem2hex(&regs->e6, ptr, 4, 0);
1406                         ptr = mem2hex(&regs->e7, ptr, 4, 0);
1407
1408                         ptr = mem2hex(&ssp, ptr, 4, 0);
1409                         ptr = mem2hex(&regs, ptr, 4, 0);
1410                         ptr = mem2hex(&regs->sp, ptr, 4, 0);
1411                         ptr = mem2hex(&regs->mcrh, ptr, 4, 0);  /* 26 */
1412                         ptr = mem2hex(&regs->mcrl, ptr, 4, 0);
1413                         ptr = mem2hex(&regs->mcvf, ptr, 4, 0);
1414
1415                         ptr = mem2hex(&gdbstub_fpcr, ptr, 4, 0); /* 29 - FPCR */
1416                         ptr = mem2hex(&zero, ptr, 4, 0);
1417                         ptr = mem2hex(&zero, ptr, 4, 0);
1418                         for (loop = 0; loop < 32; loop++)
1419                                 ptr = mem2hex(&gdbstub_fpufs_array[loop],
1420                                               ptr, 4, 0); /* 32 - FS0-31 */
1421
1422                         break;
1423
1424                         /*
1425                          * set the value of the CPU registers - return OK
1426                          */
1427                 case 'G':
1428                 {
1429                         const char *ptr;
1430
1431                         ptr = &input_buffer[1];
1432                         ptr = hex2mem(ptr, &regs->d0, 4, 0);
1433                         ptr = hex2mem(ptr, &regs->d1, 4, 0);
1434                         ptr = hex2mem(ptr, &regs->d2, 4, 0);
1435                         ptr = hex2mem(ptr, &regs->d3, 4, 0);
1436                         ptr = hex2mem(ptr, &regs->a0, 4, 0);
1437                         ptr = hex2mem(ptr, &regs->a1, 4, 0);
1438                         ptr = hex2mem(ptr, &regs->a2, 4, 0);
1439                         ptr = hex2mem(ptr, &regs->a3, 4, 0);
1440
1441                         ptr = hex2mem(ptr, &ssp, 4, 0);         /* 8 */
1442                         ptr = hex2mem(ptr, &regs->pc, 4, 0);
1443                         ptr = hex2mem(ptr, &regs->mdr, 4, 0);
1444                         ptr = hex2mem(ptr, &regs->epsw, 4, 0);
1445                         ptr = hex2mem(ptr, &regs->lir, 4, 0);
1446                         ptr = hex2mem(ptr, &regs->lar, 4, 0);
1447                         ptr = hex2mem(ptr, &regs->mdrq, 4, 0);
1448
1449                         ptr = hex2mem(ptr, &regs->e0, 4, 0);    /* 15 */
1450                         ptr = hex2mem(ptr, &regs->e1, 4, 0);
1451                         ptr = hex2mem(ptr, &regs->e2, 4, 0);
1452                         ptr = hex2mem(ptr, &regs->e3, 4, 0);
1453                         ptr = hex2mem(ptr, &regs->e4, 4, 0);
1454                         ptr = hex2mem(ptr, &regs->e5, 4, 0);
1455                         ptr = hex2mem(ptr, &regs->e6, 4, 0);
1456                         ptr = hex2mem(ptr, &regs->e7, 4, 0);
1457
1458                         ptr = hex2mem(ptr, &ssp, 4, 0);
1459                         ptr = hex2mem(ptr, &zero, 4, 0);
1460                         ptr = hex2mem(ptr, &regs->sp, 4, 0);
1461                         ptr = hex2mem(ptr, &regs->mcrh, 4, 0);  /* 26 */
1462                         ptr = hex2mem(ptr, &regs->mcrl, 4, 0);
1463                         ptr = hex2mem(ptr, &regs->mcvf, 4, 0);
1464
1465                         ptr = hex2mem(ptr, &zero, 4, 0);        /* 29 - FPCR */
1466                         ptr = hex2mem(ptr, &zero, 4, 0);
1467                         ptr = hex2mem(ptr, &zero, 4, 0);
1468                         for (loop = 0; loop < 32; loop++)     /* 32 - FS0-31 */
1469                                 ptr = hex2mem(ptr, &zero, 4, 0);
1470
1471 #if 0
1472                         /*
1473                          * See if the stack pointer has moved. If so, then copy
1474                          * the saved locals and ins to the new location.
