linux/kernel/debug/kdb/kdb_support.c
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   1/*
   2 * Kernel Debugger Architecture Independent Support Functions
   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 * 03/02/13    added new 2.5 kallsyms <xavier.bru@bull.net>
  11 */
  12
  13#include <stdarg.h>
  14#include <linux/types.h>
  15#include <linux/sched.h>
  16#include <linux/mm.h>
  17#include <linux/kallsyms.h>
  18#include <linux/stddef.h>
  19#include <linux/vmalloc.h>
  20#include <linux/ptrace.h>
  21#include <linux/module.h>
  22#include <linux/highmem.h>
  23#include <linux/hardirq.h>
  24#include <linux/delay.h>
  25#include <linux/uaccess.h>
  26#include <linux/kdb.h>
  27#include <linux/slab.h>
  28#include "kdb_private.h"
  29
  30/*
  31 * kdbgetsymval - Return the address of the given symbol.
  32 *
  33 * Parameters:
  34 *      symname Character string containing symbol name
  35 *      symtab  Structure to receive results
  36 * Returns:
  37 *      0       Symbol not found, symtab zero filled
  38 *      1       Symbol mapped to module/symbol/section, data in symtab
  39 */
  40int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
  41{
  42        if (KDB_DEBUG(AR))
  43                kdb_printf("kdbgetsymval: symname=%s, symtab=%p\n", symname,
  44                           symtab);
  45        memset(symtab, 0, sizeof(*symtab));
  46        symtab->sym_start = kallsyms_lookup_name(symname);
  47        if (symtab->sym_start) {
  48                if (KDB_DEBUG(AR))
  49                        kdb_printf("kdbgetsymval: returns 1, "
  50                                   "symtab->sym_start=0x%lx\n",
  51                                   symtab->sym_start);
  52                return 1;
  53        }
  54        if (KDB_DEBUG(AR))
  55                kdb_printf("kdbgetsymval: returns 0\n");
  56        return 0;
  57}
  58EXPORT_SYMBOL(kdbgetsymval);
  59
  60static char *kdb_name_table[100];       /* arbitrary size */
  61
  62/*
  63 * kdbnearsym - Return the name of the symbol with the nearest address
  64 *      less than 'addr'.
  65 *
  66 * Parameters:
  67 *      addr    Address to check for symbol near
  68 *      symtab  Structure to receive results
  69 * Returns:
  70 *      0       No sections contain this address, symtab zero filled
  71 *      1       Address mapped to module/symbol/section, data in symtab
  72 * Remarks:
  73 *      2.6 kallsyms has a "feature" where it unpacks the name into a
  74 *      string.  If that string is reused before the caller expects it
  75 *      then the caller sees its string change without warning.  To
  76 *      avoid cluttering up the main kdb code with lots of kdb_strdup,
  77 *      tests and kfree calls, kdbnearsym maintains an LRU list of the
  78 *      last few unique strings.  The list is sized large enough to
  79 *      hold active strings, no kdb caller of kdbnearsym makes more
  80 *      than ~20 later calls before using a saved value.
  81 */
  82int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
  83{
  84        int ret = 0;
  85        unsigned long symbolsize = 0;
  86        unsigned long offset = 0;
  87#define knt1_size 128           /* must be >= kallsyms table size */
  88        char *knt1 = NULL;
  89
  90        if (KDB_DEBUG(AR))
  91                kdb_printf("kdbnearsym: addr=0x%lx, symtab=%p\n", addr, symtab);
  92        memset(symtab, 0, sizeof(*symtab));
  93
  94        if (addr < 4096)
  95                goto out;
  96        knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC);
  97        if (!knt1) {
  98                kdb_printf("kdbnearsym: addr=0x%lx cannot kmalloc knt1\n",
  99                           addr);
 100                goto out;
 101        }
 102        symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
 103                                (char **)(&symtab->mod_name), knt1);
 104        if (offset > 8*1024*1024) {
 105                symtab->sym_name = NULL;
 106                addr = offset = symbolsize = 0;
 107        }
 108        symtab->sym_start = addr - offset;
 109        symtab->sym_end = symtab->sym_start + symbolsize;
 110        ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
 111
 112        if (ret) {
 113                int i;
 114                /* Another 2.6 kallsyms "feature".  Sometimes the sym_name is
 115                 * set but the buffer passed into kallsyms_lookup is not used,
 116                 * so it contains garbage.  The caller has to work out which
 117                 * buffer needs to be saved.
