arch/mips/kernel/gdb-stub.c

   1 /*
   2  *  arch/mips/kernel/gdb-stub.c
   3  *
   4  *  Originally written by Glenn Engel, Lake Stevens Instrument Division
   5  *
   6  *  Contributed by HP Systems
   7  *
   8  *  Modified for SPARC by Stu Grossman, Cygnus Support.
   9  *
  10  *  Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
  11  *  Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
  12  *
  13  *  Copyright (C) 1995 Andreas Busse
  14  *
  15  *  Copyright (C) 2003 MontaVista Software Inc.
  16  *  Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
  17  */
  18
  19 /*
  20  *  To enable debugger support, two things need to happen.  One, a
  21  *  call to set_debug_traps() is necessary in order to allow any breakpoints
  22  *  or error conditions to be properly intercepted and reported to gdb.
  23  *  Two, a breakpoint needs to be generated to begin communication.  This
  24  *  is most easily accomplished by a call to breakpoint().  Breakpoint()
  25  *  simulates a breakpoint by executing a BREAK instruction.
  26  *
  27  *
  28  *    The following gdb commands are supported:
  29  *
  30  * command          function                               Return value
  31  *
  32  *    g             return the value of the CPU registers  hex data or ENN
  33  *    G             set the value of the CPU registers     OK or ENN
  34  *
  35  *    mAA..AA,LLLL  Read LLLL bytes at address AA..AA      hex data or ENN
  36  *    MAA..AA,LLLL: Write LLLL bytes at address AA.AA      OK or ENN
  37  *
  38  *    c             Resume at current address              SNN   ( signal NN)
  39  *    cAA..AA       Continue at address AA..AA             SNN
  40  *
  41  *    s             Step one instruction                   SNN
  42  *    sAA..AA       Step one instruction from AA..AA       SNN
  43  *
  44  *    k             kill
  45  *
  46  *    ?             What was the last sigval ?             SNN   (signal NN)
  47  *
  48  *    bBB..BB       Set baud rate to BB..BB                OK or BNN, then sets
  49  *                                                         baud rate
  50  *
  51  * All commands and responses are sent with a packet which includes a
  52  * checksum.  A packet consists of
  53  *
  54  * $<packet info>#<checksum>.
  55  *
  56  * where
  57  * <packet info> :: <characters representing the command or response>
  58  * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
  59  *
  60  * When a packet is received, it is first acknowledged with either '+' or '-'.
  61  * '+' indicates a successful transfer.  '-' indicates a failed transfer.
  62  *
  63  * Example:
  64  *
  65  * Host:                  Reply:
  66  * $m0,10#2a               +$00010203040506070809101112131415#42
  67  *
  68  *
  69  *  ==============
  70  *  MORE EXAMPLES:
  71  *  ==============
  72  *
  73  *  For reference -- the following are the steps that one
  74  *  company took (RidgeRun Inc) to get remote gdb debugging
  75  *  going. In this scenario the host machine was a PC and the
  76  *  target platform was a Galileo EVB64120A MIPS evaluation
  77  *  board.
  78  *
  79  *  Step 1:
  80  *  First download gdb-5.0.tar.gz from the internet.
  81  *  and then build/install the package.
  82  *
  83  *  Example:
  84  *    $ tar zxf gdb-5.0.tar.gz
  85  *    $ cd gdb-5.0
  86  *    $ ./configure --target=mips-linux-elf
  87  *    $ make
  88  *    $ install
  89  *    $ which mips-linux-elf-gdb
  90  *    /usr/local/bin/mips-linux-elf-gdb
  91  *
  92  *  Step 2:
  93  *  Configure linux for remote debugging and build it.
  94  *
  95  *  Example:
  96  *    $ cd ~/linux
  97  *    $ make menuconfig <go to "Kernel Hacking" and turn on remote debugging>
  98  *    $ make
  99  *
 100  *  Step 3:
 101  *  Download the kernel to the remote target and start
 102  *  the kernel running. It will promptly halt and wait
 103  *  for the host gdb session to connect. It does this
 104  *  since the "Kernel Hacking" option has defined
 105  *  CONFIG_KGDB which in turn enables your calls
 106  *  to:
 107  *     set_debug_traps();
 108  *     breakpoint();
 109  *
 110  *  Step 4:
 111  *  Start the gdb session on the host.
 112  *
 113  *  Example:
 114  *    $ mips-linux-elf-gdb vmlinux
 115  *    (gdb) set remotebaud 115200
 116  *    (gdb) target remote /dev/ttyS1
 117  *    ...at this point you are connected to
 118  *       the remote target and can use gdb
 119  *       in the normal fasion. Setting
 120  *       breakpoints, single stepping,
 121  *       printing variables, etc.