1475                          */
1476                         unsigned long *newsp = (unsigned long *) registers[SP];
1477                         if (sp != newsp)
1478                                 sp = memcpy(newsp, sp, 16 * 4);
1479 #endif
1480
1481                         gdbstub_strcpy(output_buffer, "OK");
1482                 }
1483                 break;
1484
1485                 /*
1486                  * mAA..AA,LLLL  Read LLLL bytes at address AA..AA
1487                  */
1488                 case 'm':
1489                         ptr = &input_buffer[1];
1490
1491                         if (hexToInt(&ptr, &addr) &&
1492                             *ptr++ == ',' &&
1493                             hexToInt(&ptr, &length)
1494                             ) {
1495                                 if (mem2hex((char *) addr, output_buffer,
1496                                             length, 1))
1497                                         break;
1498                                 gdbstub_strcpy(output_buffer, "E03");
1499                         } else {
1500                                 gdbstub_strcpy(output_buffer, "E01");
1501                         }
1502                         break;
1503
1504                         /*
1505                          * MAA..AA,LLLL: Write LLLL bytes at address AA.AA
1506                          * return OK
1507                          */
1508                 case 'M':
1509                         ptr = &input_buffer[1];
1510
1511                         if (hexToInt(&ptr, &addr) &&
1512                             *ptr++ == ',' &&
1513                             hexToInt(&ptr, &length) &&
1514                             *ptr++ == ':'
1515                             ) {
1516                                 if (hex2mem(ptr, (char *) addr, length, 1))
1517                                         gdbstub_strcpy(output_buffer, "OK");
1518                                 else
1519                                         gdbstub_strcpy(output_buffer, "E03");
1520
1521                                 gdbstub_flush_caches = 1;
1522                         } else {
1523                                 gdbstub_strcpy(output_buffer, "E02");
1524                         }
1525                         break;
1526
1527                         /*
1528                          * cAA..AA    Continue at address AA..AA(optional)
1529                          */
1530                 case 'c':
1531                         /* try to read optional parameter, pc unchanged if no
1532                          * parm */
1533
1534                         ptr = &input_buffer[1];
1535                         if (hexToInt(&ptr, &addr))
1536                                 regs->pc = addr;
1537                         goto done;
1538
1539                         /*
1540                          * kill the program
1541                          */
1542                 case 'k' :
1543                         goto done;      /* just continue */
1544
1545                         /*
1546                          * Reset the whole machine (FIXME: system dependent)
1547                          */
1548                 case 'r':
1549                         break;
1550
1551                         /*
1552                          * Step to next instruction
1553                          */
1554                 case 's':
1555                         /*
1556                          * using the T flag doesn't seem to perform single
1557                          * stepping (it seems to wind up being caught by the
1558                          * JTAG unit), so we have to use breakpoints and
1559                          * continue instead.
