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/user.h>
  21 #include <linux/smp.h>
  22 #include <linux/reboot.h>
  23 #include <linux/delay.h>
  24 #include <linux/pm.h>
  25 #include <linux/init.h>
  26 #include <linux/slab.h>
  27
  28 #include <asm/auxio.h>
  29 #include <asm/oplib.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/page.h>
  32 #include <asm/pgalloc.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/delay.h>
  35 #include <asm/processor.h>
  36 #include <asm/psr.h>
  37 #include <asm/elf.h>
  38 #include <asm/prom.h>
  39 #include <asm/unistd.h>
  40 #include <asm/setup.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                 schedule_preempt_disabled();
 117                 check_pgt_cache();
 118         }
 119 }
 120
 121 #else
 122
 123 /* This is being executed in task 0 'user space'. */
 124 void cpu_idle(void)
 125 {
 126         set_thread_flag(TIF_POLLING_NRFLAG);
 127         /* endless idle loop with no priority at all */
 128         while(1) {
 129 #ifdef CONFIG_SPARC_LEON
 130                 if (pm_idle) {
 131                         while (!need_resched())
 132                                 (*pm_idle)();
 133                 } else
 134 #endif
 135                 {
 136                         while (!need_resched())
 137                                 cpu_relax();
 138                 }
 139                 schedule_preempt_disabled();
 140                 check_pgt_cache();
 141         }
 142 }
 143
 144 #endif
 145
 146 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
 147 void machine_halt(void)
 148 {
 149         local_irq_enable();
 150         mdelay(8);
 151         local_irq_disable();
 152         prom_halt();
 153         panic("Halt failed!");
 154 }
 155
 156 void machine_restart(char * cmd)
 157 {
 158         char *p;
 159
 160         local_irq_enable();
 161         mdelay(8);
 162         local_irq_disable();
 163
 164         p = strchr (reboot_command, '\n');
 165         if (p) *p = 0;
 166         if (cmd)
 167                 prom_reboot(cmd);
 168         if (*reboot_command)
 169                 prom_reboot(reboot_command);
 170         prom_feval ("reset");
 171         panic("Reboot failed!");
 172 }
 173
 174 void machine_power_off(void)
 175 {
 176         if (auxio_power_register &&
 177             (strcmp(of_console_device->type, "serial") || scons_pwroff))
 178                 *auxio_power_register |= AUXIO_POWER_OFF;
 179         machine_halt();
 180 }
 181
 182 #if 0
 183
 184 static DEFINE_SPINLOCK(sparc_backtrace_lock);
 185
 186 void __show_backtrace(unsigned long fp)
 187 {
 188         struct reg_window32 *rw;
 189         unsigned long flags;
 190         int cpu = smp_processor_id();
 191
 192         spin_lock_irqsave(&sparc_backtrace_lock, flags);
 193
 194         rw = (struct reg_window32 *)fp;
 195         while(rw && (((unsigned long) rw) >= PAGE_OFFSET) &&
 196             !(((unsigned long) rw) & 0x7)) {
 197                 printk("CPU[%d]: ARGS[%08lx,%08lx,%08lx,%08lx,%08lx,%08lx] "
 198                        "FP[%08lx] CALLER[%08lx]: ", cpu,
 199                        rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 200                        rw->ins[4], rw->ins[5],
 201                        rw->ins[6],
 202                        rw->ins[7]);
 203                 printk("%pS\n", (void *) rw->ins[7]);
 204                 rw = (struct reg_window32 *) rw->ins[6];
 205         }
 206         spin_unlock_irqrestore(&sparc_backtrace_lock, flags);
 207 }
 208
 209 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
 210 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
 211 #define __GET_FP(fp) __asm__ __volatile__("mov %%i6, %0" : "=r" (fp))
 212
 213 void show_backtrace(void)
 214 {
 215         unsigned long fp;
 216
 217         __SAVE; __SAVE; __SAVE; __SAVE;
 218         __SAVE; __SAVE; __SAVE; __SAVE;
 219         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 220         __RESTORE; __RESTORE; __RESTORE; __RESTORE;
 221
 222         __GET_FP(fp);
 223
 224         __show_backtrace(fp);
 225 }
 226
 227 #ifdef CONFIG_SMP
 228 void smp_show_backtrace_all_cpus(void)
 229 {
 230         xc0((smpfunc_t) show_backtrace);
