arch/powerpc/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 #include <linux/config.h>
  20 #include <linux/errno.h>
  21 #include <linux/sched.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/smp.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/stddef.h>
  27 #include <linux/unistd.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/slab.h>
  30 #include <linux/user.h>
  31 #include <linux/elf.h>
  32 #include <linux/init.h>
  33 #include <linux/prctl.h>
  34 #include <linux/init_task.h>
  35 #include <linux/module.h>
  36 #include <linux/kallsyms.h>
  37 #include <linux/mqueue.h>
  38 #include <linux/hardirq.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/prom.h>
  47
  48 extern unsigned long _get_SP(void);
  49
  50 #ifndef CONFIG_SMP
  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 #endif
  55
  56 static struct fs_struct init_fs = INIT_FS;
  57 static struct files_struct init_files = INIT_FILES;
  58 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  59 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  60 struct mm_struct init_mm = INIT_MM(init_mm);
  61 EXPORT_SYMBOL(init_mm);
  62
  63 /* this is 8kB-aligned so we can get to the thread_info struct
  64    at the base of it from the stack pointer with 1 integer instruction. */
  65 union thread_union init_thread_union
  66         __attribute__((__section__(".data.init_task"))) =
  67 { INIT_THREAD_INFO(init_task) };
  68
  69 /* initial task structure */
  70 struct task_struct init_task = INIT_TASK(init_task);
  71 EXPORT_SYMBOL(init_task);
  72
  73 /* only used to get secondary processor up */
  74 struct task_struct *current_set[NR_CPUS] = {&init_task, };
  75
  76 /*
  77  * Make sure the floating-point register state in the
  78  * the thread_struct is up to date for task tsk.
  79  */
  80 void flush_fp_to_thread(struct task_struct *tsk)
  81 {
  82         if (tsk->thread.regs) {
  83                 /*
  84                  * We need to disable preemption here because if we didn't,
  85                  * another process could get scheduled after the regs->msr
  86                  * test but before we have finished saving the FP registers
  87                  * to the thread_struct.  That process could take over the
  88                  * FPU, and then when we get scheduled again we would store
  89                  * bogus values for the remaining FP registers.
  90                  */
  91                 preempt_disable();
  92                 if (tsk->thread.regs->msr & MSR_FP) {
  93 #ifdef CONFIG_SMP
  94                         /*
  95                          * This should only ever be called for current or
  96                          * for a stopped child process.  Since we save away
  97                          * the FP register state on context switch on SMP,
  98                          * there is something wrong if a stopped child appears
  99                          * to still have its FP state in the CPU registers.
 100                          */
 101                         BUG_ON(tsk != current);
 102 #endif
 103                         giveup_fpu(current);
 104                 }
 105                 preempt_enable();
 106         }
 107 }
 108
 109 void enable_kernel_fp(void)
 110 {
 111         WARN_ON(preemptible());
 112
 113 #ifdef CONFIG_SMP
 114         if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 115                 giveup_fpu(current);
 116         else
 117                 giveup_fpu(NULL);       /* just enables FP for kernel */
 118 #else
 119         giveup_fpu(last_task_used_math);
 120 #endif /* CONFIG_SMP */
 121 }
 122 EXPORT_SYMBOL(enable_kernel_fp);
 123
 124 int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 125 {
 126         if (!tsk->thread.regs)
 127                 return 0;
 128         flush_fp_to_thread(current);
 129
 130         memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
 131
 132         return 1;
 133 }
 134
 135 #ifdef CONFIG_ALTIVEC
 136 void enable_kernel_altivec(void)
 137 {
 138         WARN_ON(preemptible());
 139
 140 #ifdef CONFIG_SMP
 141         if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 142                 giveup_altivec(current);
 143         else
 144                 giveup_altivec(NULL);   /* just enable AltiVec for kernel - force */
 145 #else
 146         giveup_altivec(last_task_used_altivec);
 147 #endif /* CONFIG_SMP */
 148 }
 149 EXPORT_SYMBOL(enable_kernel_altivec);
 150
 151 /*
 152  * Make sure the VMX/Altivec register state in the
 153  * the thread_struct is up to date for task tsk.
