arch/sparc/kernel/process_32.c

   1 /*  linux/arch/sparc/kernel/process.c
   2  *
   3  *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
   4  *  Copyright (C) 1996 Eddie C. Dost   (ecd@skynet.be)
   5  */
   6
   7 /*
   8  * This file handles the architecture-dependent parts of process handling..
   9  */
  10
  11 #include <stdarg.h>
  12
  13 #include <linux/errno.h>
  14 #include <linux/module.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/mm.h>
  18 #include <linux/stddef.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/slab.h>
  21 #include <linux/user.h>
  22 #include <linux/smp.h>
  23 #include <linux/reboot.h>
  24 #include <linux/delay.h>
  25 #include <linux/pm.h>
  26 #include <linux/init.h>
  27
  28 #include <asm/auxio.h>
  29 #include <asm/oplib.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/system.h>
  32 #include <asm/page.h>
  33 #include <asm/pgalloc.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/delay.h>
  36 #include <asm/processor.h>
  37 #include <asm/psr.h>
  38 #include <asm/elf.h>
  39 #include <asm/prom.h>
  40 #include <asm/unistd.h>
  41
  42 /*
  43  * Power management idle function
  44  * Set in pm platform drivers (apc.c and pmc.c)
  45  */
  46 void (*pm_idle)(void);
  47 EXPORT_SYMBOL(pm_idle);
  48
  49 /*
  50  * Power-off handler instantiation for pm.h compliance
  51  * This is done via auxio, but could be used as a fallback
  52  * handler when auxio is not present-- unused for now...
  53  */
  54 void (*pm_power_off)(void) = machine_power_off;
  55 EXPORT_SYMBOL(pm_power_off);
  56
  57 /*
  58  * sysctl - toggle power-off restriction for serial console
  59  * systems in machine_power_off()
  60  */
  61 int scons_pwroff = 1;
  62
  63 extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *);
  64
  65 struct task_struct *last_task_used_math = NULL;
  66 struct thread_info *current_set[NR_CPUS];
  67
  68 #ifndef CONFIG_SMP
  69
  70 #define SUN4C_FAULT_HIGH 100
  71
  72 /*
  73  * the idle loop on a Sparc... ;)
  74  */
  75 void cpu_idle(void)
  76 {
  77         /* endless idle loop with no priority at all */
  78         for (;;) {
  79                 if (ARCH_SUN4C) {
  80                         static int count = HZ;
  81                         static unsigned long last_jiffies;
  82                         static unsigned long last_faults;
  83                         static unsigned long fps;
  84                         unsigned long now;
  85                         unsigned long faults;
  86
  87                         extern unsigned long sun4c_kernel_faults;
  88                         extern void sun4c_grow_kernel_ring(void);
  89
  90                         local_irq_disable();
  91                         now = jiffies;
  92                         count -= (now - last_jiffies);
  93                         last_jiffies = now;
  94                         if (count < 0) {
  95                                 count += HZ;
  96                                 faults = sun4c_kernel_faults;
  97                                 fps = (fps + (faults - last_faults)) >> 1;
  98                                 last_faults = faults;
  99 #if 0
 100                                 printk("kernel faults / second = %ld\n", fps);
 101 #endif
 102                                 if (fps >= SUN4C_FAULT_HIGH) {
 103                                         sun4c_grow_kernel_ring();
 104                                 }
 105                         }
 106                         local_irq_enable();
 107                 }
 108
 109                 if (pm_idle) {
 110                         while (!need_resched())
 111                                 (*pm_idle)();
 112                 } else {
 113                         while (!need_resched())
 114                                 cpu_relax();
 115                 }
 116                 preempt_enable_no_resched();
 117                 schedule();
 118                 preempt_disable();
 119                 check_pgt_cache();
 120         }
 121 }
 122
 123 #else
 124
 125 /* This is being executed in task 0 'user space'. */
 126 void cpu_idle(void)
 127 {
 128         set_thread_flag(TIF_POLLING_NRFLAG);
 129         /* endless idle loop with no priority at all */
 130         while(1) {
 131                 while (!need_resched())
 132                         cpu_relax();
 133                 preempt_enable_no_resched();
 134                 schedule();
 135                 preempt_disable();
 136                 check_pgt_cache();
 137         }
 138 }
 139
 140 #endif
 141
 142 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
 143 void machine_halt(void)
 144 {
 145         local_irq_enable();
 146         mdelay(8);
 147         local_irq_disable();
 148         prom_halt();
 149         panic("Halt failed!");
 150 }
 151
 152 void machine_restart(char * cmd)
 153 {
 154         char *p;
 155
 156         local_irq_enable();
 157         mdelay(8);
 158         local_irq_disable();
 159
 160         p = strchr (reboot_command, '\n');
