arch/ppc64/kernel/process.c

   1 /*
   2  *  linux/arch/ppc64/kernel/process.c
   3  *
   4  *  Derived from "arch/i386/kernel/process.c"
   5  *    Copyright (C) 1995  Linus Torvalds
   6  *
   7  *  Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
   8  *  Paul Mackerras (paulus@cs.anu.edu.au)
   9  *
  10  *  PowerPC version
  11  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  12  *
  13  *  This program is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU General Public License
  15  *  as published by the Free Software Foundation; either version
  16  *  2 of the License, or (at your option) any later version.
  17  */
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/errno.h>
  22 #include <linux/sched.h>
  23 #include <linux/kernel.h>
  24 #include <linux/mm.h>
  25 #include <linux/smp.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/stddef.h>
  28 #include <linux/unistd.h>
  29 #include <linux/slab.h>
  30 #include <linux/user.h>
  31 #include <linux/elf.h>
  32 #include <linux/init.h>
  33 #include <linux/init_task.h>
  34 #include <linux/prctl.h>
  35 #include <linux/ptrace.h>
  36 #include <linux/kallsyms.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/utsname.h>
  39
  40 #include <asm/pgtable.h>
  41 #include <asm/uaccess.h>
  42 #include <asm/system.h>
  43 #include <asm/io.h>
  44 #include <asm/processor.h>
  45 #include <asm/mmu.h>
  46 #include <asm/mmu_context.h>
  47 #include <asm/prom.h>
  48 #include <asm/ppcdebug.h>
  49 #include <asm/machdep.h>
  50 #include <asm/iSeries/HvCallHpt.h>
  51 #include <asm/cputable.h>
  52 #include <asm/sections.h>
  53 #include <asm/tlbflush.h>
  54
  55 #ifndef CONFIG_SMP
  56 struct task_struct *last_task_used_math = NULL;
  57 struct task_struct *last_task_used_altivec = NULL;
  58 #endif
  59
  60 struct mm_struct ioremap_mm = {
  61         .pgd            = ioremap_dir,
  62         .mm_users       = ATOMIC_INIT(2),
  63         .mm_count       = ATOMIC_INIT(1),
  64         .cpu_vm_mask    = CPU_MASK_ALL,
  65         .page_table_lock = SPIN_LOCK_UNLOCKED,
  66 };
  67
  68 /*
  69  * Make sure the floating-point register state in the
  70  * the thread_struct is up to date for task tsk.
  71  */
  72 void flush_fp_to_thread(struct task_struct *tsk)
  73 {
  74         if (tsk->thread.regs) {
  75                 /*
  76                  * We need to disable preemption here because if we didn't,
  77                  * another process could get scheduled after the regs->msr
  78                  * test but before we have finished saving the FP registers
  79                  * to the thread_struct.  That process could take over the
  80                  * FPU, and then when we get scheduled again we would store
  81                  * bogus values for the remaining FP registers.
  82                  */
  83                 preempt_disable();
  84                 if (tsk->thread.regs->msr & MSR_FP) {
  85 #ifdef CONFIG_SMP
  86                         /*
  87                          * This should only ever be called for current or
  88                          * for a stopped child process.  Since we save away
  89                          * the FP register state on context switch on SMP,
  90                          * there is something wrong if a stopped child appears
  91                          * to still have its FP state in the CPU registers.