 122  */
 123 #include <linux/config.h>
 124 #include <linux/string.h>
 125 #include <linux/kernel.h>
 126 #include <linux/signal.h>
 127 #include <linux/sched.h>
 128 #include <linux/mm.h>
 129 #include <linux/console.h>
 130 #include <linux/init.h>
 131 #include <linux/smp.h>
 132 #include <linux/spinlock.h>
 133 #include <linux/slab.h>
 134 #include <linux/reboot.h>
 135
 136 #include <asm/asm.h>
 137 #include <asm/cacheflush.h>
 138 #include <asm/mipsregs.h>
 139 #include <asm/pgtable.h>
 140 #include <asm/system.h>
 141 #include <asm/gdb-stub.h>
 142 #include <asm/inst.h>
 143
 144 /*
 145  * external low-level support routines
 146  */
 147
 148 extern int putDebugChar(char c);    /* write a single character      */
 149 extern char getDebugChar(void);     /* read and return a single char */
 150 extern void trap_low(void);
 151
 152 /*
 153  * breakpoint and test functions
 154  */
 155 extern void breakpoint(void);
 156 extern void breakinst(void);
 157 extern void async_breakpoint(void);
 158 extern void async_breakinst(void);
 159 extern void adel(void);
 160
 161 /*
 162  * local prototypes
 163  */
 164
 165 static void getpacket(char *buffer);
 166 static void putpacket(char *buffer);
 167 static int computeSignal(int tt);
 168 static int hex(unsigned char ch);
 169 static int hexToInt(char **ptr, int *intValue);
 170 static int hexToLong(char **ptr, long *longValue);
 171 static unsigned char *mem2hex(char *mem, char *buf, int count, int may_fault);
 172 void handle_exception(struct gdb_regs *regs);
 173
 174 /*
 175  * spin locks for smp case
 176  */
 177 static spinlock_t kgdb_lock = SPIN_LOCK_UNLOCKED;
 178 static spinlock_t kgdb_cpulock[NR_CPUS] = { [0 ... NR_CPUS-1] = SPIN_LOCK_UNLOCKED};
 179
 180 /*
 181  * BUFMAX defines the maximum number of characters in inbound/outbound buffers
 182  * at least NUMREGBYTES*2 are needed for register packets
 183  */
 184 #define BUFMAX 2048
 185
 186 static char input_buffer[BUFMAX];
 187 static char output_buffer[BUFMAX];
 188 static int initialized; /* !0 means we've been initialized */
 189 static int kgdb_started;
 190 static const char hexchars[]="0123456789abcdef";
 191
 192 /* Used to prevent crashes in memory access.  Note that they'll crash anyway if
 193    we haven't set up fault handlers yet... */
 194 int kgdb_read_byte(unsigned char *address, unsigned char *dest);
 195 int kgdb_write_byte(unsigned char val, unsigned char *dest);
 196
 197 /*
 198  * Convert ch from a hex digit to an int
 199  */
 200 static int hex(unsigned char ch)
 201 {
 202         if (ch >= 'a' && ch <= 'f')
 203                 return ch-'a'+10;
 204         if (ch >= '0' && ch <= '9')
 205                 return ch-'0';
 206         if (ch >= 'A' && ch <= 'F')
 207                 return ch-'A'+10;
 208         return -1;
 209 }
 210
 211 /*
 212  * scan for the sequence $<data>#<checksum>
 213  */
 214 static void getpacket(char *buffer)
 215 {
 216         unsigned char checksum;
 217         unsigned char xmitcsum;
 218         int i;
 219         int count;
 220         unsigned char ch;
 221
 222         do {
 223                 /*
 224                  * wait around for the start character,
 225                  * ignore all other characters
 226                  */
 227                 while ((ch = (getDebugChar() & 0x7f)) != '$') ;
 228
 229                 checksum = 0;
 230                 xmitcsum = -1;
 231                 count = 0;
 232
 233                 /*
 234                  * now, read until a # or end of buffer is found
 235                  */
 236                 while (count < BUFMAX) {
 237                         ch = getDebugChar();
 238                         if (ch == '#')
 239                                 break;
 240                         checksum = checksum + ch;
 241                         buffer[count] = ch;
 242                         count = count + 1;
 243                 }
 244
 245                 if (count >= BUFMAX)
 246                         continue;
 247
 248                 buffer[count] = 0;
 249
 250                 if (ch == '#') {
 251                         xmitcsum = hex(getDebugChar() & 0x7f) << 4;
 252                         xmitcsum |= hex(getDebugChar() & 0x7f);
 253
 254                         if (checksum != xmitcsum)
 255                                 putDebugChar('-');      /* failed checksum */
 256                         else {
 257                                 putDebugChar('+'); /* successful transfer */
 258
 259                                 /*
 260                                  * if a sequence char is present,
 261                                  * reply the sequence ID
 262                                  */
 263                                 if (buffer[2] == ':') {
 264                                         putDebugChar(buffer[0]);
 265                                         putDebugChar(buffer[1]);
 266
 267                                         /*
 268                                          * remove sequence chars from buffer
 269                                          */
 270                                         count = strlen(buffer);
 271                                         for (i=3; i <= count; i++)
 272                                                 buffer[i-3] = buffer[i];
 273                                 }
 274                         }
 275                 }
 276         }
 277         while (checksum != xmitcsum);
 278 }
 279
 280 /*
 281  * send the packet in buffer.
