arch/sh/kernel/traps.c

   1 /* $Id: traps.c,v 1.16 2004/03/16 00:10:54 lethal Exp $
   2  *
   3  *  linux/arch/sh/traps.c
   4  *
   5  *  SuperH version: Copyright (C) 1999 Niibe Yutaka
   6  *                  Copyright (C) 2000 Philipp Rumpf
   7  *                  Copyright (C) 2000 David Howells
   8  *                  Copyright (C) 2002, 2003 Paul Mundt
   9  */
  10
  11 /*
  12  * 'Traps.c' handles hardware traps and faults after we have saved some
  13  * state in 'entry.S'.
  14  */
  15 #include <linux/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <linux/errno.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/timer.h>
  22 #include <linux/mm.h>
  23 #include <linux/smp.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/init.h>
  26 #include <linux/delay.h>
  27 #include <linux/spinlock.h>
  28 #include <linux/module.h>
  29 #include <linux/kallsyms.h>
  30
  31 #include <asm/system.h>
  32 #include <asm/uaccess.h>
  33 #include <asm/io.h>
  34 #include <asm/atomic.h>
  35 #include <asm/processor.h>
  36 #include <asm/sections.h>
  37
  38 #ifdef CONFIG_SH_KGDB
  39 #include <asm/kgdb.h>
  40 #define CHK_REMOTE_DEBUG(regs)                                               \
  41 {                                                                            \
  42   if ((kgdb_debug_hook != (kgdb_debug_hook_t *) NULL) && (!user_mode(regs))) \
  43   {                                                                          \
  44     (*kgdb_debug_hook)(regs);                                                \
  45   }                                                                          \
  46 }
  47 #else
  48 #define CHK_REMOTE_DEBUG(regs)
  49 #endif
  50
  51 #define DO_ERROR(trapnr, signr, str, name, tsk)                         \
  52 asmlinkage void do_##name(unsigned long r4, unsigned long r5,           \
  53                           unsigned long r6, unsigned long r7,           \
  54                           struct pt_regs regs)                          \
  55 {                                                                       \
  56         unsigned long error_code;                                       \
  57                                                                         \
  58         /* Check if it's a DSP instruction */                           \
  59         if (is_dsp_inst(&regs)) {                                       \
  60                 /* Enable DSP mode, and restart instruction. */         \
  61                 regs.sr |= SR_DSP;                                      \
  62                 return;                                                 \
  63         }                                                               \
  64                                                                         \
  65         asm volatile("stc       r2_bank, %0": "=r" (error_code));       \
  66         local_irq_enable();                                             \
  67         tsk->thread.error_code = error_code;                            \
  68         tsk->thread.trap_no = trapnr;                                   \
  69         CHK_REMOTE_DEBUG(&regs);                                        \
  70         force_sig(signr, tsk);                                          \
  71         die_if_no_fixup(str,&regs,error_code);                          \
  72 }
  73
  74 #ifdef CONFIG_CPU_SH2
  75 #define TRAP_RESERVED_INST      4
  76 #define TRAP_ILLEGAL_SLOT_INST  6
  77 #else
  78 #define TRAP_RESERVED_INST      12
  79 #define TRAP_ILLEGAL_SLOT_INST  13
  80 #endif
  81
  82 /*
  83  * These constants are for searching for possible module text
  84  * segments.  VMALLOC_OFFSET comes from mm/vmalloc.c; MODULE_RANGE is
  85  * a guess of how much space is likely to be vmalloced.
