arch/ppc/kernel/process.c

   1 /*
   2  *  arch/ppc/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
  20 #include <linux/config.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/ptrace.h>
  30 #include <linux/slab.h>
  31 #include <linux/user.h>
  32 #include <linux/elf.h>
  33 #include <linux/init.h>
  34 #include <linux/prctl.h>
  35 #include <linux/init_task.h>
  36 #include <linux/module.h>
  37 #include <linux/kallsyms.h>
  38 #include <linux/mqueue.h>
  39 #include <linux/hardirq.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/prom.h>
  48
  49 extern unsigned long _get_SP(void);
  50
  51 struct task_struct *last_task_used_math = NULL;
  52 struct task_struct *last_task_used_altivec = NULL;
  53 struct task_struct *last_task_used_spe = NULL;
  54
  55 static struct fs_struct init_fs = INIT_FS;
  56 static struct files_struct init_files = INIT_FILES;
  57 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  58 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  59 struct mm_struct init_mm = INIT_MM(init_mm);
  60 EXPORT_SYMBOL(init_mm);
  61
  62 /* this is 8kB-aligned so we can get to the thread_info struct
  63    at the base of it from the stack pointer with 1 integer instruction. */
  64 union thread_union init_thread_union
  65         __attribute__((__section__(".data.init_task"))) =
  66 { INIT_THREAD_INFO(init_task) };
  67
  68 /* initial task structure */
  69 struct task_struct init_task = INIT_TASK(init_task);
  70 EXPORT_SYMBOL(init_task);
  71
  72 /* only used to get secondary processor up */
  73 struct task_struct *current_set[NR_CPUS] = {&init_task, };
  74
  75 #undef SHOW_TASK_SWITCHES
  76 #undef CHECK_STACK
  77
  78 #if defined(CHECK_STACK)
  79 unsigned long
  80 kernel_stack_top(struct task_struct *tsk)
  81 {
  82         return ((unsigned long)tsk) + sizeof(union task_union);
  83 }
  84
  85 unsigned long
  86 task_top(struct task_struct *tsk)
  87 {
  88         return ((unsigned long)tsk) + sizeof(struct thread_info);
  89 }
  90
  91 /* check to make sure the kernel stack is healthy */
  92 int check_stack(struct task_struct *tsk)
  93 {
  94         unsigned long stack_top = kernel_stack_top(tsk);
  95         unsigned long tsk_top = task_top(tsk);
  96         int ret = 0;
  97
  98 #if 0
  99         /* check thread magic */
 100         if ( tsk->thread.magic != THREAD_MAGIC )
 101         {
 102                 ret |= 1;
 103                 printk("thread.magic bad: %08x\n", tsk->thread.magic);
 104         }
 105 #endif
 106
 107         if ( !tsk )
 108                 printk("check_stack(): tsk bad tsk %p\n",tsk);
 109
 110         /* check if stored ksp is bad */
 111         if ( (tsk->thread.ksp > stack_top) || (tsk->thread.ksp < tsk_top) )
 112         {
 113                 printk("stack out of bounds: %s/%d\n"
 114                        " tsk_top %08lx ksp %08lx stack_top %08lx\n",
 115                        tsk->comm,tsk->pid,
 116                        tsk_top, tsk->thread.ksp, stack_top);
 117                 ret |= 2;
 118         }
 119
 120         /* check if stack ptr RIGHT NOW is bad */
 121         if ( (tsk == current) && ((_get_SP() > stack_top ) || (_get_SP() < tsk_top)) )
 122         {
 123                 printk("current stack ptr out of bounds: %s/%d\n"
 124                        " tsk_top %08lx sp %08lx stack_top %08lx\n",
 125                        current->comm,current->pid,
 126                        tsk_top, _get_SP(), stack_top);
 127                 ret |= 4;
 128         }
 129
 130 #if 0
 131         /* check amount of free stack */
 132         for ( i = (unsigned long *)task_top(tsk) ; i < kernel_stack_top(tsk) ; i++ )
 133         {
 134                 if ( !i )
