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 (strncasecmp(argv[nextarg], "datar", sizeof("datar")) == 0)
  56                         bp->bp_type = BP_ACCESS_WATCHPOINT;
  57                 else if (strncasecmp(argv[nextarg], "dataw", sizeof("dataw")) == 0)
  58                         bp->bp_type = BP_WRITE_WATCHPOINT;
  59                 else if (strncasecmp(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                 if (!bp->bp_type) {
 157                         kdb_printf("Software breakpoints are unavailable.\n"
 158                                    "  Boot the kernel with rodata=off\n"
 159                                    "  OR use hw breaks: help bph\n");
 160                 }
 161                 return 1;
 162         }
 163         return 0;
 164 }
 165
 166 /*
 167  * kdb_bp_install
 168  *
 169  *      Install kdb_breakpoints prior to returning from the
 170  *      kernel debugger.  This allows the kdb_breakpoints to be set
 171  *      upon functions that are used internally by kdb, such as
 172  *      printk().  This function is only called once per kdb session.
 173  */
 174 void kdb_bp_install(struct pt_regs *regs)
 175 {
 176         int i;
 177
 178         for (i = 0; i < KDB_MAXBPT; i++) {
 179                 kdb_bp_t *bp = &kdb_breakpoints[i];
 180
 181                 if (KDB_DEBUG(BP)) {
 182                         kdb_printf("%s: bp %d bp_enabled %d\n",
 183                                    __func__, i, bp->bp_enabled);
 184                 }
 185                 if (bp->bp_enabled)
 186                         _kdb_bp_install(regs, bp);
 187         }
 188 }
 189
 190 /*
 191  * kdb_bp_remove
 192  *
 193  *      Remove kdb_breakpoints upon entry to the kernel debugger.
 194  *
 195  * Parameters:
 196  *      None.
 197  * Outputs:
 198  *      None.
 199  * Returns:
 200  *      None.
 201  * Locking:
 202  *      None.
 203  * Remarks:
 204  */
 205 void kdb_bp_remove(void)
 206 {
 207         int i;
 208
 209         for (i = KDB_MAXBPT - 1; i >= 0; i--) {
 210                 kdb_bp_t *bp = &kdb_breakpoints[i];
 211
 212                 if (KDB_DEBUG(BP)) {
 213                         kdb_printf("%s: bp %d bp_enabled %d\n",
 214                                    __func__, i, bp->bp_enabled);
 215                 }
 216                 if (bp->bp_enabled)
 217                         _kdb_bp_remove(bp);
 218         }
 219 }
 220
 221
 222 /*
 223  * kdb_printbp
 224  *
 225  *      Internal function to format and print a breakpoint entry.
 226  *
 227  * Parameters:
 228  *      None.
 229  * Outputs:
 230  *      None.
 231  * Returns:
 232  *      None.
 233  * Locking:
 234  *      None.
 235  * Remarks:
 236  */
 237
 238 static void kdb_printbp(kdb_bp_t *bp, int i)
 239 {
 240         kdb_printf("%s ", kdb_bptype(bp));
 241         kdb_printf("BP #%d at ", i);
 242         kdb_symbol_print(bp->bp_addr, NULL, KDB_SP_DEFAULT);
 243
 244         if (bp->bp_enabled)
 245                 kdb_printf("\n    is enabled");
 246         else
 247                 kdb_printf("\n    is disabled");
 248
 249         kdb_printf("\taddr at %016lx, hardtype=%d installed=%d\n",
 250                    bp->bp_addr, bp->bp_type, bp->bp_installed);
 251
 252         kdb_printf("\n");
 253 }
 254
 255 /*
 256  * kdb_bp
 257  *
 258  *      Handle the bp commands.
 259  *
 260  *      [bp|bph] <addr-expression> [DATAR|DATAW]
 261  *
 262  * Parameters:
 263  *      argc    Count of arguments in argv
 264  *      argv    Space delimited command line arguments
 265  * Outputs:
 266  *      None.
 267  * Returns:
 268  *      Zero for success, a kdb diagnostic if failure.
 269  * Locking:
 270  *      None.
 271  * Remarks:
 272  *
 273  *      bp      Set breakpoint on all cpus.  Only use hardware assist if need.