  86  */
  87 #define VMALLOC_OFFSET (8*1024*1024)
  88 #define MODULE_RANGE (8*1024*1024)
  89
  90 spinlock_t die_lock;
  91
  92 void die(const char * str, struct pt_regs * regs, long err)
  93 {
  94         static int die_counter;
  95
  96         console_verbose();
  97         spin_lock_irq(&die_lock);
  98         printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
  99         CHK_REMOTE_DEBUG(regs);
 100         show_regs(regs);
 101         spin_unlock_irq(&die_lock);
 102         do_exit(SIGSEGV);
 103 }
 104
 105 static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
 106 {
 107         if (!user_mode(regs))
 108                 die(str, regs, err);
 109 }
 110
 111 static int handle_unaligned_notify_count = 10;
 112
 113 /*
 114  * try and fix up kernelspace address errors
 115  * - userspace errors just cause EFAULT to be returned, resulting in SEGV
 116  * - kernel/userspace interfaces cause a jump to an appropriate handler
 117  * - other kernel errors are bad
 118  * - return 0 if fixed-up, -EFAULT if non-fatal (to the kernel) fault
 119  */
 120 static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
 121 {
 122         if (!user_mode(regs))
 123         {
 124                 const struct exception_table_entry *fixup;
 125                 fixup = search_exception_tables(regs->pc);
 126                 if (fixup) {
 127                         regs->pc = fixup->fixup;
 128                         return 0;
 129                 }
 130                 die(str, regs, err);
 131         }
 132         return -EFAULT;
 133 }
 134
 135 /*
 136  * handle an instruction that does an unaligned memory access by emulating the
 137  * desired behaviour
 138  * - note that PC _may not_ point to the faulting instruction
 139  *   (if that instruction is in a branch delay slot)
 140  * - return 0 if emulation okay, -EFAULT on existential error
 141  */
 142 static int handle_unaligned_ins(u16 instruction, struct pt_regs *regs)
 143 {
 144         int ret, index, count;
 145         unsigned long *rm, *rn;
 146         unsigned char *src, *dst;
 147
 148         index = (instruction>>8)&15;    /* 0x0F00 */
 149         rn = &regs->regs[index];
 150
 151         index = (instruction>>4)&15;    /* 0x00F0 */
 152         rm = &regs->regs[index];
 153
 154         count = 1<<(instruction&3);
 155
 156         ret = -EFAULT;
 157         switch (instruction>>12) {
 158         case 0: /* mov.[bwl] to/from memory via r0+rn */
 159                 if (instruction & 8) {
 160                         /* from memory */
 161                         src = (unsigned char*) *rm;
 162                         src += regs->regs[0];
 163                         dst = (unsigned char*) rn;
 164                         *(unsigned long*)dst = 0;
 165
 166 #ifdef __LITTLE_ENDIAN__
 167                         if (copy_from_user(dst, src, count))
 168                                 goto fetch_fault;
 169
 170                         if ((count == 2) && dst[1] & 0x80) {
 171                                 dst[2] = 0xff;
 172                                 dst[3] = 0xff;
 173                         }
 174 #else
 175                         dst += 4-count;
 176
 177                         if (__copy_user(dst, src, count))
 178                                 goto fetch_fault;
 179
 180                         if ((count == 2) && dst[2] & 0x80) {
 181                                 dst[0] = 0xff;
 182                                 dst[1] = 0xff;
 183                         }
 184 #endif
 185                 } else {
 186                         /* to memory */
 187                         src = (unsigned char*) rm;
 188 #if !defined(__LITTLE_ENDIAN__)
 189                         src += 4-count;
 190 #endif
 191                         dst = (unsigned char*) *rn;
 192                         dst += regs->regs[0];
 193
 194                         if (copy_to_user(dst, src, count))
 195                                 goto fetch_fault;
 196                 }
 197                 ret = 0;
 198                 break;
 199
 200         case 1: /* mov.l Rm,@(disp,Rn) */
 201                 src = (unsigned char*) rm;
 202                 dst = (unsigned char*) *rn;
 203                 dst += (instruction&0x000F)<<2;
 204
 205                 if (copy_to_user(dst,src,4))
 206                         goto fetch_fault;
 207                 ret = 0;
 208                 break;
 209
 210         case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
 211                 if (instruction & 4)
 212                         *rn -= count;
 213                 src = (unsigned char*) rm;
 214                 dst = (unsigned char*) *rn;
 215 #if !defined(__LITTLE_ENDIAN__)
 216                 src += 4-count;
 217 #endif
 218                 if (copy_to_user(dst, src, count))
 219                         goto fetch_fault;