 135                         printk("check_stack(): i = %p\n", i);
 136                 if ( *i != 0 )
 137                 {
 138                         /* only notify if it's less than 900 bytes */
 139                         if ( (i - (unsigned long *)task_top(tsk))  < 900 )
 140                                 printk("%d bytes free on stack\n",
 141                                        i - task_top(tsk));
 142                         break;
 143                 }
 144         }
 145 #endif
 146
 147         if (ret)
 148         {
 149                 panic("bad kernel stack");
 150         }
 151         return(ret);
 152 }
 153 #endif /* defined(CHECK_STACK) */
 154
 155 #ifdef CONFIG_ALTIVEC
 156 int
 157 dump_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 158 {
 159         if (regs->msr & MSR_VEC)
 160                 giveup_altivec(current);
 161         memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
 162         return 1;
 163 }
 164
 165 void
 166 enable_kernel_altivec(void)
 167 {
 168         WARN_ON(preemptible());
 169
 170 #ifdef CONFIG_SMP
 171         if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 172                 giveup_altivec(current);
 173         else
 174                 giveup_altivec(NULL);   /* just enable AltiVec for kernel - force */
 175 #else
 176         giveup_altivec(last_task_used_altivec);
 177 #endif /* __SMP __ */
 178 }
 179 EXPORT_SYMBOL(enable_kernel_altivec);
 180 #endif /* CONFIG_ALTIVEC */
 181
 182 #ifdef CONFIG_SPE
 183 int
 184 dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
 185 {
 186         if (regs->msr & MSR_SPE)
 187                 giveup_spe(current);
 188         /* We copy u32 evr[32] + u64 acc + u32 spefscr -> 35 */
 189         memcpy(evrregs, &current->thread.evr[0], sizeof(u32) * 35);
 190         return 1;
 191 }
 192
 193 void
 194 enable_kernel_spe(void)
 195 {
 196         WARN_ON(preemptible());
 197
 198 #ifdef CONFIG_SMP
 199         if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
 200                 giveup_spe(current);
 201         else
 202                 giveup_spe(NULL);       /* just enable SPE for kernel - force */
 203 #else
 204         giveup_spe(last_task_used_spe);
 205 #endif /* __SMP __ */
 206 }
 207 EXPORT_SYMBOL(enable_kernel_spe);
 208 #endif /* CONFIG_SPE */
 209
 210 void
 211 enable_kernel_fp(void)
 212 {
 213         WARN_ON(preemptible());
 214
 215 #ifdef CONFIG_SMP
 216         if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 217                 giveup_fpu(current);
 218         else
 219                 giveup_fpu(NULL);       /* just enables FP for kernel */
 220 #else
 221         giveup_fpu(last_task_used_math);
 222 #endif /* CONFIG_SMP */
 223 }
 224 EXPORT_SYMBOL(enable_kernel_fp);
 225
 226 int
 227 dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 228 {
 229         preempt_disable();
 230         if (tsk->thread.regs && (tsk->thread.regs->msr & MSR_FP))
 231                 giveup_fpu(tsk);
 232         preempt_enable();
 233         memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
 234         return 1;
 235 }
 236
 237 struct task_struct *__switch_to(struct task_struct *prev,
 238         struct task_struct *new)
 239 {
 240         struct thread_struct *new_thread, *old_thread;
 241         unsigned long s;
 242         struct task_struct *last;
 243
 244         local_irq_save(s);
 245 #ifdef CHECK_STACK
 246         check_stack(prev);
 247         check_stack(new);
 248 #endif
 249
 250 #ifdef CONFIG_SMP
 251         /* avoid complexity of lazy save/restore of fpu
 252          * by just saving it every time we switch out if
 253          * this task used the fpu during the last quantum.
