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 #ifdef CONFIG_DEBUG_RODATA
 157                 if (!bp->bp_type) {
 158                         kdb_printf("Software breakpoints are unavailable.\n"
 159                                    "  Change the kernel CONFIG_DEBUG_RODATA=n\n"
 160                                    "  OR use hw breaks: help bph\n");
 161                 }
 162 #endif
 163                 return 1;
 164         }
 165         return 0;
 166 }
 167
 168 /*
 169  * kdb_bp_install
 170  *
 171  *      Install kdb_breakpoints prior to returning from the
 172  *      kernel debugger.  This allows the kdb_breakpoints to be set
 173  *      upon functions that are used internally by kdb, such as
 174  *      printk().  This function is only called once per kdb session.
 175  */
 176 void kdb_bp_install(struct pt_regs *regs)
 177 {
 178         int i;
 179
 180         for (i = 0; i < KDB_MAXBPT; i++) {
 181                 kdb_bp_t *bp = &kdb_breakpoints[i];
 182
 183                 if (KDB_DEBUG(BP)) {
 184                         kdb_printf("%s: bp %d bp_enabled %d\n",
 185                                    __func__, i, bp->bp_enabled);
 186                 }
 187                 if (bp->bp_enabled)
 188                         _kdb_bp_install(regs, bp);
 189         }
 190 }
 191
 192 /*
 193  * kdb_bp_remove
 194  *
 195  *      Remove kdb_breakpoints upon entry to the kernel debugger.
 196  *
 197  * Parameters:
 198  *      None.
 199  * Outputs:
 200  *      None.
 201  * Returns:
 202  *      None.
 203  * Locking:
 204  *      None.
 205  * Remarks:
 206  */
 207 void kdb_bp_remove(void)
 208 {
 209         int i;
 210
 211         for (i = KDB_MAXBPT - 1; i >= 0; i--) {
 212                 kdb_bp_t *bp = &kdb_breakpoints[i];
 213
 214                 if (KDB_DEBUG(BP)) {
 215                         kdb_printf("%s: bp %d bp_enabled %d\n",
 216                                    __func__, i, bp->bp_enabled);
 217                 }
 218                 if (bp->bp_enabled)
 219                         _kdb_bp_remove(bp);
 220         }
 221 }
 222
 223
 224 /*
 225  * kdb_printbp
 226  *
 227  *      Internal function to format and print a breakpoint entry.
 228  *
 229  * Parameters:
 230  *      None.
 231  * Outputs:
 232  *      None.
 233  * Returns:
 234  *      None.
 235  * Locking:
 236  *      None.
 237  * Remarks:
 238  */
 239
 240 static void kdb_printbp(kdb_bp_t *bp, int i)
 241 {
 242         kdb_printf("%s ", kdb_bptype(bp));
 243         kdb_printf("BP #%d at ", i);
 244         kdb_symbol_print(bp->bp_addr, NULL, KDB_SP_DEFAULT);
 245
 246         if (bp->bp_enabled)
 247                 kdb_printf("\n    is enabled");
 248         else
 249                 kdb_printf("\n    is disabled");
 250
 251         kdb_printf("\taddr at %016lx, hardtype=%d installed=%d\n",
 252                    bp->bp_addr, bp->bp_type, bp->bp_installed);
 253
 254         kdb_printf("\n");
 255 }
 256
 257 /*
 258  * kdb_bp
 259  *
 260  *      Handle the bp commands.
 261  *
 262  *      [bp|bph] <addr-expression> [DATAR|DATAW]
 263  *
 264  * Parameters:
 265  *      argc    Count of arguments in argv
 266  *      argv    Space delimited command line arguments
 267  * Outputs:
 268  *      None.
 269  * Returns:
 270  *      Zero for success, a kdb diagnostic if failure.
 271  * Locking:
 272  *      None.
 273  * Remarks:
 274  *
 275  *      bp      Set breakpoint on all cpus.  Only use hardware assist if need.
