xref: /linux/arch/sparc/kernel/process_64.c (revision 1268fbc746ea1cd279886a740dcbad4ba5232225)
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/system.h>
36 #include <asm/page.h>
37 #include <asm/pgalloc.h>
38 #include <asm/pgtable.h>
39 #include <asm/processor.h>
40 #include <asm/pstate.h>
41 #include <asm/elf.h>
42 #include <asm/fpumacro.h>
43 #include <asm/head.h>
44 #include <asm/cpudata.h>
45 #include <asm/mmu_context.h>
46 #include <asm/unistd.h>
47 #include <asm/hypervisor.h>
48 #include <asm/syscalls.h>
49 #include <asm/irq_regs.h>
50 #include <asm/smp.h>
51 
52 #include "kstack.h"
53 
54 static void sparc64_yield(int cpu)
55 {
56 	if (tlb_type != hypervisor) {
57 		touch_nmi_watchdog();
58 		return;
59 	}
60 
61 	clear_thread_flag(TIF_POLLING_NRFLAG);
62 	smp_mb__after_clear_bit();
63 
64 	while (!need_resched() && !cpu_is_offline(cpu)) {
65 		unsigned long pstate;
66 
67 		/* Disable interrupts. */
68 		__asm__ __volatile__(
69 			"rdpr %%pstate, %0\n\t"
70 			"andn %0, %1, %0\n\t"
71 			"wrpr %0, %%g0, %%pstate"
72 			: "=&r" (pstate)
73 			: "i" (PSTATE_IE));
74 
75 		if (!need_resched() && !cpu_is_offline(cpu))
76 			sun4v_cpu_yield();
77 
78 		/* Re-enable interrupts. */
79 		__asm__ __volatile__(
80 			"rdpr %%pstate, %0\n\t"
81 			"or %0, %1, %0\n\t"
82 			"wrpr %0, %%g0, %%pstate"
83 			: "=&r" (pstate)
84 			: "i" (PSTATE_IE));
85 	}
86 
87 	set_thread_flag(TIF_POLLING_NRFLAG);
88 }
89 
90 /* The idle loop on sparc64. */
91 void cpu_idle(void)
92 {
93 	int cpu = smp_processor_id();
94 
95 	set_thread_flag(TIF_POLLING_NRFLAG);
96 
97 	while(1) {
98 		tick_nohz_idle_enter();
99 		rcu_idle_enter();
100 
101 		while (!need_resched() && !cpu_is_offline(cpu))
102 			sparc64_yield(cpu);
103 
104 		rcu_idle_exit();
105 		tick_nohz_idle_exit();
106 
107 		preempt_enable_no_resched();
108 
109 #ifdef CONFIG_HOTPLUG_CPU
110 		if (cpu_is_offline(cpu))
111 			cpu_play_dead();
112 #endif
113 
114 		schedule();
115 		preempt_disable();
116 	}
117 }
118 
119 #ifdef CONFIG_COMPAT
120 static void show_regwindow32(struct pt_regs *regs)
121 {
122 	struct reg_window32 __user *rw;
123 	struct reg_window32 r_w;
124 	mm_segment_t old_fs;
125 
126 	__asm__ __volatile__ ("flushw");
127 	rw = compat_ptr((unsigned)regs->u_regs[14]);
128 	old_fs = get_fs();
129 	set_fs (USER_DS);
130 	if (copy_from_user (&r_w, rw, sizeof(r_w))) {
131 		set_fs (old_fs);
132 		return;
133 	}
134 
135 	set_fs (old_fs);
136 	printk("l0: %08x l1: %08x l2: %08x l3: %08x "
137 	       "l4: %08x l5: %08x l6: %08x l7: %08x\n",
138 	       r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
139 	       r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
140 	printk("i0: %08x i1: %08x i2: %08x i3: %08x "
141 	       "i4: %08x i5: %08x i6: %08x i7: %08x\n",
142 	       r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
143 	       r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
144 }
145 #else
146 #define show_regwindow32(regs)	do { } while (0)
147 #endif
148 
149 static void show_regwindow(struct pt_regs *regs)
150 {
151 	struct reg_window __user *rw;
152 	struct reg_window *rwk;
153 	struct reg_window r_w;
154 	mm_segment_t old_fs;
155 
156 	if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
157 		__asm__ __volatile__ ("flushw");
158 		rw = (struct reg_window __user *)
159 			(regs->u_regs[14] + STACK_BIAS);