  92                          */
  93                         BUG_ON(tsk != current);
  94 #endif
  95                         giveup_fpu(current);
  96                 }
  97                 preempt_enable();
  98         }
  99 }
 100
 101 void enable_kernel_fp(void)
 102 {
 103         WARN_ON(preemptible());
 104
 105 #ifdef CONFIG_SMP
 106         if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 107                 giveup_fpu(current);
 108         else
 109                 giveup_fpu(NULL);       /* just enables FP for kernel */
 110 #else
 111         giveup_fpu(last_task_used_math);
 112 #endif /* CONFIG_SMP */
 113 }
 114 EXPORT_SYMBOL(enable_kernel_fp);
 115
 116 int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 117 {
 118         if (!tsk->thread.regs)
 119                 return 0;
 120         flush_fp_to_thread(current);
 121
 122         memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
 123
 124         return 1;
 125 }
 126
 127 #ifdef CONFIG_ALTIVEC
 128
 129 void enable_kernel_altivec(void)
 130 {
 131         WARN_ON(preemptible());
 132
 133 #ifdef CONFIG_SMP
 134         if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 135                 giveup_altivec(current);
 136         else
 137                 giveup_altivec(NULL);   /* just enables FP for kernel */
 138 #else
 139         giveup_altivec(last_task_used_altivec);
 140 #endif /* CONFIG_SMP */
 141 }
 142 EXPORT_SYMBOL(enable_kernel_altivec);
 143
 144 /*
 145  * Make sure the VMX/Altivec register state in the
 146  * the thread_struct is up to date for task tsk.
 147  */
 148 void flush_altivec_to_thread(struct task_struct *tsk)
 149 {
 150         if (tsk->thread.regs) {
 151                 preempt_disable();
 152                 if (tsk->thread.regs->msr & MSR_VEC) {
 153 #ifdef CONFIG_SMP
 154                         BUG_ON(tsk != current);
 155 #endif
 156                         giveup_altivec(current);
 157                 }
 158                 preempt_enable();
 159         }
 160 }
 161
 162 int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 163 {
 164         flush_altivec_to_thread(current);
 165         memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
 166         return 1;
 167 }
 168
 169 #endif /* CONFIG_ALTIVEC */
 170
 171 struct task_struct *__switch_to(struct task_struct *prev,
 172                                 struct task_struct *new)
 173 {
 174         struct thread_struct *new_thread, *old_thread;
 175         unsigned long flags;
 176         struct task_struct *last;
 177
 178 #ifdef CONFIG_SMP
 179         /* avoid complexity of lazy save/restore of fpu
 180          * by just saving it every time we switch out if
 181          * this task used the fpu during the last quantum.
 182          *
 183          * If it tries to use the fpu again, it'll trap and
 184          * reload its fp regs.  So we don't have to do a restore
 185          * every switch, just a save.
 186          *  -- Cort
 187          */
 188         if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
 189                 giveup_fpu(prev);
 190 #ifdef CONFIG_ALTIVEC
 191         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
 192                 giveup_altivec(prev);
 193 #endif /* CONFIG_ALTIVEC */
 194 #endif /* CONFIG_SMP */
 195
 196 #if defined(CONFIG_ALTIVEC) && !defined(CONFIG_SMP)
 197         /* Avoid the trap.  On smp this this never happens since
 198          * we don't set last_task_used_altivec -- Cort
 199          */
 200         if (new->thread.regs && last_task_used_altivec == new)
 201                 new->thread.regs->msr |= MSR_VEC;
 202 #endif /* CONFIG_ALTIVEC */
 203
 204         flush_tlb_pending();
 205
 206         new_thread = &new->thread;
 207         old_thread = &current->thread;
 208
 209         local_irq_save(flags);
 210         last = _switch(old_thread, new_thread);
 211
 212         local_irq_restore(flags);
 213
 214         return last;
 215 }
 216
 217 static int instructions_to_print = 16;
 218
 219 static void show_instructions(struct pt_regs *regs)
 220 {
 221         int i;
 222         unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