 276  *      bph     Set breakpoint on all cpus.  Force hardware register
 277  */
 278
 279 static int kdb_bp(int argc, const char **argv)
 280 {
 281         int i, bpno;
 282         kdb_bp_t *bp, *bp_check;
 283         int diag;
 284         char *symname = NULL;
 285         long offset = 0ul;
 286         int nextarg;
 287         kdb_bp_t template = {0};
 288
 289         if (argc == 0) {
 290                 /*
 291                  * Display breakpoint table
 292                  */
 293                 for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT;
 294                      bpno++, bp++) {
 295                         if (bp->bp_free)
 296                                 continue;
 297                         kdb_printbp(bp, bpno);
 298                 }
 299
 300                 return 0;
 301         }
 302
 303         nextarg = 1;
 304         diag = kdbgetaddrarg(argc, argv, &nextarg, &template.bp_addr,
 305                              &offset, &symname);
 306         if (diag)
 307                 return diag;
 308         if (!template.bp_addr)
 309                 return KDB_BADINT;
 310
 311         /*
 312          * Find an empty bp structure to allocate
 313          */
 314         for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {
 315                 if (bp->bp_free)
 316                         break;
 317         }
 318
 319         if (bpno == KDB_MAXBPT)
 320                 return KDB_TOOMANYBPT;
 321
 322         if (strcmp(argv[0], "bph") == 0) {
 323                 template.bp_type = BP_HARDWARE_BREAKPOINT;
 324                 diag = kdb_parsebp(argc, argv, &nextarg, &template);
 325                 if (diag)
 326                         return diag;
 327         } else {
 328                 template.bp_type = BP_BREAKPOINT;
 329         }
 330
 331         /*
 332          * Check for clashing breakpoints.
 333          *
 334          * Note, in this design we can't have hardware breakpoints
 335          * enabled for both read and write on the same address.
 336          */
 337         for (i = 0, bp_check = kdb_breakpoints; i < KDB_MAXBPT;
 338              i++, bp_check++) {
 339                 if (!bp_check->bp_free &&
 340                     bp_check->bp_addr == template.bp_addr) {
 341                         kdb_printf("You already have a breakpoint at "
 342                                    kdb_bfd_vma_fmt0 "\n", template.bp_addr);
 343                         return KDB_DUPBPT;
 344                 }
 345         }
 346
 347         template.bp_enabled = 1;
 348
 349         /*
 350          * Actually allocate the breakpoint found earlier
 351          */
 352         *bp = template;
 353         bp->bp_free = 0;
 354
 355         kdb_printbp(bp, bpno);
 356
 357         return 0;
 358 }
 359
 360 /*
 361  * kdb_bc
 362  *
 363  *      Handles the 'bc', 'be', and 'bd' commands
 364  *
 365  *      [bd|bc|be] <breakpoint-number>
 366  *      [bd|bc|be] *
 367  *
 368  * Parameters:
 369  *      argc    Count of arguments in argv
 370  *      argv    Space delimited command line arguments
 371  * Outputs:
 372  *      None.
 373  * Returns:
 374  *      Zero for success, a kdb diagnostic for failure
 375  * Locking:
 376  *      None.
 377  * Remarks:
 378  */
 379 static int kdb_bc(int argc, const char **argv)
 380 {
 381         unsigned long addr;
 382         kdb_bp_t *bp = NULL;
 383         int lowbp = KDB_MAXBPT;
 384         int highbp = 0;
 385         int done = 0;
 386         int i;
 387         int diag = 0;
 388
 389         int cmd;                        /* KDBCMD_B? */
 390 #define KDBCMD_BC       0
 391 #define KDBCMD_BE       1
 392 #define KDBCMD_BD       2
 393
 394         if (strcmp(argv[0], "be") == 0)
 395                 cmd = KDBCMD_BE;
 396         else if (strcmp(argv[0], "bd") == 0)
 397                 cmd = KDBCMD_BD;
 398         else
 399                 cmd = KDBCMD_BC;
 400
 401         if (argc != 1)
 402                 return KDB_ARGCOUNT;
 403
 404         if (strcmp(argv[1], "*") == 0) {
 405                 lowbp = 0;
 406                 highbp = KDB_MAXBPT;
 407         } else {
 408                 diag = kdbgetularg(argv[1], &addr);
 409                 if (diag)
 410                         return diag;
 411
 412                 /*
 413                  * For addresses less than the maximum breakpoint number,
 414                  * assume that the breakpoint number is desired.
 415                  */
 416                 if (addr < KDB_MAXBPT) {
 417                         bp = &kdb_breakpoints[addr];
 418                         lowbp = highbp = addr;
 419                         highbp++;
 420                 } else {
 421                         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT;
 422                             i++, bp++) {
 423                                 if (bp->bp_addr == addr) {
 424                                         lowbp = highbp = i;
 425                                         highbp++;
 426                                         break;
 427                                 }
 428                         }
 429                 }
 430         }
 431
 432         /*
 433          * Now operate on the set of breakpoints matching the input
 434          * criteria (either '*' for all, or an individual breakpoint).