160 		rwk = (struct reg_window *)
161 			(regs->u_regs[14] + STACK_BIAS);
162 		if (!(regs->tstate & TSTATE_PRIV)) {
163 			old_fs = get_fs();
164 			set_fs (USER_DS);
165 			if (copy_from_user (&r_w, rw, sizeof(r_w))) {
166 				set_fs (old_fs);
167 				return;
168 			}
169 			rwk = &r_w;
170 			set_fs (old_fs);
171 		}
172 	} else {
173 		show_regwindow32(regs);
174 		return;
175 	}
176 	printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
177 	       rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
178 	printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
179 	       rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
180 	printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
181 	       rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
182 	printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
183 	       rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
184 	if (regs->tstate & TSTATE_PRIV)
185 		printk("I7: <%pS>\n", (void *) rwk->ins[7]);
186 }
187 
188 void show_regs(struct pt_regs *regs)
189 {
190 	printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x    %s\n", regs->tstate,
191 	       regs->tpc, regs->tnpc, regs->y, print_tainted());
192 	printk("TPC: <%pS>\n", (void *) regs->tpc);
193 	printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
194 	       regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
195 	       regs->u_regs[3]);
196 	printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
197 	       regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
198 	       regs->u_regs[7]);
199 	printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
200 	       regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
201 	       regs->u_regs[11]);
202 	printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
203 	       regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
204 	       regs->u_regs[15]);
205 	printk("RPC: <%pS>\n", (void *) regs->u_regs[15]);
206 	show_regwindow(regs);
207 	show_stack(current, (unsigned long *) regs->u_regs[UREG_FP]);
208 }
209 
210 struct global_reg_snapshot global_reg_snapshot[NR_CPUS];
211 static DEFINE_SPINLOCK(global_reg_snapshot_lock);
212 
213 static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
214 			      int this_cpu)
215 {
216 	flushw_all();
217 
218 	global_reg_snapshot[this_cpu].tstate = regs->tstate;
219 	global_reg_snapshot[this_cpu].tpc = regs->tpc;
220 	global_reg_snapshot[this_cpu].tnpc = regs->tnpc;
221 	global_reg_snapshot[this_cpu].o7 = regs->u_regs[UREG_I7];
222 
223 	if (regs->tstate & TSTATE_PRIV) {
224 		struct reg_window *rw;
225 
226 		rw = (struct reg_window *)
227 			(regs->u_regs[UREG_FP] + STACK_BIAS);
228 		if (kstack_valid(tp, (unsigned long) rw)) {
229 			global_reg_snapshot[this_cpu].i7 = rw->ins[7];
230 			rw = (struct reg_window *)
231 				(rw->ins[6] + STACK_BIAS);
232 			if (kstack_valid(tp, (unsigned long) rw))
233 				global_reg_snapshot[this_cpu].rpc = rw->ins[7];
234 		}
235 	} else {
236 		global_reg_snapshot[this_cpu].i7 = 0;
237 		global_reg_snapshot[this_cpu].rpc = 0;
238 	}
239 	global_reg_snapshot[this_cpu].thread = tp;
240 }
241 
242 /* In order to avoid hangs we do not try to synchronize with the
243  * global register dump client cpus.  The last store they make is to
244  * the thread pointer, so do a short poll waiting for that to become
245  * non-NULL.