 223                         sizeof(int));
 224
 225         printk("Instruction dump:");
 226
 227         for (i = 0; i < instructions_to_print; i++) {
 228                 int instr;
 229
 230                 if (!(i % 8))
 231                         printk("\n");
 232
 233                 if (((REGION_ID(pc) != KERNEL_REGION_ID) &&
 234                      (REGION_ID(pc) != VMALLOC_REGION_ID)) ||
 235                      __get_user(instr, (unsigned int *)pc)) {
 236                         printk("XXXXXXXX ");
 237                 } else {
 238                         if (regs->nip == pc)
 239                                 printk("<%08x> ", instr);
 240                         else
 241                                 printk("%08x ", instr);
 242                 }
 243
 244                 pc += sizeof(int);
 245         }
 246
 247         printk("\n");
 248 }
 249
 250 void show_regs(struct pt_regs * regs)
 251 {
 252         int i;
 253         unsigned long trap;
 254
 255         printk("NIP: %016lX XER: %08X LR: %016lX CTR: %016lX\n",
 256                regs->nip, (unsigned int)regs->xer, regs->link, regs->ctr);
 257         printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
 258                regs, regs->trap, print_tainted(), system_utsname.release);
 259         printk("MSR: %016lx EE: %01x PR: %01x FP: %01x ME: %01x "
 260                "IR/DR: %01x%01x CR: %08X\n",
 261                regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
 262                regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
 263                regs->msr&MSR_IR ? 1 : 0,
 264                regs->msr&MSR_DR ? 1 : 0,
 265                (unsigned int)regs->ccr);
 266         trap = TRAP(regs);
 267         printk("DAR: %016lx DSISR: %016lx\n", regs->dar, regs->dsisr);
 268         printk("TASK: %p[%d] '%s' THREAD: %p",
 269                current, current->pid, current->comm, current->thread_info);
 270
 271 #ifdef CONFIG_SMP
 272         printk(" CPU: %d", smp_processor_id());
 273 #endif /* CONFIG_SMP */
 274
 275         for (i = 0; i < 32; i++) {
 276                 if ((i % 4) == 0) {
 277                         printk("\n" KERN_INFO "GPR%02d: ", i);
 278                 }
 279
 280                 printk("%016lX ", regs->gpr[i]);
 281                 if (i == 13 && !FULL_REGS(regs))
 282                         break;
 283         }
 284         printk("\n");
 285         /*
 286          * Lookup NIP late so we have the best change of getting the
 287          * above info out without failing
 288          */
 289         printk("NIP [%016lx] ", regs->nip);
 290         print_symbol("%s\n", regs->nip);
 291         printk("LR [%016lx] ", regs->link);
 292         print_symbol("%s\n", regs->link);
 293         show_stack(current, (unsigned long *)regs->gpr[1]);
 294         if (!user_mode(regs))
 295                 show_instructions(regs);
 296 }
 297
 298 void exit_thread(void)
 299 {
 300 #ifndef CONFIG_SMP
 301         if (last_task_used_math == current)
 302                 last_task_used_math = NULL;
 303 #ifdef CONFIG_ALTIVEC
 304         if (last_task_used_altivec == current)
 305                 last_task_used_altivec = NULL;
 306 #endif /* CONFIG_ALTIVEC */
 307 #endif /* CONFIG_SMP */
 308 }
 309
 310 void flush_thread(void)
 311 {
 312         struct thread_info *t = current_thread_info();
 313
 314         if (t->flags & _TIF_ABI_PENDING)
 315                 t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
 316
 317 #ifndef CONFIG_SMP
 318         if (last_task_used_math == current)
 319                 last_task_used_math = NULL;
 320 #ifdef CONFIG_ALTIVEC
 321         if (last_task_used_altivec == current)
 322                 last_task_used_altivec = NULL;
 323 #endif /* CONFIG_ALTIVEC */
 324 #endif /* CONFIG_SMP */
 325 }
 326
 327 void
 328 release_thread(struct task_struct *t)
 329 {
 330 }
 331
 332
 333 /*
 334  * This gets called before we allocate a new thread and copy
 335  * the current task into it.
 336  */
 337 void prepare_to_copy(struct task_struct *tsk)
 338 {
 339         flush_fp_to_thread(current);
 340         flush_altivec_to_thread(current);
 341 }
 342
 343 /*
 344  * Copy a thread..