 282  */
 283 static void putpacket(char *buffer)
 284 {
 285         unsigned char checksum;
 286         int count;
 287         unsigned char ch;
 288
 289         /*
 290          * $<packet info>#<checksum>.
 291          */
 292
 293         do {
 294                 putDebugChar('$');
 295                 checksum = 0;
 296                 count = 0;
 297
 298                 while ((ch = buffer[count]) != 0) {
 299                         if (!(putDebugChar(ch)))
 300                                 return;
 301                         checksum += ch;
 302                         count += 1;
 303                 }
 304
 305                 putDebugChar('#');
 306                 putDebugChar(hexchars[checksum >> 4]);
 307                 putDebugChar(hexchars[checksum & 0xf]);
 308
 309         }
 310         while ((getDebugChar() & 0x7f) != '+');
 311 }
 312
 313
 314 /*
 315  * Convert the memory pointed to by mem into hex, placing result in buf.
 316  * Return a pointer to the last char put in buf (null), in case of mem fault,
 317  * return 0.
 318  * may_fault is non-zero if we are reading from arbitrary memory, but is currently
 319  * not used.
 320  */
 321 static unsigned char *mem2hex(char *mem, char *buf, int count, int may_fault)
 322 {
 323         unsigned char ch;
 324
 325         while (count-- > 0) {
 326                 if (kgdb_read_byte(mem++, &ch) != 0)
 327                         return 0;
 328                 *buf++ = hexchars[ch >> 4];
 329                 *buf++ = hexchars[ch & 0xf];
 330         }
 331
 332         *buf = 0;
 333
 334         return buf;
 335 }
 336
 337 /*
 338  * convert the hex array pointed to by buf into binary to be placed in mem
 339  * return a pointer to the character AFTER the last byte written
 340  * may_fault is non-zero if we are reading from arbitrary memory, but is currently
 341  * not used.
 342  */
 343 static char *hex2mem(char *buf, char *mem, int count, int binary, int may_fault)
 344 {
 345         int i;
 346         unsigned char ch;
 347
 348         for (i=0; i<count; i++)
 349         {
 350                 if (binary) {
 351                         ch = *buf++;
 352                         if (ch == 0x7d)
 353                                 ch = 0x20 ^ *buf++;
 354                 }
 355                 else {
 356                         ch = hex(*buf++) << 4;
 357                         ch |= hex(*buf++);
 358                 }
 359                 if (kgdb_write_byte(ch, mem++) != 0)
 360                         return 0;
 361         }
 362
 363         return mem;
 364 }
 365
 366 /*
 367  * This table contains the mapping between SPARC hardware trap types, and
 368  * signals, which are primarily what GDB understands.  It also indicates
 369  * which hardware traps we need to commandeer when initializing the stub.
 370  */
 371 static struct hard_trap_info {
 372         unsigned char tt;               /* Trap type code for MIPS R3xxx and R4xxx */
 373         unsigned char signo;            /* Signal that we map this trap into */
 374 } hard_trap_info[] = {
 375         { 6, SIGBUS },                  /* instruction bus error */
 376         { 7, SIGBUS },                  /* data bus error */
 377         { 9, SIGTRAP },                 /* break */
 378         { 10, SIGILL },                 /* reserved instruction */
 379 /*      { 11, SIGILL },         */      /* CPU unusable */
 380         { 12, SIGFPE },                 /* overflow */
 381         { 13, SIGTRAP },                /* trap */
 382         { 14, SIGSEGV },                /* virtual instruction cache coherency */
 383         { 15, SIGFPE },                 /* floating point exception */
 384         { 23, SIGSEGV },                /* watch */
 385         { 31, SIGSEGV },                /* virtual data cache coherency */
 386         { 0, 0}                         /* Must be last */
 387 };
 388
 389 /* Save the normal trap handlers for user-mode traps. */
 390 void *saved_vectors[32];
 391
 392 /*
 393  * Set up exception handlers for tracing and breakpoints
 394  */
 395 void set_debug_traps(void)
 396 {
 397         struct hard_trap_info *ht;
 398         unsigned long flags;
 399         unsigned char c;
 400
 401         local_irq_save(flags);
 402         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
 403                 saved_vectors[ht->tt] = set_except_vector(ht->tt, trap_low);
 404
 405         putDebugChar('+'); /* 'hello world' */
 406         /*
 407          * In case GDB is started before us, ack any packets
 408          * (presumably "$?#xx") sitting there.