 274  *      bph     Set breakpoint on all cpus.  Force hardware register
 275  */
 276
 277 static int kdb_bp(int argc, const char **argv)
 278 {
 279         int i, bpno;
 280         kdb_bp_t *bp, *bp_check;
 281         int diag;
 282         char *symname = NULL;
 283         long offset = 0ul;
 284         int nextarg;
 285         kdb_bp_t template = {0};
 286
 287         if (argc == 0) {
 288                 /*
 289                  * Display breakpoint table
 290                  */
 291                 for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT;
 292                      bpno++, bp++) {
 293                         if (bp->bp_free)
 294                                 continue;
 295                         kdb_printbp(bp, bpno);
 296                 }
 297
 298                 return 0;
 299         }
 300
 301         nextarg = 1;
 302         diag = kdbgetaddrarg(argc, argv, &nextarg, &template.bp_addr,
 303                              &offset, &symname);
 304         if (diag)
 305                 return diag;
 306         if (!template.bp_addr)
 307                 return KDB_BADINT;
 308
 309         /*
 310          * Find an empty bp structure to allocate
 311          */
 312         for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {
 313                 if (bp->bp_free)
 314                         break;
 315         }
 316
 317         if (bpno == KDB_MAXBPT)
 318                 return KDB_TOOMANYBPT;
 319
 320         if (strcmp(argv[0], "bph") == 0) {
 321                 template.bp_type = BP_HARDWARE_BREAKPOINT;
 322                 diag = kdb_parsebp(argc, argv, &nextarg, &template);
 323                 if (diag)
 324                         return diag;
 325         } else {
 326                 template.bp_type = BP_BREAKPOINT;
 327         }
 328
 329         /*
 330          * Check for clashing breakpoints.
 331          *
 332          * Note, in this design we can't have hardware breakpoints
 333          * enabled for both read and write on the same address.
 334          */
 335         for (i = 0, bp_check = kdb_breakpoints; i < KDB_MAXBPT;
 336              i++, bp_check++) {
 337                 if (!bp_check->bp_free &&
 338                     bp_check->bp_addr == template.bp_addr) {
 339                         kdb_printf("You already have a breakpoint at "
 340                                    kdb_bfd_vma_fmt0 "\n", template.bp_addr);
 341                         return KDB_DUPBPT;
 342                 }
 343         }
 344
 345         template.bp_enabled = 1;
 346
 347         /*
 348          * Actually allocate the breakpoint found earlier
 349          */
 350         *bp = template;
 351         bp->bp_free = 0;
 352
 353         kdb_printbp(bp, bpno);
 354
 355         return 0;
 356 }
 357
 358 /*
 359  * kdb_bc
 360  *
 361  *      Handles the 'bc', 'be', and 'bd' commands
 362  *
 363  *      [bd|bc|be] <breakpoint-number>
 364  *      [bd|bc|be] *
 365  *
 366  * Parameters:
 367  *      argc    Count of arguments in argv
 368  *      argv    Space delimited command line arguments
 369  * Outputs:
 370  *      None.
 371  * Returns:
 372  *      Zero for success, a kdb diagnostic for failure
 373  * Locking:
 374  *      None.
 375  * Remarks:
 376  */
 377 static int kdb_bc(int argc, const char **argv)
 378 {
 379         unsigned long addr;
 380         kdb_bp_t *bp = NULL;
 381         int lowbp = KDB_MAXBPT;
 382         int highbp = 0;
 383         int done = 0;
 384         int i;
 385         int diag = 0;
 386
 387         int cmd;                        /* KDBCMD_B? */
 388 #define KDBCMD_BC       0
 389 #define KDBCMD_BE       1
 390 #define KDBCMD_BD       2
 391
 392         if (strcmp(argv[0], "be") == 0)
 393                 cmd = KDBCMD_BE;
 394         else if (strcmp(argv[0], "bd") == 0)
 395                 cmd = KDBCMD_BD;
 396         else
 397                 cmd = KDBCMD_BC;
 398
 399         if (argc != 1)
 400                 return KDB_ARGCOUNT;
 401
 402         if (strcmp(argv[1], "*") == 0) {
 403                 lowbp = 0;
 404                 highbp = KDB_MAXBPT;
 405         } else {
 406                 diag = kdbgetularg(argv[1], &addr);
 407                 if (diag)
 408                         return diag;
 409
 410                 /*
 411                  * For addresses less than the maximum breakpoint number,
 412                  * assume that the breakpoint number is desired.
 413                  */
 414                 if (addr < KDB_MAXBPT) {
 415                         bp = &kdb_breakpoints[addr];
 416                         lowbp = highbp = addr;
 417                         highbp++;
 418                 } else {
 419                         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT;
 420                             i++, bp++) {
 421                                 if (bp->bp_addr == addr) {
 422                                         lowbp = highbp = i;
 423                                         highbp++;
 424                                         break;
 425                                 }
 426                         }
 427                 }
 428         }
 429
 430         /*
 431          * Now operate on the set of breakpoints matching the input
 432          * criteria (either '*' for all, or an individual breakpoint).