 161         if (p) *p = 0;
 162         if (cmd)
 163                 prom_reboot(cmd);
 164         if (*reboot_command)
 165                 prom_reboot(reboot_command);
 166         prom_feval ("reset");
 167         panic("Reboot failed!");
 168 }
 169
 170 void machine_power_off(void)
 171 {
 172         if (auxio_power_register &&
 173             (strcmp(of_console_device->type, "serial") || scons_pwroff))
 174                 *auxio_power_register |= AUXIO_POWER_OFF;
 175         machine_halt();
 176 }
 177
 178 #if 0
 179
 180 static DEFINE_SPINLOCK(sparc_backtrace_lock);
 181
 182 void __show_backtrace(unsigned long fp)
 183 {
 184         struct reg_window32 *rw;
 185         unsigned long flags;
 186         int cpu = smp_processor_id();
 187
 188         spin_lock_irqsave(&sparc_backtrace_lock, flags);
 189
 190         rw = (struct reg_window32 *)fp;
 191         while(rw && (((unsigned long) rw) >= PAGE_OFFSET) &&
 192             !(((unsigned long) rw) & 0x7)) {
 193                 printk("CPU[%d]: ARGS[%08lx,%08lx,%08lx,%08lx,%08lx,%08lx] "
 194                        "FP[%08lx] CALLER[%08lx]: ", cpu,
 195                        rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 196                        rw->ins[4], rw->ins[5],
 197                        rw->ins[6],
 198                        rw->ins[7]);
 199                 printk("%pS\n", (void *) rw->ins[7]);
 200                 rw = (struct reg_window32 *) rw->ins[6];
 201         }
 202         spin_unlock_irqrestore(&sparc_backtrace_lock, flags);
 203 }
 204
 205 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
 206 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
 207 #define __GET_FP(fp) __asm__ __volatile__("mov %%i6, %0" : "=r" (fp))
 208
 209 void show_backtrace(void)
 210 {
 211         unsigned long fp;
 212
 213         __SAVE; __SAVE; __SAVE; __SAVE;
 214         __SAVE; __SAVE; __SAVE; __SAVE;
 215         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 216         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 217
 218         __GET_FP(fp);
 219
 220         __show_backtrace(fp);
 221 }
 222
 223 #ifdef CONFIG_SMP
 224 void smp_show_backtrace_all_cpus(void)
 225 {
 226         xc0((smpfunc_t) show_backtrace);
 227         show_backtrace();
 228 }
 229 #endif
 230
 231 void show_stackframe(struct sparc_stackf *sf)
 232 {
 233         unsigned long size;
 234         unsigned long *stk;
 235         int i;
 236
 237         printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
 238                "l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
 239                sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
 240                sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
 241         printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
 242                "i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
 243                sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
 244                sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
 245         printk("sp: %08lx x0: %08lx x1: %08lx x2: %08lx "
 246                "x3: %08lx x4: %08lx x5: %08lx xx: %08lx\n",
 247                (unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
 248                sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
 249                sf->xxargs[0]);
 250         size = ((unsigned long)sf->fp) - ((unsigned long)sf);
 251         size -= STACKFRAME_SZ;
 252         stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
 253         i = 0;
 254         do {
 255                 printk("s%d: %08lx\n", i++, *stk++);
 256         } while ((size -= sizeof(unsigned long)));
 257 }
 258 #endif
 259
 260 void show_regs(struct pt_regs *r)
 261 {
 262         struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];
 263
 264         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
 265                r->psr, r->pc, r->npc, r->y, print_tainted());
 266         printk("PC: <%pS>\n", (void *) r->pc);
 267         printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 268                r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
 269                r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
 270         printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 271                r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
 272                r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
 273         printk("RPC: <%pS>\n", (void *) r->u_regs[15]);
 274
 275         printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 276                rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
 277                rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
 278         printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 279                rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 280                rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
 281 }
 282
 283 /*
 284  * The show_stack is an external API which we do not use ourselves.
