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 #include <linux/kprobes.h>
  40
  41 #include <asm/pgtable.h>
  42 #include <asm/uaccess.h>
  43 #include <asm/system.h>
  44 #include <asm/io.h>
  45 #include <asm/processor.h>
  46 #include <asm/mmu.h>
  47 #include <asm/mmu_context.h>
  48 #include <asm/prom.h>
  49 #include <asm/ppcdebug.h>
  50 #include <asm/machdep.h>
  51 #include <asm/iSeries/HvCallHpt.h>
  52 #include <asm/cputable.h>
  53 #include <asm/sections.h>
  54 #include <asm/tlbflush.h>
  55 #include <asm/time.h>
  56
  57 #ifndef CONFIG_SMP
  58 struct task_struct *last_task_used_math = NULL;
  59 struct task_struct *last_task_used_altivec = NULL;
  60 #endif
  61
  62 /*
  63  * Make sure the floating-point register state in the
  64  * the thread_struct is up to date for task tsk.
  65  */
  66 void flush_fp_to_thread(struct task_struct *tsk)
  67 {
  68         if (tsk->thread.regs) {
  69                 /*
  70                  * We need to disable preemption here because if we didn't,
  71                  * another process could get scheduled after the regs->msr
  72                  * test but before we have finished saving the FP registers
  73                  * to the thread_struct.  That process could take over the
  74                  * FPU, and then when we get scheduled again we would store
  75                  * bogus values for the remaining FP registers.
  76                  */
  77                 preempt_disable();
  78                 if (tsk->thread.regs->msr & MSR_FP) {
  79 #ifdef CONFIG_SMP
  80                         /*
  81                          * This should only ever be called for current or
  82                          * for a stopped child process.  Since we save away
  83                          * the FP register state on context switch on SMP,
  84                          * there is something wrong if a stopped child appears
  85                          * to still have its FP state in the CPU registers.
  86                          */
  87                         BUG_ON(tsk != current);
  88 #endif
  89                         giveup_fpu(current);
  90                 }
  91                 preempt_enable();
  92         }
  93 }
  94
  95 void enable_kernel_fp(void)
  96 {
  97         WARN_ON(preemptible());
  98
  99 #ifdef CONFIG_SMP
 100         if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 101                 giveup_fpu(current);
 102         else
 103                 giveup_fpu(NULL);       /* just enables FP for kernel */
 104 #else
 105         giveup_fpu(last_task_used_math);
 106 #endif /* CONFIG_SMP */
 107 }
 108 EXPORT_SYMBOL(enable_kernel_fp);
 109
 110 int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 111 {
 112         if (!tsk->thread.regs)
 113                 return 0;
 114         flush_fp_to_thread(current);
 115
 116         memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
 117
 118         return 1;
 119 }
 120
 121 #ifdef CONFIG_ALTIVEC
 122
 123 void enable_kernel_altivec(void)
 124 {
 125         WARN_ON(preemptible());
 126
 127 #ifdef CONFIG_SMP
 128         if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 129                 giveup_altivec(current);
 130         else
 131                 giveup_altivec(NULL);   /* just enables FP for kernel */
 132 #else
 133         giveup_altivec(last_task_used_altivec);
 134 #endif /* CONFIG_SMP */
 135 }
 136 EXPORT_SYMBOL(enable_kernel_altivec);
 137
 138 /*
 139  * Make sure the VMX/Altivec register state in the
 140  * the thread_struct is up to date for task tsk.
 141  */
 142 void flush_altivec_to_thread(struct task_struct *tsk)
 143 {
 144         if (tsk->thread.regs) {
 145                 preempt_disable();
 146                 if (tsk->thread.regs->msr & MSR_VEC) {
 147 #ifdef CONFIG_SMP
 148                         BUG_ON(tsk != current);
 149 #endif
 150                         giveup_altivec(current);
 151                 }
 152                 preempt_enable();
 153         }
 154 }
 155
 156 int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 157 {
 158         flush_altivec_to_thread(current);
 159         memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
 160         return 1;
 161 }
 162
 163 #endif /* CONFIG_ALTIVEC */
 164
 165 DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
 166
 167 struct task_struct *__switch_to(struct task_struct *prev,
 168                                 struct task_struct *new)
 169 {
 170         struct thread_struct *new_thread, *old_thread;
 171         unsigned long flags;
 172         struct task_struct *last;
 173
 174 #ifdef CONFIG_SMP
 175         /* avoid complexity of lazy save/restore of fpu
 176          * by just saving it every time we switch out if
 177          * this task used the fpu during the last quantum.