 154  */
 155 void flush_altivec_to_thread(struct task_struct *tsk)
 156 {
 157         if (tsk->thread.regs) {
 158                 preempt_disable();
 159                 if (tsk->thread.regs->msr & MSR_VEC) {
 160 #ifdef CONFIG_SMP
 161                         BUG_ON(tsk != current);
 162 #endif
 163                         giveup_altivec(current);
 164                 }
 165                 preempt_enable();
 166         }
 167 }
 168
 169 int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 170 {
 171         flush_altivec_to_thread(current);
 172         memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
 173         return 1;
 174 }
 175 #endif /* CONFIG_ALTIVEC */
 176
 177 #ifdef CONFIG_SPE
 178
 179 void enable_kernel_spe(void)
 180 {
 181         WARN_ON(preemptible());
 182
 183 #ifdef CONFIG_SMP
 184         if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
 185                 giveup_spe(current);
 186         else
 187                 giveup_spe(NULL);       /* just enable SPE for kernel - force */
 188 #else
 189         giveup_spe(last_task_used_spe);
 190 #endif /* __SMP __ */
 191 }
 192 EXPORT_SYMBOL(enable_kernel_spe);
 193
 194 void flush_spe_to_thread(struct task_struct *tsk)
 195 {
 196         if (tsk->thread.regs) {
 197                 preempt_disable();
 198                 if (tsk->thread.regs->msr & MSR_SPE) {
 199 #ifdef CONFIG_SMP
 200                         BUG_ON(tsk != current);
 201 #endif
 202                         giveup_spe(current);
 203                 }
 204                 preempt_enable();
 205         }
 206 }
 207
 208 int dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
 209 {
 210         flush_spe_to_thread(current);
 211         /* We copy u32 evr[32] + u64 acc + u32 spefscr -> 35 */
 212         memcpy(evrregs, &current->thread.evr[0], sizeof(u32) * 35);
 213         return 1;
 214 }
 215 #endif /* CONFIG_SPE */
 216
 217 static void set_dabr_spr(unsigned long val)
 218 {
 219         mtspr(SPRN_DABR, val);
 220 }
 221
 222 int set_dabr(unsigned long dabr)
 223 {
 224         int ret = 0;
 225
 226 #ifdef CONFIG_PPC64
 227         if (firmware_has_feature(FW_FEATURE_XDABR)) {
 228                 /* We want to catch accesses from kernel and userspace */
 229                 unsigned long flags = H_DABRX_KERNEL|H_DABRX_USER;
 230                 ret = plpar_set_xdabr(dabr, flags);
 231         } else if (firmware_has_feature(FW_FEATURE_DABR)) {
 232                 ret = plpar_set_dabr(dabr);
 233         } else
 234 #endif
 235                 set_dabr_spr(dabr);
 236
 237         return ret;
 238 }
 239
 240 static DEFINE_PER_CPU(unsigned long, current_dabr);
 241
 242 struct task_struct *__switch_to(struct task_struct *prev,
 243         struct task_struct *new)
 244 {
 245         struct thread_struct *new_thread, *old_thread;
 246         unsigned long flags;
 247         struct task_struct *last;
 248
 249 #ifdef CONFIG_SMP
 250         /* avoid complexity of lazy save/restore of fpu
 251          * by just saving it every time we switch out if
 252          * this task used the fpu during the last quantum.
 253          *
 254          * If it tries to use the fpu again, it'll trap and
 255          * reload its fp regs.  So we don't have to do a restore
 256          * every switch, just a save.
 257          *  -- Cort
 258          */
 259         if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
 260                 giveup_fpu(prev);
 261 #ifdef CONFIG_ALTIVEC
 262         /*
 263          * If the previous thread used altivec in the last quantum
 264          * (thus changing altivec regs) then save them.
 265          * We used to check the VRSAVE register but not all apps
 266          * set it, so we don't rely on it now (and in fact we need
 267          * to save & restore VSCR even if VRSAVE == 0).  -- paulus
 268          *
 269          * On SMP we always save/restore altivec regs just to avoid the
 270          * complexity of changing processors.