 285  * The oops is printed in die_if_kernel.
 286  */
 287 void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 288 {
 289         unsigned long pc, fp;
 290         unsigned long task_base;
 291         struct reg_window32 *rw;
 292         int count = 0;
 293
 294         if (tsk != NULL)
 295                 task_base = (unsigned long) task_stack_page(tsk);
 296         else
 297                 task_base = (unsigned long) current_thread_info();
 298
 299         fp = (unsigned long) _ksp;
 300         do {
 301                 /* Bogus frame pointer? */
 302                 if (fp < (task_base + sizeof(struct thread_info)) ||
 303                     fp >= (task_base + (PAGE_SIZE << 1)))
 304                         break;
 305                 rw = (struct reg_window32 *) fp;
 306                 pc = rw->ins[7];
 307                 printk("[%08lx : ", pc);
 308                 printk("%pS ] ", (void *) pc);
 309                 fp = rw->ins[6];
 310         } while (++count < 16);
 311         printk("\n");
 312 }
 313
 314 void dump_stack(void)
 315 {
 316         unsigned long *ksp;
 317
 318         __asm__ __volatile__("mov       %%fp, %0"
 319                              : "=r" (ksp));
 320         show_stack(current, ksp);
 321 }
 322
 323 EXPORT_SYMBOL(dump_stack);
 324
 325 /*
 326  * Note: sparc64 has a pretty intricated thread_saved_pc, check it out.
 327  */
 328 unsigned long thread_saved_pc(struct task_struct *tsk)
 329 {
 330         return task_thread_info(tsk)->kpc;
 331 }
 332
 333 /*
 334  * Free current thread data structures etc..
 335  */
 336 void exit_thread(void)
 337 {
 338 #ifndef CONFIG_SMP
 339         if(last_task_used_math == current) {
 340 #else
 341         if (test_thread_flag(TIF_USEDFPU)) {
 342 #endif
 343                 /* Keep process from leaving FPU in a bogon state. */
 344                 put_psr(get_psr() | PSR_EF);
 345                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 346                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 347 #ifndef CONFIG_SMP
 348                 last_task_used_math = NULL;
 349 #else
 350                 clear_thread_flag(TIF_USEDFPU);
 351 #endif
 352         }
 353 }
 354
 355 void flush_thread(void)
 356 {
 357         current_thread_info()->w_saved = 0;
 358
 359 #ifndef CONFIG_SMP
 360         if(last_task_used_math == current) {
 361 #else
 362         if (test_thread_flag(TIF_USEDFPU)) {
 363 #endif
 364                 /* Clean the fpu. */
 365                 put_psr(get_psr() | PSR_EF);
 366                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 367                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 368 #ifndef CONFIG_SMP
 369                 last_task_used_math = NULL;
 370 #else
 371                 clear_thread_flag(TIF_USEDFPU);
 372 #endif
 373         }
 374
 375         /* Now, this task is no longer a kernel thread. */
 376         current->thread.current_ds = USER_DS;
 377         if (current->thread.flags & SPARC_FLAG_KTHREAD) {
 378                 current->thread.flags &= ~SPARC_FLAG_KTHREAD;
 379
 380                 /* We must fixup kregs as well. */
 381                 /* XXX This was not fixed for ti for a while, worked. Unused? */
 382                 current->thread.kregs = (struct pt_regs *)
 383                     (task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
 384         }
 385 }
 386
 387 static inline struct sparc_stackf __user *
 388 clone_stackframe(struct sparc_stackf __user *dst,
 389                  struct sparc_stackf __user *src)
 390 {
 391         unsigned long size, fp;
 392         struct sparc_stackf *tmp;
 393         struct sparc_stackf __user *sp;
 394
 395         if (get_user(tmp, &src->fp))
 396                 return NULL;
 397
 398         fp = (unsigned long) tmp;
 399         size = (fp - ((unsigned long) src));
 400         fp = (unsigned long) dst;
 401         sp = (struct sparc_stackf __user *)(fp - size);
 402
 403         /* do_fork() grabs the parent semaphore, we must release it
 404          * temporarily so we can build the child clone stack frame
 405          * without deadlocking.
