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         char *symname = NULL;
 278         long offset = 0ul;
 279         int nextarg;
 280         kdb_bp_t template = {0};
 281
 282         if (argc == 0) {
 283                 /*
 284                  * Display breakpoint table
 285                  */
 286                 for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT;
 287                      bpno++, bp++) {
 288                         if (bp->bp_free)
 289                                 continue;
 290                         kdb_printbp(bp, bpno);
 291                 }
 292
 293                 return 0;
 294         }
 295
 296         nextarg = 1;
 297         diag = kdbgetaddrarg(argc, argv, &nextarg, &template.bp_addr,
 298                              &offset, &symname);
 299         if (diag)
 300                 return diag;
 301         if (!template.bp_addr)
 302                 return KDB_BADINT;
 303
 304         /*
 305          * Find an empty bp structure to allocate
 306          */
 307         for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {
 308                 if (bp->bp_free)
 309                         break;
 310         }
 311
 312         if (bpno == KDB_MAXBPT)
 313                 return KDB_TOOMANYBPT;
 314
 315         if (strcmp(argv[0], "bph") == 0) {
 316                 template.bp_type = BP_HARDWARE_BREAKPOINT;
 317                 diag = kdb_parsebp(argc, argv, &nextarg, &template);
 318                 if (diag)
 319                         return diag;
 320         } else {
 321                 template.bp_type = BP_BREAKPOINT;
 322         }
 323
 324         /*
 325          * Check for clashing breakpoints.
 326          *
 327          * Note, in this design we can't have hardware breakpoints
 328          * enabled for both read and write on the same address.
 329          */
 330         for (i = 0, bp_check = kdb_breakpoints; i < KDB_MAXBPT;
 331              i++, bp_check++) {
 332                 if (!bp_check->bp_free &&
 333                     bp_check->bp_addr == template.bp_addr) {
 334                         kdb_printf("You already have a breakpoint at "
 335                                    kdb_bfd_vma_fmt0 "\n", template.bp_addr);
 336                         return KDB_DUPBPT;
 337                 }
 338         }
 339
 340         template.bp_enabled = 1;
 341
 342         /*
 343          * Actually allocate the breakpoint found earlier
 344          */
 345         *bp = template;
 346         bp->bp_free = 0;
 347
 348         kdb_printbp(bp, bpno);
 349
 350         return 0;
 351 }
 352
 353 /*
 354  * kdb_bc
 355  *
 356  *      Handles the 'bc', 'be', and 'bd' commands
 357  *
 358  *      [bd|bc|be] <breakpoint-number>
 359  *      [bd|bc|be] *
 360  *
 361  * Parameters:
 362  *      argc    Count of arguments in argv
 363  *      argv    Space delimited command line arguments
 364  * Outputs:
 365  *      None.
 366  * Returns:
 367  *      Zero for success, a kdb diagnostic for failure
 368  * Locking:
 369  *      None.
 370  * Remarks:
 371  */
 372 static int kdb_bc(int argc, const char **argv)
 373 {
 374         unsigned long addr;
 375         kdb_bp_t *bp = NULL;
 376         int lowbp = KDB_MAXBPT;
 377         int highbp = 0;
 378         int done = 0;
 379         int i;
 380         int diag = 0;
 381
 382         int cmd;                        /* KDBCMD_B? */
 383 #define KDBCMD_BC       0
 384 #define KDBCMD_BE       1
 385 #define KDBCMD_BD       2
 386
 387         if (strcmp(argv[0], "be") == 0)
 388                 cmd = KDBCMD_BE;
 389         else if (strcmp(argv[0], "bd") == 0)
 390                 cmd = KDBCMD_BD;
 391         else
 392                 cmd = KDBCMD_BC;
 393
 394         if (argc != 1)
 395                 return KDB_ARGCOUNT;
 396
 397         if (strcmp(argv[1], "*") == 0) {
 398                 lowbp = 0;
 399                 highbp = KDB_MAXBPT;
 400         } else {
 401                 diag = kdbgetularg(argv[1], &addr);
 402                 if (diag)
 403                         return diag;
 404
 405                 /*
 406                  * For addresses less than the maximum breakpoint number,
 407                  * assume that the breakpoint number is desired.
 408                  */
 409                 if (addr < KDB_MAXBPT) {
 410                         bp = &kdb_breakpoints[addr];
 411                         lowbp = highbp = addr;
 412                         highbp++;
 413                 } else {
 414                         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT;
 415                             i++, bp++) {
 416                                 if (bp->bp_addr == addr) {
 417                                         lowbp = highbp = i;
 418                                         highbp++;
 419                                         break;
 420                                 }
 421                         }
 422                 }
 423         }
 424
 425         /*
 426          * Now operate on the set of breakpoints matching the input
 427          * criteria (either '*' for all, or an individual breakpoint).