 178          *
 179          * If it tries to use the fpu again, it'll trap and
 180          * reload its fp regs.  So we don't have to do a restore
 181          * every switch, just a save.
 182          *  -- Cort
 183          */
 184         if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
 185                 giveup_fpu(prev);
 186 #ifdef CONFIG_ALTIVEC
 187         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
 188                 giveup_altivec(prev);
 189 #endif /* CONFIG_ALTIVEC */
 190 #endif /* CONFIG_SMP */
 191
 192 #if defined(CONFIG_ALTIVEC) && !defined(CONFIG_SMP)
 193         /* Avoid the trap.  On smp this this never happens since
 194          * we don't set last_task_used_altivec -- Cort
 195          */
 196         if (new->thread.regs && last_task_used_altivec == new)
 197                 new->thread.regs->msr |= MSR_VEC;
 198 #endif /* CONFIG_ALTIVEC */
 199
 200         flush_tlb_pending();
 201
 202         new_thread = &new->thread;
 203         old_thread = &current->thread;
 204
 205 /* Collect purr utilization data per process and per processor wise */
 206 /* purr is nothing but processor time base                          */
 207
 208 #if defined(CONFIG_PPC_PSERIES)
 209         if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
 210                 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
 211                 long unsigned start_tb, current_tb;
 212                 start_tb = old_thread->start_tb;
 213                 cu->current_tb = current_tb = mfspr(SPRN_PURR);
 214                 old_thread->accum_tb += (current_tb - start_tb);
 215                 new_thread->start_tb = current_tb;
 216         }
 217 #endif
 218
 219
 220         local_irq_save(flags);
 221         last = _switch(old_thread, new_thread);
 222
 223         local_irq_restore(flags);
 224
 225         return last;
 226 }
 227
 228 static int instructions_to_print = 16;
 229
 230 static void show_instructions(struct pt_regs *regs)
 231 {
 232         int i;
 233         unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
 234                         sizeof(int));
 235
 236         printk("Instruction dump:");
 237
 238         for (i = 0; i < instructions_to_print; i++) {
 239                 int instr;
 240
 241                 if (!(i % 8))
 242                         printk("\n");
 243
 244                 if (((REGION_ID(pc) != KERNEL_REGION_ID) &&
 245                      (REGION_ID(pc) != VMALLOC_REGION_ID)) ||
 246                      __get_user(instr, (unsigned int *)pc)) {
 247                         printk("XXXXXXXX ");
 248                 } else {
 249                         if (regs->nip == pc)
 250                                 printk("<%08x> ", instr);
 251                         else
 252                                 printk("%08x ", instr);
 253                 }
 254
 255                 pc += sizeof(int);
 256         }
 257
 258         printk("\n");
 259 }
 260
 261 void show_regs(struct pt_regs * regs)
 262 {
 263         int i;
 264         unsigned long trap;
 265
 266         printk("NIP: %016lX XER: %08X LR: %016lX CTR: %016lX\n",
 267                regs->nip, (unsigned int)regs->xer, regs->link, regs->ctr);
 268         printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
 269                regs, regs->trap, print_tainted(), system_utsname.release);
 270         printk("MSR: %016lx EE: %01x PR: %01x FP: %01x ME: %01x "
 271                "IR/DR: %01x%01x CR: %08X\n",
 272                regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
 273                regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
 274                regs->msr&MSR_IR ? 1 : 0,
 275                regs->msr&MSR_DR ? 1 : 0,
 276                (unsigned int)regs->ccr);
 277         trap = TRAP(regs);
 278         printk("DAR: %016lx DSISR: %016lx\n", regs->dar, regs->dsisr);
 279         printk("TASK: %p[%d] '%s' THREAD: %p",
 280                current, current->pid, current->comm, current->thread_info);
 281
 282 #ifdef CONFIG_SMP
 283         printk(" CPU: %d", smp_processor_id());
 284 #endif /* CONFIG_SMP */
 285
 286         for (i = 0; i < 32; i++) {
 287                 if ((i % 4) == 0) {
 288                         printk("\n" KERN_INFO "GPR%02d: ", i);
 289                 }
 290
 291                 printk("%016lX ", regs->gpr[i]);
 292                 if (i == 13 && !FULL_REGS(regs))
 293                         break;
 294         }
 295         printk("\n");
 296         /*