 231         show_backtrace();
 232 }
 233 #endif
 234
 235 void show_stackframe(struct sparc_stackf *sf)
 236 {
 237         unsigned long size;
 238         unsigned long *stk;
 239         int i;
 240
 241         printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
 242                "l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
 243                sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
 244                sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
 245         printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
 246                "i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
 247                sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
 248                sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
 249         printk("sp: %08lx x0: %08lx x1: %08lx x2: %08lx "
 250                "x3: %08lx x4: %08lx x5: %08lx xx: %08lx\n",
 251                (unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
 252                sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
 253                sf->xxargs[0]);
 254         size = ((unsigned long)sf->fp) - ((unsigned long)sf);
 255         size -= STACKFRAME_SZ;
 256         stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
 257         i = 0;
 258         do {
 259                 printk("s%d: %08lx\n", i++, *stk++);
 260         } while ((size -= sizeof(unsigned long)));
 261 }
 262 #endif
 263
 264 void show_regs(struct pt_regs *r)
 265 {
 266         struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];
 267
 268         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
 269                r->psr, r->pc, r->npc, r->y, print_tainted());
 270         printk("PC: <%pS>\n", (void *) r->pc);
 271         printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 272                r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
 273                r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
 274         printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 275                r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
 276                r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
 277         printk("RPC: <%pS>\n", (void *) r->u_regs[15]);
 278
 279         printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 280                rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
 281                rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
 282         printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 283                rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 284                rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
 285 }
 286
 287 /*
 288  * The show_stack is an external API which we do not use ourselves.
 289  * The oops is printed in die_if_kernel.
 290  */
 291 void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 292 {
 293         unsigned long pc, fp;
 294         unsigned long task_base;
 295         struct reg_window32 *rw;
 296         int count = 0;
 297
 298         if (tsk != NULL)
 299                 task_base = (unsigned long) task_stack_page(tsk);
 300         else
 301                 task_base = (unsigned long) current_thread_info();
 302
 303         fp = (unsigned long) _ksp;
 304         do {
 305                 /* Bogus frame pointer? */
 306                 if (fp < (task_base + sizeof(struct thread_info)) ||
 307                     fp >= (task_base + (PAGE_SIZE << 1)))
 308                         break;
 309                 rw = (struct reg_window32 *) fp;
 310                 pc = rw->ins[7];
 311                 printk("[%08lx : ", pc);
 312                 printk("%pS ] ", (void *) pc);
 313                 fp = rw->ins[6];
 314         } while (++count < 16);
 315         printk("\n");
 316 }
 317
 318 void dump_stack(void)
 319 {
 320         unsigned long *ksp;
 321
 322         __asm__ __volatile__("mov       %%fp, %0"
 323                              : "=r" (ksp));
 324         show_stack(current, ksp);
 325 }
 326
 327 EXPORT_SYMBOL(dump_stack);
 328
 329 /*
 330  * Note: sparc64 has a pretty intricated thread_saved_pc, check it out.