 409          */
 410         while((c = getDebugChar()) != '$');
 411         while((c = getDebugChar()) != '#');
 412         c = getDebugChar(); /* eat first csum byte */
 413         c = getDebugChar(); /* eat second csum byte */
 414         putDebugChar('+'); /* ack it */
 415
 416         initialized = 1;
 417         local_irq_restore(flags);
 418 }
 419
 420 void restore_debug_traps(void)
 421 {
 422         struct hard_trap_info *ht;
 423         unsigned long flags;
 424
 425         local_irq_save(flags);
 426         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
 427                 set_except_vector(ht->tt, saved_vectors[ht->tt]);
 428         local_irq_restore(flags);
 429 }
 430
 431 /*
 432  * Convert the MIPS hardware trap type code to a Unix signal number.
 433  */
 434 static int computeSignal(int tt)
 435 {
 436         struct hard_trap_info *ht;
 437
 438         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
 439                 if (ht->tt == tt)
 440                         return ht->signo;
 441
 442         return SIGHUP;          /* default for things we don't know about */
 443 }
 444
 445 /*
 446  * While we find nice hex chars, build an int.
 447  * Return number of chars processed.
 448  */
 449 static int hexToInt(char **ptr, int *intValue)
 450 {
 451         int numChars = 0;
 452         int hexValue;
 453
 454         *intValue = 0;
 455
 456         while (**ptr) {
 457                 hexValue = hex(**ptr);
 458                 if (hexValue < 0)
 459                         break;
 460
 461                 *intValue = (*intValue << 4) | hexValue;
 462                 numChars ++;
 463
 464                 (*ptr)++;
 465         }
 466
 467         return (numChars);
 468 }
 469
 470 static int hexToLong(char **ptr, long *longValue)
 471 {
 472         int numChars = 0;
 473         int hexValue;
 474
 475         *longValue = 0;
 476
 477         while (**ptr) {
 478                 hexValue = hex(**ptr);
 479                 if (hexValue < 0)
 480                         break;
 481
 482                 *longValue = (*longValue << 4) | hexValue;
 483                 numChars ++;
 484
 485                 (*ptr)++;
 486         }
 487
 488         return numChars;
 489 }
 490
 491
 492 #if 0
 493 /*
 494  * Print registers (on target console)
 495  * Used only to debug the stub...
 496  */
 497 void show_gdbregs(struct gdb_regs * regs)
 498 {
 499         /*
 500          * Saved main processor registers
 501          */
 502         printk("$0 : %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
 503                regs->reg0, regs->reg1, regs->reg2, regs->reg3,
 504                regs->reg4, regs->reg5, regs->reg6, regs->reg7);
 505         printk("$8 : %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
 506                regs->reg8, regs->reg9, regs->reg10, regs->reg11,
 507                regs->reg12, regs->reg13, regs->reg14, regs->reg15);
 508         printk("$16: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
 509                regs->reg16, regs->reg17, regs->reg18, regs->reg19,
 510                regs->reg20, regs->reg21, regs->reg22, regs->reg23);
 511         printk("$24: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
 512                regs->reg24, regs->reg25, regs->reg26, regs->reg27,
 513                regs->reg28, regs->reg29, regs->reg30, regs->reg31);
 514
 515         /*
 516          * Saved cp0 registers
 517          */
 518         printk("epc  : %08lx\nStatus: %08lx\nCause : %08lx\n",
 519                regs->cp0_epc, regs->cp0_status, regs->cp0_cause);
 520 }
 521 #endif /* dead code */
 522
 523 /*
 524  * We single-step by setting breakpoints. When an exception
 525  * is handled, we need to restore the instructions hoisted
 526  * when the breakpoints were set.
 527  *
 528  * This is where we save the original instructions.
 529  */
 530 static struct gdb_bp_save {
 531         unsigned long addr;
 532         unsigned int val;
 533 } step_bp[2];
 534
 535 #define BP 0x0000000d  /* break opcode */
 536
 537 /*
 538  * Set breakpoint instructions for single stepping.
