arch/sparc/kernel/process.c

   1 /*  $Id: process.c,v 1.158 2001/11/26 23:45:00 davem Exp $
   2  *  linux/arch/sparc/kernel/process.c
   3  *
   4  *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  *  Copyright (C) 1996 Eddie C. Dost   (ecd@skynet.be)
   6  */
   7
   8 /*
   9  * This file handles the architecture-dependent parts of process handling..
  10  */
  11
  12 #define __KERNEL_SYSCALLS__
  13 #include <stdarg.h>
  14
  15 #include <linux/errno.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/stddef.h>
  20 #include <linux/unistd.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/slab.h>
  23 #include <linux/user.h>
  24 #include <linux/a.out.h>
  25 #include <linux/config.h>
  26 #include <linux/smp.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/reboot.h>
  29 #include <linux/delay.h>
  30 #include <linux/pm.h>
  31
  32 #include <asm/auxio.h>
  33 #include <asm/oplib.h>
  34 #include <asm/uaccess.h>
  35 #include <asm/system.h>
  36 #include <asm/page.h>
  37 #include <asm/pgalloc.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/delay.h>
  40 #include <asm/processor.h>
  41 #include <asm/psr.h>
  42 #include <asm/elf.h>
  43
  44 /*
  45  * Power management idle function
  46  * Set in pm platform drivers
  47  */
  48 void (*pm_idle)(void);
  49
  50 /*
  51  * Power-off handler instantiation for pm.h compliance
  52  * This is done via auxio, but could be used as a fallback
  53  * handler when auxio is not present-- unused for now...
  54  */
  55 void (*pm_power_off)(void);
  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 task_struct *current_set[NR_CPUS] = {&init_task, };
  67
  68 #ifndef CONFIG_SMP
  69
  70 #define SUN4C_FAULT_HIGH 100
  71
  72 /*
  73  * the idle loop on a Sparc... ;)
  74  */
  75 int cpu_idle(void)
  76 {
  77         int ret = -EPERM;
  78
  79         if (current->pid != 0)
  80                 goto out;
  81
  82         /* endless idle loop with no priority at all */
  83         current->nice = 20;
  84         current->counter = -100;
  85         init_idle();
  86
  87         for (;;) {
  88                 if (ARCH_SUN4C_SUN4) {
  89                         static int count = HZ;
  90                         static unsigned long last_jiffies;
  91                         static unsigned long last_faults;
  92                         static unsigned long fps;
  93                         unsigned long now;
  94                         unsigned long faults;
  95                         unsigned long flags;
  96
  97                         extern unsigned long sun4c_kernel_faults;
  98                         extern void sun4c_grow_kernel_ring(void);
  99
 100                         save_and_cli(flags);
 101                         now = jiffies;
 102                         count -= (now - last_jiffies);
 103                         last_jiffies = now;
 104                         if (count < 0) {
 105                                 count += HZ;
 106                                 faults = sun4c_kernel_faults;
 107                                 fps = (fps + (faults - last_faults)) >> 1;
 108                                 last_faults = faults;
 109 #if 0
 110                                 printk("kernel faults / second = %ld\n", fps);
 111 #endif
 112                                 if (fps >= SUN4C_FAULT_HIGH) {
 113                                         sun4c_grow_kernel_ring();
 114                                 }
 115                         }
 116                         restore_flags(flags);
 117                 }
 118
 119                 while((!current->need_resched) && pm_idle) {
 120                                 (*pm_idle)();
 121                 }
 122
 123                 schedule();
 124                 check_pgt_cache();
 125         }
 126         ret = 0;
 127 out:
 128         return ret;
 129 }
 130
 131 #else
 132
 133 /* This is being executed in task 0 'user space'. */
 134 int cpu_idle(void)
 135 {
 136         /* endless idle loop with no priority at all */
 137         current->nice = 20;
 138         current->counter = -100;
 139         init_idle();
 140
 141         while(1) {
 142                 if(current->need_resched) {
 143                         schedule();
 144                         check_pgt_cache();
 145                 }
 146                 barrier(); /* or else gcc optimizes... */
 147         }
 148 }
 149
 150 #endif
 151
 152 extern char reboot_command [];
 153
 154 extern int serial_console;
 155
 156 #ifdef CONFIG_SUN_CONSOLE
 157 extern void (*prom_palette)(int);
 158 #endif