 435          */
 436         for (bp = &kdb_breakpoints[lowbp], i = lowbp;
 437             i < highbp;
 438             i++, bp++) {
 439                 if (bp->bp_free)
 440                         continue;
 441
 442                 done++;
 443
 444                 switch (cmd) {
 445                 case KDBCMD_BC:
 446                         bp->bp_enabled = 0;
 447
 448                         kdb_printf("Breakpoint %d at "
 449                                    kdb_bfd_vma_fmt " cleared\n",
 450                                    i, bp->bp_addr);
 451
 452                         bp->bp_addr = 0;
 453                         bp->bp_free = 1;
 454
 455                         break;
 456                 case KDBCMD_BE:
 457                         bp->bp_enabled = 1;
 458
 459                         kdb_printf("Breakpoint %d at "
 460                                    kdb_bfd_vma_fmt " enabled",
 461                                    i, bp->bp_addr);
 462
 463                         kdb_printf("\n");
 464                         break;
 465                 case KDBCMD_BD:
 466                         if (!bp->bp_enabled)
 467                                 break;
 468
 469                         bp->bp_enabled = 0;
 470
 471                         kdb_printf("Breakpoint %d at "
 472                                    kdb_bfd_vma_fmt " disabled\n",
 473                                    i, bp->bp_addr);
 474
 475                         break;
 476                 }
 477                 if (bp->bp_delay && (cmd == KDBCMD_BC || cmd == KDBCMD_BD)) {
 478                         bp->bp_delay = 0;
 479                         KDB_STATE_CLEAR(SSBPT);
 480                 }
 481         }
 482
 483         return (!done) ? KDB_BPTNOTFOUND : 0;
 484 }
 485
 486 /*
 487  * kdb_ss
 488  *
 489  *      Process the 'ss' (Single Step) and 'ssb' (Single Step to Branch)
 490  *      commands.
 491  *
 492  *      ss
 493  *      ssb
 494  *
 495  * Parameters:
 496  *      argc    Argument count
 497  *      argv    Argument vector
 498  * Outputs:
 499  *      None.
 500  * Returns:
 501  *      KDB_CMD_SS[B] for success, a kdb error if failure.
 502  * Locking:
 503  *      None.
 504  * Remarks:
 505  *
 506  *      Set the arch specific option to trigger a debug trap after the next
 507  *      instruction.
 508  *
 509  *      For 'ssb', set the trace flag in the debug trap handler
 510  *      after printing the current insn and return directly without
 511  *      invoking the kdb command processor, until a branch instruction
 512  *      is encountered.
 513  */
 514
 515 static int kdb_ss(int argc, const char **argv)
 516 {
 517         int ssb = 0;
 518
 519         ssb = (strcmp(argv[0], "ssb") == 0);
 520         if (argc != 0)
 521                 return KDB_ARGCOUNT;
 522         /*
 523          * Set trace flag and go.
 524          */
 525         KDB_STATE_SET(DOING_SS);
 526         if (ssb) {
 527                 KDB_STATE_SET(DOING_SSB);
 528                 return KDB_CMD_SSB;
 529         }
 530         return KDB_CMD_SS;
 531 }
 532
 533 /* Initialize the breakpoint table and register breakpoint commands. */
 534
 535 void __init kdb_initbptab(void)
 536 {
 537         int i;
 538         kdb_bp_t *bp;
 539
 540         /*
 541          * First time initialization.
 542          */
 543         memset(&kdb_breakpoints, '\0', sizeof(kdb_breakpoints));
 544
 545         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
 546                 bp->bp_free = 1;
 547
 548         kdb_register_repeat("bp", kdb_bp, "[<vaddr>]",
 549                 "Set/Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 550         kdb_register_repeat("bl", kdb_bp, "[<vaddr>]",
 551                 "Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
 552         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
 553                 kdb_register_repeat("bph", kdb_bp, "[<vaddr>]",
 554                 "[datar [length]|dataw [length]]   Set hw brk", 0, KDB_REPEAT_NO_ARGS);
 555         kdb_register_repeat("bc", kdb_bc, "<bpnum>",
 556                 "Clear Breakpoint", 0, KDB_REPEAT_NONE);
 557         kdb_register_repeat("be", kdb_bc, "<bpnum>",
 558                 "Enable Breakpoint", 0, KDB_REPEAT_NONE);
 559         kdb_register_repeat("bd", kdb_bc, "<bpnum>",
 560                 "Disable Breakpoint", 0, KDB_REPEAT_NONE);
 561
 562         kdb_register_repeat("ss", kdb_ss, "",
 563                 "Single Step", 1, KDB_REPEAT_NO_ARGS);
 564         kdb_register_repeat("ssb", kdb_ss, "",
 565                 "Single step to branch/call", 0, KDB_REPEAT_NO_ARGS);
 566         /*
 567          * Architecture dependent initialization.
 568          */
 569 }