 345  */
 346 int
 347 copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 348             unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 349 {
 350         struct pt_regs *childregs, *kregs;
 351         extern void ret_from_fork(void);
 352         unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;
 353
 354         /* Copy registers */
 355         sp -= sizeof(struct pt_regs);
 356         childregs = (struct pt_regs *) sp;
 357         *childregs = *regs;
 358         if ((childregs->msr & MSR_PR) == 0) {
 359                 /* for kernel thread, set stackptr in new task */
 360                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
 361                 p->thread.regs = NULL;  /* no user register state */
 362                 clear_ti_thread_flag(p->thread_info, TIF_32BIT);
 363 #ifdef CONFIG_PPC_ISERIES
 364                 set_ti_thread_flag(p->thread_info, TIF_RUN_LIGHT);
 365 #endif
 366         } else {
 367                 childregs->gpr[1] = usp;
 368                 p->thread.regs = childregs;
 369                 if (clone_flags & CLONE_SETTLS) {
 370                         if (test_thread_flag(TIF_32BIT))
 371                                 childregs->gpr[2] = childregs->gpr[6];
 372                         else
 373                                 childregs->gpr[13] = childregs->gpr[6];
 374                 }
 375         }
 376         childregs->gpr[3] = 0;  /* Result from fork() */
 377         sp -= STACK_FRAME_OVERHEAD;
 378
 379         /*
 380          * The way this works is that at some point in the future
 381          * some task will call _switch to switch to the new task.
 382          * That will pop off the stack frame created below and start
 383          * the new task running at ret_from_fork.  The new task will
 384          * do some house keeping and then return from the fork or clone
 385          * system call, using the stack frame created above.
 386          */
 387         sp -= sizeof(struct pt_regs);
 388         kregs = (struct pt_regs *) sp;
 389         sp -= STACK_FRAME_OVERHEAD;
 390         p->thread.ksp = sp;
 391         if (cur_cpu_spec->cpu_features & CPU_FTR_SLB) {
 392                 unsigned long sp_vsid = get_kernel_vsid(sp);
 393
 394                 sp_vsid <<= SLB_VSID_SHIFT;
 395                 sp_vsid |= SLB_VSID_KERNEL;
 396                 if (cur_cpu_spec->cpu_features & CPU_FTR_16M_PAGE)
 397                         sp_vsid |= SLB_VSID_L;
 398
 399                 p->thread.ksp_vsid = sp_vsid;
 400         }
 401
 402         /*
 403          * The PPC64 ABI makes use of a TOC to contain function
 404          * pointers.  The function (ret_from_except) is actually a pointer
 405          * to the TOC entry.  The first entry is a pointer to the actual
 406          * function.
 407          */
 408         kregs->nip = *((unsigned long *)ret_from_fork);
 409
 410         return 0;
 411 }
 412
 413 /*
 414  * Set up a thread for executing a new program
 415  */
 416 void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp)
 417 {
 418         unsigned long entry, toc, load_addr = regs->gpr[2];
 419
 420         /* fdptr is a relocated pointer to the function descriptor for
 421          * the elf _start routine.  The first entry in the function
 422          * descriptor is the entry address of _start and the second
 423          * entry is the TOC value we need to use.
 424          */
 425         set_fs(USER_DS);
 426         __get_user(entry, (unsigned long __user *)fdptr);
 427         __get_user(toc, (unsigned long __user *)fdptr+1);
 428
 429         /* Check whether the e_entry function descriptor entries
 430          * need to be relocated before we can use them.
 431          */
 432         if (load_addr != 0) {
 433                 entry += load_addr;
 434                 toc   += load_addr;
 435         }
 436
 437         /*
 438          * If we exec out of a kernel thread then thread.regs will not be
 439          * set. Do it now.
