xref: /linux/arch/sparc/kernel/process_64.c (revision 95e9fd10f06cb5642028b6b851e32b8c8afb4571)
1 /*  arch/sparc64/kernel/process.c
2  *
3  *  Copyright (C) 1995, 1996, 2008 David S. Miller (davem@davemloft.net)
4  *  Copyright (C) 1996       Eddie C. Dost   (ecd@skynet.be)
5  *  Copyright (C) 1997, 1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
6  */
7 
8 /*
9  * This file handles the architecture-dependent parts of process handling..
10  */
11 
12 #include <stdarg.h>
13 
14 #include <linux/errno.h>
15 #include <linux/export.h>
16 #include <linux/sched.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
19 #include <linux/fs.h>
20 #include <linux/smp.h>
21 #include <linux/stddef.h>
22 #include <linux/ptrace.h>
23 #include <linux/slab.h>
24 #include <linux/user.h>
25 #include <linux/delay.h>
26 #include <linux/compat.h>
27 #include <linux/tick.h>
28 #include <linux/init.h>
29 #include <linux/cpu.h>
30 #include <linux/elfcore.h>
31 #include <linux/sysrq.h>
32 #include <linux/nmi.h>
33 
34 #include <asm/uaccess.h>
35 #include <asm/page.h>
36 #include <asm/pgalloc.h>
37 #include <asm/pgtable.h>
38 #include <asm/processor.h>
39 #include <asm/pstate.h>
40 #include <asm/elf.h>
41 #include <asm/fpumacro.h>
42 #include <asm/head.h>
43 #include <asm/cpudata.h>
44 #include <asm/mmu_context.h>
45 #include <asm/unistd.h>
46 #include <asm/hypervisor.h>
47 #include <asm/syscalls.h>
48 #include <asm/irq_regs.h>
49 #include <asm/smp.h>
50 
51 #include "kstack.h"
52 
53 static void sparc64_yield(int cpu)
54 {
55 	if (tlb_type != hypervisor) {
56 		touch_nmi_watchdog();
57 		return;
58 	}
59 
60 	clear_thread_flag(TIF_POLLING_NRFLAG);
61 	smp_mb__after_clear_bit();
62 
63 	while (!need_resched() && !cpu_is_offline(cpu)) {
64 		unsigned long pstate;
65 
66 		/* Disable interrupts. */
67 		__asm__ __volatile__(
68 			"rdpr %%pstate, %0\n\t"
69 			"andn %0, %1, %0\n\t"
70 			"wrpr %0, %%g0, %%pstate"
71 			: "=&r" (pstate)
72 			: "i" (PSTATE_IE));
73 
74 		if (!need_resched() && !cpu_is_offline(cpu))
75 			sun4v_cpu_yield();
76 
77 		/* Re-enable interrupts. */
78 		__asm__ __volatile__(
79 			"rdpr %%pstate, %0\n\t"
80 			"or %0, %1, %0\n\t"
81 			"wrpr %0, %%g0, %%pstate"
82 			: "=&r" (pstate)
83 			: "i" (PSTATE_IE));
84 	}
85 
86 	set_thread_flag(TIF_POLLING_NRFLAG);
87 }
88 
89 /* The idle loop on sparc64. */
90 void cpu_idle(void)
91 {
92 	int cpu = smp_processor_id();
93 
94 	set_thread_flag(TIF_POLLING_NRFLAG);
95 
96 	while(1) {
97 		tick_nohz_idle_enter();
98 		rcu_idle_enter();
99 
100 		while (!need_resched() && !cpu_is_offline(cpu))
101 			sparc64_yield(cpu);
102 
103 		rcu_idle_exit();
104 		tick_nohz_idle_exit();
105 
106 #ifdef CONFIG_HOTPLUG_CPU
107 		if (cpu_is_offline(cpu)) {
108 			sched_preempt_enable_no_resched();
109 			cpu_play_dead();
110 		}
111 #endif
112 		schedule_preempt_disabled();
113 	}
114 }
115 
116 #ifdef CONFIG_COMPAT
117 static void show_regwindow32(struct pt_regs *regs)
118 {
119 	struct reg_window32 __user *rw;
120 	struct reg_window32 r_w;
121 	mm_segment_t old_fs;
122 
123 	__asm__ __volatile__ ("flushw");
124 	rw = compat_ptr((unsigned)regs->u_regs[14]);
125 	old_fs = get_fs();
126 	set_fs (USER_DS);
127 	if (copy_from_user (&r_w, rw, sizeof(r_w))) {
128 		set_fs (old_fs);
129 		return;
130 	}
131 
132 	set_fs (old_fs);
133 	printk("l0: %08x l1: %08x l2: %08x l3: %08x "
134 	       "l4: %08x l5: %08x l6: %08x l7: %08x\n",
135 	       r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
136 	       r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
137 	printk("i0: %08x i1: %08x i2: %08x i3: %08x "
138 	       "i4: %08x i5: %08x i6: %08x i7: %08x\n",
139 	       r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
140 	       r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
141 }
142 #else