 118                 *
 119                 * What was Rusty smoking when he wrote that code?
 120                 */
 121                if (symtab->sym_name != knt1) {
 122                        strncpy(knt1, symtab->sym_name, knt1_size);
 123                        knt1[knt1_size-1] = '\0';
 124                }
 125                for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
 126                        if (kdb_name_table[i] &&
 127                            strcmp(kdb_name_table[i], knt1) == 0)
 128                                break;
 129                }
 130                if (i >= ARRAY_SIZE(kdb_name_table)) {
 131                        debug_kfree(kdb_name_table[0]);
 132                        memcpy(kdb_name_table, kdb_name_table+1,
 133                               sizeof(kdb_name_table[0]) *
 134                               (ARRAY_SIZE(kdb_name_table)-1));
 135                } else {
 136                        debug_kfree(knt1);
 137                        knt1 = kdb_name_table[i];
 138                        memcpy(kdb_name_table+i, kdb_name_table+i+1,
 139                               sizeof(kdb_name_table[0]) *
 140                               (ARRAY_SIZE(kdb_name_table)-i-1));
 141                }
 142                i = ARRAY_SIZE(kdb_name_table) - 1;
 143                kdb_name_table[i] = knt1;
 144                symtab->sym_name = kdb_name_table[i];
 145                knt1 = NULL;
 146        }
 147
 148        if (symtab->mod_name == NULL)
 149                symtab->mod_name = "kernel";
 150        if (KDB_DEBUG(AR))
 151                kdb_printf("kdbnearsym: returns %d symtab->sym_start=0x%lx, "
 152                   "symtab->mod_name=%p, symtab->sym_name=%p (%s)\n", ret,
 153                   symtab->sym_start, symtab->mod_name, symtab->sym_name,
 154                   symtab->sym_name);
 155
 156out:
 157        debug_kfree(knt1);
 158        return ret;
 159}
 160
 161void kdbnearsym_cleanup(void)
 162{
 163        int i;
 164        for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
 165                if (kdb_name_table[i]) {
 166                        debug_kfree(kdb_name_table[i]);
 167                        kdb_name_table[i] = NULL;
 168                }
 169        }
 170}
 171
 172static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
 173
 174/*
 175 * kallsyms_symbol_complete
 176 *
 177 * Parameters:
 178 *      prefix_name     prefix of a symbol name to lookup
 179 *      max_len         maximum length that can be returned
 180 * Returns:
 181 *      Number of symbols which match the given prefix.
 182 * Notes:
 183 *      prefix_name is changed to contain the longest unique prefix that
 184 *      starts with this prefix (tab completion).
 185 */
 186int kallsyms_symbol_complete(char *prefix_name, int max_len)
 187{
 188        loff_t pos = 0;
 189        int prefix_len = strlen(prefix_name), prev_len = 0;
 190        int i, number = 0;
 191        const char *name;
 192
 193        while ((name = kdb_walk_kallsyms(&pos))) {
 194                if (strncmp(name, prefix_name, prefix_len) == 0) {
 195                        strcpy(ks_namebuf, name);
 196                        /* Work out the longest name that matches the prefix */
 197                        if (++number == 1) {
 198                                prev_len = min_t(int, max_len-1,
 199                                                 strlen(ks_namebuf));
 200                                memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
 201                                ks_namebuf_prev[prev_len] = '\0';
 202                                continue;
 203                        }
 204                        for (i = 0; i < prev_len; i++) {
 205                                if (ks_namebuf[i] != ks_namebuf_prev[i]) {
 206                                        prev_len = i;
 207                                        ks_namebuf_prev[i] = '\0';
 208                                        break;
 209                                }
 210                        }
 211                }
 212        }
 213        if (prev_len > prefix_len)
 214                memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
 215        return number;
 216}
 217
 218/*
 219 * kallsyms_symbol_next
 220 *
 221 * Parameters:
 222 *      prefix_name     prefix of a symbol name to lookup
 223 *      flag    0 means search from the head, 1 means continue search.
 224 * Returns:
 225 *      1 if a symbol matches the given prefix.