 440          */
 441         if (!current->thread.regs) {
 442                 unsigned long childregs = (unsigned long)current->thread_info +
 443                                                 THREAD_SIZE;
 444                 childregs -= sizeof(struct pt_regs);
 445                 current->thread.regs = (struct pt_regs *)childregs;
 446         }
 447
 448         regs->nip = entry;
 449         regs->gpr[1] = sp;
 450         regs->gpr[2] = toc;
 451         regs->msr = MSR_USER64;
 452 #ifndef CONFIG_SMP
 453         if (last_task_used_math == current)
 454                 last_task_used_math = 0;
 455 #endif /* CONFIG_SMP */
 456         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
 457         current->thread.fpscr = 0;
 458 #ifdef CONFIG_ALTIVEC
 459 #ifndef CONFIG_SMP
 460         if (last_task_used_altivec == current)
 461                 last_task_used_altivec = 0;
 462 #endif /* CONFIG_SMP */
 463         memset(current->thread.vr, 0, sizeof(current->thread.vr));
 464         current->thread.vscr.u[0] = 0;
 465         current->thread.vscr.u[1] = 0;
 466         current->thread.vscr.u[2] = 0;
 467         current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
 468         current->thread.vrsave = 0;
 469         current->thread.used_vr = 0;
 470 #endif /* CONFIG_ALTIVEC */
 471 }
 472
 473 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 474 {
 475         struct pt_regs *regs = tsk->thread.regs;
 476
 477         if (val > PR_FP_EXC_PRECISE)
 478                 return -EINVAL;
 479         tsk->thread.fpexc_mode = __pack_fe01(val);
 480         if (regs != NULL && (regs->msr & MSR_FP) != 0)
 481                 regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
 482                         | tsk->thread.fpexc_mode;
 483         return 0;
 484 }
 485
 486 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 487 {
 488         unsigned int val;
 489
 490         val = __unpack_fe01(tsk->thread.fpexc_mode);
 491         return put_user(val, (unsigned int __user *) adr);
 492 }
 493
 494 int sys_clone(unsigned long clone_flags, unsigned long p2, unsigned long p3,
 495               unsigned long p4, unsigned long p5, unsigned long p6,
 496               struct pt_regs *regs)
 497 {
 498         unsigned long parent_tidptr = 0;
 499         unsigned long child_tidptr = 0;
 500
 501         if (p2 == 0)
 502                 p2 = regs->gpr[1];      /* stack pointer for child */
 503
 504         if (clone_flags & (CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
 505                            CLONE_CHILD_CLEARTID)) {
 506                 parent_tidptr = p3;
 507                 child_tidptr = p5;
 508                 if (test_thread_flag(TIF_32BIT)) {
 509                         parent_tidptr &= 0xffffffff;
 510                         child_tidptr &= 0xffffffff;
 511                 }
 512         }
 513
 514         return do_fork(clone_flags, p2, regs, 0,
 515                     (int __user *)parent_tidptr, (int __user *)child_tidptr);
 516 }
 517
 518 int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
 519              unsigned long p4, unsigned long p5, unsigned long p6,
 520              struct pt_regs *regs)
 521 {
 522         return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
 523 }
 524
 525 int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
 526               unsigned long p4, unsigned long p5, unsigned long p6,
 527               struct pt_regs *regs)
 528 {
 529         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1], regs, 0,
 530                     NULL, NULL);
 531 }
 532
 533 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
 534                unsigned long a3, unsigned long a4, unsigned long a5,
 535                struct pt_regs *regs)
 536 {
 537         int error;
 538         char * filename;
 539
 540         filename = getname((char __user *) a0);
 541         error = PTR_ERR(filename);
 542         if (IS_ERR(filename))
 543                 goto out;
 544         flush_fp_to_thread(current);
 545         flush_altivec_to_thread(current);
 546         error = do_execve(filename, (char __user * __user *) a1,
 547                                     (char __user * __user *) a2, regs);
