kernel/debug/kdb/kdb_bp.c

   1 /*
   2  * Kernel Debugger Architecture Independent Breakpoint Handler
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
   9  * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
  10  */
  11
  12 #include <linux/string.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/kdb.h>
  16 #include <linux/kgdb.h>
  17 #include <linux/smp.h>
  18 #include <linux/sched.h>
  19 #include <linux/interrupt.h>
  20 #include "kdb_private.h"
  21
  22 /*
  23  * Table of kdb_breakpoints
  24  */
  25 kdb_bp_t kdb_breakpoints[KDB_MAXBPT];
  26
  27 static void kdb_setsinglestep(struct pt_regs *regs)
  28 {
  29         KDB_STATE_SET(DOING_SS);
  30 }
  31
  32 static char *kdb_rwtypes[] = {
  33         "Instruction(i)",
  34         "Instruction(Register)",
  35         "Data Write",
  36         "I/O",
  37         "Data Access"
  38 };
  39
  40 static char *kdb_bptype(kdb_bp_t *bp)
  41 {
  42         if (bp->bp_type < 0 || bp->bp_type > 4)
  43                 return "";
  44
  45         return kdb_rwtypes[bp->bp_type];
  46 }
  47
  48 static int kdb_parsebp(int argc, const char **argv, int *nextargp, kdb_bp_t *bp)
  49 {
  50         int nextarg = *nextargp;
  51         int diag;
  52
  53         bp->bph_length = 1;
  54         if ((argc + 1) != nextarg) {
  55                 if (strnicmp(argv[nextarg], "datar", sizeof("datar")) == 0)
  56                         bp->bp_type = BP_ACCESS_WATCHPOINT;
  57                 else if (strnicmp(argv[nextarg], "dataw", sizeof("dataw")) == 0)
  58                         bp->bp_type = BP_WRITE_WATCHPOINT;
  59                 else if (strnicmp(argv[nextarg], "inst", sizeof("inst")) == 0)
  60                         bp->bp_type = BP_HARDWARE_BREAKPOINT;
  61                 else
  62                         return KDB_ARGCOUNT;
  63
  64                 bp->bph_length = 1;
  65
  66                 nextarg++;
  67
  68                 if ((argc + 1) != nextarg) {
  69                         unsigned long len;
  70
  71                         diag = kdbgetularg((char *)argv[nextarg],
  72                                            &len);
  73                         if (diag)
  74                                 return diag;
  75
  76
  77                         if (len > 8)
  78                                 return KDB_BADLENGTH;
  79
  80                         bp->bph_length = len;
  81                         nextarg++;
  82                 }
  83
  84                 if ((argc + 1) != nextarg)
  85                         return KDB_ARGCOUNT;
  86         }
  87
  88         *nextargp = nextarg;
  89         return 0;
  90 }
  91
  92 static int _kdb_bp_remove(kdb_bp_t *bp)
  93 {
  94         int ret = 1;
  95         if (!bp->bp_installed)
  96                 return ret;
  97         if (!bp->bp_type)
  98                 ret = dbg_remove_sw_break(bp->bp_addr);
  99         else
 100                 ret = arch_kgdb_ops.remove_hw_breakpoint(bp->bp_addr,
 101                          bp->bph_length,
 102                          bp->bp_type);
 103         if (ret == 0)
 104                 bp->bp_installed = 0;
 105         return ret;
 106 }
 107
 108 static void kdb_handle_bp(struct pt_regs *regs, kdb_bp_t *bp)
 109 {
 110         if (KDB_DEBUG(BP))
 111                 kdb_printf("regs->ip = 0x%lx\n", instruction_pointer(regs));
 112
 113         /*
 114          * Setup single step
 115          */
 116         kdb_setsinglestep(regs);
 117
 118         /*
 119          * Reset delay attribute
 120          */
 121         bp->bp_delay = 0;
 122         bp->bp_delayed = 1;
 123 }
 124
 125 static int _kdb_bp_install(struct pt_regs *regs, kdb_bp_t *bp)
 126 {
 127         int ret;
 128         /*
 129          * Install the breakpoint, if it is not already installed.