 254          *
 255          * If it tries to use the fpu again, it'll trap and
 256          * reload its fp regs.  So we don't have to do a restore
 257          * every switch, just a save.
 258          *  -- Cort
 259          */
 260         if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
 261                 giveup_fpu(prev);
 262 #ifdef CONFIG_ALTIVEC
 263         /*
 264          * If the previous thread used altivec in the last quantum
 265          * (thus changing altivec regs) then save them.
 266          * We used to check the VRSAVE register but not all apps
 267          * set it, so we don't rely on it now (and in fact we need
 268          * to save & restore VSCR even if VRSAVE == 0).  -- paulus
 269          *
 270          * On SMP we always save/restore altivec regs just to avoid the
 271          * complexity of changing processors.
 272          *  -- Cort
 273          */
 274         if ((prev->thread.regs && (prev->thread.regs->msr & MSR_VEC)))
 275                 giveup_altivec(prev);
 276 #endif /* CONFIG_ALTIVEC */
 277 #ifdef CONFIG_SPE
 278         /*
 279          * If the previous thread used spe in the last quantum
 280          * (thus changing spe regs) then save them.
 281          *
 282          * On SMP we always save/restore spe regs just to avoid the
 283          * complexity of changing processors.
 284          */
 285         if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
 286                 giveup_spe(prev);
 287 #endif /* CONFIG_SPE */
 288 #endif /* CONFIG_SMP */
 289
 290         /* Avoid the trap.  On smp this this never happens since
 291          * we don't set last_task_used_altivec -- Cort
 292          */
 293         if (new->thread.regs && last_task_used_altivec == new)
 294                 new->thread.regs->msr |= MSR_VEC;
 295 #ifdef CONFIG_SPE
 296         /* Avoid the trap.  On smp this this never happens since
 297          * we don't set last_task_used_spe
 298          */
 299         if (new->thread.regs && last_task_used_spe == new)
 300                 new->thread.regs->msr |= MSR_SPE;
 301 #endif /* CONFIG_SPE */
 302         new_thread = &new->thread;
 303         old_thread = &current->thread;
 304         last = _switch(old_thread, new_thread);
 305         local_irq_restore(s);
 306         return last;
 307 }
 308
 309 void show_regs(struct pt_regs * regs)
 310 {
 311         int i, trap;
 312
 313         printk("NIP: %08lX LR: %08lX SP: %08lX REGS: %p TRAP: %04lx    %s\n",
 314                regs->nip, regs->link, regs->gpr[1], regs, regs->trap,
 315                print_tainted());
 316         printk("MSR: %08lx EE: %01x PR: %01x FP: %01x ME: %01x IR/DR: %01x%01x\n",
 317                regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
 318                regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
 319                regs->msr&MSR_IR ? 1 : 0,
 320                regs->msr&MSR_DR ? 1 : 0);
 321         trap = TRAP(regs);
 322         if (trap == 0x300 || trap == 0x600)
 323                 printk("DAR: %08lX, DSISR: %08lX\n", regs->dar, regs->dsisr);
 324         printk("TASK = %p[%d] '%s' THREAD: %p",
 325                current, current->pid, current->comm, current->thread_info);
 326         printk("Last syscall: %ld ", current->thread.last_syscall);
 327
 328 #if defined(CONFIG_4xx) && defined(DCRN_PLB0_BEAR)
 329         printk("\nPLB0: bear= 0x%8.8x acr=   0x%8.8x besr=  0x%8.8x\n",
 330             mfdcr(DCRN_PLB0_BEAR), mfdcr(DCRN_PLB0_ACR),
 331             mfdcr(DCRN_PLB0_BESR));
 332 #endif
 333 #if defined(CONFIG_4xx) && defined(DCRN_POB0_BEAR)
 334         printk("PLB0 to OPB: bear= 0x%8.8x besr0= 0x%8.8x besr1= 0x%8.8x\n",
 335             mfdcr(DCRN_POB0_BEAR), mfdcr(DCRN_POB0_BESR0),
 336             mfdcr(DCRN_POB0_BESR1));
 337 #endif
 338
 339 #ifdef CONFIG_SMP