 271          *  -- Cort
 272          */
 273         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
 274                 giveup_altivec(prev);
 275         /* Avoid the trap.  On smp this this never happens since
 276          * we don't set last_task_used_altivec -- Cort
 277          */
 278         if (new->thread.regs && last_task_used_altivec == new)
 279                 new->thread.regs->msr |= MSR_VEC;
 280 #endif /* CONFIG_ALTIVEC */
 281 #ifdef CONFIG_SPE
 282         /*
 283          * If the previous thread used spe in the last quantum
 284          * (thus changing spe regs) then save them.
 285          *
 286          * On SMP we always save/restore spe regs just to avoid the
 287          * complexity of changing processors.
 288          */
 289         if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
 290                 giveup_spe(prev);
 291         /* Avoid the trap.  On smp this this never happens since
 292          * we don't set last_task_used_spe
 293          */
 294         if (new->thread.regs && last_task_used_spe == new)
 295                 new->thread.regs->msr |= MSR_SPE;
 296 #endif /* CONFIG_SPE */
 297 #endif /* CONFIG_SMP */
 298
 299 #ifdef CONFIG_PPC64     /* for now */
 300         if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
 301                 set_dabr(new->thread.dabr);
 302                 __get_cpu_var(current_dabr) = new->thread.dabr;
 303         }
 304 #endif
 305
 306         new_thread = &new->thread;
 307         old_thread = &current->thread;
 308         local_irq_save(flags);
 309         last = _switch(old_thread, new_thread);
 310
 311         local_irq_restore(flags);
 312
 313         return last;
 314 }
 315
 316 void show_regs(struct pt_regs * regs)
 317 {
 318         int i, trap;
 319
 320         printk("NIP: %08lX LR: %08lX SP: %08lX REGS: %p TRAP: %04lx    %s\n",
 321                regs->nip, regs->link, regs->gpr[1], regs, regs->trap,
 322                print_tainted());
 323         printk("MSR: %08lx EE: %01x PR: %01x FP: %01x ME: %01x IR/DR: %01x%01x\n",
 324                regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
 325                regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
 326                regs->msr&MSR_IR ? 1 : 0,
 327                regs->msr&MSR_DR ? 1 : 0);
 328         trap = TRAP(regs);
 329         if (trap == 0x300 || trap == 0x600)
 330                 printk("DAR: %08lX, DSISR: %08lX\n", regs->dar, regs->dsisr);
 331         printk("TASK = %p[%d] '%s' THREAD: %p\n",
 332                current, current->pid, current->comm, current->thread_info);
 333         printk("Last syscall: %ld ", current->thread.last_syscall);
 334
 335 #ifdef CONFIG_SMP
 336         printk(" CPU: %d", smp_processor_id());
 337 #endif /* CONFIG_SMP */
 338
 339         for (i = 0;  i < 32;  i++) {
 340                 long r;
 341                 if ((i % 8) == 0)
 342                         printk("\n" KERN_INFO "GPR%02d: ", i);
 343                 if (__get_user(r, &regs->gpr[i]))
 344                         break;
 345                 printk("%08lX ", r);
 346                 if (i == 12 && !FULL_REGS(regs))
 347                         break;
 348         }
 349         printk("\n");
 350 #ifdef CONFIG_KALLSYMS
 351         /*
 352          * Lookup NIP late so we have the best change of getting the
 353          * above info out without failing
 354          */
 355         printk("NIP [%08lx] ", regs->nip);
 356         print_symbol("%s\n", regs->nip);
 357         printk("LR [%08lx] ", regs->link);
 358         print_symbol("%s\n", regs->link);
 359 #endif
 360         show_stack(current, (unsigned long *) regs->gpr[1]);
 361 }
 362
 363 void exit_thread(void)
 364 {
 365 #ifndef CONFIG_SMP
 366         if (last_task_used_math == current)
 367                 last_task_used_math = NULL;
 368 #ifdef CONFIG_ALTIVEC
 369         if (last_task_used_altivec == current)
 370                 last_task_used_altivec = NULL;
 371 #endif /* CONFIG_ALTIVEC */
 372 #ifdef CONFIG_SPE
 373         if (last_task_used_spe == current)
 374                 last_task_used_spe = NULL;
 375 #endif
 376 #endif /* CONFIG_SMP */
 377 }
 378
 379 void flush_thread(void)
 380 {
 381 #ifndef CONFIG_SMP
 382         if (last_task_used_math == current)
 383                 last_task_used_math = NULL;
 384 #ifdef CONFIG_ALTIVEC
 385         if (last_task_used_altivec == current)
 386                 last_task_used_altivec = NULL;
 387 #endif /* CONFIG_ALTIVEC */
 388 #ifdef CONFIG_SPE
 389         if (last_task_used_spe == current)
 390                 last_task_used_spe = NULL;
 391 #endif
 392 #endif /* CONFIG_SMP */
 393
 394 #ifdef CONFIG_PPC64     /* for now */
 395         if (current->thread.dabr) {
 396                 current->thread.dabr = 0;
 397                 set_dabr(0);
 398         }
 399 #endif
 400 }
 401
 402 void
 403 release_thread(struct task_struct *t)
 404 {
 405 }
 406
 407 /*
 408  * This gets called before we allocate a new thread and copy
 409  * the current task into it.