 130          */
 131
 132         if (KDB_DEBUG(BP))
 133                 kdb_printf("%s: bp_installed %d\n",
 134                            __func__, bp->bp_installed);
 135         if (!KDB_STATE(SSBPT))
 136                 bp->bp_delay = 0;
 137         if (bp->bp_installed)
 138                 return 1;
 139         if (bp->bp_delay || (bp->bp_delayed && KDB_STATE(DOING_SS))) {
 140                 if (KDB_DEBUG(BP))
 141                         kdb_printf("%s: delayed bp\n", __func__);
 142                 kdb_handle_bp(regs, bp);
 143                 return 0;
 144         }
 145         if (!bp->bp_type)
 146                 ret = dbg_set_sw_break(bp->bp_addr);
 147         else
 148                 ret = arch_kgdb_ops.set_hw_breakpoint(bp->bp_addr,
 149                          bp->bph_length,
 150                          bp->bp_type);
 151         if (ret == 0) {
 152                 bp->bp_installed = 1;
 153         } else {
 154                 kdb_printf("%s: failed to set breakpoint at 0x%lx\n",
 155                            __func__, bp->bp_addr);
 156                 return 1;
 157         }
 158         return 0;
 159 }
 160
 161 /*
 162  * kdb_bp_install
 163  *
 164  *      Install kdb_breakpoints prior to returning from the
 165  *      kernel debugger.  This allows the kdb_breakpoints to be set
 166  *      upon functions that are used internally by kdb, such as
 167  *      printk().  This function is only called once per kdb session.
 168  */
 169 void kdb_bp_install(struct pt_regs *regs)
 170 {
 171         int i;
 172
 173         for (i = 0; i < KDB_MAXBPT; i++) {
 174                 kdb_bp_t *bp = &kdb_breakpoints[i];
 175
 176                 if (KDB_DEBUG(BP)) {
 177                         kdb_printf("%s: bp %d bp_enabled %d\n",
 178                                    __func__, i, bp->bp_enabled);
 179                 }
 180                 if (bp->bp_enabled)
 181                         _kdb_bp_install(regs, bp);
 182         }
 183 }
 184
 185 /*
 186  * kdb_bp_remove
 187  *
 188  *      Remove kdb_breakpoints upon entry to the kernel debugger.
 189  *
 190  * Parameters:
 191  *      None.
 192  * Outputs:
 193  *      None.
 194  * Returns:
 195  *      None.
 196  * Locking:
 197  *      None.
 198  * Remarks:
 199  */
 200 void kdb_bp_remove(void)
 201 {
 202         int i;
 203
 204         for (i = KDB_MAXBPT - 1; i >= 0; i--) {
 205                 kdb_bp_t *bp = &kdb_breakpoints[i];
 206
 207                 if (KDB_DEBUG(BP)) {
 208                         kdb_printf("%s: bp %d bp_enabled %d\n",
 209                                    __func__, i, bp->bp_enabled);
 210                 }
 211                 if (bp->bp_enabled)
 212                         _kdb_bp_remove(bp);
 213         }
 214 }
 215
 216
 217 /*
 218  * kdb_printbp
 219  *
 220  *      Internal function to format and print a breakpoint entry.
 221  *
 222  * Parameters:
 223  *      None.
 224  * Outputs:
 225  *      None.
 226  * Returns:
 227  *      None.
 228  * Locking:
 229  *      None.
 230  * Remarks:
 231  */
 232
 233 static void kdb_printbp(kdb_bp_t *bp, int i)
 234 {
 235         kdb_printf("%s ", kdb_bptype(bp));
 236         kdb_printf("BP #%d at ", i);
 237         kdb_symbol_print(bp->bp_addr, NULL, KDB_SP_DEFAULT);
 238
 239         if (bp->bp_enabled)
 240                 kdb_printf("\n    is enabled");
 241         else
 242                 kdb_printf("\n    is disabled");
 243
 244         kdb_printf("\taddr at %016lx, hardtype=%d installed=%d\n",
 245                    bp->bp_addr, bp->bp_type, bp->bp_installed);
 246
 247         kdb_printf("\n");
 248 }
 249
 250 /*
 251  * kdb_bp
 252  *
 253  *      Handle the bp commands.
 254  *
 255  *      [bp|bph] <addr-expression> [DATAR|DATAW]
 256  *
 257  * Parameters:
 258  *      argc    Count of arguments in argv
 259  *      argv    Space delimited command line arguments
 260  * Outputs:
 261  *      None.
 262  * Returns:
 263  *      Zero for success, a kdb diagnostic if failure.
 264  * Locking:
 265  *      None.
 266  * Remarks:
 267  *
 268  *      bp      Set breakpoint on all cpus.  Only use hardware assist if need.