 433          */
 434         for (bp = &kdb_breakpoints[lowbp], i = lowbp;
 435             i < highbp;
 436             i++, bp++) {
 437                 if (bp->bp_free)
 438                         continue;
 439
 440                 done++;
 441
 442                 switch (cmd) {
 443                 case KDBCMD_BC:
 444                         bp->bp_enabled = 0;
 445
 446                         kdb_printf("Breakpoint %d at "
 447                                    kdb_bfd_vma_fmt " cleared\n",
 448                                    i, bp->bp_addr);
 449
 450                         bp->bp_addr = 0;
 451                         bp->bp_free = 1;
 452
 453                         break;
 454                 case KDBCMD_BE:
 455                         bp->bp_enabled = 1;
 456
 457                         kdb_printf("Breakpoint %d at "
 458                                    kdb_bfd_vma_fmt " enabled",
 459                                    i, bp->bp_addr);
 460
 461                         kdb_printf("\n");
 462                         break;
 463                 case KDBCMD_BD:
 464                         if (!bp->bp_enabled)
 465                                 break;
 466
 467                         bp->bp_enabled = 0;
 468
 469                         kdb_printf("Breakpoint %d at "
 470                                    kdb_bfd_vma_fmt " disabled\n",
 471                                    i, bp->bp_addr);
 472
 473                         break;
 474                 }
 475                 if (bp->bp_delay && (cmd == KDBCMD_BC || cmd == KDBCMD_BD)) {
 476                         bp->bp_delay = 0;
 477                         KDB_STATE_CLEAR(SSBPT);
 478                 }
 479         }
 480
 481         return (!done) ? KDB_BPTNOTFOUND : 0;
 482 }
 483
 484 /*
 485  * kdb_ss
 486  *
 487  *      Process the 'ss' (Single Step) command.
 488  *
 489  *      ss
 490  *
 491  * Parameters:
 492  *      argc    Argument count
 493  *      argv    Argument vector
 494  * Outputs:
 495  *      None.
 496  * Returns:
 497  *      KDB_CMD_SS for success, a kdb error if failure.
 498  * Locking:
 499  *      None.
 500  * Remarks:
 501  *
 502  *      Set the arch specific option to trigger a debug trap after the next
 503  *      instruction.
 504  */
 505
 506 static int kdb_ss(int argc, const char **argv)
 507 {
 508         if (argc != 0)
 509                 return KDB_ARGCOUNT;
 510         /*
 511          * Set trace flag and go.
 512          */
 513         KDB_STATE_SET(DOING_SS);
 514         return KDB_CMD_SS;
 515 }
 516
 517 /* Initialize the breakpoint table and register breakpoint commands. */
 518
 519 void __init kdb_initbptab(void)
 520 {
 521         int i;
 522         kdb_bp_t *bp;
 523
 524         /*
 525          * First time initialization.
 526          */
 527         memset(&kdb_breakpoints, '\0', sizeof(kdb_breakpoints));
 528
 529         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
 530                 bp->bp_free = 1;
 531
 532         kdb_register_flags("bp", kdb_bp, "[<vaddr>]",
 533                 "Set/Display breakpoints", 0,
 534                 KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 535         kdb_register_flags("bl", kdb_bp, "[<vaddr>]",
 536                 "Display breakpoints", 0,
 537                 KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 538         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
 539                 kdb_register_flags("bph", kdb_bp, "[<vaddr>]",
 540                 "[datar [length]|dataw [length]]   Set hw brk", 0,
 541                 KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 542         kdb_register_flags("bc", kdb_bc, "<bpnum>",
 543                 "Clear Breakpoint", 0,
 544                 KDB_ENABLE_FLOW_CTRL);
 545         kdb_register_flags("be", kdb_bc, "<bpnum>",
 546                 "Enable Breakpoint", 0,
 547                 KDB_ENABLE_FLOW_CTRL);
 548         kdb_register_flags("bd", kdb_bc, "<bpnum>",
 549                 "Disable Breakpoint", 0,
 550                 KDB_ENABLE_FLOW_CTRL);
 551
 552         kdb_register_flags("ss", kdb_ss, "",
 553                 "Single Step", 1,
 554                 KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 555         /*
 556          * Architecture dependent initialization.
 557          */
 558 }