 539  */
 540 static void single_step(struct gdb_regs *regs)
 541 {
 542         union mips_instruction insn;
 543         unsigned long targ;
 544         int is_branch, is_cond, i;
 545
 546         targ = regs->cp0_epc;
 547         insn.word = *(unsigned int *)targ;
 548         is_branch = is_cond = 0;
 549
 550         switch (insn.i_format.opcode) {
 551         /*
 552          * jr and jalr are in r_format format.
 553          */
 554         case spec_op:
 555                 switch (insn.r_format.func) {
 556                 case jalr_op:
 557                 case jr_op:
 558                         targ = *(&regs->reg0 + insn.r_format.rs);
 559                         is_branch = 1;
 560                         break;
 561                 }
 562                 break;
 563
 564         /*
 565          * This group contains:
 566          * bltz_op, bgez_op, bltzl_op, bgezl_op,
 567          * bltzal_op, bgezal_op, bltzall_op, bgezall_op.
 568          */
 569         case bcond_op:
 570                 is_branch = is_cond = 1;
 571                 targ += 4 + (insn.i_format.simmediate << 2);
 572                 break;
 573
 574         /*
 575          * These are unconditional and in j_format.
 576          */
 577         case jal_op:
 578         case j_op:
 579                 is_branch = 1;
 580                 targ += 4;
 581                 targ >>= 28;
 582                 targ <<= 28;
 583                 targ |= (insn.j_format.target << 2);
 584                 break;
 585
 586         /*
 587          * These are conditional.
 588          */
 589         case beq_op:
 590         case beql_op:
 591         case bne_op:
 592         case bnel_op:
 593         case blez_op:
 594         case blezl_op:
 595         case bgtz_op:
 596         case bgtzl_op:
 597         case cop0_op:
 598         case cop1_op:
 599         case cop2_op:
 600         case cop1x_op:
 601                 is_branch = is_cond = 1;
 602                 targ += 4 + (insn.i_format.simmediate << 2);
 603                 break;
 604         }
 605
 606         if (is_branch) {
 607                 i = 0;
 608                 if (is_cond && targ != (regs->cp0_epc + 8)) {
 609                         step_bp[i].addr = regs->cp0_epc + 8;
 610                         step_bp[i++].val = *(unsigned *)(regs->cp0_epc + 8);
 611                         *(unsigned *)(regs->cp0_epc + 8) = BP;
 612                 }
 613                 step_bp[i].addr = targ;
 614                 step_bp[i].val  = *(unsigned *)targ;
 615                 *(unsigned *)targ = BP;
 616         } else {
 617                 step_bp[0].addr = regs->cp0_epc + 4;
 618                 step_bp[0].val  = *(unsigned *)(regs->cp0_epc + 4);
 619                 *(unsigned *)(regs->cp0_epc + 4) = BP;
 620         }
 621 }
 622
 623 /*
 624  *  If asynchronously interrupted by gdb, then we need to set a breakpoint
 625  *  at the interrupted instruction so that we wind up stopped with a
 626  *  reasonable stack frame.
 627  */
 628 static struct gdb_bp_save async_bp;
 629
 630 /*
 631  * Swap the interrupted EPC with our asynchronous breakpoint routine.
 632  * This is safer than stuffing the breakpoint in-place, since no cache
 633  * flushes (or resulting smp_call_functions) are required.  The
 634  * assumption is that only one CPU will be handling asynchronous bp's,
 635  * and only one can be active at a time.
 636  */
 637 extern spinlock_t smp_call_lock;
 638 void set_async_breakpoint(unsigned long *epc)
 639 {
 640         /* skip breaking into userland */
 641         if ((*epc & 0x80000000) == 0)
 642                 return;
 643
 644         /* avoid deadlock if someone is make IPC */
 645         if (spin_is_locked(&smp_call_lock))
 646                 return;
 647
 648         async_bp.addr = *epc;
 649         *epc = (unsigned long)async_breakpoint;
 650 }
 651
 652 void kgdb_wait(void *arg)
 653 {
 654         unsigned flags;
 655         int cpu = smp_processor_id();
 656
 657         local_irq_save(flags);
 658
 659         spin_lock(&kgdb_cpulock[cpu]);
 660         spin_unlock(&kgdb_cpulock[cpu]);
 661
 662         local_irq_restore(flags);
 663 }
 664
 665
 666 /*
 667  * This function does all command processing for interfacing to gdb.  It
 668  * returns 1 if you should skip the instruction at the trap address, 0
 669  * otherwise.