 297          * Lookup NIP late so we have the best change of getting the
 298          * above info out without failing
 299          */
 300         printk("NIP [%016lx] ", regs->nip);
 301         print_symbol("%s\n", regs->nip);
 302         printk("LR [%016lx] ", regs->link);
 303         print_symbol("%s\n", regs->link);
 304         show_stack(current, (unsigned long *)regs->gpr[1]);
 305         if (!user_mode(regs))
 306                 show_instructions(regs);
 307 }
 308
 309 void exit_thread(void)
 310 {
 311         kprobe_flush_task(current);
 312
 313 #ifndef CONFIG_SMP
 314         if (last_task_used_math == current)
 315                 last_task_used_math = NULL;
 316 #ifdef CONFIG_ALTIVEC
 317         if (last_task_used_altivec == current)
 318                 last_task_used_altivec = NULL;
 319 #endif /* CONFIG_ALTIVEC */
 320 #endif /* CONFIG_SMP */
 321 }
 322
 323 void flush_thread(void)
 324 {
 325         struct thread_info *t = current_thread_info();
 326
 327         kprobe_flush_task(current);
 328         if (t->flags & _TIF_ABI_PENDING)
 329                 t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
 330
 331 #ifndef CONFIG_SMP
 332         if (last_task_used_math == current)
 333                 last_task_used_math = NULL;
 334 #ifdef CONFIG_ALTIVEC
 335         if (last_task_used_altivec == current)
 336                 last_task_used_altivec = NULL;
 337 #endif /* CONFIG_ALTIVEC */
 338 #endif /* CONFIG_SMP */
 339 }
 340
 341 void
 342 release_thread(struct task_struct *t)
 343 {
 344 }
 345
 346
 347 /*
 348  * This gets called before we allocate a new thread and copy
 349  * the current task into it.
 350  */
 351 void prepare_to_copy(struct task_struct *tsk)
 352 {
 353         flush_fp_to_thread(current);
 354         flush_altivec_to_thread(current);
 355 }
 356
 357 /*
 358  * Copy a thread..
 359  */
 360 int
 361 copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 362             unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 363 {
 364         struct pt_regs *childregs, *kregs;
 365         extern void ret_from_fork(void);
 366         unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;
 367
 368         /* Copy registers */
 369         sp -= sizeof(struct pt_regs);
 370         childregs = (struct pt_regs *) sp;
 371         *childregs = *regs;
 372         if ((childregs->msr & MSR_PR) == 0) {
 373                 /* for kernel thread, set stackptr in new task */
 374                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
 375                 p->thread.regs = NULL;  /* no user register state */
 376                 clear_ti_thread_flag(p->thread_info, TIF_32BIT);
 377         } else {
 378                 childregs->gpr[1] = usp;
 379                 p->thread.regs = childregs;
 380                 if (clone_flags & CLONE_SETTLS) {
 381                         if (test_thread_flag(TIF_32BIT))
 382                                 childregs->gpr[2] = childregs->gpr[6];
 383                         else
 384                                 childregs->gpr[13] = childregs->gpr[6];
 385                 }
 386         }
 387         childregs->gpr[3] = 0;  /* Result from fork() */
 388         sp -= STACK_FRAME_OVERHEAD;
 389
 390         /*
 391          * The way this works is that at some point in the future
 392          * some task will call _switch to switch to the new task.
 393          * That will pop off the stack frame created below and start
 394          * the new task running at ret_from_fork.  The new task will
 395          * do some house keeping and then return from the fork or clone
 396          * system call, using the stack frame created above.
 397          */
 398         sp -= sizeof(struct pt_regs);
 399         kregs = (struct pt_regs *) sp;
 400         sp -= STACK_FRAME_OVERHEAD;
 401         p->thread.ksp = sp;
 402         if (cpu_has_feature(CPU_FTR_SLB)) {
 403                 unsigned long sp_vsid = get_kernel_vsid(sp);
 404
 405                 sp_vsid <<= SLB_VSID_SHIFT;
 406                 sp_vsid |= SLB_VSID_KERNEL;
 407                 if (cpu_has_feature(CPU_FTR_16M_PAGE))
 408                         sp_vsid |= SLB_VSID_L;
 409
 410                 p->thread.ksp_vsid = sp_vsid;
 411         }
 412
 413         /*
 414          * The PPC64 ABI makes use of a TOC to contain function
 415          * pointers.  The function (ret_from_except) is actually a pointer
 416          * to the TOC entry.  The first entry is a pointer to the actual
 417          * function.