 220                 ret = 0;
 221                 break;
 222
 223         case 5: /* mov.l @(disp,Rm),Rn */
 224                 src = (unsigned char*) *rm;
 225                 src += (instruction&0x000F)<<2;
 226                 dst = (unsigned char*) rn;
 227                 *(unsigned long*)dst = 0;
 228
 229                 if (copy_from_user(dst,src,4))
 230                         goto fetch_fault;
 231                 ret = 0;
 232                 break;
 233
 234         case 6: /* mov.[bwl] from memory, possibly with post-increment */
 235                 src = (unsigned char*) *rm;
 236                 if (instruction & 4)
 237                         *rm += count;
 238                 dst = (unsigned char*) rn;
 239                 *(unsigned long*)dst = 0;
 240
 241 #ifdef __LITTLE_ENDIAN__
 242                 if (copy_from_user(dst, src, count))
 243                         goto fetch_fault;
 244
 245                 if ((count == 2) && dst[1] & 0x80) {
 246                         dst[2] = 0xff;
 247                         dst[3] = 0xff;
 248                 }
 249 #else
 250                 dst += 4-count;
 251
 252                 if (copy_from_user(dst, src, count))
 253                         goto fetch_fault;
 254
 255                 if ((count == 2) && dst[2] & 0x80) {
 256                         dst[0] = 0xff;
 257                         dst[1] = 0xff;
 258                 }
 259 #endif
 260                 ret = 0;
 261                 break;
 262
 263         case 8:
 264                 switch ((instruction&0xFF00)>>8) {
 265                 case 0x81: /* mov.w R0,@(disp,Rn) */
 266                         src = (unsigned char*) &regs->regs[0];
 267 #if !defined(__LITTLE_ENDIAN__)
 268                         src += 2;
 269 #endif
 270                         dst = (unsigned char*) *rm; /* called Rn in the spec */
 271                         dst += (instruction&0x000F)<<1;
 272
 273                         if (copy_to_user(dst, src, 2))
 274                                 goto fetch_fault;
 275                         ret = 0;
 276                         break;
 277
 278                 case 0x85: /* mov.w @(disp,Rm),R0 */
 279                         src = (unsigned char*) *rm;
 280                         src += (instruction&0x000F)<<1;
 281                         dst = (unsigned char*) &regs->regs[0];
 282                         *(unsigned long*)dst = 0;
 283
 284 #if !defined(__LITTLE_ENDIAN__)
 285                         dst += 2;
 286 #endif
 287
 288                         if (copy_from_user(dst, src, 2))
 289                                 goto fetch_fault;
 290
 291 #ifdef __LITTLE_ENDIAN__
 292                         if (dst[1] & 0x80) {
 293                                 dst[2] = 0xff;
 294                                 dst[3] = 0xff;
 295                         }
 296 #else
 297                         if (dst[2] & 0x80) {
 298                                 dst[0] = 0xff;
 299                                 dst[1] = 0xff;
 300                         }
 301 #endif
 302                         ret = 0;
 303                         break;
 304                 }
 305                 break;
 306         }
 307         return ret;
 308
 309  fetch_fault:
 310         /* Argh. Address not only misaligned but also non-existent.
 311          * Raise an EFAULT and see if it's trapped
 312          */
 313         return die_if_no_fixup("Fault in unaligned fixup", regs, 0);
 314 }
 315
 316 /*
 317  * emulate the instruction in the delay slot
 318  * - fetches the instruction from PC+2
 319  */
 320 static inline int handle_unaligned_delayslot(struct pt_regs *regs)
 321 {
 322         u16 instruction;
 323
 324         if (copy_from_user(&instruction, (u16 *)(regs->pc+2), 2)) {
 325                 /* the instruction-fetch faulted */
 326                 if (user_mode(regs))
 327                         return -EFAULT;
 328
 329                 /* kernel */
 330                 die("delay-slot-insn faulting in handle_unaligned_delayslot", regs, 0);
 331         }
 332
 333         return handle_unaligned_ins(instruction,regs);
 334 }
 335
 336 /*
 337  * handle an instruction that does an unaligned memory access
 338  * - have to be careful of branch delay-slot instructions that fault
 339  *  SH3:
 340  *   - if the branch would be taken PC points to the branch
 341  *   - if the branch would not be taken, PC points to delay-slot
 342  *  SH4:
 343  *   - PC always points to delayed branch
 344  * - return 0 if handled, -EFAULT if failed (may not return if in kernel)
 345  */
 346
 347 /* Macros to determine offset from current PC for branch instructions */
 348 /* Explicit type coercion is used to force sign extension where needed */
 349 #define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
 350 #define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)
 351