246  */
247 static void __global_reg_poll(struct global_reg_snapshot *gp)
248 {
249 	int limit = 0;
250 
251 	while (!gp->thread && ++limit < 100) {
252 		barrier();
253 		udelay(1);
254 	}
255 }
256 
257 void arch_trigger_all_cpu_backtrace(void)
258 {
259 	struct thread_info *tp = current_thread_info();
260 	struct pt_regs *regs = get_irq_regs();
261 	unsigned long flags;
262 	int this_cpu, cpu;
263 
264 	if (!regs)
265 		regs = tp->kregs;
266 
267 	spin_lock_irqsave(&global_reg_snapshot_lock, flags);
268 
269 	memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));
270 
271 	this_cpu = raw_smp_processor_id();
272 
273 	__global_reg_self(tp, regs, this_cpu);
274 
275 	smp_fetch_global_regs();
276 
277 	for_each_online_cpu(cpu) {
278 		struct global_reg_snapshot *gp = &global_reg_snapshot[cpu];
279 
280 		__global_reg_poll(gp);
281 
282 		tp = gp->thread;
283 		printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n",
284 		       (cpu == this_cpu ? '*' : ' '), cpu,
285 		       gp->tstate, gp->tpc, gp->tnpc,
286 		       ((tp && tp->task) ? tp->task->comm : "NULL"),
287 		       ((tp && tp->task) ? tp->task->pid : -1));
288 
289 		if (gp->tstate & TSTATE_PRIV) {
290 			printk("             TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
291 			       (void *) gp->tpc,
292 			       (void *) gp->o7,
293 			       (void *) gp->i7,
294 			       (void *) gp->rpc);
295 		} else {
296 			printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
297 			       gp->tpc, gp->o7, gp->i7, gp->rpc);
298 		}
299 	}
300 
301 	memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));
302 
303 	spin_unlock_irqrestore(&global_reg_snapshot_lock, flags);
304 }
305 
306 #ifdef CONFIG_MAGIC_SYSRQ
307 
308 static void sysrq_handle_globreg(int key)
309 {
310 	arch_trigger_all_cpu_backtrace();
311 }
312 
313 static struct sysrq_key_op sparc_globalreg_op = {
314 	.handler	= sysrq_handle_globreg,
315 	.help_msg	= "Globalregs",
316 	.action_msg	= "Show Global CPU Regs",
317 };
318 
319 static int __init sparc_globreg_init(void)
320 {
321 	return register_sysrq_key('y', &sparc_globalreg_op);
322 }
323 
324 core_initcall(sparc_globreg_init);
325 
326 #endif
327 
328 unsigned long thread_saved_pc(struct task_struct *tsk)
329 {
330 	struct thread_info *ti = task_thread_info(tsk);
331 	unsigned long ret = 0xdeadbeefUL;
332 
333 	if (ti && ti->ksp) {
334 		unsigned long *sp;
335 		sp = (unsigned long *)(ti->ksp + STACK_BIAS);
336 		if (((unsigned long)sp & (sizeof(long) - 1)) == 0UL &&
337 		    sp[14]) {
338 			unsigned long *fp;
339 			fp = (unsigned long *)(sp[14] + STACK_BIAS);
340 			if (((unsigned long)fp & (sizeof(long) - 1)) == 0UL)
341 				ret = fp[15];
342 		}
343 	}
344 	return ret;
345 }
346 
347 /* Free current thread data structures etc.. */
348 void exit_thread(void)
349 {
350 	struct thread_info *t = current_thread_info();
351 
352 	if (t->utraps) {
353 		if (t->utraps[0] < 2)
354 			kfree (t->utraps);
355 		else
356 			t->utraps[0]--;
357 	}
358 }
359 
360 void flush_thread(void)
361 {
362 	struct thread_info *t = current_thread_info();
363 	struct mm_struct *mm;
364 
365 	mm = t->task->mm;
366 	if (mm)
367 		tsb_context_switch(mm);
368 
369 	set_thread_wsaved(0);
370 
371 	/* Clear FPU register state. */
372 	t->fpsaved[0] = 0;
373 }
374 
375 /* It's a bit more tricky when 64-bit tasks are involved... */
376 static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
377 {
378 	unsigned long fp, distance, rval;
379 
380 	if (!(test_thread_flag(TIF_32BIT))) {
381 		csp += STACK_BIAS;
382 		psp += STACK_BIAS;
383 		__get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
384 		fp += STACK_BIAS;
385 	} else
386 		__get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));
387 
388 	/* Now align the stack as this is mandatory in the Sparc ABI
389 	 * due to how register windows work.  This hides the
390 	 * restriction from thread libraries etc.