 410  */
 411 void prepare_to_copy(struct task_struct *tsk)
 412 {
 413         flush_fp_to_thread(current);
 414         flush_altivec_to_thread(current);
 415         flush_spe_to_thread(current);
 416 }
 417
 418 /*
 419  * Copy a thread..
 420  */
 421 int
 422 copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 423             unsigned long unused,
 424             struct task_struct *p, struct pt_regs *regs)
 425 {
 426         struct pt_regs *childregs, *kregs;
 427         extern void ret_from_fork(void);
 428         unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;
 429         unsigned long childframe;
 430
 431         CHECK_FULL_REGS(regs);
 432         /* Copy registers */
 433         sp -= sizeof(struct pt_regs);
 434         childregs = (struct pt_regs *) sp;
 435         *childregs = *regs;
 436         if ((childregs->msr & MSR_PR) == 0) {
 437                 /* for kernel thread, set `current' and stackptr in new task */
 438                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
 439                 childregs->gpr[2] = (unsigned long) p;
 440                 p->thread.regs = NULL;  /* no user register state */
 441         } else {
 442                 childregs->gpr[1] = usp;
 443                 p->thread.regs = childregs;
 444                 if (clone_flags & CLONE_SETTLS)
 445                         childregs->gpr[2] = childregs->gpr[6];
 446         }
 447         childregs->gpr[3] = 0;  /* Result from fork() */
 448         sp -= STACK_FRAME_OVERHEAD;
 449         childframe = sp;
 450
 451         /*
 452          * The way this works is that at some point in the future
 453          * some task will call _switch to switch to the new task.
 454          * That will pop off the stack frame created below and start
 455          * the new task running at ret_from_fork.  The new task will
 456          * do some house keeping and then return from the fork or clone
 457          * system call, using the stack frame created above.