 352 static int handle_unaligned_access(u16 instruction, struct pt_regs *regs)
 353 {
 354         u_int rm;
 355         int ret, index;
 356
 357         index = (instruction>>8)&15;    /* 0x0F00 */
 358         rm = regs->regs[index];
 359
 360         /* shout about the first ten userspace fixups */
 361         if (user_mode(regs) && handle_unaligned_notify_count>0) {
 362                 handle_unaligned_notify_count--;
 363
 364                 printk("Fixing up unaligned userspace access in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
 365                        current->comm,current->pid,(u16*)regs->pc,instruction);
 366         }
 367
 368         ret = -EFAULT;
 369         switch (instruction&0xF000) {
 370         case 0x0000:
 371                 if (instruction==0x000B) {
 372                         /* rts */
 373                         ret = handle_unaligned_delayslot(regs);
 374                         if (ret==0)
 375                                 regs->pc = regs->pr;
 376                 }
 377                 else if ((instruction&0x00FF)==0x0023) {
 378                         /* braf @Rm */
 379                         ret = handle_unaligned_delayslot(regs);
 380                         if (ret==0)
 381                                 regs->pc += rm + 4;
 382                 }
 383                 else if ((instruction&0x00FF)==0x0003) {
 384                         /* bsrf @Rm */
 385                         ret = handle_unaligned_delayslot(regs);
 386                         if (ret==0) {
 387                                 regs->pr = regs->pc + 4;
 388                                 regs->pc += rm + 4;
 389                         }
 390                 }
 391                 else {
 392                         /* mov.[bwl] to/from memory via r0+rn */
 393                         goto simple;
 394                 }
 395                 break;
 396
 397         case 0x1000: /* mov.l Rm,@(disp,Rn) */
 398                 goto simple;
 399
 400         case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
 401                 goto simple;
 402
 403         case 0x4000:
 404                 if ((instruction&0x00FF)==0x002B) {
 405                         /* jmp @Rm */
 406                         ret = handle_unaligned_delayslot(regs);
 407                         if (ret==0)
 408                                 regs->pc = rm;
 409                 }
 410                 else if ((instruction&0x00FF)==0x000B) {
 411                         /* jsr @Rm */
 412                         ret = handle_unaligned_delayslot(regs);
 413                         if (ret==0) {
 414                                 regs->pr = regs->pc + 4;
 415                                 regs->pc = rm;
 416                         }
 417                 }
 418                 else {
 419                         /* mov.[bwl] to/from memory via r0+rn */
 420                         goto simple;
 421                 }
 422                 break;
 423
 424         case 0x5000: /* mov.l @(disp,Rm),Rn */
 425                 goto simple;
 426
 427         case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
 428                 goto simple;
 429
 430         case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
 431                 switch (instruction&0x0F00) {
 432                 case 0x0100: /* mov.w R0,@(disp,Rm) */
 433                         goto simple;
 434                 case 0x0500: /* mov.w @(disp,Rm),R0 */
 435                         goto simple;
 436                 case 0x0B00: /* bf   lab - no delayslot*/
 437                         break;
 438                 case 0x0F00: /* bf/s lab */
 439                         ret = handle_unaligned_delayslot(regs);
 440                         if (ret==0) {
 441 #if defined(CONFIG_CPU_SH4)
 442                                 if ((regs->sr & 0x00000001) != 0)
 443                                         regs->pc += 4; /* next after slot */
 444                                 else
 445 #endif
 446                                         regs->pc += SH_PC_8BIT_OFFSET(instruction);
 447                         }
 448                         break;
 449                 case 0x0900: /* bt   lab - no delayslot */
 450                         break;
 451                 case 0x0D00: /* bt/s lab */
 452                         ret = handle_unaligned_delayslot(regs);
 453                         if (ret==0) {
 454 #if defined(CONFIG_CPU_SH4)
 455                                 if ((regs->sr & 0x00000001) == 0)
 456                                         regs->pc += 4; /* next after slot */
 457                                 else
 458 #endif
 459                                         regs->pc += SH_PC_8BIT_OFFSET(instruction);
 460                         }
 461                         break;
 462                 }
 463                 break;
 464