1560                          */
1561                         if (gdbstub_single_step(regs) < 0)
1562                                 /* ignore any fault error for now */
1563                                 gdbstub_printk("unable to set single-step"
1564                                                " bp\n");
1565                         goto done;
1566
1567                         /*
1568                          * Set baud rate (bBB)
1569                          */
1570                 case 'b':
1571                         do {
1572                                 int baudrate;
1573
1574                                 ptr = &input_buffer[1];
1575                                 if (!hexToInt(&ptr, &baudrate)) {
1576                                         gdbstub_strcpy(output_buffer, "B01");
1577                                         break;
1578                                 }
1579
1580                                 if (baudrate) {
1581                                         /* ACK before changing speed */
1582                                         putpacket("OK");
1583                                         gdbstub_io_set_baud(baudrate);
1584                                 }
1585                         } while (0);
1586                         break;
1587
1588                         /*
1589                          * Set breakpoint
1590                          */
1591                 case 'Z':
1592                         ptr = &input_buffer[1];
1593
1594                         if (!hexToInt(&ptr, &loop) || *ptr++ != ',' ||
1595                             !hexToInt(&ptr, &addr) || *ptr++ != ',' ||
1596                             !hexToInt(&ptr, &length)
1597                             ) {
1598                                 gdbstub_strcpy(output_buffer, "E01");
1599                                 break;
1600                         }
1601
1602                         /* only support software breakpoints */
1603                         gdbstub_strcpy(output_buffer, "E03");
1604                         if (loop != 0 ||
1605                             length < 1 ||
1606                             length > 7 ||
1607                             (unsigned long) addr < 4096)
1608                                 break;
1609
1610                         if (gdbstub_set_breakpoint((u8 *) addr, length) < 0)
1611                                 break;
1612
1613                         gdbstub_strcpy(output_buffer, "OK");
1614                         break;
1615
1616                         /*
1617                          * Clear breakpoint
1618                          */
1619                 case 'z':
1620                         ptr = &input_buffer[1];
1621
1622                         if (!hexToInt(&ptr, &loop) || *ptr++ != ',' ||
1623                             !hexToInt(&ptr, &addr) || *ptr++ != ',' ||
1624                             !hexToInt(&ptr, &length)
1625                             ) {
1626                                 gdbstub_strcpy(output_buffer, "E01");
1627                                 break;
1628                         }
1629
1630                         /* only support software breakpoints */
1631                         gdbstub_strcpy(output_buffer, "E03");
1632                         if (loop != 0 ||
1633                             length < 1 ||
1634                             length > 7 ||
1635                             (unsigned long) addr < 4096)
1636                                 break;
1637
1638                         if (gdbstub_clear_breakpoint((u8 *) addr, length) < 0)
1639                                 break;
1640
1641                         gdbstub_strcpy(output_buffer, "OK");
1642                         break;
1643
1644                 default:
1645                         gdbstub_proto("### GDB Unsupported Cmd '%s'\n",
1646                                       input_buffer);
1647                         break;
1648                 }
1649
1650                 /* reply to the request */
1651                 putpacket(output_buffer);
1652         }
1653
1654 done:
1655         /*
1656          * Need to flush the instruction cache here, as we may
1657          * have deposited a breakpoint, and the icache probably
1658          * has no way of knowing that a data ref to some location
1659          * may have changed something that is in the instruction