143 #define show_regwindow32(regs)	do { } while (0)
144 #endif
145 
146 static void show_regwindow(struct pt_regs *regs)
147 {
148 	struct reg_window __user *rw;
149 	struct reg_window *rwk;
150 	struct reg_window r_w;
151 	mm_segment_t old_fs;
152 
153 	if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
154 		__asm__ __volatile__ ("flushw");
155 		rw = (struct reg_window __user *)
156 			(regs->u_regs[14] + STACK_BIAS);
157 		rwk = (struct reg_window *)
158 			(regs->u_regs[14] + STACK_BIAS);
159 		if (!(regs->tstate & TSTATE_PRIV)) {
160 			old_fs = get_fs();
161 			set_fs (USER_DS);
162 			if (copy_from_user (&r_w, rw, sizeof(r_w))) {
163 				set_fs (old_fs);
164 				return;
165 			}
166 			rwk = &r_w;
167 			set_fs (old_fs);
168 		}
169 	} else {
170 		show_regwindow32(regs);
171 		return;
172 	}
173 	printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
174 	       rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
175 	printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
176 	       rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
177 	printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
178 	       rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
179 	printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
180 	       rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
181 	if (regs->tstate & TSTATE_PRIV)
182 		printk("I7: <%pS>\n", (void *) rwk->ins[7]);
183 }
184 
185 void show_regs(struct pt_regs *regs)
186 {
187 	printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x    %s\n", regs->tstate,
188 	       regs->tpc, regs->tnpc, regs->y, print_tainted());
189 	printk("TPC: <%pS>\n", (void *) regs->tpc);
190 	printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
191 	       regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
192 	       regs->u_regs[3]);
193 	printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
194 	       regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
195 	       regs->u_regs[7]);
196 	printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
197 	       regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
198 	       regs->u_regs[11]);
199 	printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
200 	       regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
201 	       regs->u_regs[15]);
202 	printk("RPC: <%pS>\n", (void *) regs->u_regs[15]);
203 	show_regwindow(regs);
204 	show_stack(current, (unsigned long *) regs->u_regs[UREG_FP]);
205 }
206 
207 struct global_reg_snapshot global_reg_snapshot[NR_CPUS];
208 static DEFINE_SPINLOCK(global_reg_snapshot_lock);
209 
210 static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
211 			      int this_cpu)
212 {
213 	flushw_all();
214 
215 	global_reg_snapshot[this_cpu].tstate = regs->tstate;
216 	global_reg_snapshot[this_cpu].tpc = regs->tpc;
217 	global_reg_snapshot[this_cpu].tnpc = regs->tnpc;
218 	global_reg_snapshot[this_cpu].o7 = regs->u_regs[UREG_I7];
219 
220 	if (regs->tstate & TSTATE_PRIV) {
221 		struct reg_window *rw;
222 
223 		rw = (struct reg_window *)
224 			(regs->u_regs[UREG_FP] + STACK_BIAS);
225 		if (kstack_valid(tp, (unsigned long) rw)) {
226 			global_reg_snapshot[this_cpu].i7 = rw->ins[7];
227 			rw = (struct reg_window *)
228 				(rw->ins[6] + STACK_BIAS);
229 			if (kstack_valid(tp, (unsigned long) rw))
230 				global_reg_snapshot[this_cpu].rpc = rw->ins[7];
231 		}
232 	} else {
233 		global_reg_snapshot[this_cpu].i7 = 0;
234 		global_reg_snapshot[this_cpu].rpc = 0;
235 	}
236 	global_reg_snapshot[this_cpu].thread = tp;
237 }
238 
239 /* In order to avoid hangs we do not try to synchronize with the
240  * global register dump client cpus.  The last store they make is to
241  * the thread pointer, so do a short poll waiting for that to become
242  * non-NULL.