 340         printk(" CPU: %d", smp_processor_id());
 341 #endif /* CONFIG_SMP */
 342
 343         for (i = 0;  i < 32;  i++) {
 344                 long r;
 345                 if ((i % 8) == 0)
 346                         printk("\n" KERN_INFO "GPR%02d: ", i);
 347                 if (__get_user(r, &regs->gpr[i]))
 348                         break;
 349                 printk("%08lX ", r);
 350                 if (i == 12 && !FULL_REGS(regs))
 351                         break;
 352         }
 353         printk("\n");
 354 #ifdef CONFIG_KALLSYMS
 355         /*
 356          * Lookup NIP late so we have the best change of getting the
 357          * above info out without failing
 358          */
 359         printk("NIP [%08lx] ", regs->nip);
 360         print_symbol("%s\n", regs->nip);
 361         printk("LR [%08lx] ", regs->link);
 362         print_symbol("%s\n", regs->link);
 363 #endif
 364         show_stack(current, (unsigned long *) regs->gpr[1]);
 365 }
 366
 367 void exit_thread(void)
 368 {
 369         if (last_task_used_math == current)
 370                 last_task_used_math = NULL;
 371         if (last_task_used_altivec == current)
 372                 last_task_used_altivec = NULL;
 373 }
 374
 375 void flush_thread(void)
 376 {
 377         if (last_task_used_math == current)
 378                 last_task_used_math = NULL;
 379         if (last_task_used_altivec == current)
 380                 last_task_used_altivec = NULL;
 381 }
 382
 383 void
 384 release_thread(struct task_struct *t)
 385 {
 386 }
 387
 388 /*
 389  * This gets called before we allocate a new thread and copy
 390  * the current task into it.
 391  */
 392 void prepare_to_copy(struct task_struct *tsk)
 393 {
 394         struct pt_regs *regs = tsk->thread.regs;
 395
 396         if (regs == NULL)
 397                 return;
 398         preempt_disable();
 399         if (regs->msr & MSR_FP)
 400                 giveup_fpu(current);
 401 #ifdef CONFIG_ALTIVEC
 402         if (regs->msr & MSR_VEC)
 403                 giveup_altivec(current);
 404 #endif /* CONFIG_ALTIVEC */
 405 #ifdef CONFIG_SPE
 406         if (regs->msr & MSR_SPE)
 407                 giveup_spe(current);
 408 #endif /* CONFIG_SPE */
 409         preempt_enable();
 410 }
 411
 412 /*
 413  * Copy a thread..
 414  */
 415 int
 416 copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 417             unsigned long unused,
 418             struct task_struct *p, struct pt_regs *regs)
 419 {
 420         struct pt_regs *childregs, *kregs;
 421         extern void ret_from_fork(void);
 422         unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;
 423         unsigned long childframe;
 424
 425         p->set_child_tid = p->clear_child_tid = NULL;
 426
 427         CHECK_FULL_REGS(regs);
 428         /* Copy registers */
 429         sp -= sizeof(struct pt_regs);
 430         childregs = (struct pt_regs *) sp;
 431         *childregs = *regs;
 432         if ((childregs->msr & MSR_PR) == 0) {
 433                 /* for kernel thread, set `current' and stackptr in new task */
 434                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
 435                 childregs->gpr[2] = (unsigned long) p;
 436                 p->thread.regs = NULL;  /* no user register state */
 437         } else {
 438                 childregs->gpr[1] = usp;
 439                 p->thread.regs = childregs;
 440                 if (clone_flags & CLONE_SETTLS)
 441                         childregs->gpr[2] = childregs->gpr[6];
 442         }
 443         childregs->gpr[3] = 0;  /* Result from fork() */
 444         sp -= STACK_FRAME_OVERHEAD;
 445         childframe = sp;
 446
 447         /*
 448          * The way this works is that at some point in the future
 449          * some task will call _switch to switch to the new task.