 159
 160 void machine_halt(void)
 161 {
 162         sti();
 163         mdelay(8);
 164         cli();
 165 #ifdef CONFIG_SUN_CONSOLE
 166         if (!serial_console && prom_palette)
 167                 prom_palette (1);
 168 #endif
 169         prom_halt();
 170         panic("Halt failed!");
 171 }
 172
 173 void machine_restart(char * cmd)
 174 {
 175         char *p;
 176
 177         sti();
 178         mdelay(8);
 179         cli();
 180
 181         p = strchr (reboot_command, '\n');
 182         if (p) *p = 0;
 183 #ifdef CONFIG_SUN_CONSOLE
 184         if (!serial_console && prom_palette)
 185                 prom_palette (1);
 186 #endif
 187         if (cmd)
 188                 prom_reboot(cmd);
 189         if (*reboot_command)
 190                 prom_reboot(reboot_command);
 191         prom_feval ("reset");
 192         panic("Reboot failed!");
 193 }
 194
 195 void machine_power_off(void)
 196 {
 197 #ifdef CONFIG_SUN_AUXIO
 198         if (auxio_power_register && (!serial_console || scons_pwroff))
 199                 *auxio_power_register |= AUXIO_POWER_OFF;
 200 #endif
 201         machine_halt();
 202 }
 203
 204 void show_regwindow(struct reg_window *rw)
 205 {
 206         printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
 207                "l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
 208                rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
 209                rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
 210         printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
 211                "i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
 212                rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 213                rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
 214 }
 215
 216 static spinlock_t sparc_backtrace_lock = SPIN_LOCK_UNLOCKED;
 217
 218 void __show_backtrace(unsigned long fp)
 219 {
 220         struct reg_window *rw;
 221         unsigned long flags;
 222         int cpu = smp_processor_id();
 223
 224         spin_lock_irqsave(&sparc_backtrace_lock, flags);
 225
 226         rw = (struct reg_window *)fp;
 227         while(rw && (((unsigned long) rw) >= PAGE_OFFSET) &&
 228             !(((unsigned long) rw) & 0x7)) {
 229                 printk("CPU[%d]: ARGS[%08lx,%08lx,%08lx,%08lx,%08lx,%08lx] "
 230                        "FP[%08lx] CALLER[%08lx]\n", cpu,
 231                        rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 232                        rw->ins[4], rw->ins[5],
 233                        rw->ins[6],
 234                        rw->ins[7]);
 235                 rw = (struct reg_window *) rw->ins[6];
 236         }
 237         spin_unlock_irqrestore(&sparc_backtrace_lock, flags);
 238 }
 239
 240 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
 241 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
 242 #define __GET_FP(fp) __asm__ __volatile__("mov %%i6, %0" : "=r" (fp))
 243
 244 void show_backtrace(void)
 245 {
 246         unsigned long fp;
 247
 248         __SAVE; __SAVE; __SAVE; __SAVE;
 249         __SAVE; __SAVE; __SAVE; __SAVE;
 250         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 251         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 252
 253         __GET_FP(fp);
 254
 255         __show_backtrace(fp);
 256 }
 257
 258 #ifdef CONFIG_SMP
 259 void smp_show_backtrace_all_cpus(void)
 260 {
 261         xc0((smpfunc_t) show_backtrace);
 262         show_backtrace();
 263 }
 264 #endif
 265
 266 void show_stackframe(struct sparc_stackf *sf)
 267 {
 268         unsigned long size;
 269         unsigned long *stk;
 270         int i;
 271
 272         printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
 273                "l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
 274                sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
 275                sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
 276         printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
 277                "i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
 278                sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
 279                sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
 280         printk("sp: %08lx x0: %08lx x1: %08lx x2: %08lx "
 281                "x3: %08lx x4: %08lx x5: %08lx xx: %08lx\n",
 282                (unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
 283                sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
 284                sf->xxargs[0]);