243  */
244 static void __global_reg_poll(struct global_reg_snapshot *gp)
245 {
246 	int limit = 0;
247 
248 	while (!gp->thread && ++limit < 100) {
249 		barrier();
250 		udelay(1);
251 	}
252 }
253 
254 void arch_trigger_all_cpu_backtrace(void)
255 {
256 	struct thread_info *tp = current_thread_info();
257 	struct pt_regs *regs = get_irq_regs();
258 	unsigned long flags;
259 	int this_cpu, cpu;
260 
261 	if (!regs)
262 		regs = tp->kregs;
263 
264 	spin_lock_irqsave(&global_reg_snapshot_lock, flags);
265 
266 	memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));
267 
268 	this_cpu = raw_smp_processor_id();
269 
270 	__global_reg_self(tp, regs, this_cpu);
271 
272 	smp_fetch_global_regs();
273 
274 	for_each_online_cpu(cpu) {
275 		struct global_reg_snapshot *gp = &global_reg_snapshot[cpu];
276 
277 		__global_reg_poll(gp);
278 
279 		tp = gp->thread;
280 		printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n",
281 		       (cpu == this_cpu ? '*' : ' '), cpu,
282 		       gp->tstate, gp->tpc, gp->tnpc,
283 		       ((tp && tp->task) ? tp->task->comm : "NULL"),
284 		       ((tp && tp->task) ? tp->task->pid : -1));
285 
286 		if (gp->tstate & TSTATE_PRIV) {
287 			printk("             TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
288 			       (void *) gp->tpc,
289 			       (void *) gp->o7,
290 			       (void *) gp->i7,
291 			       (void *) gp->rpc);
292 		} else {
293 			printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
294 			       gp->tpc, gp->o7, gp->i7, gp->rpc);
295 		}
296 	}
297 
298 	memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));
299 
300 	spin_unlock_irqrestore(&global_reg_snapshot_lock, flags);
301 }
302 
303 #ifdef CONFIG_MAGIC_SYSRQ
304 
305 static void sysrq_handle_globreg(int key)
306 {
307 	arch_trigger_all_cpu_backtrace();
308 }
309 
310 static struct sysrq_key_op sparc_globalreg_op = {
311 	.handler	= sysrq_handle_globreg,
312 	.help_msg	= "Globalregs",
313 	.action_msg	= "Show Global CPU Regs",
314 };
315 
316 static int __init sparc_globreg_init(void)
317 {
318 	return register_sysrq_key('y', &sparc_globalreg_op);
319 }
320 
321 core_initcall(sparc_globreg_init);
322 
323 #endif
324 
325 unsigned long thread_saved_pc(struct task_struct *tsk)
326 {
327 	struct thread_info *ti = task_thread_info(tsk);
328 	unsigned long ret = 0xdeadbeefUL;
329 
330 	if (ti && ti->ksp) {
331 		unsigned long *sp;
332 		sp = (unsigned long *)(ti->ksp + STACK_BIAS);
333 		if (((unsigned long)sp & (sizeof(long) - 1)) == 0UL &&
334 		    sp[14]) {
335 			unsigned long *fp;
336 			fp = (unsigned long *)(sp[14] + STACK_BIAS);
337 			if (((unsigned long)fp & (sizeof(long) - 1)) == 0UL)
338 				ret = fp[15];
339 		}
340 	}
341 	return ret;
342 }
343 
344 /* Free current thread data structures etc.. */
345 void exit_thread(void)
346 {
347 	struct thread_info *t = current_thread_info();
348 
349 	if (t->utraps) {
350 		if (t->utraps[0] < 2)
351 			kfree (t->utraps);
352 		else
353 			t->utraps[0]--;
354 	}
355 }
356 
357 void flush_thread(void)
358 {
359 	struct thread_info *t = current_thread_info();
360 	struct mm_struct *mm;
361 
362 	mm = t->task->mm;
363 	if (mm)
364 		tsb_context_switch(mm);