 406          */
 407         if (__copy_user(sp, src, size))
 408                 sp = NULL;
 409         else if (put_user(fp, &sp->fp))
 410                 sp = NULL;
 411
 412         return sp;
 413 }
 414
 415 asmlinkage int sparc_do_fork(unsigned long clone_flags,
 416                              unsigned long stack_start,
 417                              struct pt_regs *regs,
 418                              unsigned long stack_size)
 419 {
 420         unsigned long parent_tid_ptr, child_tid_ptr;
 421         unsigned long orig_i1 = regs->u_regs[UREG_I1];
 422         long ret;
 423
 424         parent_tid_ptr = regs->u_regs[UREG_I2];
 425         child_tid_ptr = regs->u_regs[UREG_I4];
 426
 427         ret = do_fork(clone_flags, stack_start,
 428                       regs, stack_size,
 429                       (int __user *) parent_tid_ptr,
 430                       (int __user *) child_tid_ptr);
 431
 432         /* If we get an error and potentially restart the system
 433          * call, we're screwed because copy_thread() clobbered
 434          * the parent's %o1.  So detect that case and restore it
 435          * here.
 436          */
 437         if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
 438                 regs->u_regs[UREG_I1] = orig_i1;
 439
 440         return ret;
 441 }
 442
 443 /* Copy a Sparc thread.  The fork() return value conventions
 444  * under SunOS are nothing short of bletcherous:
 445  * Parent -->  %o0 == childs  pid, %o1 == 0
 446  * Child  -->  %o0 == parents pid, %o1 == 1
 447  *
 448  * NOTE: We have a separate fork kpsr/kwim because
 449  *       the parent could change these values between
 450  *       sys_fork invocation and when we reach here
 451  *       if the parent should sleep while trying to
 452  *       allocate the task_struct and kernel stack in
 453  *       do_fork().
 454  * XXX See comment above sys_vfork in sparc64. todo.
 455  */
 456 extern void ret_from_fork(void);
 457
 458 int copy_thread(unsigned long clone_flags, unsigned long sp,
 459                 unsigned long unused,
 460                 struct task_struct *p, struct pt_regs *regs)
 461 {
 462         struct thread_info *ti = task_thread_info(p);
 463         struct pt_regs *childregs;
 464         char *new_stack;
 465
 466 #ifndef CONFIG_SMP
 467         if(last_task_used_math == current) {
 468 #else
 469         if (test_thread_flag(TIF_USEDFPU)) {
 470 #endif
 471                 put_psr(get_psr() | PSR_EF);
 472                 fpsave(&p->thread.float_regs[0], &p->thread.fsr,
 473                        &p->thread.fpqueue[0], &p->thread.fpqdepth);
 474 #ifdef CONFIG_SMP
 475                 clear_thread_flag(TIF_USEDFPU);
 476 #endif
 477         }
 478
 479         /*
 480          *  p->thread_info         new_stack   childregs
 481          *  !                      !           !             {if(PSR_PS) }
 482          *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
 483          *  +----- - - - - - ------+===========+============={+==========}+
 484          */
 485         new_stack = task_stack_page(p) + THREAD_SIZE;
 486         if (regs->psr & PSR_PS)
 487                 new_stack -= STACKFRAME_SZ;
 488         new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
 489         memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
 490         childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
 491
 492         /*
 493          * A new process must start with interrupts closed in 2.5,
 494          * because this is how Mingo's scheduler works (see schedule_tail
 495          * and finish_arch_switch). If we do not do it, a timer interrupt hits
 496          * before we unlock, attempts to re-take the rq->lock, and then we die.