 285         size = ((unsigned long)sf->fp) - ((unsigned long)sf);
 286         size -= STACKFRAME_SZ;
 287         stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
 288         i = 0;
 289         do {
 290                 printk("s%d: %08lx\n", i++, *stk++);
 291         } while ((size -= sizeof(unsigned long)));
 292 }
 293
 294 void show_regs(struct pt_regs * regs)
 295 {
 296         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n", regs->psr,
 297                regs->pc, regs->npc, regs->y, print_tainted());
 298         printk("g0: %08lx g1: %08lx g2: %08lx g3: %08lx ",
 299                regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
 300                regs->u_regs[3]);
 301         printk("g4: %08lx g5: %08lx g6: %08lx g7: %08lx\n",
 302                regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
 303                regs->u_regs[7]);
 304         printk("o0: %08lx o1: %08lx o2: %08lx o3: %08lx ",
 305                regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
 306                regs->u_regs[11]);
 307         printk("o4: %08lx o5: %08lx sp: %08lx o7: %08lx\n",
 308                regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
 309                regs->u_regs[15]);
 310         show_regwindow((struct reg_window *)regs->u_regs[14]);
 311 }
 312
 313 void show_trace_task(struct task_struct *tsk)
 314 {
 315         unsigned long pc, fp;
 316         unsigned long task_base = (unsigned long) tsk;
 317         struct reg_window *rw;
 318         int count = 0;
 319
 320         if (!tsk)
 321                 return;
 322
 323         fp = tsk->thread.ksp;
 324         do {
 325                 /* Bogus frame pointer? */
 326                 if (fp < (task_base + sizeof(struct task_struct)) ||
 327                     fp >= (task_base + (PAGE_SIZE << 1)))
 328                         break;
 329                 rw = (struct reg_window *) fp;
 330                 pc = rw->ins[7];
 331                 printk("[%08lx] ", pc);
 332                 fp = rw->ins[6];
 333         } while (++count < 16);
 334         printk("\n");
 335 }
 336
 337 /*
 338  * Free current thread data structures etc..
 339  */
 340 void exit_thread(void)
 341 {
 342 #ifndef CONFIG_SMP
 343         if(last_task_used_math == current) {
 344 #else
 345         if(current->flags & PF_USEDFPU) {
 346 #endif
 347                 /* Keep process from leaving FPU in a bogon state. */
 348                 put_psr(get_psr() | PSR_EF);
 349                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 350                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 351 #ifndef CONFIG_SMP
 352                 last_task_used_math = NULL;
 353 #else
 354                 current->flags &= ~PF_USEDFPU;
 355 #endif
 356         }
 357 }
 358
 359 void flush_thread(void)
 360 {
 361         current->thread.w_saved = 0;
 362
 363         /* No new signal delivery by default */
 364         current->thread.new_signal = 0;
 365 #ifndef CONFIG_SMP
 366         if(last_task_used_math == current) {
 367 #else
 368         if(current->flags & PF_USEDFPU) {
 369 #endif
 370                 /* Clean the fpu. */
 371                 put_psr(get_psr() | PSR_EF);
 372                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 373                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 374 #ifndef CONFIG_SMP
 375                 last_task_used_math = NULL;
 376 #else
 377                 current->flags &= ~PF_USEDFPU;
 378 #endif
 379         }
 380
 381         /* Now, this task is no longer a kernel thread. */
 382         current->thread.current_ds = USER_DS;
 383         if (current->thread.flags & SPARC_FLAG_KTHREAD) {
 384                 current->thread.flags &= ~SPARC_FLAG_KTHREAD;
 385
 386                 /* We must fixup kregs as well. */
 387                 current->thread.kregs = (struct pt_regs *)
 388                         (((unsigned long)current) +
 389                          (TASK_UNION_SIZE - TRACEREG_SZ));
 390         }
 391 }
 392
 393 static __inline__ struct sparc_stackf *
 394 clone_stackframe(struct sparc_stackf *dst, struct sparc_stackf *src)
 395 {
 396         unsigned long size;
 397         struct sparc_stackf *sp;
 398
 399         size = ((unsigned long)src->fp) - ((unsigned long)src);
 400         sp = (struct sparc_stackf *)(((unsigned long)dst) - size);
 401
 402         /* do_fork() grabs the parent semaphore, we must release it
 403          * temporarily so we can build the child clone stack frame
 404          * without deadlocking.