 226 *      0 if no string found
 227 */
 228int kallsyms_symbol_next(char *prefix_name, int flag)
 229{
 230        int prefix_len = strlen(prefix_name);
 231        static loff_t pos;
 232        const char *name;
 233
 234        if (!flag)
 235                pos = 0;
 236
 237        while ((name = kdb_walk_kallsyms(&pos))) {
 238                if (strncmp(name, prefix_name, prefix_len) == 0) {
 239                        strncpy(prefix_name, name, strlen(name)+1);
 240                        return 1;
 241                }
 242        }
 243        return 0;
 244}
 245
 246/*
 247 * kdb_symbol_print - Standard method for printing a symbol name and offset.
 248 * Inputs:
 249 *      addr    Address to be printed.
 250 *      symtab  Address of symbol data, if NULL this routine does its
 251 *              own lookup.
 252 *      punc    Punctuation for string, bit field.
 253 * Remarks:
 254 *      The string and its punctuation is only printed if the address
 255 *      is inside the kernel, except that the value is always printed
 256 *      when requested.
 257 */
 258void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
 259                      unsigned int punc)
 260{
 261        kdb_symtab_t symtab, *symtab_p2;
 262        if (symtab_p) {
 263                symtab_p2 = (kdb_symtab_t *)symtab_p;
 264        } else {
 265                symtab_p2 = &symtab;
 266                kdbnearsym(addr, symtab_p2);
 267        }
 268        if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
 269                return;
 270        if (punc & KDB_SP_SPACEB)
 271                kdb_printf(" ");
 272        if (punc & KDB_SP_VALUE)
 273                kdb_printf(kdb_machreg_fmt0, addr);
 274        if (symtab_p2->sym_name) {
 275                if (punc & KDB_SP_VALUE)
 276                        kdb_printf(" ");
 277                if (punc & KDB_SP_PAREN)
 278                        kdb_printf("(");
 279                if (strcmp(symtab_p2->mod_name, "kernel"))
 280                        kdb_printf("[%s]", symtab_p2->mod_name);
 281                kdb_printf("%s", symtab_p2->sym_name);
 282                if (addr != symtab_p2->sym_start)
 283                        kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
 284                if (punc & KDB_SP_SYMSIZE)
 285                        kdb_printf("/0x%lx",
 286                                   symtab_p2->sym_end - symtab_p2->sym_start);
 287                if (punc & KDB_SP_PAREN)
 288                        kdb_printf(")");
 289        }
 290        if (punc & KDB_SP_SPACEA)
 291                kdb_printf(" ");
 292        if (punc & KDB_SP_NEWLINE)
 293                kdb_printf("\n");
 294}
 295
 296/*
 297 * kdb_strdup - kdb equivalent of strdup, for disasm code.
 298 * Inputs:
 299 *      str     The string to duplicate.
 300 *      type    Flags to kmalloc for the new string.
 301 * Returns:
 302 *      Address of the new string, NULL if storage could not be allocated.
 303 * Remarks:
 304 *      This is not in lib/string.c because it uses kmalloc which is not
 305 *      available when string.o is used in boot loaders.
 306 */
 307char *kdb_strdup(const char *str, gfp_t type)
 308{
 309        int n = strlen(str)+1;
 310        char *s = kmalloc(n, type);
 311        if (!s)
 312                return NULL;
 313        return strcpy(s, str);
 314}
 315
 316/*
 317 * kdb_getarea_size - Read an area of data.  The kdb equivalent of
 318 *      copy_from_user, with kdb messages for invalid addresses.
 319 * Inputs:
 320 *      res     Pointer to the area to receive the result.
 321 *      addr    Address of the area to copy.
 322 *      size    Size of the area.
 323 * Returns:
 324 *      0 for success, < 0 for error.
 325 */
 326int kdb_getarea_size(void *res, unsigned long addr, size_t size)
 327{
 328        int ret = probe_kernel_read((char *)res, (char *)addr, size);
 329        if (ret) {
 330                if (!KDB_STATE(SUPPRESS)) {
 331                        kdb_printf("kdb_getarea: Bad address 0x%lx\n", addr);
 332                        KDB_STATE_SET(SUPPRESS);
 333                }
 334                ret = KDB_BADADDR;
 335        } else {
 336                KDB_STATE_CLEAR(SUPPRESS);
 337        }
 338        return ret;
 339}
 340
 341/*
 342 * kdb_putarea_size - Write an area of data.  The kdb equivalent of
 343 *      copy_to_user, with kdb messages for invalid addresses.