391 	 */
392 	csp &= ~15UL;
393 
394 	distance = fp - psp;
395 	rval = (csp - distance);
396 	if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
397 		rval = 0;
398 	else if (test_thread_flag(TIF_32BIT)) {
399 		if (put_user(((u32)csp),
400 			     &(((struct reg_window32 __user *)rval)->ins[6])))
401 			rval = 0;
402 	} else {
403 		if (put_user(((u64)csp - STACK_BIAS),
404 			     &(((struct reg_window __user *)rval)->ins[6])))
405 			rval = 0;
406 		else
407 			rval = rval - STACK_BIAS;
408 	}
409 
410 	return rval;
411 }
412 
413 /* Standard stuff. */
414 static inline void shift_window_buffer(int first_win, int last_win,
415 				       struct thread_info *t)
416 {
417 	int i;
418 
419 	for (i = first_win; i < last_win; i++) {
420 		t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
421 		memcpy(&t->reg_window[i], &t->reg_window[i+1],
422 		       sizeof(struct reg_window));
423 	}
424 }
425 
426 void synchronize_user_stack(void)
427 {
428 	struct thread_info *t = current_thread_info();
429 	unsigned long window;
430 
431 	flush_user_windows();
432 	if ((window = get_thread_wsaved()) != 0) {
433 		int winsize = sizeof(struct reg_window);
434 		int bias = 0;
435 
436 		if (test_thread_flag(TIF_32BIT))
437 			winsize = sizeof(struct reg_window32);
438 		else
439 			bias = STACK_BIAS;
440 
441 		window -= 1;
442 		do {
443 			unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
444 			struct reg_window *rwin = &t->reg_window[window];
445 
446 			if (!copy_to_user((char __user *)sp, rwin, winsize)) {
447 				shift_window_buffer(window, get_thread_wsaved() - 1, t);
448 				set_thread_wsaved(get_thread_wsaved() - 1);
449 			}
450 		} while (window--);
451 	}
452 }
453 
454 static void stack_unaligned(unsigned long sp)
455 {
456 	siginfo_t info;
457 
458 	info.si_signo = SIGBUS;
459 	info.si_errno = 0;
460 	info.si_code = BUS_ADRALN;
461 	info.si_addr = (void __user *) sp;
462 	info.si_trapno = 0;
463 	force_sig_info(SIGBUS, &info, current);
464 }
465 
466 void fault_in_user_windows(void)
467 {
468 	struct thread_info *t = current_thread_info();
469 	unsigned long window;
470 	int winsize = sizeof(struct reg_window);
471 	int bias = 0;
472 
473 	if (test_thread_flag(TIF_32BIT))
474 		winsize = sizeof(struct reg_window32);
475 	else
476 		bias = STACK_BIAS;
477 
478 	flush_user_windows();
479 	window = get_thread_wsaved();
480 
481 	if (likely(window != 0)) {
482 		window -= 1;
483 		do {
484 			unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
485 			struct reg_window *rwin = &t->reg_window[window];
486 
487 			if (unlikely(sp & 0x7UL))
488 				stack_unaligned(sp);
489 
490 			if (unlikely(copy_to_user((char __user *)sp,
491 						  rwin, winsize)))
492 				goto barf;
493 		} while (window--);
494 	}
495 	set_thread_wsaved(0);
496 	return;
497 
498 barf:
499 	set_thread_wsaved(window + 1);
500 	do_exit(SIGILL);
501 }
502 
503 asmlinkage long sparc_do_fork(unsigned long clone_flags,
504 			      unsigned long stack_start,
505 			      struct pt_regs *regs,
506 			      unsigned long stack_size)
507 {
508 	int __user *parent_tid_ptr, *child_tid_ptr;
509 	unsigned long orig_i1 = regs->u_regs[UREG_I1];
510 	long ret;
511 
512 #ifdef CONFIG_COMPAT
513 	if (test_thread_flag(TIF_32BIT)) {
514 		parent_tid_ptr = compat_ptr(regs->u_regs[UREG_I2]);
515 		child_tid_ptr = compat_ptr(regs->u_regs[UREG_I4]);
516 	} else
517 #endif
518 	{