365 
366 	set_thread_wsaved(0);
367 
368 	/* Clear FPU register state. */
369 	t->fpsaved[0] = 0;
370 }
371 
372 /* It's a bit more tricky when 64-bit tasks are involved... */
373 static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
374 {
375 	unsigned long fp, distance, rval;
376 
377 	if (!(test_thread_flag(TIF_32BIT))) {
378 		csp += STACK_BIAS;
379 		psp += STACK_BIAS;
380 		__get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
381 		fp += STACK_BIAS;
382 	} else
383 		__get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));
384 
385 	/* Now align the stack as this is mandatory in the Sparc ABI
386 	 * due to how register windows work.  This hides the
387 	 * restriction from thread libraries etc.
388 	 */
389 	csp &= ~15UL;
390 
391 	distance = fp - psp;
392 	rval = (csp - distance);
393 	if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
394 		rval = 0;
395 	else if (test_thread_flag(TIF_32BIT)) {
396 		if (put_user(((u32)csp),
397 			     &(((struct reg_window32 __user *)rval)->ins[6])))
398 			rval = 0;
399 	} else {
400 		if (put_user(((u64)csp - STACK_BIAS),
401 			     &(((struct reg_window __user *)rval)->ins[6])))
402 			rval = 0;
403 		else
404 			rval = rval - STACK_BIAS;
405 	}
406 
407 	return rval;
408 }
409 
410 /* Standard stuff. */
411 static inline void shift_window_buffer(int first_win, int last_win,
412 				       struct thread_info *t)
413 {
414 	int i;
415 
416 	for (i = first_win; i < last_win; i++) {
417 		t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
418 		memcpy(&t->reg_window[i], &t->reg_window[i+1],
419 		       sizeof(struct reg_window));
420 	}
421 }
422 
423 void synchronize_user_stack(void)
424 {
425 	struct thread_info *t = current_thread_info();
426 	unsigned long window;
427 
428 	flush_user_windows();
429 	if ((window = get_thread_wsaved()) != 0) {
430 		int winsize = sizeof(struct reg_window);
431 		int bias = 0;
432 
433 		if (test_thread_flag(TIF_32BIT))
434 			winsize = sizeof(struct reg_window32);
435 		else
436 			bias = STACK_BIAS;
437 
438 		window -= 1;
439 		do {
440 			unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
441 			struct reg_window *rwin = &t->reg_window[window];
442 
443 			if (!copy_to_user((char __user *)sp, rwin, winsize)) {
444 				shift_window_buffer(window, get_thread_wsaved() - 1, t);
445 				set_thread_wsaved(get_thread_wsaved() - 1);
446 			}
447 		} while (window--);
448 	}
449 }
450 
451 static void stack_unaligned(unsigned long sp)
452 {
453 	siginfo_t info;
454 
455 	info.si_signo = SIGBUS;
456 	info.si_errno = 0;
457 	info.si_code = BUS_ADRALN;
458 	info.si_addr = (void __user *) sp;
459 	info.si_trapno = 0;
460 	force_sig_info(SIGBUS, &info, current);
461 }
462 
463 void fault_in_user_windows(void)
464 {
465 	struct thread_info *t = current_thread_info();
466 	unsigned long window;
467 	int winsize = sizeof(struct reg_window);
468 	int bias = 0;
469 
470 	if (test_thread_flag(TIF_32BIT))
471 		winsize = sizeof(struct reg_window32);
472 	else
473 		bias = STACK_BIAS;
474 
475 	flush_user_windows();
476 	window = get_thread_wsaved();
477 
478 	if (likely(window != 0)) {
479 		window -= 1;
480 		do {