 344 * Inputs:
 345 *      addr    Address of the area to write to.
 346 *      res     Pointer to the area holding the data.
 347 *      size    Size of the area.
 348 * Returns:
 349 *      0 for success, < 0 for error.
 350 */
 351int kdb_putarea_size(unsigned long addr, void *res, size_t size)
 352{
 353        int ret = probe_kernel_read((char *)addr, (char *)res, size);
 354        if (ret) {
 355                if (!KDB_STATE(SUPPRESS)) {
 356                        kdb_printf("kdb_putarea: Bad address 0x%lx\n", addr);
 357                        KDB_STATE_SET(SUPPRESS);
 358                }
 359                ret = KDB_BADADDR;
 360        } else {
 361                KDB_STATE_CLEAR(SUPPRESS);
 362        }
 363        return ret;
 364}
 365
 366/*
 367 * kdb_getphys - Read data from a physical address. Validate the
 368 *      address is in range, use kmap_atomic() to get data
 369 *      similar to kdb_getarea() - but for phys addresses
 370 * Inputs:
 371 *      res     Pointer to the word to receive the result
 372 *      addr    Physical address of the area to copy
 373 *      size    Size of the area
 374 * Returns:
 375 *      0 for success, < 0 for error.
 376 */
 377static int kdb_getphys(void *res, unsigned long addr, size_t size)
 378{
 379        unsigned long pfn;
 380        void *vaddr;
 381        struct page *page;
 382
 383        pfn = (addr >> PAGE_SHIFT);
 384        if (!pfn_valid(pfn))
 385                return 1;
 386        page = pfn_to_page(pfn);
 387        vaddr = kmap_atomic(page);
 388        memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
 389        kunmap_atomic(vaddr);
 390
 391        return 0;
 392}
 393
 394/*
 395 * kdb_getphysword
 396 * Inputs:
 397 *      word    Pointer to the word to receive the result.
 398 *      addr    Address of the area to copy.
 399 *      size    Size of the area.
 400 * Returns:
 401 *      0 for success, < 0 for error.
 402 */
 403int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
 404{
 405        int diag;
 406        __u8  w1;
 407        __u16 w2;
 408        __u32 w4;
 409        __u64 w8;
 410        *word = 0;      /* Default value if addr or size is invalid */
 411
 412        switch (size) {
 413        case 1:
 414                diag = kdb_getphys(&w1, addr, sizeof(w1));
 415                if (!diag)
 416                        *word = w1;
 417                break;
 418        case 2:
 419                diag = kdb_getphys(&w2, addr, sizeof(w2));
 420                if (!diag)
 421                        *word = w2;
 422                break;
 423        case 4:
 424                diag = kdb_getphys(&w4, addr, sizeof(w4));
 425                if (!diag)
 426                        *word = w4;
 427                break;
 428        case 8:
 429                if (size <= sizeof(*word)) {
 430                        diag = kdb_getphys(&w8, addr, sizeof(w8));
 431                        if (!diag)
 432                                *word = w8;
 433                        break;
 434                }
 435                /* drop through */
 436        default:
 437                diag = KDB_BADWIDTH;
 438                kdb_printf("kdb_getphysword: bad width %ld\n", (long) size);
 439        }
 440        return diag;
 441}
 442
 443/*
 444 * kdb_getword - Read a binary value.  Unlike kdb_getarea, this treats
 445 *      data as numbers.
 446 * Inputs:
 447 *      word    Pointer to the word to receive the result.
 448 *      addr    Address of the area to copy.
 449 *      size    Size of the area.
 450 * Returns:
 451 *      0 for success, < 0 for error.