 458          */
 459         sp -= sizeof(struct pt_regs);
 460         kregs = (struct pt_regs *) sp;
 461         sp -= STACK_FRAME_OVERHEAD;
 462         p->thread.ksp = sp;
 463         kregs->nip = (unsigned long)ret_from_fork;
 464
 465         p->thread.last_syscall = -1;
 466
 467         return 0;
 468 }
 469
 470 /*
 471  * Set up a thread for executing a new program
 472  */
 473 void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
 474 {
 475         set_fs(USER_DS);
 476         memset(regs->gpr, 0, sizeof(regs->gpr));
 477         regs->ctr = 0;
 478         regs->link = 0;
 479         regs->xer = 0;
 480         regs->ccr = 0;
 481         regs->mq = 0;
 482         regs->nip = nip;
 483         regs->gpr[1] = sp;
 484         regs->msr = MSR_USER;
 485 #ifndef CONFIG_SMP
 486         if (last_task_used_math == current)
 487                 last_task_used_math = NULL;
 488 #ifdef CONFIG_ALTIVEC
 489         if (last_task_used_altivec == current)
 490                 last_task_used_altivec = NULL;
 491 #endif
 492 #ifdef CONFIG_SPE
 493         if (last_task_used_spe == current)
 494                 last_task_used_spe = NULL;
 495 #endif
 496 #endif /* CONFIG_SMP */
 497         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
 498         current->thread.fpscr = 0;
 499 #ifdef CONFIG_ALTIVEC
 500         memset(current->thread.vr, 0, sizeof(current->thread.vr));
 501         memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
 502         current->thread.vrsave = 0;
 503         current->thread.used_vr = 0;
 504 #endif /* CONFIG_ALTIVEC */
 505 #ifdef CONFIG_SPE
 506         memset(current->thread.evr, 0, sizeof(current->thread.evr));
 507         current->thread.acc = 0;
 508         current->thread.spefscr = 0;
 509         current->thread.used_spe = 0;
 510 #endif /* CONFIG_SPE */
 511 }
 512
 513 #define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
 514                 | PR_FP_EXC_RES | PR_FP_EXC_INV)
 515
 516 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 517 {
 518         struct pt_regs *regs = tsk->thread.regs;
 519
 520         /* This is a bit hairy.  If we are an SPE enabled  processor
 521          * (have embedded fp) we store the IEEE exception enable flags in
 522          * fpexc_mode.  fpexc_mode is also used for setting FP exception
 523          * mode (asyn, precise, disabled) for 'Classic' FP. */
 524         if (val & PR_FP_EXC_SW_ENABLE) {
 525 #ifdef CONFIG_SPE
 526                 tsk->thread.fpexc_mode = val &
 527                         (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
 528 #else
 529                 return -EINVAL;
 530 #endif
 531         } else {
 532                 /* on a CONFIG_SPE this does not hurt us.  The bits that
 533                  * __pack_fe01 use do not overlap with bits used for
 534                  * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
 535                  * on CONFIG_SPE implementations are reserved so writing to
 536                  * them does not change anything */
 537                 if (val > PR_FP_EXC_PRECISE)
 538                         return -EINVAL;
 539                 tsk->thread.fpexc_mode = __pack_fe01(val);
 540                 if (regs != NULL && (regs->msr & MSR_FP) != 0)
 541                         regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
 542                                 | tsk->thread.fpexc_mode;
 543         }
 544         return 0;
 545 }
 546
 547 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 548 {
 549         unsigned int val;
 550
 551         if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
 552 #ifdef CONFIG_SPE
 553                 val = tsk->thread.fpexc_mode;
 554 #else
 555                 return -EINVAL;
 556 #endif
 557         else
 558                 val = __unpack_fe01(tsk->thread.fpexc_mode);
 559         return put_user(val, (unsigned int __user *) adr);
 560 }
 561
 562 int sys_clone(unsigned long clone_flags, unsigned long usp,
 563               int __user *parent_tidp, void __user *child_threadptr,
 564               int __user *child_tidp, int p6,
 565               struct pt_regs *regs)
 566 {
 567         CHECK_FULL_REGS(regs);
 568         if (usp == 0)
 569                 usp = regs->gpr[1];     /* stack pointer for child */
 570         return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
 571 }
 572
 573 int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
 574              unsigned long p4, unsigned long p5, unsigned long p6,
 575              struct pt_regs *regs)
 576 {
 577         CHECK_FULL_REGS(regs);
 578         return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
 579 }
 580
 581 int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
 582               unsigned long p4, unsigned long p5, unsigned long p6,
 583               struct pt_regs *regs)
 584 {
 585         CHECK_FULL_REGS(regs);
 586         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