481 			unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
482 			struct reg_window *rwin = &t->reg_window[window];
483 
484 			if (unlikely(sp & 0x7UL))
485 				stack_unaligned(sp);
486 
487 			if (unlikely(copy_to_user((char __user *)sp,
488 						  rwin, winsize)))
489 				goto barf;
490 		} while (window--);
491 	}
492 	set_thread_wsaved(0);
493 	return;
494 
495 barf:
496 	set_thread_wsaved(window + 1);
497 	do_exit(SIGILL);
498 }
499 
500 asmlinkage long sparc_do_fork(unsigned long clone_flags,
501 			      unsigned long stack_start,
502 			      struct pt_regs *regs,
503 			      unsigned long stack_size)
504 {
505 	int __user *parent_tid_ptr, *child_tid_ptr;
506 	unsigned long orig_i1 = regs->u_regs[UREG_I1];
507 	long ret;
508 
509 #ifdef CONFIG_COMPAT
510 	if (test_thread_flag(TIF_32BIT)) {
511 		parent_tid_ptr = compat_ptr(regs->u_regs[UREG_I2]);
512 		child_tid_ptr = compat_ptr(regs->u_regs[UREG_I4]);
513 	} else
514 #endif
515 	{
516 		parent_tid_ptr = (int __user *) regs->u_regs[UREG_I2];
517 		child_tid_ptr = (int __user *) regs->u_regs[UREG_I4];
518 	}
519 
520 	ret = do_fork(clone_flags, stack_start,
521 		      regs, stack_size,
522 		      parent_tid_ptr, child_tid_ptr);
523 
524 	/* If we get an error and potentially restart the system
525 	 * call, we're screwed because copy_thread() clobbered
526 	 * the parent's %o1.  So detect that case and restore it
527 	 * here.
528 	 */
529 	if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
530 		regs->u_regs[UREG_I1] = orig_i1;
531 
532 	return ret;
533 }
534 
535 /* Copy a Sparc thread.  The fork() return value conventions
536  * under SunOS are nothing short of bletcherous:
537  * Parent -->  %o0 == childs  pid, %o1 == 0
538  * Child  -->  %o0 == parents pid, %o1 == 1
539  */
540 int copy_thread(unsigned long clone_flags, unsigned long sp,
541 		unsigned long unused,
542 		struct task_struct *p, struct pt_regs *regs)
543 {
544 	struct thread_info *t = task_thread_info(p);
545 	struct sparc_stackf *parent_sf;
546 	unsigned long child_stack_sz;
547 	char *child_trap_frame;
548 	int kernel_thread;
549 
550 	kernel_thread = (regs->tstate & TSTATE_PRIV) ? 1 : 0;
551 	parent_sf = ((struct sparc_stackf *) regs) - 1;
552 
553 	/* Calculate offset to stack_frame & pt_regs */
554 	child_stack_sz = ((STACKFRAME_SZ + TRACEREG_SZ) +
555 			  (kernel_thread ? STACKFRAME_SZ : 0));
556 	child_trap_frame = (task_stack_page(p) +
557 			    (THREAD_SIZE - child_stack_sz));
558 	memcpy(child_trap_frame, parent_sf, child_stack_sz);
559 
560 	t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) |
561 				 (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |
562 		(((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);
563 	t->new_child = 1;
564 	t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
565 	t->kregs = (struct pt_regs *) (child_trap_frame +
566 				       sizeof(struct sparc_stackf));
567 	t->fpsaved[0] = 0;
568 
569 	if (kernel_thread) {
570 		struct sparc_stackf *child_sf = (struct sparc_stackf *)
571 			(child_trap_frame + (STACKFRAME_SZ + TRACEREG_SZ));
572 
573 		/* Zero terminate the stack backtrace.  */
574 		child_sf->fp = NULL;
575 		t->kregs->u_regs[UREG_FP] =