 418          */
 419         kregs->nip = *((unsigned long *)ret_from_fork);
 420
 421         return 0;
 422 }
 423
 424 /*
 425  * Set up a thread for executing a new program
 426  */
 427 void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp)
 428 {
 429         unsigned long entry, toc, load_addr = regs->gpr[2];
 430
 431         /* fdptr is a relocated pointer to the function descriptor for
 432          * the elf _start routine.  The first entry in the function
 433          * descriptor is the entry address of _start and the second
 434          * entry is the TOC value we need to use.
 435          */
 436         set_fs(USER_DS);
 437         __get_user(entry, (unsigned long __user *)fdptr);
 438         __get_user(toc, (unsigned long __user *)fdptr+1);
 439
 440         /* Check whether the e_entry function descriptor entries
 441          * need to be relocated before we can use them.
 442          */
 443         if (load_addr != 0) {
 444                 entry += load_addr;
 445                 toc   += load_addr;
 446         }
 447
 448         /*
 449          * If we exec out of a kernel thread then thread.regs will not be
 450          * set. Do it now.
 451          */
 452         if (!current->thread.regs) {
 453                 unsigned long childregs = (unsigned long)current->thread_info +
 454                                                 THREAD_SIZE;
 455                 childregs -= sizeof(struct pt_regs);
 456                 current->thread.regs = (struct pt_regs *)childregs;
 457         }
 458
 459         regs->nip = entry;
 460         regs->gpr[1] = sp;
 461         regs->gpr[2] = toc;
 462         regs->msr = MSR_USER64;
 463 #ifndef CONFIG_SMP
 464         if (last_task_used_math == current)
 465                 last_task_used_math = 0;
 466 #endif /* CONFIG_SMP */
 467         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
 468         current->thread.fpscr = 0;
 469 #ifdef CONFIG_ALTIVEC
 470 #ifndef CONFIG_SMP
 471         if (last_task_used_altivec == current)
 472                 last_task_used_altivec = 0;
 473 #endif /* CONFIG_SMP */
 474         memset(current->thread.vr, 0, sizeof(current->thread.vr));
 475         current->thread.vscr.u[0] = 0;
 476         current->thread.vscr.u[1] = 0;
 477         current->thread.vscr.u[2] = 0;
 478         current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
 479         current->thread.vrsave = 0;
 480         current->thread.used_vr = 0;
 481 #endif /* CONFIG_ALTIVEC */
 482 }
 483 EXPORT_SYMBOL(start_thread);
 484
 485 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 486 {
 487         struct pt_regs *regs = tsk->thread.regs;
 488
 489         if (val > PR_FP_EXC_PRECISE)
 490                 return -EINVAL;
 491         tsk->thread.fpexc_mode = __pack_fe01(val);
 492         if (regs != NULL && (regs->msr & MSR_FP) != 0)
 493                 regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
 494                         | tsk->thread.fpexc_mode;
 495         return 0;
 496 }
 497
 498 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 499 {
 500         unsigned int val;
 501
 502         val = __unpack_fe01(tsk->thread.fpexc_mode);
 503         return put_user(val, (unsigned int __user *) adr);
 504 }
 505
 506 int sys_clone(unsigned long clone_flags, unsigned long p2, unsigned long p3,
 507               unsigned long p4, unsigned long p5, unsigned long p6,
 508               struct pt_regs *regs)
 509 {
 510         unsigned long parent_tidptr = 0;
 511         unsigned long child_tidptr = 0;
 512
 513         if (p2 == 0)
 514                 p2 = regs->gpr[1];      /* stack pointer for child */
 515
 516         if (clone_flags & (CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
 517                            CLONE_CHILD_CLEARTID)) {
 518                 parent_tidptr = p3;
 519                 child_tidptr = p5;
 520                 if (test_thread_flag(TIF_32BIT)) {
 521                         parent_tidptr &= 0xffffffff;
 522                         child_tidptr &= 0xffffffff;
 523                 }
 524         }
 525
 526         return do_fork(clone_flags, p2, regs, 0,
 527                     (int __user *)parent_tidptr, (int __user *)child_tidptr);
 528 }
 529
 530 int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
 531              unsigned long p4, unsigned long p5, unsigned long p6,
 532              struct pt_regs *regs)
 533 {
 534         return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
 535 }
 536
 537 int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
 538               unsigned long p4, unsigned long p5, unsigned long p6,
 539               struct pt_regs *regs)
 540 {
 541         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1], regs, 0,
 542                     NULL, NULL);
 543 }
 544