 587                         regs, 0, NULL, NULL);
 588 }
 589
 590 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
 591                unsigned long a3, unsigned long a4, unsigned long a5,
 592                struct pt_regs *regs)
 593 {
 594         int error;
 595         char * filename;
 596
 597         filename = getname((char __user *) a0);
 598         error = PTR_ERR(filename);
 599         if (IS_ERR(filename))
 600                 goto out;
 601         flush_fp_to_thread(current);
 602         flush_altivec_to_thread(current);
 603         flush_spe_to_thread(current);
 604         if (error == 0) {
 605                 task_lock(current);
 606                 current->ptrace &= ~PT_DTRACE;
 607                 task_unlock(current);
 608         }
 609         putname(filename);
 610 out:
 611         return error;
 612 }
 613
 614 static int validate_sp(unsigned long sp, struct task_struct *p,
 615                        unsigned long nbytes)
 616 {
 617         unsigned long stack_page = (unsigned long)p->thread_info;
 618
 619         if (sp >= stack_page + sizeof(struct thread_struct)
 620             && sp <= stack_page + THREAD_SIZE - nbytes)
 621                 return 1;
 622
 623 #ifdef CONFIG_IRQSTACKS
 624         stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
 625         if (sp >= stack_page + sizeof(struct thread_struct)
 626             && sp <= stack_page + THREAD_SIZE - nbytes)
 627                 return 1;
 628
 629         stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
 630         if (sp >= stack_page + sizeof(struct thread_struct)
 631             && sp <= stack_page + THREAD_SIZE - nbytes)
 632                 return 1;
 633 #endif
 634
 635         return 0;
 636 }
 637
 638 void dump_stack(void)
 639 {
 640         show_stack(current, NULL);
 641 }
 642
 643 EXPORT_SYMBOL(dump_stack);
 644
 645 void show_stack(struct task_struct *tsk, unsigned long *stack)
 646 {
 647         unsigned long sp, stack_top, prev_sp, ret;
 648         int count = 0;
 649         unsigned long next_exc = 0;
 650         struct pt_regs *regs;
 651         extern char ret_from_except, ret_from_except_full, ret_from_syscall;
 652
 653         sp = (unsigned long) stack;
 654         if (tsk == NULL)
 655                 tsk = current;
 656         if (sp == 0) {
 657                 if (tsk == current)
 658                         asm("mr %0,1" : "=r" (sp));
 659                 else
 660                         sp = tsk->thread.ksp;
 661         }
 662
 663         prev_sp = (unsigned long) (tsk->thread_info + 1);
 664         stack_top = (unsigned long) tsk->thread_info + THREAD_SIZE;
 665         while (count < 16 && sp > prev_sp && sp < stack_top && (sp & 3) == 0) {
 666                 if (count == 0) {
 667                         printk("Call trace:");
 668 #ifdef CONFIG_KALLSYMS
 669                         printk("\n");
 670 #endif
 671                 } else {
 672                         if (next_exc) {
 673                                 ret = next_exc;
 674                                 next_exc = 0;
 675                         } else
 676                                 ret = *(unsigned long *)(sp + 4);
 677                         printk(" [%08lx] ", ret);
 678 #ifdef CONFIG_KALLSYMS
 679                         print_symbol("%s", ret);
 680                         printk("\n");
 681 #endif
 682                         if (ret == (unsigned long) &ret_from_except
 683                             || ret == (unsigned long) &ret_from_except_full
 684                             || ret == (unsigned long) &ret_from_syscall) {
 685                                 /* sp + 16 points to an exception frame */
 686                                 regs = (struct pt_regs *) (sp + 16);
 687                                 if (sp + 16 + sizeof(*regs) <= stack_top)
 688                                         next_exc = regs->nip;
 689                         }
 690                 }
 691                 ++count;
 692                 sp = *(unsigned long *)sp;
 693         }
 694 #ifndef CONFIG_KALLSYMS
 695         if (count > 0)
 696                 printk("\n");
 697 #endif
 698 }
 699
 700 unsigned long get_wchan(struct task_struct *p)
 701 {
 702         unsigned long ip, sp;
 703         int count = 0;
 704
 705         if (!p || p == current || p->state == TASK_RUNNING)
 706                 return 0;
 707
 708         sp = p->thread.ksp;
 709         if (!validate_sp(sp, p, 16))
 710                 return 0;
 711
 712         do {
 713                 sp = *(unsigned long *)sp;
 714                 if (!validate_sp(sp, p, 16))
 715                         return 0;
 716                 if (count > 0) {
 717                         ip = *(unsigned long *)(sp + 4);
 718                         if (!in_sched_functions(ip))
 719                                 return ip;
 720                 }
 721         } while (count++ < 16);
 722         return 0;
 723 }
 724 EXPORT_SYMBOL(get_wchan);