 670  */
 671 void handle_exception (struct gdb_regs *regs)
 672 {
 673         int trap;                       /* Trap type */
 674         int sigval;
 675         long addr;
 676         int length;
 677         char *ptr;
 678         unsigned long *stack;
 679         int i;
 680         int bflag = 0;
 681
 682         kgdb_started = 1;
 683
 684         /*
 685          * acquire the big kgdb spinlock
 686          */
 687         if (!spin_trylock(&kgdb_lock)) {
 688                 /*
 689                  * some other CPU has the lock, we should go back to
 690                  * receive the gdb_wait IPC
 691                  */
 692                 return;
 693         }
 694
 695         /*
 696          * If we're in async_breakpoint(), restore the real EPC from
 697          * the breakpoint.
 698          */
 699         if (regs->cp0_epc == (unsigned long)async_breakinst) {
 700                 regs->cp0_epc = async_bp.addr;
 701                 async_bp.addr = 0;
 702         }
 703
 704         /*
 705          * acquire the CPU spinlocks
 706          */
 707         for (i = num_online_cpus()-1; i >= 0; i--)
 708                 if (spin_trylock(&kgdb_cpulock[i]) == 0)
 709                         panic("kgdb: couldn't get cpulock %d\n", i);
 710
 711         /*
 712          * force other cpus to enter kgdb
 713          */
 714         smp_call_function(kgdb_wait, NULL, 0, 0);
 715
 716         /*
 717          * If we're in breakpoint() increment the PC
 718          */
 719         trap = (regs->cp0_cause & 0x7c) >> 2;
 720         if (trap == 9 && regs->cp0_epc == (unsigned long)breakinst)
 721                 regs->cp0_epc += 4;
 722
 723         /*
 724          * If we were single_stepping, restore the opcodes hoisted
 725          * for the breakpoint[s].
 726          */
 727         if (step_bp[0].addr) {
 728                 *(unsigned *)step_bp[0].addr = step_bp[0].val;
 729                 step_bp[0].addr = 0;
 730
 731                 if (step_bp[1].addr) {
 732                         *(unsigned *)step_bp[1].addr = step_bp[1].val;
 733                         step_bp[1].addr = 0;
 734                 }
 735         }
 736
 737         stack = (long *)regs->reg29;                    /* stack ptr */
 738         sigval = computeSignal(trap);
 739
 740         /*
 741          * reply to host that an exception has occurred
 742          */
 743         ptr = output_buffer;
 744
 745         /*
 746          * Send trap type (converted to signal)
 747          */
 748         *ptr++ = 'T';
 749         *ptr++ = hexchars[sigval >> 4];
 750         *ptr++ = hexchars[sigval & 0xf];
 751
 752         /*
 753          * Send Error PC
 754          */
 755         *ptr++ = hexchars[REG_EPC >> 4];
 756         *ptr++ = hexchars[REG_EPC & 0xf];
 757         *ptr++ = ':';
 758         ptr = mem2hex((char *)&regs->cp0_epc, ptr, sizeof(long), 0);
 759         *ptr++ = ';';
 760
 761         /*
 762          * Send frame pointer
 763          */
 764         *ptr++ = hexchars[REG_FP >> 4];
 765         *ptr++ = hexchars[REG_FP & 0xf];
 766         *ptr++ = ':';
 767         ptr = mem2hex((char *)&regs->reg30, ptr, sizeof(long), 0);
 768         *ptr++ = ';';
 769
 770         /*
 771          * Send stack pointer
 772          */
 773         *ptr++ = hexchars[REG_SP >> 4];
 774         *ptr++ = hexchars[REG_SP & 0xf];
 775         *ptr++ = ':';
 776         ptr = mem2hex((char *)&regs->reg29, ptr, sizeof(long), 0);
 777         *ptr++ = ';';
 778
 779         *ptr++ = 0;
 780         putpacket(output_buffer);       /* send it off... */
 781
 782         /*
 783          * Wait for input from remote GDB
 784          */
 785         while (1) {
 786                 output_buffer[0] = 0;
 787                 getpacket(input_buffer);
 788
 789                 switch (input_buffer[0])
 790                 {
 791                 case '?':
 792                         output_buffer[0] = 'S';
 793                         output_buffer[1] = hexchars[sigval >> 4];
 794                         output_buffer[2] = hexchars[sigval & 0xf];
 795                         output_buffer[3] = 0;
 796                         break;
 797
 798                 /*
 799                  * Detach debugger; let CPU run
 800                  */
 801                 case 'D':
 802                         putpacket(output_buffer);
 803                         goto finish_kgdb;
 804                         break;
 805
 806                 case 'd':
 807                         /* toggle debug flag */
 808                         break;
 809
 810                 /*
 811                  * Return the value of the CPU registers
 812                  */
 813                 case 'g':
 814                         ptr = output_buffer;