 465         case 0xA000: /* bra label */
 466                 ret = handle_unaligned_delayslot(regs);
 467                 if (ret==0)
 468                         regs->pc += SH_PC_12BIT_OFFSET(instruction);
 469                 break;
 470
 471         case 0xB000: /* bsr label */
 472                 ret = handle_unaligned_delayslot(regs);
 473                 if (ret==0) {
 474                         regs->pr = regs->pc + 4;
 475                         regs->pc += SH_PC_12BIT_OFFSET(instruction);
 476                 }
 477                 break;
 478         }
 479         return ret;
 480
 481         /* handle non-delay-slot instruction */
 482  simple:
 483         ret = handle_unaligned_ins(instruction,regs);
 484         if (ret==0)
 485                 regs->pc += 2;
 486         return ret;
 487 }
 488
 489 /*
 490  * Handle various address error exceptions
 491  */
 492 asmlinkage void do_address_error(struct pt_regs *regs,
 493                                  unsigned long writeaccess,
 494                                  unsigned long address)
 495 {
 496         unsigned long error_code;
 497         mm_segment_t oldfs;
 498         u16 instruction;
 499         int tmp;
 500
 501         asm volatile("stc       r2_bank,%0": "=r" (error_code));
 502
 503         oldfs = get_fs();
 504
 505         if (user_mode(regs)) {
 506                 local_irq_enable();
 507                 current->thread.error_code = error_code;
 508                 current->thread.trap_no = (writeaccess) ? 8 : 7;
 509
 510                 /* bad PC is not something we can fix */
 511                 if (regs->pc & 1)
 512                         goto uspace_segv;
 513
 514                 set_fs(USER_DS);
 515                 if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
 516                         /* Argh. Fault on the instruction itself.
 517                            This should never happen non-SMP
 518                         */
 519                         set_fs(oldfs);
 520                         goto uspace_segv;
 521                 }
 522
 523                 tmp = handle_unaligned_access(instruction, regs);
 524                 set_fs(oldfs);
 525
 526                 if (tmp==0)
 527                         return; /* sorted */
 528
 529         uspace_segv:
 530                 printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
 531                 force_sig(SIGSEGV, current);
 532         } else {
 533                 if (regs->pc & 1)
 534                         die("unaligned program counter", regs, error_code);
 535
 536                 set_fs(KERNEL_DS);
 537                 if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
 538                         /* Argh. Fault on the instruction itself.
 539                            This should never happen non-SMP
 540                         */
 541                         set_fs(oldfs);
 542                         die("insn faulting in do_address_error", regs, 0);
 543                 }
 544
 545                 handle_unaligned_access(instruction, regs);
 546                 set_fs(oldfs);
 547         }
 548 }
 549
 550 #ifdef CONFIG_SH_DSP
 551 /*
 552  *      SH-DSP support gerg@snapgear.com.
 553  */
 554 int is_dsp_inst(struct pt_regs *regs)
 555 {
 556         unsigned short inst;
 557
 558         /*
 559          * Safe guard if DSP mode is already enabled or we're lacking
 560          * the DSP altogether.
 561          */
 562         if (!test_bit(CPU_HAS_DSP, &(cpu_data->flags)) || (regs->sr & SR_DSP))
 563                 return 0;
 564
 565         get_user(inst, ((unsigned short *) regs->pc));
 566
 567         inst &= 0xf000;
 568
 569         /* Check for any type of DSP or support instruction */
 570         if ((inst == 0xf000) || (inst == 0x4000))
 571                 return 1;
 572
 573         return 0;
 574 }
 575 #else
 576 #define is_dsp_inst(regs)       (0)
 577 #endif /* CONFIG_SH_DSP */
 578
 579 DO_ERROR(TRAP_RESERVED_INST, SIGILL, "reserved instruction", reserved_inst, current)
 580 DO_ERROR(TRAP_ILLEGAL_SLOT_INST, SIGILL, "illegal slot instruction", illegal_slot_inst, current)
 581
 582 asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
 583                                    unsigned long r6, unsigned long r7,
 584                                    struct pt_regs regs)
 585 {
 586         long ex;
 587         asm volatile("stc       r2_bank, %0" : "=r" (ex));
 588         die_if_kernel("exception", &regs, ex);
 589 }
 590
 591 #if defined(CONFIG_SH_STANDARD_BIOS)
 592 void *gdb_vbr_vector;
 593
 594 static inline void __init gdb_vbr_init(void)
 595 {
 596         register unsigned long vbr;
 597
 598         /*
 599          * Read the old value of the VBR register to initialise
 600          * the vector through which debug and BIOS traps are
 601          * delegated by the Linux trap handler.