519 		parent_tid_ptr = (int __user *) regs->u_regs[UREG_I2];
520 		child_tid_ptr = (int __user *) regs->u_regs[UREG_I4];
521 	}
522 
523 	ret = do_fork(clone_flags, stack_start,
524 		      regs, stack_size,
525 		      parent_tid_ptr, child_tid_ptr);
526 
527 	/* If we get an error and potentially restart the system
528 	 * call, we're screwed because copy_thread() clobbered
529 	 * the parent's %o1.  So detect that case and restore it
530 	 * here.
531 	 */
532 	if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
533 		regs->u_regs[UREG_I1] = orig_i1;
534 
535 	return ret;
536 }
537 
538 /* Copy a Sparc thread.  The fork() return value conventions
539  * under SunOS are nothing short of bletcherous:
540  * Parent -->  %o0 == childs  pid, %o1 == 0
541  * Child  -->  %o0 == parents pid, %o1 == 1
542  */
543 int copy_thread(unsigned long clone_flags, unsigned long sp,
544 		unsigned long unused,
545 		struct task_struct *p, struct pt_regs *regs)
546 {
547 	struct thread_info *t = task_thread_info(p);
548 	struct sparc_stackf *parent_sf;
549 	unsigned long child_stack_sz;
550 	char *child_trap_frame;
551 	int kernel_thread;
552 
553 	kernel_thread = (regs->tstate & TSTATE_PRIV) ? 1 : 0;
554 	parent_sf = ((struct sparc_stackf *) regs) - 1;
555 
556 	/* Calculate offset to stack_frame & pt_regs */
557 	child_stack_sz = ((STACKFRAME_SZ + TRACEREG_SZ) +
558 			  (kernel_thread ? STACKFRAME_SZ : 0));
559 	child_trap_frame = (task_stack_page(p) +
560 			    (THREAD_SIZE - child_stack_sz));
561 	memcpy(child_trap_frame, parent_sf, child_stack_sz);
562 
563 	t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) |
564 				 (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |
565 		(((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);
566 	t->new_child = 1;
567 	t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
568 	t->kregs = (struct pt_regs *) (child_trap_frame +
569 				       sizeof(struct sparc_stackf));
570 	t->fpsaved[0] = 0;
571 
572 	if (kernel_thread) {
573 		struct sparc_stackf *child_sf = (struct sparc_stackf *)
574 			(child_trap_frame + (STACKFRAME_SZ + TRACEREG_SZ));
575 
576 		/* Zero terminate the stack backtrace.  */
577 		child_sf->fp = NULL;
578 		t->kregs->u_regs[UREG_FP] =
579 		  ((unsigned long) child_sf) - STACK_BIAS;
580 
581 		t->flags |= ((long)ASI_P << TI_FLAG_CURRENT_DS_SHIFT);
582 		t->kregs->u_regs[UREG_G6] = (unsigned long) t;
583 		t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
584 	} else {
585 		if (t->flags & _TIF_32BIT) {
586 			sp &= 0x00000000ffffffffUL;
587 			regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
588 		}
589 		t->kregs->u_regs[UREG_FP] = sp;
590 		t->flags |= ((long)ASI_AIUS << TI_FLAG_CURRENT_DS_SHIFT);
591 		if (sp != regs->u_regs[UREG_FP]) {
592 			unsigned long csp;
593 
594 			csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
595 			if (!csp)
596 				return -EFAULT;
597 			t->kregs->u_regs[UREG_FP] = csp;
598 		}
599 		if (t->utraps)
600 			t->utraps[0]++;
601 	}
602 
603 	/* Set the return value for the child. */
604 	t->kregs->u_regs[UREG_I0] = current->pid;
605 	t->kregs->u_regs[UREG_I1] = 1;
606 
607 	/* Set the second return value for the parent. */
608 	regs->u_regs[UREG_I1] = 0;
609 
610 	if (clone_flags & CLONE_SETTLS)
611 		t->kregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];
612 
613 	return 0;
614 }
615 
616 /*
617  * This is the mechanism for creating a new kernel thread.