 450          * That will pop off the stack frame created below and start
 451          * the new task running at ret_from_fork.  The new task will
 452          * do some house keeping and then return from the fork or clone
 453          * system call, using the stack frame created above.
 454          */
 455         sp -= sizeof(struct pt_regs);
 456         kregs = (struct pt_regs *) sp;
 457         sp -= STACK_FRAME_OVERHEAD;
 458         p->thread.ksp = sp;
 459         kregs->nip = (unsigned long)ret_from_fork;
 460
 461         p->thread.last_syscall = -1;
 462
 463         return 0;
 464 }
 465
 466 /*
 467  * Set up a thread for executing a new program
 468  */
 469 void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
 470 {
 471         set_fs(USER_DS);
 472         memset(regs->gpr, 0, sizeof(regs->gpr));
 473         regs->ctr = 0;
 474         regs->link = 0;
 475         regs->xer = 0;
 476         regs->ccr = 0;
 477         regs->mq = 0;
 478         regs->nip = nip;
 479         regs->gpr[1] = sp;
 480         regs->msr = MSR_USER;
 481         if (last_task_used_math == current)
 482                 last_task_used_math = NULL;
 483         if (last_task_used_altivec == current)
 484                 last_task_used_altivec = NULL;
 485         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
 486         current->thread.fpscr = 0;
 487 #ifdef CONFIG_ALTIVEC
 488         memset(current->thread.vr, 0, sizeof(current->thread.vr));
 489         memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
 490         current->thread.vrsave = 0;
 491         current->thread.used_vr = 0;
 492 #endif /* CONFIG_ALTIVEC */
 493 #ifdef CONFIG_SPE
 494         memset(current->thread.evr, 0, sizeof(current->thread.evr));
 495         current->thread.acc = 0;
 496         current->thread.spefscr = 0;
 497         current->thread.used_spe = 0;
 498 #endif /* CONFIG_SPE */
 499 }
 500
 501 #define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
 502                 | PR_FP_EXC_RES | PR_FP_EXC_INV)
 503
 504 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 505 {
 506         struct pt_regs *regs = tsk->thread.regs;
 507
 508         /* This is a bit hairy.  If we are an SPE enabled  processor
 509          * (have embedded fp) we store the IEEE exception enable flags in
 510          * fpexc_mode.  fpexc_mode is also used for setting FP exception
 511          * mode (asyn, precise, disabled) for 'Classic' FP. */
 512         if (val & PR_FP_EXC_SW_ENABLE) {
 513 #ifdef CONFIG_SPE
 514                 tsk->thread.fpexc_mode = val &
 515                         (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
 516 #else
 517                 return -EINVAL;
 518 #endif
 519         } else {
 520                 /* on a CONFIG_SPE this does not hurt us.  The bits that
 521                  * __pack_fe01 use do not overlap with bits used for
 522                  * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
 523                  * on CONFIG_SPE implementations are reserved so writing to
 524                  * them does not change anything */
 525                 if (val > PR_FP_EXC_PRECISE)
 526                         return -EINVAL;
 527                 tsk->thread.fpexc_mode = __pack_fe01(val);
 528                 if (regs != NULL && (regs->msr & MSR_FP) != 0)
 529                         regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
 530                                 | tsk->thread.fpexc_mode;
 531         }
 532         return 0;
 533 }
 534
 535 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 536 {
 537         unsigned int val;
 538
 539         if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
 540 #ifdef CONFIG_SPE
 541                 val = tsk->thread.fpexc_mode;
 542 #else
 543                 return -EINVAL;
 544 #endif
 545         else
 546                 val = __unpack_fe01(tsk->thread.fpexc_mode);
 547         return put_user(val, (unsigned int __user *) adr);
 548 }
 549
 550 int sys_clone(unsigned long clone_flags, unsigned long usp,
 551               int __user *parent_tidp, void __user *child_threadptr,
 552               int __user *child_tidp, int p6,
 553               struct pt_regs *regs)
 554 {
 555         CHECK_FULL_REGS(regs);
 556         if (usp == 0)