 497          * Thus, kpsr|=PSR_PIL.
 498          */
 499         ti->ksp = (unsigned long) new_stack;
 500         ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
 501         ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
 502         ti->kwim = current->thread.fork_kwim;
 503
 504         if(regs->psr & PSR_PS) {
 505                 extern struct pt_regs fake_swapper_regs;
 506
 507                 p->thread.kregs = &fake_swapper_regs;
 508                 new_stack += STACKFRAME_SZ + TRACEREG_SZ;
 509                 childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
 510                 p->thread.flags |= SPARC_FLAG_KTHREAD;
 511                 p->thread.current_ds = KERNEL_DS;
 512                 memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
 513                 childregs->u_regs[UREG_G6] = (unsigned long) ti;
 514         } else {
 515                 p->thread.kregs = childregs;
 516                 childregs->u_regs[UREG_FP] = sp;
 517                 p->thread.flags &= ~SPARC_FLAG_KTHREAD;
 518                 p->thread.current_ds = USER_DS;
 519
 520                 if (sp != regs->u_regs[UREG_FP]) {
 521                         struct sparc_stackf __user *childstack;
 522                         struct sparc_stackf __user *parentstack;
 523
 524                         /*
 525                          * This is a clone() call with supplied user stack.
 526                          * Set some valid stack frames to give to the child.
 527                          */
 528                         childstack = (struct sparc_stackf __user *)
 529                                 (sp & ~0x7UL);
 530                         parentstack = (struct sparc_stackf __user *)
 531                                 regs->u_regs[UREG_FP];
 532
 533 #if 0
 534                         printk("clone: parent stack:\n");
 535                         show_stackframe(parentstack);
 536 #endif
 537
 538                         childstack = clone_stackframe(childstack, parentstack);
 539                         if (!childstack)
 540                                 return -EFAULT;
 541
 542 #if 0
 543                         printk("clone: child stack:\n");
 544                         show_stackframe(childstack);
 545 #endif
 546
 547                         childregs->u_regs[UREG_FP] = (unsigned long)childstack;
 548                 }
 549         }
 550
 551 #ifdef CONFIG_SMP
 552         /* FPU must be disabled on SMP. */
 553         childregs->psr &= ~PSR_EF;
 554 #endif
 555
 556         /* Set the return value for the child. */
 557         childregs->u_regs[UREG_I0] = current->pid;
 558         childregs->u_regs[UREG_I1] = 1;
 559
 560         /* Set the return value for the parent. */
 561         regs->u_regs[UREG_I1] = 0;
 562
 563         if (clone_flags & CLONE_SETTLS)
 564                 childregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];
 565
 566         return 0;
 567 }
 568
 569 /*
 570  * fill in the fpu structure for a core dump.
 571  */
 572 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
 573 {
 574         if (used_math()) {
 575                 memset(fpregs, 0, sizeof(*fpregs));
 576                 fpregs->pr_q_entrysize = 8;
 577                 return 1;
 578         }
 579 #ifdef CONFIG_SMP
 580         if (test_thread_flag(TIF_USEDFPU)) {
 581                 put_psr(get_psr() | PSR_EF);
 582                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 583                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 584                 if (regs != NULL) {
 585                         regs->psr &= ~(PSR_EF);
 586                         clear_thread_flag(TIF_USEDFPU);
 587                 }
 588         }
 589 #else
 590         if (current == last_task_used_math) {
 591                 put_psr(get_psr() | PSR_EF);
 592                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 593                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 594                 if (regs != NULL) {
 595                         regs->psr &= ~(PSR_EF);
 596                         last_task_used_math = NULL;
 597                 }
 598         }
 599 #endif
 600         memcpy(&fpregs->pr_fr.pr_regs[0],
 601                &current->thread.float_regs[0],
 602                (sizeof(unsigned long) * 32));
 603         fpregs->pr_fsr = current->thread.fsr;
 604         fpregs->pr_qcnt = current->thread.fpqdepth;
 605         fpregs->pr_q_entrysize = 8;
 606         fpregs->pr_en = 1;
 607         if(fpregs->pr_qcnt != 0) {
 608                 memcpy(&fpregs->pr_q[0],
 609                        &current->thread.fpqueue[0],
 610                        sizeof(struct fpq) * fpregs->pr_qcnt);
 611         }
 612         /* Zero out the rest. */
 613         memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
 614                sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
 615         return 1;
 616 }
 617
 618 /*
 619  * sparc_execve() executes a new program after the asm stub has set
 620  * things up for us.  This should basically do what I want it to.