 331  */
 332 unsigned long thread_saved_pc(struct task_struct *tsk)
 333 {
 334         return task_thread_info(tsk)->kpc;
 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 (test_thread_flag(TIF_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                 clear_thread_flag(TIF_USEDFPU);
 355 #endif
 356         }
 357 }
 358
 359 void flush_thread(void)
 360 {
 361         current_thread_info()->w_saved = 0;
 362
 363 #ifndef CONFIG_SMP
 364         if(last_task_used_math == current) {
 365 #else
 366         if (test_thread_flag(TIF_USEDFPU)) {
 367 #endif
 368                 /* Clean the fpu. */
 369                 put_psr(get_psr() | PSR_EF);
 370                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 371                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 372 #ifndef CONFIG_SMP
 373                 last_task_used_math = NULL;
 374 #else
 375                 clear_thread_flag(TIF_USEDFPU);
 376 #endif
 377         }
 378
 379         /* This task is no longer a kernel thread. */
 380         if (current->thread.flags & SPARC_FLAG_KTHREAD) {
 381                 current->thread.flags &= ~SPARC_FLAG_KTHREAD;
 382
 383                 /* We must fixup kregs as well. */
 384                 /* XXX This was not fixed for ti for a while, worked. Unused? */
 385                 current->thread.kregs = (struct pt_regs *)
 386                     (task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
 387         }
 388 }
 389
 390 static inline struct sparc_stackf __user *
 391 clone_stackframe(struct sparc_stackf __user *dst,
 392                  struct sparc_stackf __user *src)
 393 {
 394         unsigned long size, fp;
 395         struct sparc_stackf *tmp;
 396         struct sparc_stackf __user *sp;
 397
 398         if (get_user(tmp, &src->fp))
 399                 return NULL;
 400
 401         fp = (unsigned long) tmp;
 402         size = (fp - ((unsigned long) src));
 403         fp = (unsigned long) dst;
 404         sp = (struct sparc_stackf __user *)(fp - size);
 405
 406         /* do_fork() grabs the parent semaphore, we must release it
 407          * temporarily so we can build the child clone stack frame
 408          * without deadlocking.
 409          */
 410         if (__copy_user(sp, src, size))
 411                 sp = NULL;
 412         else if (put_user(fp, &sp->fp))
 413                 sp = NULL;
 414
 415         return sp;
 416 }
 417
 418 asmlinkage int sparc_do_fork(unsigned long clone_flags,
 419                              unsigned long stack_start,
 420                              struct pt_regs *regs,
 421                              unsigned long stack_size)
 422 {
 423         unsigned long parent_tid_ptr, child_tid_ptr;
 424         unsigned long orig_i1 = regs->u_regs[UREG_I1];
 425         long ret;
 426
 427         parent_tid_ptr = regs->u_regs[UREG_I2];
 428         child_tid_ptr = regs->u_regs[UREG_I4];
 429
 430         ret = do_fork(clone_flags, stack_start,
 431                       regs, stack_size,
 432                       (int __user *) parent_tid_ptr,
 433                       (int __user *) child_tid_ptr);
 434
 435         /* If we get an error and potentially restart the system
 436          * call, we're screwed because copy_thread() clobbered
 437          * the parent's %o1.  So detect that case and restore it
 438          * here.
 439          */
 440         if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
 441                 regs->u_regs[UREG_I1] = orig_i1;
 442
 443         return ret;
 444 }
 445
 446 /* Copy a Sparc thread.  The fork() return value conventions
 447  * under SunOS are nothing short of bletcherous:
 448  * Parent -->  %o0 == childs  pid, %o1 == 0
 449  * Child  -->  %o0 == parents pid, %o1 == 1
 450  *
 451  * NOTE: We have a separate fork kpsr/kwim because
 452  *       the parent could change these values between
 453  *       sys_fork invocation and when we reach here
 454  *       if the parent should sleep while trying to
 455  *       allocate the task_struct and kernel stack in
 456  *       do_fork().
 457  * XXX See comment above sys_vfork in sparc64. todo.
 458  */
 459 extern void ret_from_fork(void);
 460
 461 int copy_thread(unsigned long clone_flags, unsigned long sp,
 462                 unsigned long unused,
 463                 struct task_struct *p, struct pt_regs *regs)
 464 {
 465         struct thread_info *ti = task_thread_info(p);
 466         struct pt_regs *childregs;
 467         char *new_stack;
 468
 469 #ifndef CONFIG_SMP
 470         if(last_task_used_math == current) {
 471 #else
 472         if (test_thread_flag(TIF_USEDFPU)) {
 473 #endif
 474                 put_psr(get_psr() | PSR_EF);
 475                 fpsave(&p->thread.float_regs[0], &p->thread.fsr,
 476                        &p->thread.fpqueue[0], &p->thread.fpqdepth);
 477 #ifdef CONFIG_SMP
 478                 clear_thread_flag(TIF_USEDFPU);
 479 #endif
 480         }
 481
 482         /*
 483          *  p->thread_info         new_stack   childregs
 484          *  !                      !           !             {if(PSR_PS) }
 485          *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
 486          *  +----- - - - - - ------+===========+============={+==========}+
 487          */
 488         new_stack = task_stack_page(p) + THREAD_SIZE;
 489         if (regs->psr & PSR_PS)
 490                 new_stack -= STACKFRAME_SZ;
 491         new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
 492         memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
 493         childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
 494
 495         /*
 496          * A new process must start with interrupts closed in 2.5,
 497          * because this is how Mingo's scheduler works (see schedule_tail
 498          * and finish_arch_switch). If we do not do it, a timer interrupt hits
 499          * before we unlock, attempts to re-take the rq->lock, and then we die.