 428          */
 429         for (bp = &kdb_breakpoints[lowbp], i = lowbp;
 430             i < highbp;
 431             i++, bp++) {
 432                 if (bp->bp_free)
 433                         continue;
 434
 435                 done++;
 436
 437                 switch (cmd) {
 438                 case KDBCMD_BC:
 439                         bp->bp_enabled = 0;
 440
 441                         kdb_printf("Breakpoint %d at "
 442                                    kdb_bfd_vma_fmt " cleared\n",
 443                                    i, bp->bp_addr);
 444
 445                         bp->bp_addr = 0;
 446                         bp->bp_free = 1;
 447
 448                         break;
 449                 case KDBCMD_BE:
 450                         bp->bp_enabled = 1;
 451
 452                         kdb_printf("Breakpoint %d at "
 453                                    kdb_bfd_vma_fmt " enabled",
 454                                    i, bp->bp_addr);
 455
 456                         kdb_printf("\n");
 457                         break;
 458                 case KDBCMD_BD:
 459                         if (!bp->bp_enabled)
 460                                 break;
 461
 462                         bp->bp_enabled = 0;
 463
 464                         kdb_printf("Breakpoint %d at "
 465                                    kdb_bfd_vma_fmt " disabled\n",
 466                                    i, bp->bp_addr);
 467
 468                         break;
 469                 }
 470                 if (bp->bp_delay && (cmd == KDBCMD_BC || cmd == KDBCMD_BD)) {
 471                         bp->bp_delay = 0;
 472                         KDB_STATE_CLEAR(SSBPT);
 473                 }
 474         }
 475
 476         return (!done) ? KDB_BPTNOTFOUND : 0;
 477 }
 478
 479 /*
 480  * kdb_ss
 481  *
 482  *      Process the 'ss' (Single Step) and 'ssb' (Single Step to Branch)
 483  *      commands.
 484  *
 485  *      ss
 486  *      ssb
 487  *
 488  * Parameters:
 489  *      argc    Argument count
 490  *      argv    Argument vector
 491  * Outputs:
 492  *      None.
 493  * Returns:
 494  *      KDB_CMD_SS[B] for success, a kdb error if failure.
 495  * Locking:
 496  *      None.
 497  * Remarks:
 498  *
 499  *      Set the arch specific option to trigger a debug trap after the next
 500  *      instruction.
 501  *
 502  *      For 'ssb', set the trace flag in the debug trap handler
 503  *      after printing the current insn and return directly without
 504  *      invoking the kdb command processor, until a branch instruction
 505  *      is encountered.
 506  */
 507
 508 static int kdb_ss(int argc, const char **argv)
 509 {
 510         int ssb = 0;
 511
 512         ssb = (strcmp(argv[0], "ssb") == 0);
 513         if (argc != 0)
 514                 return KDB_ARGCOUNT;
 515         /*
 516          * Set trace flag and go.
 517          */
 518         KDB_STATE_SET(DOING_SS);
 519         if (ssb) {
 520                 KDB_STATE_SET(DOING_SSB);
 521                 return KDB_CMD_SSB;
 522         }
 523         return KDB_CMD_SS;
 524 }
 525
 526 /* Initialize the breakpoint table and register breakpoint commands. */
 527
 528 void __init kdb_initbptab(void)
 529 {
 530         int i;
 531         kdb_bp_t *bp;
 532
 533         /*
 534          * First time initialization.
 535          */
 536         memset(&kdb_breakpoints, '\0', sizeof(kdb_breakpoints));
 537
 538         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
 539                 bp->bp_free = 1;
 540
 541         kdb_register_repeat("bp", kdb_bp, "[<vaddr>]",
 542                 "Set/Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 543         kdb_register_repeat("bl", kdb_bp, "[<vaddr>]",
 544                 "Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 545         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
 546                 kdb_register_repeat("bph", kdb_bp, "[<vaddr>]",
 547                 "[datar [length]|dataw [length]]   Set hw brk", 0, KDB_REPEAT_NO_ARGS);
 548         kdb_register_repeat("bc", kdb_bc, "<bpnum>",
 549                 "Clear Breakpoint", 0, KDB_REPEAT_NONE);
 550         kdb_register_repeat("be", kdb_bc, "<bpnum>",
 551                 "Enable Breakpoint", 0, KDB_REPEAT_NONE);
 552         kdb_register_repeat("bd", kdb_bc, "<bpnum>",
 553                 "Disable Breakpoint", 0, KDB_REPEAT_NONE);
 554
 555         kdb_register_repeat("ss", kdb_ss, "",
 556                 "Single Step", 1, KDB_REPEAT_NO_ARGS);
 557         kdb_register_repeat("ssb", kdb_ss, "",
 558                 "Single step to branch/call", 0, KDB_REPEAT_NO_ARGS);
 559         /*
 560          * Architecture dependent initialization.
 561          */
 562 }