576 		  ((unsigned long) child_sf) - STACK_BIAS;
577 
578 		t->flags |= ((long)ASI_P << TI_FLAG_CURRENT_DS_SHIFT);
579 		t->kregs->u_regs[UREG_G6] = (unsigned long) t;
580 		t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
581 	} else {
582 		if (t->flags & _TIF_32BIT) {
583 			sp &= 0x00000000ffffffffUL;
584 			regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
585 		}
586 		t->kregs->u_regs[UREG_FP] = sp;
587 		t->flags |= ((long)ASI_AIUS << TI_FLAG_CURRENT_DS_SHIFT);
588 		if (sp != regs->u_regs[UREG_FP]) {
589 			unsigned long csp;
590 
591 			csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
592 			if (!csp)
593 				return -EFAULT;
594 			t->kregs->u_regs[UREG_FP] = csp;
595 		}
596 		if (t->utraps)
597 			t->utraps[0]++;
598 	}
599 
600 	/* Set the return value for the child. */
601 	t->kregs->u_regs[UREG_I0] = current->pid;
602 	t->kregs->u_regs[UREG_I1] = 1;
603 
604 	/* Set the second return value for the parent. */
605 	regs->u_regs[UREG_I1] = 0;
606 
607 	if (clone_flags & CLONE_SETTLS)
608 		t->kregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];
609 
610 	return 0;
611 }
612 
613 /*
614  * This is the mechanism for creating a new kernel thread.
615  *
616  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
617  * who haven't done an "execve()") should use this: it will work within
618  * a system call from a "real" process, but the process memory space will
619  * not be freed until both the parent and the child have exited.
620  */
621 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
622 {
623 	long retval;
624 
625 	/* If the parent runs before fn(arg) is called by the child,
626 	 * the input registers of this function can be clobbered.
627 	 * So we stash 'fn' and 'arg' into global registers which
628 	 * will not be modified by the parent.
629 	 */
630 	__asm__ __volatile__("mov %4, %%g2\n\t"	   /* Save FN into global */
631 			     "mov %5, %%g3\n\t"	   /* Save ARG into global */
632 			     "mov %1, %%g1\n\t"	   /* Clone syscall nr. */
633 			     "mov %2, %%o0\n\t"	   /* Clone flags. */
634 			     "mov 0, %%o1\n\t"	   /* usp arg == 0 */
635 			     "t 0x6d\n\t"	   /* Linux/Sparc clone(). */
636 			     "brz,a,pn %%o1, 1f\n\t" /* Parent, just return. */
637 			     " mov %%o0, %0\n\t"
638 			     "jmpl %%g2, %%o7\n\t"   /* Call the function. */
639 			     " mov %%g3, %%o0\n\t"   /* Set arg in delay. */
640 			     "mov %3, %%g1\n\t"
641 			     "t 0x6d\n\t"	   /* Linux/Sparc exit(). */
642 			     /* Notreached by child. */
643 			     "1:" :
644 			     "=r" (retval) :
645 			     "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
646 			     "i" (__NR_exit),  "r" (fn), "r" (arg) :
647 			     "g1", "g2", "g3", "o0", "o1", "memory", "cc");
648 	return retval;
649 }
650 EXPORT_SYMBOL(kernel_thread);
651 
652 typedef struct {
653 	union {
654 		unsigned int	pr_regs[32];
655 		unsigned long	pr_dregs[16];
656 	} pr_fr;
657 	unsigned int __unused;
658 	unsigned int	pr_fsr;
659 	unsigned char	pr_qcnt;
660 	unsigned char	pr_q_entrysize;
661 	unsigned char	pr_en;
662 	unsigned int	pr_q[64];
663 } elf_fpregset_t32;
664 
665 /*
666  * fill in the fpu structure for a core dump.