618  *
619  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
620  * who haven't done an "execve()") should use this: it will work within
621  * a system call from a "real" process, but the process memory space will
622  * not be freed until both the parent and the child have exited.
623  */
624 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
625 {
626 	long retval;
627 
628 	/* If the parent runs before fn(arg) is called by the child,
629 	 * the input registers of this function can be clobbered.
630 	 * So we stash 'fn' and 'arg' into global registers which
631 	 * will not be modified by the parent.
632 	 */
633 	__asm__ __volatile__("mov %4, %%g2\n\t"	   /* Save FN into global */
634 			     "mov %5, %%g3\n\t"	   /* Save ARG into global */
635 			     "mov %1, %%g1\n\t"	   /* Clone syscall nr. */
636 			     "mov %2, %%o0\n\t"	   /* Clone flags. */
637 			     "mov 0, %%o1\n\t"	   /* usp arg == 0 */
638 			     "t 0x6d\n\t"	   /* Linux/Sparc clone(). */
639 			     "brz,a,pn %%o1, 1f\n\t" /* Parent, just return. */
640 			     " mov %%o0, %0\n\t"
641 			     "jmpl %%g2, %%o7\n\t"   /* Call the function. */
642 			     " mov %%g3, %%o0\n\t"   /* Set arg in delay. */
643 			     "mov %3, %%g1\n\t"
644 			     "t 0x6d\n\t"	   /* Linux/Sparc exit(). */
645 			     /* Notreached by child. */
646 			     "1:" :
647 			     "=r" (retval) :
648 			     "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
649 			     "i" (__NR_exit),  "r" (fn), "r" (arg) :
650 			     "g1", "g2", "g3", "o0", "o1", "memory", "cc");
651 	return retval;
652 }
653 EXPORT_SYMBOL(kernel_thread);
654 
655 typedef struct {
656 	union {
657 		unsigned int	pr_regs[32];
658 		unsigned long	pr_dregs[16];
659 	} pr_fr;
660 	unsigned int __unused;
661 	unsigned int	pr_fsr;
662 	unsigned char	pr_qcnt;
663 	unsigned char	pr_q_entrysize;
664 	unsigned char	pr_en;
665 	unsigned int	pr_q[64];
666 } elf_fpregset_t32;
667 
668 /*
669  * fill in the fpu structure for a core dump.