 405          */
 406         if (copy_to_user(sp, src, size))
 407                 sp = (struct sparc_stackf *) 0;
 408         else if (put_user(dst, &sp->fp))
 409                 sp = (struct sparc_stackf *) 0;
 410
 411         return sp;
 412 }
 413
 414
 415 /* Copy a Sparc thread.  The fork() return value conventions
 416  * under SunOS are nothing short of bletcherous:
 417  * Parent -->  %o0 == childs  pid, %o1 == 0
 418  * Child  -->  %o0 == parents pid, %o1 == 1
 419  *
 420  * NOTE: We have a separate fork kpsr/kwim because
 421  *       the parent could change these values between
 422  *       sys_fork invocation and when we reach here
 423  *       if the parent should sleep while trying to
 424  *       allocate the task_struct and kernel stack in
 425  *       do_fork().
 426  */
 427 extern void ret_from_fork(void);
 428
 429 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
 430                 unsigned long unused,
 431                 struct task_struct *p, struct pt_regs *regs)
 432 {
 433         struct pt_regs *childregs;
 434         char *new_stack;
 435
 436 #ifndef CONFIG_SMP
 437         if(last_task_used_math == current) {
 438 #else
 439         if(current->flags & PF_USEDFPU) {
 440 #endif
 441                 put_psr(get_psr() | PSR_EF);
 442                 fpsave(&p->thread.float_regs[0], &p->thread.fsr,
 443                        &p->thread.fpqueue[0], &p->thread.fpqdepth);
 444 #ifdef CONFIG_SMP
 445                 current->flags &= ~PF_USEDFPU;
 446 #endif
 447         }
 448
 449         /*
 450          *  p                      new_stack   childregs
 451          *  !                      !           !             {if(PSR_PS) }
 452          *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
 453          *  +----- - - - - - ------+===========+============={+==========}+
 454          */
 455         new_stack = (char*)p + TASK_UNION_SIZE;
 456         if (regs->psr & PSR_PS)
 457                 new_stack -= STACKFRAME_SZ;
 458         new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
 459         memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
 460         childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
 461
 462         p->thread.ksp = (unsigned long) new_stack;
 463         p->thread.kpc = (((unsigned long) ret_from_fork) - 0x8);
 464         p->thread.kpsr = current->thread.fork_kpsr;
 465         p->thread.kwim = current->thread.fork_kwim;
 466
 467         /* This is used for sun4c only */
 468         atomic_set(&p->thread.refcount, 1);
 469
 470         if(regs->psr & PSR_PS) {
 471                 extern struct pt_regs fake_swapper_regs;
 472
 473                 p->thread.kregs = &fake_swapper_regs;
 474                 new_stack += STACKFRAME_SZ + TRACEREG_SZ;
 475                 childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
 476                 p->thread.flags |= SPARC_FLAG_KTHREAD;
 477                 p->thread.current_ds = KERNEL_DS;
 478                 memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
 479                 childregs->u_regs[UREG_G6] = (unsigned long) p;
 480         } else {
 481                 p->thread.kregs = childregs;
 482                 childregs->u_regs[UREG_FP] = sp;
 483                 p->thread.flags &= ~SPARC_FLAG_KTHREAD;
 484                 p->thread.current_ds = USER_DS;
 485
 486                 if (sp != regs->u_regs[UREG_FP]) {
 487                         struct sparc_stackf *childstack;
 488                         struct sparc_stackf *parentstack;
 489
 490                         /*
 491                          * This is a clone() call with supplied user stack.