 500          * Thus, kpsr|=PSR_PIL.
 501          */
 502         ti->ksp = (unsigned long) new_stack;
 503         ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
 504         ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
 505         ti->kwim = current->thread.fork_kwim;
 506
 507         if(regs->psr & PSR_PS) {
 508                 extern struct pt_regs fake_swapper_regs;
 509
 510                 p->thread.kregs = &fake_swapper_regs;
 511                 new_stack += STACKFRAME_SZ + TRACEREG_SZ;
 512                 childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
 513                 p->thread.flags |= SPARC_FLAG_KTHREAD;
 514                 p->thread.current_ds = KERNEL_DS;
 515                 memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
 516                 childregs->u_regs[UREG_G6] = (unsigned long) ti;
 517         } else {
 518                 p->thread.kregs = childregs;
 519                 childregs->u_regs[UREG_FP] = sp;
 520                 p->thread.flags &= ~SPARC_FLAG_KTHREAD;
 521                 p->thread.current_ds = USER_DS;
 522
 523                 if (sp != regs->u_regs[UREG_FP]) {
 524                         struct sparc_stackf __user *childstack;
 525                         struct sparc_stackf __user *parentstack;
 526
 527                         /*
 528                          * This is a clone() call with supplied user stack.
 529                          * Set some valid stack frames to give to the child.
 530                          */
 531                         childstack = (struct sparc_stackf __user *)
 532                                 (sp & ~0xfUL);
 533                         parentstack = (struct sparc_stackf __user *)
 534                                 regs->u_regs[UREG_FP];
 535
 536 #if 0
 537                         printk("clone: parent stack:\n");
 538                         show_stackframe(parentstack);
 539 #endif
 540
 541                         childstack = clone_stackframe(childstack, parentstack);
 542                         if (!childstack)
 543                                 return -EFAULT;
 544
 545 #if 0
 546                         printk("clone: child stack:\n");
 547                         show_stackframe(childstack);
 548 #endif
 549
 550                         childregs->u_regs[UREG_FP] = (unsigned long)childstack;
 551                 }
 552         }
 553
 554 #ifdef CONFIG_SMP
 555         /* FPU must be disabled on SMP. */
 556         childregs->psr &= ~PSR_EF;
 557 #endif
 558
 559         /* Set the return value for the child. */
 560         childregs->u_regs[UREG_I0] = current->pid;
 561         childregs->u_regs[UREG_I1] = 1;
 562
 563         /* Set the return value for the parent. */
 564         regs->u_regs[UREG_I1] = 0;
 565
 566         if (clone_flags & CLONE_SETTLS)
 567                 childregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];
 568
 569         return 0;
 570 }
 571
 572 /*
 573  * fill in the fpu structure for a core dump.
 574  */
 575 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
 576 {
 577         if (used_math()) {
 578                 memset(fpregs, 0, sizeof(*fpregs));
 579                 fpregs->pr_q_entrysize = 8;
 580                 return 1;
 581         }
 582 #ifdef CONFIG_SMP
 583         if (test_thread_flag(TIF_USEDFPU)) {
 584                 put_psr(get_psr() | PSR_EF);
 585                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 586                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 587                 if (regs != NULL) {
 588                         regs->psr &= ~(PSR_EF);
 589                         clear_thread_flag(TIF_USEDFPU);
 590                 }
 591         }
 592 #else
 593         if (current == last_task_used_math) {
 594                 put_psr(get_psr() | PSR_EF);
 595                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 596                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 597                 if (regs != NULL) {
 598                         regs->psr &= ~(PSR_EF);
 599                         last_task_used_math = NULL;
 600                 }
 601         }
 602 #endif
 603         memcpy(&fpregs->pr_fr.pr_regs[0],
 604                &current->thread.float_regs[0],
 605                (sizeof(unsigned long) * 32));
 606         fpregs->pr_fsr = current->thread.fsr;
 607         fpregs->pr_qcnt = current->thread.fpqdepth;
 608         fpregs->pr_q_entrysize = 8;
 609         fpregs->pr_en = 1;
 610         if(fpregs->pr_qcnt != 0) {
 611                 memcpy(&fpregs->pr_q[0],
 612                        &current->thread.fpqueue[0],
 613                        sizeof(struct fpq) * fpregs->pr_qcnt);
 614         }
 615         /* Zero out the rest. */
 616         memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
 617                sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
 618         return 1;
 619 }
 620
 621 /*
 622  * sparc_execve() executes a new program after the asm stub has set
 623  * things up for us.  This should basically do what I want it to.