 269  *      bph     Set breakpoint on all cpus.  Force hardware register
 270  */
 271
 272 static int kdb_bp(int argc, const char **argv)
 273 {
 274         int i, bpno;
 275         kdb_bp_t *bp, *bp_check;
 276         int diag;
 277         int free;
 278         char *symname = NULL;
 279         long offset = 0ul;
 280         int nextarg;
 281         kdb_bp_t template = {0};
 282
 283         if (argc == 0) {
 284                 /*
 285                  * Display breakpoint table
 286                  */
 287                 for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT;
 288                      bpno++, bp++) {
 289                         if (bp->bp_free)
 290                                 continue;
 291                         kdb_printbp(bp, bpno);
 292                 }
 293
 294                 return 0;
 295         }
 296
 297         nextarg = 1;
 298         diag = kdbgetaddrarg(argc, argv, &nextarg, &template.bp_addr,
 299                              &offset, &symname);
 300         if (diag)
 301                 return diag;
 302         if (!template.bp_addr)
 303                 return KDB_BADINT;
 304
 305         /*
 306          * Find an empty bp structure to allocate
 307          */
 308         free = KDB_MAXBPT;
 309         for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {
 310                 if (bp->bp_free)
 311                         break;
 312         }
 313
 314         if (bpno == KDB_MAXBPT)
 315                 return KDB_TOOMANYBPT;
 316
 317         if (strcmp(argv[0], "bph") == 0) {
 318                 template.bp_type = BP_HARDWARE_BREAKPOINT;
 319                 diag = kdb_parsebp(argc, argv, &nextarg, &template);
 320                 if (diag)
 321                         return diag;
 322         } else {
 323                 template.bp_type = BP_BREAKPOINT;
 324         }
 325
 326         /*
 327          * Check for clashing breakpoints.
 328          *
 329          * Note, in this design we can't have hardware breakpoints
 330          * enabled for both read and write on the same address.
 331          */
 332         for (i = 0, bp_check = kdb_breakpoints; i < KDB_MAXBPT;
 333              i++, bp_check++) {
 334                 if (!bp_check->bp_free &&
 335                     bp_check->bp_addr == template.bp_addr) {
 336                         kdb_printf("You already have a breakpoint at "
 337                                    kdb_bfd_vma_fmt0 "\n", template.bp_addr);
 338                         return KDB_DUPBPT;
 339                 }
 340         }
 341
 342         template.bp_enabled = 1;
 343
 344         /*
 345          * Actually allocate the breakpoint found earlier
 346          */
 347         *bp = template;
 348         bp->bp_free = 0;
 349
 350         kdb_printbp(bp, bpno);
 351
 352         return 0;
 353 }
 354
 355 /*
 356  * kdb_bc
 357  *
 358  *      Handles the 'bc', 'be', and 'bd' commands
 359  *
 360  *      [bd|bc|be] <breakpoint-number>
 361  *      [bd|bc|be] *
 362  *
 363  * Parameters:
 364  *      argc    Count of arguments in argv
 365  *      argv    Space delimited command line arguments
 366  * Outputs:
 367  *      None.
 368  * Returns:
 369  *      Zero for success, a kdb diagnostic for failure
 370  * Locking:
 371  *      None.
 372  * Remarks:
 373  */
 374 static int kdb_bc(int argc, const char **argv)
 375 {
 376         unsigned long addr;
 377         kdb_bp_t *bp = NULL;
 378         int lowbp = KDB_MAXBPT;
 379         int highbp = 0;
 380         int done = 0;
 381         int i;
 382         int diag = 0;
 383
 384         int cmd;                        /* KDBCMD_B? */
 385 #define KDBCMD_BC       0
 386 #define KDBCMD_BE       1
 387 #define KDBCMD_BD       2
 388
 389         if (strcmp(argv[0], "be") == 0)
 390                 cmd = KDBCMD_BE;
 391         else if (strcmp(argv[0], "bd") == 0)
 392                 cmd = KDBCMD_BD;
 393         else
 394                 cmd = KDBCMD_BC;
 395
 396         if (argc != 1)
 397                 return KDB_ARGCOUNT;
 398
 399         if (strcmp(argv[1], "*") == 0) {
 400                 lowbp = 0;
 401                 highbp = KDB_MAXBPT;
 402         } else {
 403                 diag = kdbgetularg(argv[1], &addr);
 404                 if (diag)
 405                         return diag;
 406
 407                 /*
 408                  * For addresses less than the maximum breakpoint number,
 409                  * assume that the breakpoint number is desired.
 410                  */
 411                 if (addr < KDB_MAXBPT) {
 412                         bp = &kdb_breakpoints[addr];
 413                         lowbp = highbp = addr;
 414                         highbp++;
 415                 } else {
 416                         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT;
 417                             i++, bp++) {
 418                                 if (bp->bp_addr == addr) {
 419                                         lowbp = highbp = i;
 420                                         highbp++;
 421                                         break;
 422                                 }
 423                         }
 424                 }
 425         }
 426
 427         /*
 428          * Now operate on the set of breakpoints matching the input
 429          * criteria (either '*' for all, or an individual breakpoint).