 492                          * Set some valid stack frames to give to the child.
 493                          */
 494                         childstack = (struct sparc_stackf *) (sp & ~0x7UL);
 495                         parentstack = (struct sparc_stackf *) regs->u_regs[UREG_FP];
 496
 497 #if 0
 498                         printk("clone: parent stack:\n");
 499                         show_stackframe(parentstack);
 500 #endif
 501
 502                         childstack = clone_stackframe(childstack, parentstack);
 503                         if (!childstack)
 504                                 return -EFAULT;
 505
 506 #if 0
 507                         printk("clone: child stack:\n");
 508                         show_stackframe(childstack);
 509 #endif
 510
 511                         childregs->u_regs[UREG_FP] = (unsigned long)childstack;
 512                 }
 513         }
 514
 515 #ifdef CONFIG_SMP
 516         /* FPU must be disabled on SMP. */
 517         childregs->psr &= ~PSR_EF;
 518 #endif
 519
 520         /* Set the return value for the child. */
 521         childregs->u_regs[UREG_I0] = current->pid;
 522         childregs->u_regs[UREG_I1] = 1;
 523
 524         /* Set the return value for the parent. */
 525         regs->u_regs[UREG_I1] = 0;
 526
 527         return 0;
 528 }
 529
 530 /*
 531  * fill in the user structure for a core dump..
 532  */
 533 void dump_thread(struct pt_regs * regs, struct user * dump)
 534 {
 535         unsigned long first_stack_page;
 536
 537         dump->magic = SUNOS_CORE_MAGIC;
 538         dump->len = sizeof(struct user);
 539         dump->regs.psr = regs->psr;
 540         dump->regs.pc = regs->pc;
 541         dump->regs.npc = regs->npc;
 542         dump->regs.y = regs->y;
 543         /* fuck me plenty */
 544         memcpy(&dump->regs.regs[0], &regs->u_regs[1], (sizeof(unsigned long) * 15));
 545         dump->uexec = current->thread.core_exec;
 546         dump->u_tsize = (((unsigned long) current->mm->end_code) -
 547                 ((unsigned long) current->mm->start_code)) & ~(PAGE_SIZE - 1);
 548         dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1)));
 549         dump->u_dsize -= dump->u_tsize;
 550         dump->u_dsize &= ~(PAGE_SIZE - 1);
 551         first_stack_page = (regs->u_regs[UREG_FP] & ~(PAGE_SIZE - 1));
 552         dump->u_ssize = (TASK_SIZE - first_stack_page) & ~(PAGE_SIZE - 1);
 553         memcpy(&dump->fpu.fpstatus.fregs.regs[0], &current->thread.float_regs[0], (sizeof(unsigned long) * 32));
 554         dump->fpu.fpstatus.fsr = current->thread.fsr;
 555         dump->fpu.fpstatus.flags = dump->fpu.fpstatus.extra = 0;
 556         dump->fpu.fpstatus.fpq_count = current->thread.fpqdepth;
 557         memcpy(&dump->fpu.fpstatus.fpq[0], &current->thread.fpqueue[0],
 558                ((sizeof(unsigned long) * 2) * 16));
 559         dump->sigcode = 0;
 560 }
 561
 562 /*
 563  * fill in the fpu structure for a core dump.
