Make do_execve() take a const filename pointer
[linux-3.10.git] / 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/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 & ~0xfUL);
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                           (const char __user *const  __user *)
637                           regs->u_regs[base + UREG_I1],
638                           (const char __user *const  __user *)
639                           regs->u_regs[base + UREG_I2],
640                           regs);
641         putname(filename);
642 out:
643         return error;
644 }
645
646 /*
647  * This is the mechanism for creating a new kernel thread.
648  *
649  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
650  * who haven't done an "execve()") should use this: it will work within
651  * a system call from a "real" process, but the process memory space will
652  * not be freed until both the parent and the child have exited.
653  */
654 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
655 {
656         long retval;
657
658         __asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
659                              "mov %5, %%g3\n\t"    /* and arg. */
660                              "mov %1, %%g1\n\t"
661                              "mov %2, %%o0\n\t"    /* Clone flags. */
662                              "mov 0, %%o1\n\t"     /* usp arg == 0 */
663                              "t 0x10\n\t"          /* Linux/Sparc clone(). */
664                              "cmp %%o1, 0\n\t"
665                              "be 1f\n\t"           /* The parent, just return. */
666                              " nop\n\t"            /* Delay slot. */
667                              "jmpl %%g2, %%o7\n\t" /* Call the function. */
668                              " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
669                              "mov %3, %%g1\n\t"
670                              "t 0x10\n\t"          /* Linux/Sparc exit(). */
671                              /* Notreached by child. */
672                              "1: mov %%o0, %0\n\t" :
673                              "=r" (retval) :
674                              "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
675                              "i" (__NR_exit),  "r" (fn), "r" (arg) :
676                              "g1", "g2", "g3", "o0", "o1", "memory", "cc");
677         return retval;
678 }
679 EXPORT_SYMBOL(kernel_thread);
680
681 unsigned long get_wchan(struct task_struct *task)
682 {
683         unsigned long pc, fp, bias = 0;
684         unsigned long task_base = (unsigned long) task;
685         unsigned long ret = 0;
686         struct reg_window32 *rw;
687         int count = 0;
688
689         if (!task || task == current ||
690             task->state == TASK_RUNNING)
691                 goto out;
692
693         fp = task_thread_info(task)->ksp + bias;
694         do {
695                 /* Bogus frame pointer? */
696                 if (fp < (task_base + sizeof(struct thread_info)) ||
697                     fp >= (task_base + (2 * PAGE_SIZE)))
698                         break;
699                 rw = (struct reg_window32 *) fp;
700                 pc = rw->ins[7];
701                 if (!in_sched_functions(pc)) {
702                         ret = pc;
703                         goto out;
704                 }
705                 fp = rw->ins[6] + bias;
706         } while (++count < 16);
707
708 out:
709         return ret;
710 }
711