 452 */
 453int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
 454{
 455        int diag;
 456        __u8  w1;
 457        __u16 w2;
 458        __u32 w4;
 459        __u64 w8;
 460        *word = 0;      /* Default value if addr or size is invalid */
 461        switch (size) {
 462        case 1:
 463                diag = kdb_getarea(w1, addr);
 464                if (!diag)
 465                        *word = w1;
 466                break;
 467        case 2:
 468                diag = kdb_getarea(w2, addr);
 469                if (!diag)
 470                        *word = w2;
 471                break;
 472        case 4:
 473                diag = kdb_getarea(w4, addr);
 474                if (!diag)
 475                        *word = w4;
 476                break;
 477        case 8:
 478                if (size <= sizeof(*word)) {
 479                        diag = kdb_getarea(w8, addr);
 480                        if (!diag)
 481                                *word = w8;
 482                        break;
 483                }
 484                /* drop through */
 485        default:
 486                diag = KDB_BADWIDTH;
 487                kdb_printf("kdb_getword: bad width %ld\n", (long) size);
 488        }
 489        return diag;
 490}
 491
 492/*
 493 * kdb_putword - Write a binary value.  Unlike kdb_putarea, this
 494 *      treats data as numbers.
 495 * Inputs:
 496 *      addr    Address of the area to write to..
 497 *      word    The value to set.
 498 *      size    Size of the area.
 499 * Returns:
 500 *      0 for success, < 0 for error.
 501 */
 502int kdb_putword(unsigned long addr, unsigned long word, size_t size)
 503{
 504        int diag;
 505        __u8  w1;
 506        __u16 w2;
 507        __u32 w4;
 508        __u64 w8;
 509        switch (size) {
 510        case 1:
 511                w1 = word;
 512                diag = kdb_putarea(addr, w1);
 513                break;
 514        case 2:
 515                w2 = word;
 516                diag = kdb_putarea(addr, w2);
 517                break;
 518        case 4:
 519                w4 = word;
 520                diag = kdb_putarea(addr, w4);
 521                break;
 522        case 8:
 523                if (size <= sizeof(word)) {
 524                        w8 = word;
 525                        diag = kdb_putarea(addr, w8);
 526                        break;
 527                }
 528                /* drop through */
 529        default:
 530                diag = KDB_BADWIDTH;
 531                kdb_printf("kdb_putword: bad width %ld\n", (long) size);
 532        }
 533        return diag;
 534}
 535
 536/*
 537 * kdb_task_state_string - Convert a string containing any of the
 538 *      letters DRSTCZEUIMA to a mask for the process state field and
 539 *      return the value.  If no argument is supplied, return the mask
 540 *      that corresponds to environment variable PS, DRSTCZEU by
 541 *      default.
 542 * Inputs:
 543 *      s       String to convert
 544 * Returns:
 545 *      Mask for process state.
 546 * Notes:
 547 *      The mask folds data from several sources into a single long value, so
 548 *      be careful not to overlap the bits.  TASK_* bits are in the LSB,
 549 *      special cases like UNRUNNABLE are in the MSB.  As of 2.6.10-rc1 there
 550 *      is no overlap between TASK_* and EXIT_* but that may not always be
 551 *      true, so EXIT_* bits are shifted left 16 bits before being stored in
 552 *      the mask.
 553 */
 554
 555/* unrunnable is < 0 */
 556#define UNRUNNABLE      (1UL << (8*sizeof(unsigned long) - 1))
 557#define RUNNING         (1UL << (8*sizeof(unsigned long) - 2))
 558#define IDLE            (1UL << (8*sizeof(unsigned long) - 3))
 559#define DAEMON          (1UL << (8*sizeof(unsigned long) - 4))
 560
 561unsigned long kdb_task_state_string(const char *s)
 562{
 563        long res = 0;
 564        if (!s) {
 565                s = kdbgetenv("PS");
 566                if (!s)
 567                        s = "DRSTCZEU"; /* default value for ps */
 568        }
 569        while (*s) {
 570                switch (*s) {
 571                case 'D':
 572                        res |= TASK_UNINTERRUPTIBLE;
 573                        break;
 574                case 'R':
 575                        res |= RUNNING;
 576                        break;
 577                case 'S':
 578                        res |= TASK_INTERRUPTIBLE;
 579                        break;
 580                case 'T':
 581                        res |= TASK_STOPPED;
 582                        break;
 583                case 'C':
 584                        res |= TASK_TRACED;
 585                        break;
 586                case 'Z':
 587                        res |= EXIT_ZOMBIE << 16;
 588                        break;
 589                case 'E':
 590                        res |= EXIT_DEAD << 16;
 591                        break;
 592                case 'U':
 593                        res |= UNRUNNABLE;
 594                        break;
 595                case 'I':
 596                        res |= IDLE;
 597                        break;
 598                case 'M':
 599                        res |= DAEMON;
 600                        break;
 601                case 'A':
 602                        res = ~0UL;
 603                        break;
 604                default:
 605                          kdb_printf("%s: unknown flag '%c' ignored\n",
 606                                     __func__, *s);
 607                          break;
 608                }
 609                ++s;
 610        }
 611        return res;
 612}
 613
 614/*
 615 * kdb_task_state_char - Return the character that represents the task state.