 564  */
 565 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
 566 {
 567         if (current->used_math == 0) {
 568                 memset(fpregs, 0, sizeof(*fpregs));
 569                 fpregs->pr_q_entrysize = 8;
 570                 return 1;
 571         }
 572 #ifdef CONFIG_SMP
 573         if (current->flags & PF_USEDFPU) {
 574                 put_psr(get_psr() | PSR_EF);
 575                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 576                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 577                 regs->psr &= ~(PSR_EF);
 578                 current->flags &= ~(PF_USEDFPU);
 579         }
 580 #else
 581         if (current == last_task_used_math) {
 582                 put_psr(get_psr() | PSR_EF);
 583                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 584                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 585                 last_task_used_math = 0;
 586                 regs->psr &= ~(PSR_EF);
 587         }
 588 #endif
 589         memcpy(&fpregs->pr_fr.pr_regs[0],
 590                &current->thread.float_regs[0],
 591                (sizeof(unsigned long) * 32));
 592         fpregs->pr_fsr = current->thread.fsr;
 593         fpregs->pr_qcnt = current->thread.fpqdepth;
 594         fpregs->pr_q_entrysize = 8;
 595         fpregs->pr_en = 1;
 596         if(fpregs->pr_qcnt != 0) {
 597                 memcpy(&fpregs->pr_q[0],
 598                        &current->thread.fpqueue[0],
 599                        sizeof(struct fpq) * fpregs->pr_qcnt);
 600         }
 601         /* Zero out the rest. */
 602         memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
 603                sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
 604         return 1;
 605 }
 606
 607 /*
 608  * sparc_execve() executes a new program after the asm stub has set
 609  * things up for us.  This should basically do what I want it to.
 610  */
 611 asmlinkage int sparc_execve(struct pt_regs *regs)
 612 {
 613         int error, base = 0;
 614         char *filename;
 615
 616         /* Check for indirect call. */
 617         if(regs->u_regs[UREG_G1] == 0)
 618                 base = 1;
 619
 620         filename = getname((char *)regs->u_regs[base + UREG_I0]);
 621         error = PTR_ERR(filename);
 622         if(IS_ERR(filename))
 623                 goto out;
 624         error = do_execve(filename, (char **) regs->u_regs[base + UREG_I1],
 625                           (char **) regs->u_regs[base + UREG_I2], regs);
 626         putname(filename);
 627 out:
 628         return error;
 629 }
 630
 631 /*
 632  * This is the mechanism for creating a new kernel thread.
 633  *
 634  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 635  * who haven't done an "execve()") should use this: it will work within
 636  * a system call from a "real" process, but the process memory space will
 637  * not be free'd until both the parent and the child have exited.
 638  */
 639 pid_t arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 640 {
 641         long retval;
 642
 643         __asm__ __volatile("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
 644                            "mov %5, %%g3\n\t"    /* and arg. */
 645                            "mov %1, %%g1\n\t"
 646                            "mov %2, %%o0\n\t"    /* Clone flags. */
 647                            "mov 0, %%o1\n\t"     /* usp arg == 0 */
 648                            "t 0x10\n\t"          /* Linux/Sparc clone(). */
 649                            "cmp %%o1, 0\n\t"
 650                            "be 1f\n\t"           /* The parent, just return. */
 651                            " nop\n\t"            /* Delay slot. */
 652                            "jmpl %%g2, %%o7\n\t" /* Call the function. */
 653                            " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
 654                            "mov %3, %%g1\n\t"
 655                            "t 0x10\n\t"          /* Linux/Sparc exit(). */
 656                            /* Notreached by child. */
 657                            "1: mov %%o0, %0\n\t" :
 658                            "=r" (retval) :
 659                            "i" (__NR_clone), "r" (flags | CLONE_VM),
 660                            "i" (__NR_exit),  "r" (fn), "r" (arg) :
 661                            "g1", "g2", "g3", "o0", "o1", "memory", "cc");
 662         return retval;
 663 }