 545 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
 546                unsigned long a3, unsigned long a4, unsigned long a5,
 547                struct pt_regs *regs)
 548 {
 549         int error;
 550         char * filename;
 551
 552         filename = getname((char __user *) a0);
 553         error = PTR_ERR(filename);
 554         if (IS_ERR(filename))
 555                 goto out;
 556         flush_fp_to_thread(current);
 557         flush_altivec_to_thread(current);
 558         error = do_execve(filename, (char __user * __user *) a1,
 559                                     (char __user * __user *) a2, regs);
 560
 561         if (error == 0) {
 562                 task_lock(current);
 563                 current->ptrace &= ~PT_DTRACE;
 564                 task_unlock(current);
 565         }
 566         putname(filename);
 567
 568 out:
 569         return error;
 570 }
 571
 572 static int kstack_depth_to_print = 64;
 573
 574 static int validate_sp(unsigned long sp, struct task_struct *p,
 575                        unsigned long nbytes)
 576 {
 577         unsigned long stack_page = (unsigned long)p->thread_info;
 578
 579         if (sp >= stack_page + sizeof(struct thread_struct)
 580             && sp <= stack_page + THREAD_SIZE - nbytes)
 581                 return 1;
 582
 583 #ifdef CONFIG_IRQSTACKS
 584         stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
 585         if (sp >= stack_page + sizeof(struct thread_struct)
 586             && sp <= stack_page + THREAD_SIZE - nbytes)
 587                 return 1;
 588
 589         stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
 590         if (sp >= stack_page + sizeof(struct thread_struct)
 591             && sp <= stack_page + THREAD_SIZE - nbytes)
 592                 return 1;
 593 #endif
 594
 595         return 0;
 596 }
 597
 598 unsigned long get_wchan(struct task_struct *p)
 599 {
 600         unsigned long ip, sp;
 601         int count = 0;
 602
 603         if (!p || p == current || p->state == TASK_RUNNING)
 604                 return 0;
 605
 606         sp = p->thread.ksp;
 607         if (!validate_sp(sp, p, 112))
 608                 return 0;
 609
 610         do {
 611                 sp = *(unsigned long *)sp;
 612                 if (!validate_sp(sp, p, 112))
 613                         return 0;
 614                 if (count > 0) {
 615                         ip = *(unsigned long *)(sp + 16);
 616                         if (!in_sched_functions(ip))
 617                                 return ip;
 618                 }
 619         } while (count++ < 16);
 620         return 0;
 621 }
 622 EXPORT_SYMBOL(get_wchan);
 623
 624 void show_stack(struct task_struct *p, unsigned long *_sp)
 625 {
 626         unsigned long ip, newsp, lr;
 627         int count = 0;
 628         unsigned long sp = (unsigned long)_sp;
 629         int firstframe = 1;
 630
 631         if (sp == 0) {
 632                 if (p) {
 633                         sp = p->thread.ksp;
 634                 } else {
 635                         sp = __get_SP();
 636                         p = current;
 637                 }
 638         }
 639
 640         lr = 0;
 641         printk("Call Trace:\n");
 642         do {
 643                 if (!validate_sp(sp, p, 112))
 644                         return;
 645
 646                 _sp = (unsigned long *) sp;
 647                 newsp = _sp[0];
 648                 ip = _sp[2];
 649                 if (!firstframe || ip != lr) {
 650                         printk("[%016lx] [%016lx] ", sp, ip);
 651                         print_symbol("%s", ip);
 652                         if (firstframe)
 653                                 printk(" (unreliable)");
 654                         printk("\n");
 655                 }
 656                 firstframe = 0;
 657
 658                 /*
 659                  * See if this is an exception frame.
 660                  * We look for the "regshere" marker in the current frame.
 661                  */
 662                 if (validate_sp(sp, p, sizeof(struct pt_regs) + 400)
 663                     && _sp[12] == 0x7265677368657265ul) {
 664                         struct pt_regs *regs = (struct pt_regs *)
 665                                 (sp + STACK_FRAME_OVERHEAD);
 666                         printk("--- Exception: %lx", regs->trap);
 667                         print_symbol(" at %s\n", regs->nip);
 668                         lr = regs->link;
 669                         print_symbol("    LR = %s\n", lr);
 670                         firstframe = 1;
 671                 }
 672
 673                 sp = newsp;
 674         } while (count++ < kstack_depth_to_print);
 675 }
 676
 677 void dump_stack(void)
 678 {
 679         show_stack(current, (unsigned long *)__get_SP());
 680 }
 681 EXPORT_SYMBOL(dump_stack);