 616 * Inputs:
 617 *      p       struct task for the process
 618 * Returns:
 619 *      One character to represent the task state.
 620 */
 621char kdb_task_state_char (const struct task_struct *p)
 622{
 623        int cpu;
 624        char state;
 625        unsigned long tmp;
 626
 627        if (!p || probe_kernel_read(&tmp, (char *)p, sizeof(unsigned long)))
 628                return 'E';
 629
 630        cpu = kdb_process_cpu(p);
 631        state = (p->state == 0) ? 'R' :
 632                (p->state < 0) ? 'U' :
 633                (p->state & TASK_UNINTERRUPTIBLE) ? 'D' :
 634                (p->state & TASK_STOPPED) ? 'T' :
 635                (p->state & TASK_TRACED) ? 'C' :
 636                (p->exit_state & EXIT_ZOMBIE) ? 'Z' :
 637                (p->exit_state & EXIT_DEAD) ? 'E' :
 638                (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
 639        if (is_idle_task(p)) {
 640                /* Idle task.  Is it really idle, apart from the kdb
 641                 * interrupt? */
 642                if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
 643                        if (cpu != kdb_initial_cpu)
 644                                state = 'I';    /* idle task */
 645                }
 646        } else if (!p->mm && state == 'S') {
 647                state = 'M';    /* sleeping system daemon */
 648        }
 649        return state;
 650}
 651
 652/*
 653 * kdb_task_state - Return true if a process has the desired state
 654 *      given by the mask.
 655 * Inputs:
 656 *      p       struct task for the process
 657 *      mask    mask from kdb_task_state_string to select processes
 658 * Returns:
 659 *      True if the process matches at least one criteria defined by the mask.
 660 */
 661unsigned long kdb_task_state(const struct task_struct *p, unsigned long mask)
 662{
 663        char state[] = { kdb_task_state_char(p), '\0' };
 664        return (mask & kdb_task_state_string(state)) != 0;
 665}
 666
 667/*
 668 * kdb_print_nameval - Print a name and its value, converting the
 669 *      value to a symbol lookup if possible.
 670 * Inputs:
 671 *      name    field name to print
 672 *      val     value of field
 673 */
 674void kdb_print_nameval(const char *name, unsigned long val)
 675{
 676        kdb_symtab_t symtab;
 677        kdb_printf("  %-11.11s ", name);
 678        if (kdbnearsym(val, &symtab))
 679                kdb_symbol_print(val, &symtab,
 680                                 KDB_SP_VALUE|KDB_SP_SYMSIZE|KDB_SP_NEWLINE);
 681        else
 682                kdb_printf("0x%lx\n", val);
 683}
 684
 685/* Last ditch allocator for debugging, so we can still debug even when
 686 * the GFP_ATOMIC pool has been exhausted.  The algorithms are tuned
 687 * for space usage, not for speed.  One smallish memory pool, the free
 688 * chain is always in ascending address order to allow coalescing,
 689 * allocations are done in brute force best fit.
 690 */
 691
 692struct debug_alloc_header {
 693        u32 next;       /* offset of next header from start of pool */
 694        u32 size;
 695        void *caller;
 696};
 697
 698/* The memory returned by this allocator must be aligned, which means
 699 * so must the header size.  Do not assume that sizeof(struct
 700 * debug_alloc_header) is a multiple of the alignment, explicitly
 701 * calculate the overhead of this header, including the alignment.
 702 * The rest of this code must not use sizeof() on any header or
 703 * pointer to a header.