 557                 usp = regs->gpr[1];     /* stack pointer for child */
 558         return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
 559 }
 560
 561 int sys_fork(int p1, int p2, int p3, int p4, int p5, int p6,
 562              struct pt_regs *regs)
 563 {
 564         CHECK_FULL_REGS(regs);
 565         return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
 566 }
 567
 568 int sys_vfork(int p1, int p2, int p3, int p4, int p5, int p6,
 569               struct pt_regs *regs)
 570 {
 571         CHECK_FULL_REGS(regs);
 572         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
 573                         regs, 0, NULL, NULL);
 574 }
 575
 576 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
 577                unsigned long a3, unsigned long a4, unsigned long a5,
 578                struct pt_regs *regs)
 579 {
 580         int error;
 581         char * filename;
 582
 583         filename = getname((char __user *) a0);
 584         error = PTR_ERR(filename);
 585         if (IS_ERR(filename))
 586                 goto out;
 587         preempt_disable();
 588         if (regs->msr & MSR_FP)
 589                 giveup_fpu(current);
 590 #ifdef CONFIG_ALTIVEC
 591         if (regs->msr & MSR_VEC)
 592                 giveup_altivec(current);
 593 #endif /* CONFIG_ALTIVEC */
 594 #ifdef CONFIG_SPE
 595         if (regs->msr & MSR_SPE)
 596                 giveup_spe(current);
 597 #endif /* CONFIG_SPE */
 598         preempt_enable();
 599         error = do_execve(filename, (char __user *__user *) a1,
 600                           (char __user *__user *) a2, regs);
 601         if (error == 0)
 602                 current->ptrace &= ~PT_DTRACE;
 603         putname(filename);
 604 out:
 605         return error;
 606 }
 607
 608 void dump_stack(void)
 609 {
 610         show_stack(current, NULL);
 611 }
 612
 613 EXPORT_SYMBOL(dump_stack);
 614
 615 void show_stack(struct task_struct *tsk, unsigned long *stack)
 616 {
 617         unsigned long sp, stack_top, prev_sp, ret;
 618         int count = 0;
 619         unsigned long next_exc = 0;
 620         struct pt_regs *regs;
 621         extern char ret_from_except, ret_from_except_full, ret_from_syscall;
 622
 623         sp = (unsigned long) stack;
 624         if (tsk == NULL)
 625                 tsk = current;
 626         if (sp == 0) {
 627                 if (tsk == current)
 628                         asm("mr %0,1" : "=r" (sp));
 629                 else
 630                         sp = tsk->thread.ksp;
 631         }
 632
 633         prev_sp = (unsigned long) (tsk->thread_info + 1);
 634         stack_top = (unsigned long) tsk->thread_info + THREAD_SIZE;
 635         while (count < 16 && sp > prev_sp && sp < stack_top && (sp & 3) == 0) {
 636                 if (count == 0) {
 637                         printk("Call trace:");
 638 #ifdef CONFIG_KALLSYMS
 639                         printk("\n");
 640 #endif
 641                 } else {
 642                         if (next_exc) {
 643                                 ret = next_exc;
 644                                 next_exc = 0;
 645                         } else
 646                                 ret = *(unsigned long *)(sp + 4);
 647                         printk(" [%08lx] ", ret);
 648 #ifdef CONFIG_KALLSYMS
 649                         print_symbol("%s", ret);
 650                         printk("\n");
 651 #endif
 652                         if (ret == (unsigned long) &ret_from_except
 653                             || ret == (unsigned long) &ret_from_except_full
 654                             || ret == (unsigned long) &ret_from_syscall) {
 655                                 /* sp + 16 points to an exception frame */
 656                                 regs = (struct pt_regs *) (sp + 16);
 657                                 if (sp + 16 + sizeof(*regs) <= stack_top)
 658                                         next_exc = regs->nip;
 659                         }
 660                 }
 661                 ++count;
 662                 sp = *(unsigned long *)sp;
 663         }
 664 #ifndef CONFIG_KALLSYMS
 665         if (count > 0)
 666                 printk("\n");
 667 #endif
 668 }
 669
 670 #if 0
 671 /*
 672  * Low level print for debugging - Cort
 673  */
 674 int __init ll_printk(const char *fmt, ...)