 815                         ptr = mem2hex((char *)&regs->reg0, ptr, 32*sizeof(long), 0); /* r0...r31 */
 816                         ptr = mem2hex((char *)&regs->cp0_status, ptr, 6*sizeof(long), 0); /* cp0 */
 817                         ptr = mem2hex((char *)&regs->fpr0, ptr, 32*sizeof(long), 0); /* f0...31 */
 818                         ptr = mem2hex((char *)&regs->cp1_fsr, ptr, 2*sizeof(long), 0); /* cp1 */
 819                         ptr = mem2hex((char *)&regs->frame_ptr, ptr, 2*sizeof(long), 0); /* frp */
 820                         ptr = mem2hex((char *)&regs->cp0_index, ptr, 16*sizeof(long), 0); /* cp0 */
 821                         break;
 822
 823                 /*
 824                  * set the value of the CPU registers - return OK
 825                  */
 826                 case 'G':
 827                 {
 828                         ptr = &input_buffer[1];
 829                         hex2mem(ptr, (char *)&regs->reg0, 32*sizeof(long), 0, 0);
 830                         ptr += 32*(2*sizeof(long));
 831                         hex2mem(ptr, (char *)&regs->cp0_status, 6*sizeof(long), 0, 0);
 832                         ptr += 6*(2*sizeof(long));
 833                         hex2mem(ptr, (char *)&regs->fpr0, 32*sizeof(long), 0, 0);
 834                         ptr += 32*(2*sizeof(long));
 835                         hex2mem(ptr, (char *)&regs->cp1_fsr, 2*sizeof(long), 0, 0);
 836                         ptr += 2*(2*sizeof(long));
 837                         hex2mem(ptr, (char *)&regs->frame_ptr, 2*sizeof(long), 0, 0);
 838                         ptr += 2*(2*sizeof(long));
 839                         hex2mem(ptr, (char *)&regs->cp0_index, 16*sizeof(long), 0, 0);
 840                         strcpy(output_buffer,"OK");
 841                  }
 842                 break;
 843
 844                 /*
 845                  * mAA..AA,LLLL  Read LLLL bytes at address AA..AA
 846                  */
 847                 case 'm':
 848                         ptr = &input_buffer[1];
 849
 850                         if (hexToLong(&ptr, &addr)
 851                                 && *ptr++ == ','
 852                                 && hexToInt(&ptr, &length)) {
 853                                 if (mem2hex((char *)addr, output_buffer, length, 1))
 854                                         break;
 855                                 strcpy (output_buffer, "E03");
 856                         } else
 857                                 strcpy(output_buffer,"E01");
 858                         break;
 859
 860                 /*
 861                  * XAA..AA,LLLL: Write LLLL escaped binary bytes at address AA.AA
 862                  */
 863                 case 'X':
 864                         bflag = 1;
 865                         /* fall through */
 866
 867                 /*
 868                  * MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK
 869                  */
 870                 case 'M':
 871                         ptr = &input_buffer[1];
 872
 873                         if (hexToLong(&ptr, &addr)
 874                                 && *ptr++ == ','
 875                                 && hexToInt(&ptr, &length)
 876                                 && *ptr++ == ':') {
 877                                 if (hex2mem(ptr, (char *)addr, length, bflag, 1))
 878                                         strcpy(output_buffer, "OK");
 879                                 else
 880                                         strcpy(output_buffer, "E03");
 881                         }
 882                         else
 883                                 strcpy(output_buffer, "E02");
 884                         break;
 885
 886                 /*
 887                  * cAA..AA    Continue at address AA..AA(optional)
 888                  */
 889                 case 'c':
 890                         /* try to read optional parameter, pc unchanged if no parm */
 891
 892                         ptr = &input_buffer[1];
 893                         if (hexToLong(&ptr, &addr))
 894                                 regs->cp0_epc = addr;
 895
 896                         goto exit_kgdb_exception;
 897                         break;
 898
 899                 /*
 900                  * kill the program; let us try to restart the machine
 901                  * Reset the whole machine.
 902                  */
 903                 case 'k':
 904                 case 'r':
 905                         machine_restart("kgdb restarts machine");
 906                         break;
 907
 908                 /*
 909                  * Step to next instruction
 910                  */
 911                 case 's':
 912                         /*
 913                          * There is no single step insn in the MIPS ISA, so we
 914                          * use breakpoints and continue, instead.