 704 */
 705#define dah_align 8
 706#define dah_overhead ALIGN(sizeof(struct debug_alloc_header), dah_align)
 707
 708static u64 debug_alloc_pool_aligned[256*1024/dah_align];        /* 256K pool */
 709static char *debug_alloc_pool = (char *)debug_alloc_pool_aligned;
 710static u32 dah_first, dah_first_call = 1, dah_used, dah_used_max;
 711
 712/* Locking is awkward.  The debug code is called from all contexts,
 713 * including non maskable interrupts.  A normal spinlock is not safe
 714 * in NMI context.  Try to get the debug allocator lock, if it cannot
 715 * be obtained after a second then give up.  If the lock could not be
 716 * previously obtained on this cpu then only try once.
 717 *
 718 * sparse has no annotation for "this function _sometimes_ acquires a
 719 * lock", so fudge the acquire/release notation.
 720 */
 721static DEFINE_SPINLOCK(dap_lock);
 722static int get_dap_lock(void)
 723        __acquires(dap_lock)
 724{
 725        static int dap_locked = -1;
 726        int count;
 727        if (dap_locked == smp_processor_id())
 728                count = 1;
 729        else
 730                count = 1000;
 731        while (1) {
 732                if (spin_trylock(&dap_lock)) {
 733                        dap_locked = -1;
 734                        return 1;
 735                }
 736                if (!count--)
 737                        break;
 738                udelay(1000);
 739        }
 740        dap_locked = smp_processor_id();
 741        __acquire(dap_lock);
 742        return 0;
 743}
 744
 745void *debug_kmalloc(size_t size, gfp_t flags)
 746{
 747        unsigned int rem, h_offset;
 748        struct debug_alloc_header *best, *bestprev, *prev, *h;
 749        void *p = NULL;
 750        if (!get_dap_lock()) {
 751                __release(dap_lock);    /* we never actually got it */
 752                return NULL;
 753        }
 754        h = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
 755        if (dah_first_call) {
 756                h->size = sizeof(debug_alloc_pool_aligned) - dah_overhead;
 757                dah_first_call = 0;
 758        }
 759        size = ALIGN(size, dah_align);
 760        prev = best = bestprev = NULL;
 761        while (1) {
 762                if (h->size >= size && (!best || h->size < best->size)) {
 763                        best = h;
 764                        bestprev = prev;
 765                        if (h->size == size)
 766                                break;
 767                }
 768                if (!h->next)
 769                        break;
 770                prev = h;
 771                h = (struct debug_alloc_header *)(debug_alloc_pool + h->next);
 772        }
 773        if (!best)
 774                goto out;
 775        rem = best->size - size;
 776        /* The pool must always contain at least one header */
 777        if (best->next == 0 && bestprev == NULL && rem < dah_overhead)
 778                goto out;
 779        if (rem >= dah_overhead) {
 780                best->size = size;
 781                h_offset = ((char *)best - debug_alloc_pool) +
 782                           dah_overhead + best->size;
 783                h = (struct debug_alloc_header *)(debug_alloc_pool + h_offset);
 784                h->size = rem - dah_overhead;
 785                h->next = best->next;
 786        } else
 787                h_offset = best->next;
 788        best->caller = __builtin_return_address(0);
 789        dah_used += best->size;
 790        dah_used_max = max(dah_used, dah_used_max);
 791        if (bestprev)
 792                bestprev->next = h_offset;
 793        else
 794                dah_first = h_offset;
 795        p = (char *)best + dah_overhead;
 796        memset(p, POISON_INUSE, best->size - 1);
 797        *((char *)p + best->size - 1) = POISON_END;
 798out:
 799        spin_unlock(&dap_lock);
 800        return p;
 801}
 802
 803void debug_kfree(void *p)
 804{
 805        struct debug_alloc_header *h;
 806        unsigned int h_offset;
 807        if (!p)
 808                return;
 809        if ((char *)p < debug_alloc_pool ||
 810            (char *)p >= debug_alloc_pool + sizeof(debug_alloc_pool_aligned)) {
 811                kfree(p);
 812                return;
 813        }
 814        if (!get_dap_lock()) {
 815                __release(dap_lock);    /* we never actually got it */
 816                return;         /* memory leak, cannot be helped */
 817        }
 818        h = (struct debug_alloc_header *)((char *)p - dah_overhead);
 819        memset(p, POISON_FREE, h->size - 1);
 820        *((char *)p + h->size - 1) = POISON_END;