670  */
671 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
672 {
673 	unsigned long *kfpregs = current_thread_info()->fpregs;
674 	unsigned long fprs = current_thread_info()->fpsaved[0];
675 
676 	if (test_thread_flag(TIF_32BIT)) {
677 		elf_fpregset_t32 *fpregs32 = (elf_fpregset_t32 *)fpregs;
678 
679 		if (fprs & FPRS_DL)
680 			memcpy(&fpregs32->pr_fr.pr_regs[0], kfpregs,
681 			       sizeof(unsigned int) * 32);
682 		else
683 			memset(&fpregs32->pr_fr.pr_regs[0], 0,
684 			       sizeof(unsigned int) * 32);
685 		fpregs32->pr_qcnt = 0;
686 		fpregs32->pr_q_entrysize = 8;
687 		memset(&fpregs32->pr_q[0], 0,
688 		       (sizeof(unsigned int) * 64));
689 		if (fprs & FPRS_FEF) {
690 			fpregs32->pr_fsr = (unsigned int) current_thread_info()->xfsr[0];
691 			fpregs32->pr_en = 1;
692 		} else {
693 			fpregs32->pr_fsr = 0;
694 			fpregs32->pr_en = 0;
695 		}
696 	} else {
697 		if(fprs & FPRS_DL)
698 			memcpy(&fpregs->pr_regs[0], kfpregs,
699 			       sizeof(unsigned int) * 32);
700 		else
701 			memset(&fpregs->pr_regs[0], 0,
702 			       sizeof(unsigned int) * 32);
703 		if(fprs & FPRS_DU)
704 			memcpy(&fpregs->pr_regs[16], kfpregs+16,
705 			       sizeof(unsigned int) * 32);
706 		else
707 			memset(&fpregs->pr_regs[16], 0,
708 			       sizeof(unsigned int) * 32);
709 		if(fprs & FPRS_FEF) {
710 			fpregs->pr_fsr = current_thread_info()->xfsr[0];
711 			fpregs->pr_gsr = current_thread_info()->gsr[0];
712 		} else {
713 			fpregs->pr_fsr = fpregs->pr_gsr = 0;
714 		}
715 		fpregs->pr_fprs = fprs;
716 	}
717 	return 1;
718 }
719 EXPORT_SYMBOL(dump_fpu);
720 
721 /*
722  * sparc_execve() executes a new program after the asm stub has set
723  * things up for us.  This should basically do what I want it to.
724  */
725 asmlinkage int sparc_execve(struct pt_regs *regs)
726 {
727 	int error, base = 0;
728 	char *filename;
729 
730 	/* User register window flush is done by entry.S */
731 
732 	/* Check for indirect call. */
733 	if (regs->u_regs[UREG_G1] == 0)
734 		base = 1;
735 
736 	filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
737 	error = PTR_ERR(filename);
738 	if (IS_ERR(filename))
739 		goto out;
740 	error = do_execve(filename,
741 			  (const char __user *const __user *)
742 			  regs->u_regs[base + UREG_I1],
743 			  (const char __user *const __user *)
744 			  regs->u_regs[base + UREG_I2], regs);
745 	putname(filename);
746 	if (!error) {
747 		fprs_write(0);
748 		current_thread_info()->xfsr[0] = 0;
749 		current_thread_info()->fpsaved[0] = 0;
750 		regs->tstate &= ~TSTATE_PEF;
751 	}
752 out:
753 	return error;
754 }
755 
756 unsigned long get_wchan(struct task_struct *task)
757 {
758 	unsigned long pc, fp, bias = 0;
759 	struct thread_info *tp;
760 	struct reg_window *rw;
761         unsigned long ret = 0;
762 	int count = 0;
763 
764 	if (!task || task == current ||
765             task->state == TASK_RUNNING)
766 		goto out;
767 
768 	tp = task_thread_info(task);
769 	bias = STACK_BIAS;
770 	fp = task_thread_info(task)->ksp + bias;
771 
772 	do {
773 		if (!kstack_valid(tp, fp))
774 			break;
775 		rw = (struct reg_window *) fp;
776 		pc = rw->ins[7];
777 		if (!in_sched_functions(pc)) {
778 			ret = pc;
779 			goto out;
780 		}
781 		fp = rw->ins[6] + bias;
782 	} while (++count < 16);
783 
784 out:
785 	return ret;
786 }
787