 548
 549         if (error == 0) {
 550                 task_lock(current);
 551                 current->ptrace &= ~PT_DTRACE;
 552                 task_unlock(current);
 553         }
 554         putname(filename);
 555
 556 out:
 557         return error;
 558 }
 559
 560 static int kstack_depth_to_print = 64;
 561
 562 static int validate_sp(unsigned long sp, struct task_struct *p,
 563                        unsigned long nbytes)
 564 {
 565         unsigned long stack_page = (unsigned long)p->thread_info;
 566
 567         if (sp >= stack_page + sizeof(struct thread_struct)
 568             && sp <= stack_page + THREAD_SIZE - nbytes)
 569                 return 1;
 570
 571 #ifdef CONFIG_IRQSTACKS
 572         stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
 573         if (sp >= stack_page + sizeof(struct thread_struct)
 574             && sp <= stack_page + THREAD_SIZE - nbytes)
 575                 return 1;
 576
 577         stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
 578         if (sp >= stack_page + sizeof(struct thread_struct)
 579             && sp <= stack_page + THREAD_SIZE - nbytes)
 580                 return 1;
 581 #endif
 582
 583         return 0;
 584 }
 585
 586 unsigned long get_wchan(struct task_struct *p)
 587 {
 588         unsigned long ip, sp;
 589         int count = 0;
 590
 591         if (!p || p == current || p->state == TASK_RUNNING)
 592                 return 0;
 593
 594         sp = p->thread.ksp;
 595         if (!validate_sp(sp, p, 112))
 596                 return 0;
 597
 598         do {
 599                 sp = *(unsigned long *)sp;
 600                 if (!validate_sp(sp, p, 112))
 601                         return 0;
 602                 if (count > 0) {
 603                         ip = *(unsigned long *)(sp + 16);
 604                         if (!in_sched_functions(ip))
 605                                 return ip;
 606                 }
 607         } while (count++ < 16);
 608         return 0;
 609 }
 610
 611 void show_stack(struct task_struct *p, unsigned long *_sp)
 612 {
 613         unsigned long ip, newsp, lr;
 614         int count = 0;
 615         unsigned long sp = (unsigned long)_sp;
 616         int firstframe = 1;
 617
 618         if (sp == 0) {
 619                 if (p) {
 620                         sp = p->thread.ksp;
 621                 } else {
 622                         sp = __get_SP();
 623                         p = current;
 624                 }
 625         }
 626
 627         lr = 0;
 628         printk("Call Trace:\n");
 629         do {
 630                 if (!validate_sp(sp, p, 112))
 631                         return;
 632
 633                 _sp = (unsigned long *) sp;
 634                 newsp = _sp[0];
 635                 ip = _sp[2];
 636                 if (!firstframe || ip != lr) {
 637                         printk("[%016lx] [%016lx] ", sp, ip);
 638                         print_symbol("%s", ip);
 639                         if (firstframe)
 640                                 printk(" (unreliable)");
 641                         printk("\n");
 642                 }
 643                 firstframe = 0;
 644
 645                 /*
 646                  * See if this is an exception frame.
 647                  * We look for the "regshere" marker in the current frame.
 648                  */
 649                 if (validate_sp(sp, p, sizeof(struct pt_regs) + 400)
 650                     && _sp[12] == 0x7265677368657265ul) {
 651                         struct pt_regs *regs = (struct pt_regs *)
 652                                 (sp + STACK_FRAME_OVERHEAD);
 653                         printk("--- Exception: %lx", regs->trap);
 654                         print_symbol(" at %s\n", regs->nip);
 655                         lr = regs->link;
 656                         print_symbol("    LR = %s\n", lr);
 657                         firstframe = 1;
 658                 }
 659
 660                 sp = newsp;
 661         } while (count++ < kstack_depth_to_print);
 662 }
 663
 664 void dump_stack(void)
 665 {
 666         show_stack(current, (unsigned long *)__get_SP());
 667 }
 668 EXPORT_SYMBOL(dump_stack);