 821        h->caller = NULL;
 822        dah_used -= h->size;
 823        h_offset = (char *)h - debug_alloc_pool;
 824        if (h_offset < dah_first) {
 825                h->next = dah_first;
 826                dah_first = h_offset;
 827        } else {
 828                struct debug_alloc_header *prev;
 829                unsigned int prev_offset;
 830                prev = (struct debug_alloc_header *)(debug_alloc_pool +
 831                                                     dah_first);
 832                while (1) {
 833                        if (!prev->next || prev->next > h_offset)
 834                                break;
 835                        prev = (struct debug_alloc_header *)
 836                                (debug_alloc_pool + prev->next);
 837                }
 838                prev_offset = (char *)prev - debug_alloc_pool;
 839                if (prev_offset + dah_overhead + prev->size == h_offset) {
 840                        prev->size += dah_overhead + h->size;
 841                        memset(h, POISON_FREE, dah_overhead - 1);
 842                        *((char *)h + dah_overhead - 1) = POISON_END;
 843                        h = prev;
 844                        h_offset = prev_offset;
 845                } else {
 846                        h->next = prev->next;
 847                        prev->next = h_offset;
 848                }
 849        }
 850        if (h_offset + dah_overhead + h->size == h->next) {
 851                struct debug_alloc_header *next;
 852                next = (struct debug_alloc_header *)
 853                        (debug_alloc_pool + h->next);
 854                h->size += dah_overhead + next->size;
 855                h->next = next->next;
 856                memset(next, POISON_FREE, dah_overhead - 1);
 857                *((char *)next + dah_overhead - 1) = POISON_END;
 858        }
 859        spin_unlock(&dap_lock);
 860}
 861
 862void debug_kusage(void)
 863{
 864        struct debug_alloc_header *h_free, *h_used;
 865#ifdef  CONFIG_IA64
 866        /* FIXME: using dah for ia64 unwind always results in a memory leak.
 867         * Fix that memory leak first, then set debug_kusage_one_time = 1 for
 868         * all architectures.
 869         */
 870        static int debug_kusage_one_time;
 871#else
 872        static int debug_kusage_one_time = 1;
 873#endif
 874        if (!get_dap_lock()) {
 875                __release(dap_lock);    /* we never actually got it */
 876                return;
 877        }
 878        h_free = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
 879        if (dah_first == 0 &&
 880            (h_free->size == sizeof(debug_alloc_pool_aligned) - dah_overhead ||
 881             dah_first_call))
 882                goto out;
 883        if (!debug_kusage_one_time)
 884                goto out;
 885        debug_kusage_one_time = 0;
 886        kdb_printf("%s: debug_kmalloc memory leak dah_first %d\n",
 887                   __func__, dah_first);
 888        if (dah_first) {
 889                h_used = (struct debug_alloc_header *)debug_alloc_pool;
 890                kdb_printf("%s: h_used %p size %d\n", __func__, h_used,
 891                           h_used->size);
 892        }
 893        do {
 894                h_used = (struct debug_alloc_header *)
 895                          ((char *)h_free + dah_overhead + h_free->size);
 896                kdb_printf("%s: h_used %p size %d caller %p\n",
 897                           __func__, h_used, h_used->size, h_used->caller);
 898                h_free = (struct debug_alloc_header *)
 899                          (debug_alloc_pool + h_free->next);
 900        } while (h_free->next);
 901        h_used = (struct debug_alloc_header *)
 902                  ((char *)h_free + dah_overhead + h_free->size);
 903        if ((char *)h_used - debug_alloc_pool !=
 904            sizeof(debug_alloc_pool_aligned))
 905                kdb_printf("%s: h_used %p size %d caller %p\n",
 906                           __func__, h_used, h_used->size, h_used->caller);
 907out:
 908        spin_unlock(&dap_lock);
 909}
 910
 911/* Maintain a small stack of kdb_flags to allow recursion without disturbing
 912 * the global kdb state.
 913 */
 914
 915static int kdb_flags_stack[4], kdb_flags_index;
 916
 917void kdb_save_flags(void)
 918{
 919        BUG_ON(kdb_flags_index >= ARRAY_SIZE(kdb_flags_stack));
 920        kdb_flags_stack[kdb_flags_index++] = kdb_flags;
 921}
 922
 923void kdb_restore_flags(void)
 924{
 925        BUG_ON(kdb_flags_index <= 0);
 926        kdb_flags = kdb_flags_stack[--kdb_flags_index];
 927}
 928