 675 {
 676         va_list args;
 677         char buf[256];
 678         int i;
 679
 680         va_start(args, fmt);
 681         i=vsprintf(buf,fmt,args);
 682         ll_puts(buf);
 683         va_end(args);
 684         return i;
 685 }
 686
 687 int lines = 24, cols = 80;
 688 int orig_x = 0, orig_y = 0;
 689
 690 void puthex(unsigned long val)
 691 {
 692         unsigned char buf[10];
 693         int i;
 694         for (i = 7;  i >= 0;  i--)
 695         {
 696                 buf[i] = "0123456789ABCDEF"[val & 0x0F];
 697                 val >>= 4;
 698         }
 699         buf[8] = '\0';
 700         prom_print(buf);
 701 }
 702
 703 void __init ll_puts(const char *s)
 704 {
 705         int x,y;
 706         char *vidmem = (char *)/*(_ISA_MEM_BASE + 0xB8000) */0xD00B8000;
 707         char c;
 708         extern int mem_init_done;
 709
 710         if ( mem_init_done ) /* assume this means we can printk */
 711         {
 712                 printk(s);
 713                 return;
 714         }
 715
 716 #if 0
 717         if ( have_of )
 718         {
 719                 prom_print(s);
 720                 return;
 721         }
 722 #endif
 723
 724         /*
 725          * can't ll_puts on chrp without openfirmware yet.
 726          * vidmem just needs to be setup for it.
 727          * -- Cort
 728          */
 729         if ( _machine != _MACH_prep )
 730                 return;
 731         x = orig_x;
 732         y = orig_y;
 733
 734         while ( ( c = *s++ ) != '\0' ) {
 735                 if ( c == '\n' ) {
 736                         x = 0;
 737                         if ( ++y >= lines ) {
 738                                 /*scroll();*/
 739                                 /*y--;*/
 740                                 y = 0;
 741                         }
 742                 } else {
 743                         vidmem [ ( x + cols * y ) * 2 ] = c;
 744                         if ( ++x >= cols ) {
 745                                 x = 0;
 746                                 if ( ++y >= lines ) {
 747                                         /*scroll();*/
 748                                         /*y--;*/
 749                                         y = 0;
 750                                 }
 751                         }
 752                 }
 753         }
 754
 755         orig_x = x;
 756         orig_y = y;
 757 }
 758 #endif
 759
 760 unsigned long get_wchan(struct task_struct *p)
 761 {
 762         unsigned long ip, sp;
 763         unsigned long stack_page = (unsigned long) p->thread_info;
 764         int count = 0;
 765         if (!p || p == current || p->state == TASK_RUNNING)
 766                 return 0;
 767         sp = p->thread.ksp;
 768         do {
 769                 sp = *(unsigned long *)sp;
 770                 if (sp < stack_page || sp >= stack_page + 8188)
 771                         return 0;
 772                 if (count > 0) {
 773                         ip = *(unsigned long *)(sp + 4);
 774                         if (!in_sched_functions(ip))
 775                                 return ip;
 776                 }
 777         } while (count++ < 16);
 778         return 0;
 779 }