667  */
668 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
669 {
670 	unsigned long *kfpregs = current_thread_info()->fpregs;
671 	unsigned long fprs = current_thread_info()->fpsaved[0];
672 
673 	if (test_thread_flag(TIF_32BIT)) {
674 		elf_fpregset_t32 *fpregs32 = (elf_fpregset_t32 *)fpregs;
675 
676 		if (fprs & FPRS_DL)
677 			memcpy(&fpregs32->pr_fr.pr_regs[0], kfpregs,
678 			       sizeof(unsigned int) * 32);
679 		else
680 			memset(&fpregs32->pr_fr.pr_regs[0], 0,
681 			       sizeof(unsigned int) * 32);
682 		fpregs32->pr_qcnt = 0;
683 		fpregs32->pr_q_entrysize = 8;
684 		memset(&fpregs32->pr_q[0], 0,
685 		       (sizeof(unsigned int) * 64));
686 		if (fprs & FPRS_FEF) {
687 			fpregs32->pr_fsr = (unsigned int) current_thread_info()->xfsr[0];
688 			fpregs32->pr_en = 1;
689 		} else {
690 			fpregs32->pr_fsr = 0;
691 			fpregs32->pr_en = 0;
692 		}
693 	} else {
694 		if(fprs & FPRS_DL)
695 			memcpy(&fpregs->pr_regs[0], kfpregs,
696 			       sizeof(unsigned int) * 32);
697 		else
698 			memset(&fpregs->pr_regs[0], 0,
699 			       sizeof(unsigned int) * 32);
700 		if(fprs & FPRS_DU)
701 			memcpy(&fpregs->pr_regs[16], kfpregs+16,
702 			       sizeof(unsigned int) * 32);
703 		else
704 			memset(&fpregs->pr_regs[16], 0,
705 			       sizeof(unsigned int) * 32);
706 		if(fprs & FPRS_FEF) {
707 			fpregs->pr_fsr = current_thread_info()->xfsr[0];
708 			fpregs->pr_gsr = current_thread_info()->gsr[0];
709 		} else {
710 			fpregs->pr_fsr = fpregs->pr_gsr = 0;
711 		}
712 		fpregs->pr_fprs = fprs;
713 	}
714 	return 1;
715 }
716 EXPORT_SYMBOL(dump_fpu);
717 
718 /*
719  * sparc_execve() executes a new program after the asm stub has set
720  * things up for us.  This should basically do what I want it to.
721  */
722 asmlinkage int sparc_execve(struct pt_regs *regs)
723 {
724 	int error, base = 0;
725 	char *filename;
726 
727 	/* User register window flush is done by entry.S */
728 
729 	/* Check for indirect call. */
730 	if (regs->u_regs[UREG_G1] == 0)
731 		base = 1;
732 
733 	filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
734 	error = PTR_ERR(filename);
735 	if (IS_ERR(filename))
736 		goto out;
737 	error = do_execve(filename,
738 			  (const char __user *const __user *)
739 			  regs->u_regs[base + UREG_I1],
740 			  (const char __user *const __user *)
741 			  regs->u_regs[base + UREG_I2], regs);
742 	putname(filename);
743 	if (!error) {
744 		fprs_write(0);
745 		current_thread_info()->xfsr[0] = 0;
746 		current_thread_info()->fpsaved[0] = 0;
747 		regs->tstate &= ~TSTATE_PEF;
748 	}
749 out:
750 	return error;
751 }
752 
753 unsigned long get_wchan(struct task_struct *task)
754 {
755 	unsigned long pc, fp, bias = 0;
756 	struct thread_info *tp;
757 	struct reg_window *rw;
758         unsigned long ret = 0;
759 	int count = 0;
760 
761 	if (!task || task == current ||
762             task->state == TASK_RUNNING)
763 		goto out;
764 
765 	tp = task_thread_info(task);
766 	bias = STACK_BIAS;
767 	fp = task_thread_info(task)->ksp + bias;
768 
769 	do {
770 		if (!kstack_valid(tp, fp))
771 			break;
772 		rw = (struct reg_window *) fp;
773 		pc = rw->ins[7];
774 		if (!in_sched_functions(pc)) {
775 			ret = pc;
776 			goto out;
777 		}
778 		fp = rw->ins[6] + bias;
779 	} while (++count < 16);
780 
781 out:
782 	return ret;
783 }
784