 915                          */
 916                         single_step(regs);
 917                         goto exit_kgdb_exception;
 918                         /* NOTREACHED */
 919                         break;
 920
 921                 /*
 922                  * Set baud rate (bBB)
 923                  * FIXME: Needs to be written
 924                  */
 925                 case 'b':
 926                 {
 927 #if 0
 928                         int baudrate;
 929                         extern void set_timer_3();
 930
 931                         ptr = &input_buffer[1];
 932                         if (!hexToInt(&ptr, &baudrate))
 933                         {
 934                                 strcpy(output_buffer,"B01");
 935                                 break;
 936                         }
 937
 938                         /* Convert baud rate to uart clock divider */
 939
 940                         switch (baudrate)
 941                         {
 942                                 case 38400:
 943                                         baudrate = 16;
 944                                         break;
 945                                 case 19200:
 946                                         baudrate = 33;
 947                                         break;
 948                                 case 9600:
 949                                         baudrate = 65;
 950                                         break;
 951                                 default:
 952                                         baudrate = 0;
 953                                         strcpy(output_buffer,"B02");
 954                                         goto x1;
 955                         }
 956
 957                         if (baudrate) {
 958                                 putpacket("OK");        /* Ack before changing speed */
 959                                 set_timer_3(baudrate); /* Set it */
 960                         }
 961 #endif
 962                 }
 963                 break;
 964
 965                 }                       /* switch */
 966
 967                 /*
 968                  * reply to the request
 969                  */
 970
 971                 putpacket(output_buffer);
 972
 973         } /* while */
 974
 975         return;
 976
 977 finish_kgdb:
 978         restore_debug_traps();
 979
 980 exit_kgdb_exception:
 981         /* release locks so other CPUs can go */
 982         for (i = num_online_cpus()-1; i >= 0; i--)
 983                 spin_unlock(&kgdb_cpulock[i]);
 984         spin_unlock(&kgdb_lock);
 985
 986         __flush_cache_all();
 987         return;
 988 }
 989
 990 /*
 991  * This function will generate a breakpoint exception.  It is used at the
 992  * beginning of a program to sync up with a debugger and can be used
 993  * otherwise as a quick means to stop program execution and "break" into
 994  * the debugger.
 995  */
 996 void breakpoint(void)
 997 {
 998         if (!initialized)
 999                 return;
1000
1001         __asm__ __volatile__(
1002                         ".globl breakinst\n\t"
1003                         ".set\tnoreorder\n\t"
1004                         "nop\n"
1005                         "breakinst:\tbreak\n\t"
1006                         "nop\n\t"
1007                         ".set\treorder"
1008                         );
1009 }
1010
1011 /* Nothing but the break; don't pollute any registers */
1012 void async_breakpoint(void)
1013 {
1014         __asm__ __volatile__(
1015                         ".globl async_breakinst\n\t"
1016                         ".set\tnoreorder\n\t"
1017                         "nop\n"
1018                         "async_breakinst:\tbreak\n\t"
1019                         "nop\n\t"
1020                         ".set\treorder"
1021                         );
1022 }
1023
1024 void adel(void)
1025 {
1026         __asm__ __volatile__(
1027                         ".globl\tadel\n\t"
1028                         "lui\t$8,0x8000\n\t"
1029                         "lw\t$9,1($8)\n\t"
1030                         );
1031 }
1032
1033 /*
1034  * malloc is needed by gdb client in "call func()", even a private one
1035  * will make gdb happy
1036  */
1037 static void *malloc(size_t size)
1038 {
1039         return kmalloc(size, GFP_ATOMIC);
1040 }
1041
1042 static void free(void *where)
1043 {
1044         kfree(where);
1045 }
1046
1047 #ifdef CONFIG_GDB_CONSOLE
1048
1049 void gdb_putsn(const char *str, int l)
1050 {
1051         char outbuf[18];
1052
1053         if (!kgdb_started)
1054                 return;
1055
1056         outbuf[0]='O';
1057
1058         while(l) {
1059                 int i = (l>8)?8:l;
1060                 mem2hex((char *)str, &outbuf[1], i, 0);
1061                 outbuf[(i*2)+1]=0;
1062                 putpacket(outbuf);
1063                 str += i;
1064                 l -= i;
1065         }
1066 }
1067
1068 static void gdb_console_write(struct console *con, const char *s, unsigned n)
1069 {
1070         gdb_putsn(s, n);
1071 }
1072
1073 static struct console gdb_console = {
1074         .name   = "gdb",
1075         .write  = gdb_console_write,
1076         .flags  = CON_PRINTBUFFER,
1077         .index  = -1
1078 };
1079
1080 static int __init register_gdb_console(void)
1081 {
1082         register_console(&gdb_console);
1083
1084         return 0;
1085 }
1086
1087 console_initcall(register_gdb_console);
1088
1089 #endif