 624  */
 625 asmlinkage int sparc_execve(struct pt_regs *regs)
 626 {
 627         int error, base = 0;
 628         char *filename;
 629
 630         /* Check for indirect call. */
 631         if(regs->u_regs[UREG_G1] == 0)
 632                 base = 1;
 633
 634         filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
 635         error = PTR_ERR(filename);
 636         if(IS_ERR(filename))
 637                 goto out;
 638         error = do_execve(filename,
 639                           (const char __user *const  __user *)
 640                           regs->u_regs[base + UREG_I1],
 641                           (const char __user *const  __user *)
 642                           regs->u_regs[base + UREG_I2],
 643                           regs);
 644         putname(filename);
 645 out:
 646         return error;
 647 }
 648
 649 /*
 650  * This is the mechanism for creating a new kernel thread.
 651  *
 652  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 653  * who haven't done an "execve()") should use this: it will work within
 654  * a system call from a "real" process, but the process memory space will
 655  * not be freed until both the parent and the child have exited.
 656  */
 657 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 658 {
 659         long retval;
 660
 661         __asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
 662                              "mov %5, %%g3\n\t"    /* and arg. */
 663                              "mov %1, %%g1\n\t"
 664                              "mov %2, %%o0\n\t"    /* Clone flags. */
 665                              "mov 0, %%o1\n\t"     /* usp arg == 0 */
 666                              "t 0x10\n\t"          /* Linux/Sparc clone(). */
 667                              "cmp %%o1, 0\n\t"
 668                              "be 1f\n\t"           /* The parent, just return. */
 669                              " nop\n\t"            /* Delay slot. */
 670                              "jmpl %%g2, %%o7\n\t" /* Call the function. */
 671                              " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
 672                              "mov %3, %%g1\n\t"
 673                              "t 0x10\n\t"          /* Linux/Sparc exit(). */
 674                              /* Notreached by child. */
 675                              "1: mov %%o0, %0\n\t" :
 676                              "=r" (retval) :
 677                              "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
 678                              "i" (__NR_exit),  "r" (fn), "r" (arg) :
 679                              "g1", "g2", "g3", "o0", "o1", "memory", "cc");
 680         return retval;
 681 }
 682 EXPORT_SYMBOL(kernel_thread);
 683
 684 unsigned long get_wchan(struct task_struct *task)
 685 {
 686         unsigned long pc, fp, bias = 0;
 687         unsigned long task_base = (unsigned long) task;
 688         unsigned long ret = 0;
 689         struct reg_window32 *rw;
 690         int count = 0;
 691
 692         if (!task || task == current ||
 693             task->state == TASK_RUNNING)
 694                 goto out;
 695
 696         fp = task_thread_info(task)->ksp + bias;
 697         do {
 698                 /* Bogus frame pointer? */
 699                 if (fp < (task_base + sizeof(struct thread_info)) ||
 700                     fp >= (task_base + (2 * PAGE_SIZE)))
 701                         break;
 702                 rw = (struct reg_window32 *) fp;
 703                 pc = rw->ins[7];
 704                 if (!in_sched_functions(pc)) {
 705                         ret = pc;
 706                         goto out;
 707                 }
 708                 fp = rw->ins[6] + bias;
 709         } while (++count < 16);
 710
 711 out:
 712         return ret;
 713 }
 714