1660          * cache.
1661          * NB: We flush both caches, just to be sure...
1662          */
1663         if (gdbstub_flush_caches)
1664                 gdbstub_purge_cache();
1665
1666         gdbstub_load_fpu();
1667         mn10300_set_gdbleds(0);
1668         if (excep == EXCEP_NMI)
1669                 NMICR = NMICR_NMIF;
1670
1671         touch_softlockup_watchdog();
1672
1673         local_irq_restore(epsw);
1674         return 1;
1675 }
1676
1677 /*
1678  * handle event interception
1679  */
1680 asmlinkage int gdbstub_intercept(struct pt_regs *regs,
1681                                  enum exception_code excep)
1682 {
1683         static u8 notfirst = 1;
1684         int ret;
1685
1686         if (gdbstub_busy)
1687                 gdbstub_printk("--> gdbstub reentered itself\n");
1688         gdbstub_busy = 1;
1689
1690         if (notfirst) {
1691                 unsigned long mdr;
1692                 asm("mov mdr,%0" : "=d"(mdr));
1693
1694                 gdbstub_entry(
1695                         "--> gdbstub_intercept(%p,%04x) [MDR=%lx PC=%lx]\n",
1696                         regs, excep, mdr, regs->pc);
1697
1698                 gdbstub_entry(
1699                         "PC:  %08lx EPSW:  %08lx  SSP: %08lx mode: %s\n",
1700                         regs->pc, regs->epsw, (unsigned long) &ret,
1701                         user_mode(regs) ? "User" : "Super");
1702                 gdbstub_entry(
1703                         "d0:  %08lx   d1:  %08lx   d2: %08lx   d3: %08lx\n",
1704                         regs->d0, regs->d1, regs->d2, regs->d3);
1705                 gdbstub_entry(
1706                         "a0:  %08lx   a1:  %08lx   a2: %08lx   a3: %08lx\n",
1707                         regs->a0, regs->a1, regs->a2, regs->a3);
1708                 gdbstub_entry(
1709                         "e0:  %08lx   e1:  %08lx   e2: %08lx   e3: %08lx\n",
1710                         regs->e0, regs->e1, regs->e2, regs->e3);
1711                 gdbstub_entry(
1712                         "e4:  %08lx   e5:  %08lx   e6: %08lx   e7: %08lx\n",
1713                         regs->e4, regs->e5, regs->e6, regs->e7);
1714                 gdbstub_entry(
1715                         "lar: %08lx   lir: %08lx  mdr: %08lx  usp: %08lx\n",
1716                         regs->lar, regs->lir, regs->mdr, regs->sp);
1717                 gdbstub_entry(
1718                         "cvf: %08lx   crl: %08lx  crh: %08lx  drq: %08lx\n",
1719                         regs->mcvf, regs->mcrl, regs->mcrh, regs->mdrq);
1720                 gdbstub_entry(
1721                         "threadinfo=%p task=%p)\n",
1722                         current_thread_info(), current);
1723         } else {
1724                 notfirst = 1;
1725         }
1726
1727         ret = gdbstub(regs, excep);
1728
1729         gdbstub_entry("<-- gdbstub_intercept()\n");
1730         gdbstub_busy = 0;
1731         return ret;
1732 }
1733
1734 /*
1735  * handle the GDB stub itself causing an exception
1736  */
1737 asmlinkage void gdbstub_exception(struct pt_regs *regs,
1738                                   enum exception_code excep)
1739 {
1740         unsigned long mdr;
1741
1742         asm("mov mdr,%0" : "=d"(mdr));
1743         gdbstub_entry("--> gdbstub exception({%p},%04x) [MDR=%lx]\n",
1744                       regs, excep, mdr);
1745
1746         while ((unsigned long) regs == 0xffffffff) {}
1747
1748         /* handle guarded memory accesses where we know it might fault */
1749         if (regs->pc == (unsigned) gdbstub_read_byte_guard) {
1750                 regs->pc = (unsigned) gdbstub_read_byte_cont;
1751                 goto fault;
1752         }
1753
1754         if (regs->pc == (unsigned) gdbstub_read_word_guard) {
1755                 regs->pc = (unsigned) gdbstub_read_word_cont;
1756                 goto fault;
1757         }
1758
1759         if (regs->pc == (unsigned) gdbstub_read_dword_guard) {
1760                 regs->pc = (unsigned) gdbstub_read_dword_cont;
1761                 goto fault;
1762         }
1763
1764         if (regs->pc == (unsigned) gdbstub_write_byte_guard) {
1765                 regs->pc = (unsigned) gdbstub_write_byte_cont;
1766                 goto fault;
1767         }
1768
1769         if (regs->pc == (unsigned) gdbstub_write_word_guard) {
1770                 regs->pc = (unsigned) gdbstub_write_word_cont;