 621  */
 622 asmlinkage int sparc_execve(struct pt_regs *regs)
 623 {
 624         int error, base = 0;
 625         char *filename;
 626
 627         /* Check for indirect call. */
 628         if(regs->u_regs[UREG_G1] == 0)
 629                 base = 1;
 630
 631         filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
 632         error = PTR_ERR(filename);
 633         if(IS_ERR(filename))
 634                 goto out;
 635         error = do_execve(filename,
 636                           (char __user * __user *)regs->u_regs[base + UREG_I1],
 637                           (char __user * __user *)regs->u_regs[base + UREG_I2],
 638                           regs);
 639         putname(filename);
 640 out:
 641         return error;
 642 }
 643
 644 /*
 645  * This is the mechanism for creating a new kernel thread.
 646  *
 647  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 648  * who haven't done an "execve()") should use this: it will work within
 649  * a system call from a "real" process, but the process memory space will
 650  * not be freed until both the parent and the child have exited.
 651  */
 652 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 653 {
 654         long retval;
 655
 656         __asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
 657                              "mov %5, %%g3\n\t"    /* and arg. */
 658                              "mov %1, %%g1\n\t"
 659                              "mov %2, %%o0\n\t"    /* Clone flags. */
 660                              "mov 0, %%o1\n\t"     /* usp arg == 0 */
 661                              "t 0x10\n\t"          /* Linux/Sparc clone(). */
 662                              "cmp %%o1, 0\n\t"
 663                              "be 1f\n\t"           /* The parent, just return. */
 664                              " nop\n\t"            /* Delay slot. */
 665                              "jmpl %%g2, %%o7\n\t" /* Call the function. */
 666                              " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
 667                              "mov %3, %%g1\n\t"
 668                              "t 0x10\n\t"          /* Linux/Sparc exit(). */
 669                              /* Notreached by child. */
 670                              "1: mov %%o0, %0\n\t" :
 671                              "=r" (retval) :
 672                              "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
 673                              "i" (__NR_exit),  "r" (fn), "r" (arg) :
 674                              "g1", "g2", "g3", "o0", "o1", "memory", "cc");
 675         return retval;
 676 }
 677 EXPORT_SYMBOL(kernel_thread);
 678
 679 unsigned long get_wchan(struct task_struct *task)
 680 {
 681         unsigned long pc, fp, bias = 0;
 682         unsigned long task_base = (unsigned long) task;
 683         unsigned long ret = 0;
 684         struct reg_window32 *rw;
 685         int count = 0;
 686
 687         if (!task || task == current ||
 688             task->state == TASK_RUNNING)
 689                 goto out;
 690
 691         fp = task_thread_info(task)->ksp + bias;
 692         do {
 693                 /* Bogus frame pointer? */
 694                 if (fp < (task_base + sizeof(struct thread_info)) ||
 695                     fp >= (task_base + (2 * PAGE_SIZE)))
 696                         break;
 697                 rw = (struct reg_window32 *) fp;
 698                 pc = rw->ins[7];
 699                 if (!in_sched_functions(pc)) {
 700                         ret = pc;
 701                         goto out;
 702                 }
 703                 fp = rw->ins[6] + bias;
 704         } while (++count < 16);
 705
 706 out:
 707         return ret;
 708 }
 709