 430          */
 431         for (bp = &kdb_breakpoints[lowbp], i = lowbp;
 432             i < highbp;
 433             i++, bp++) {
 434                 if (bp->bp_free)
 435                         continue;
 436
 437                 done++;
 438
 439                 switch (cmd) {
 440                 case KDBCMD_BC:
 441                         bp->bp_enabled = 0;
 442
 443                         kdb_printf("Breakpoint %d at "
 444                                    kdb_bfd_vma_fmt " cleared\n",
 445                                    i, bp->bp_addr);
 446
 447                         bp->bp_addr = 0;
 448                         bp->bp_free = 1;
 449
 450                         break;
 451                 case KDBCMD_BE:
 452                         bp->bp_enabled = 1;
 453
 454                         kdb_printf("Breakpoint %d at "
 455                                    kdb_bfd_vma_fmt " enabled",
 456                                    i, bp->bp_addr);
 457
 458                         kdb_printf("\n");
 459                         break;
 460                 case KDBCMD_BD:
 461                         if (!bp->bp_enabled)
 462                                 break;
 463
 464                         bp->bp_enabled = 0;
 465
 466                         kdb_printf("Breakpoint %d at "
 467                                    kdb_bfd_vma_fmt " disabled\n",
 468                                    i, bp->bp_addr);
 469
 470                         break;
 471                 }
 472                 if (bp->bp_delay && (cmd == KDBCMD_BC || cmd == KDBCMD_BD)) {
 473                         bp->bp_delay = 0;
 474                         KDB_STATE_CLEAR(SSBPT);
 475                 }
 476         }
 477
 478         return (!done) ? KDB_BPTNOTFOUND : 0;
 479 }
 480
 481 /*
 482  * kdb_ss
 483  *
 484  *      Process the 'ss' (Single Step) and 'ssb' (Single Step to Branch)
 485  *      commands.
 486  *
 487  *      ss
 488  *      ssb
 489  *
 490  * Parameters:
 491  *      argc    Argument count
 492  *      argv    Argument vector
 493  * Outputs:
 494  *      None.
 495  * Returns:
 496  *      KDB_CMD_SS[B] for success, a kdb error if failure.
 497  * Locking:
 498  *      None.
 499  * Remarks:
 500  *
 501  *      Set the arch specific option to trigger a debug trap after the next
 502  *      instruction.
 503  *
 504  *      For 'ssb', set the trace flag in the debug trap handler
 505  *      after printing the current insn and return directly without
 506  *      invoking the kdb command processor, until a branch instruction
 507  *      is encountered.
 508  */
 509
 510 static int kdb_ss(int argc, const char **argv)
 511 {
 512         int ssb = 0;
 513
 514         ssb = (strcmp(argv[0], "ssb") == 0);
 515         if (argc != 0)
 516                 return KDB_ARGCOUNT;
 517         /*
 518          * Set trace flag and go.
 519          */
 520         KDB_STATE_SET(DOING_SS);
 521         if (ssb) {
 522                 KDB_STATE_SET(DOING_SSB);
 523                 return KDB_CMD_SSB;
 524         }
 525         return KDB_CMD_SS;
 526 }
 527
 528 /* Initialize the breakpoint table and register breakpoint commands. */
 529
 530 void __init kdb_initbptab(void)
 531 {
 532         int i;
 533         kdb_bp_t *bp;
 534
 535         /*
 536          * First time initialization.
 537          */
 538         memset(&kdb_breakpoints, '\0', sizeof(kdb_breakpoints));
 539
 540         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
 541                 bp->bp_free = 1;
 542
 543         kdb_register_repeat("bp", kdb_bp, "[<vaddr>]",
 544                 "Set/Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 545         kdb_register_repeat("bl", kdb_bp, "[<vaddr>]",
 546                 "Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 547         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
 548                 kdb_register_repeat("bph", kdb_bp, "[<vaddr>]",
 549                 "[datar [length]|dataw [length]]   Set hw brk", 0, KDB_REPEAT_NO_ARGS);
 550         kdb_register_repeat("bc", kdb_bc, "<bpnum>",
 551                 "Clear Breakpoint", 0, KDB_REPEAT_NONE);
 552         kdb_register_repeat("be", kdb_bc, "<bpnum>",
 553                 "Enable Breakpoint", 0, KDB_REPEAT_NONE);
 554         kdb_register_repeat("bd", kdb_bc, "<bpnum>",
 555                 "Disable Breakpoint", 0, KDB_REPEAT_NONE);
 556
 557         kdb_register_repeat("ss", kdb_ss, "",
 558                 "Single Step", 1, KDB_REPEAT_NO_ARGS);
 559         kdb_register_repeat("ssb", kdb_ss, "",
 560                 "Single step to branch/call", 0, KDB_REPEAT_NO_ARGS);
 561         /*
 562          * Architecture dependent initialization.
 563          */
 564 }