1771                 goto fault;
1772         }
1773
1774         if (regs->pc == (unsigned) gdbstub_write_dword_guard) {
1775                 regs->pc = (unsigned) gdbstub_write_dword_cont;
1776                 goto fault;
1777         }
1778
1779         gdbstub_printk("\n### GDB stub caused an exception ###\n");
1780
1781         /* something went horribly wrong */
1782         console_verbose();
1783         show_registers(regs);
1784
1785         panic("GDB Stub caused an unexpected exception - can't continue\n");
1786
1787         /* we caught an attempt by the stub to access silly memory */
1788 fault:
1789         gdbstub_entry("<-- gdbstub exception() = EFAULT\n");
1790         regs->d0 = -EFAULT;
1791         return;
1792 }
1793
1794 /*
1795  * send an exit message to GDB
1796  */
1797 void gdbstub_exit(int status)
1798 {
1799         unsigned char checksum;
1800         unsigned char ch;
1801         int count;
1802
1803         gdbstub_busy = 1;
1804         output_buffer[0] = 'W';
1805         output_buffer[1] = hex_asc_hi(status);
1806         output_buffer[2] = hex_asc_lo(status);
1807         output_buffer[3] = 0;
1808
1809         gdbstub_io_tx_char('$');
1810         checksum = 0;
1811         count = 0;
1812
1813         while ((ch = output_buffer[count]) != 0) {
1814                 gdbstub_io_tx_char(ch);
1815                 checksum += ch;
1816                 count += 1;
1817         }
1818
1819         gdbstub_io_tx_char('#');
1820         gdbstub_io_tx_char(hex_asc_hi(checksum));
1821         gdbstub_io_tx_char(hex_asc_lo(checksum));
1822
1823         /* make sure the output is flushed, or else RedBoot might clobber it */
1824         gdbstub_io_tx_flush();
1825
1826         gdbstub_busy = 0;
1827 }
1828
1829 /*
1830  * initialise the GDB stub
1831  */
1832 asmlinkage void __init gdbstub_init(void)
1833 {
1834 #ifdef CONFIG_GDBSTUB_IMMEDIATE
1835         unsigned char ch;
1836         int ret;
1837 #endif
1838
1839         gdbstub_busy = 1;
1840
1841         printk(KERN_INFO "%s", gdbstub_banner);
1842
1843         gdbstub_io_init();
1844
1845         gdbstub_entry("--> gdbstub_init\n");
1846
1847         /* try to talk to GDB (or anyone insane enough to want to type GDB
1848          * protocol by hand) */
1849         gdbstub_io("### GDB Tx ACK\n");
1850         gdbstub_io_tx_char('+'); /* 'hello world' */
1851
1852 #ifdef CONFIG_GDBSTUB_IMMEDIATE
1853         gdbstub_printk("GDB Stub waiting for packet\n");
1854
1855         /* in case GDB is started before us, ACK any packets that are already
1856          * sitting there (presumably "$?#xx")
1857          */
1858         do { gdbstub_io_rx_char(&ch, 0); } while (ch != '$');
1859         do { gdbstub_io_rx_char(&ch, 0); } while (ch != '#');
1860         /* eat first csum byte */
1861         do { ret = gdbstub_io_rx_char(&ch, 0); } while (ret != 0);
1862         /* eat second csum byte */
1863         do { ret = gdbstub_io_rx_char(&ch, 0); } while (ret != 0);
1864
1865         gdbstub_io("### GDB Tx NAK\n");
1866         gdbstub_io_tx_char('-'); /* NAK it */
1867
1868 #else
1869         printk("GDB Stub ready\n");
1870 #endif
1871
1872         gdbstub_busy = 0;
1873         gdbstub_entry("<-- gdbstub_init\n");
1874 }
1875
1876 /*
1877  * register the console at a more appropriate time
1878  */
1879 #ifdef CONFIG_GDBSTUB_CONSOLE
1880 static int __init gdbstub_postinit(void)
1881 {
1882         printk(KERN_NOTICE "registering console\n");
1883         register_console(&gdbstub_console);
1884         return 0;
1885 }
1886
1887 __initcall(gdbstub_postinit);
1888 #endif
1889
1890 /*
1891  * handle character reception on GDB serial port
1892  * - jump into the GDB stub if BREAK is detected on the serial line
1893  */
1894 asmlinkage void gdbstub_rx_irq(struct pt_regs *regs, enum exception_code excep)
1895 {
1896         char ch;
1897         int ret;
1898
1899         gdbstub_entry("--> gdbstub_rx_irq\n");
1900
1901         do {
1902                 ret = gdbstub_io_rx_char(&ch, 1);
1903                 if (ret != -EIO && ret != -EAGAIN) {
1904                         if (ret != -EINTR)
1905                                 gdbstub_rx_unget = ch;
1906                         gdbstub(regs, excep);
1907                 }
1908         } while (ret != -EAGAIN);
1909
1910         gdbstub_entry("<-- gdbstub_rx_irq\n");
1911 }