 602          */
 603         asm volatile("stc vbr, %0" : "=r" (vbr));
 604
 605         gdb_vbr_vector = (void *)(vbr + 0x100);
 606         printk("Setting GDB trap vector to 0x%08lx\n",
 607                (unsigned long)gdb_vbr_vector);
 608 }
 609 #endif
 610
 611 void __init per_cpu_trap_init(void)
 612 {
 613         extern void *vbr_base;
 614
 615 #ifdef CONFIG_SH_STANDARD_BIOS
 616         gdb_vbr_init();
 617 #endif
 618
 619         /* NOTE: The VBR value should be at P1
 620            (or P2, virtural "fixed" address space).
 621            It's definitely should not in physical address.  */
 622
 623         asm volatile("ldc       %0, vbr"
 624                      : /* no output */
 625                      : "r" (&vbr_base)
 626                      : "memory");
 627 }
 628
 629 void __init trap_init(void)
 630 {
 631         extern void *exception_handling_table[];
 632
 633         exception_handling_table[TRAP_RESERVED_INST]
 634                 = (void *)do_reserved_inst;
 635         exception_handling_table[TRAP_ILLEGAL_SLOT_INST]
 636                 = (void *)do_illegal_slot_inst;
 637
 638 #ifdef CONFIG_CPU_SH4
 639         if (!test_bit(CPU_HAS_FPU, &(cpu_data->flags))) {
 640                 /* For SH-4 lacking an FPU, treat floating point instructions
 641                    as reserved. */
 642                 /* entry 64 corresponds to EXPEVT=0x800 */
 643                 exception_handling_table[64] = (void *)do_reserved_inst;
 644                 exception_handling_table[65] = (void *)do_illegal_slot_inst;
 645         }
 646 #endif
 647
 648         /* Setup VBR for boot cpu */
 649         per_cpu_trap_init();
 650 }
 651
 652 void show_stack(struct task_struct *tsk, unsigned long *sp)
 653 {
 654         unsigned long *stack, addr;
 655         unsigned long module_start = VMALLOC_START;
 656         unsigned long module_end = VMALLOC_END;
 657         int i = 1;
 658
 659         if (tsk && !sp) {
 660                 sp = (unsigned long *)tsk->thread.sp;
 661         }
 662
 663         if (!sp) {
 664                 __asm__ __volatile__ (
 665                         "mov r15, %0\n\t"
 666                         "stc r7_bank, %1\n\t"
 667                         : "=r" (module_start),
 668                           "=r" (module_end)
 669                 );
 670
 671                 sp = (unsigned long *)module_start;
 672         }
 673
 674         stack = sp;
 675
 676         printk("\nCall trace: ");
 677 #ifdef CONFIG_KALLSYMS
 678         printk("\n");
 679 #endif
 680
 681         while (!kstack_end(stack)) {
 682                 addr = *stack++;
 683                 if (((addr >= (unsigned long)_text) &&
 684                      (addr <= (unsigned long)_etext)) ||
 685                     ((addr >= module_start) && (addr <= module_end))) {
 686                         /*
 687                          * For 80-columns display, 6 entry is maximum.
 688                          * NOTE: '[<8c00abcd>] ' consumes 13 columns .
 689                          */
 690 #ifndef CONFIG_KALLSYMS
 691                         if (i && ((i % 6) == 0))
 692                                 printk("\n       ");
 693 #endif
 694                         printk("[<%08lx>] ", addr);
 695                         print_symbol("%s\n", addr);
 696                         i++;
 697                 }
 698         }
 699
 700         printk("\n");
 701 }
 702
 703 void show_task(unsigned long *sp)
 704 {
 705         show_stack(NULL, sp);
 706 }
 707
 708 void dump_stack(void)
 709 {
 710         show_stack(NULL, NULL);
 711 }
 712 EXPORT_SYMBOL(dump_stack);