xref: /openbmc/linux/arch/ia64/kernel/process.c (revision 5d0e4d78)
1 /*
2  * Architecture-specific setup.
3  *
4  * Copyright (C) 1998-2003 Hewlett-Packard Co
5  *	David Mosberger-Tang <davidm@hpl.hp.com>
6  * 04/11/17 Ashok Raj	<ashok.raj@intel.com> Added CPU Hotplug Support
7  *
8  * 2005-10-07 Keith Owens <kaos@sgi.com>
9  *	      Add notify_die() hooks.
10  */
11 #include <linux/cpu.h>
12 #include <linux/pm.h>
13 #include <linux/elf.h>
14 #include <linux/errno.h>
15 #include <linux/kallsyms.h>
16 #include <linux/kernel.h>
17 #include <linux/mm.h>
18 #include <linux/slab.h>
19 #include <linux/module.h>
20 #include <linux/notifier.h>
21 #include <linux/personality.h>
22 #include <linux/sched.h>
23 #include <linux/sched/debug.h>
24 #include <linux/sched/hotplug.h>
25 #include <linux/sched/task.h>
26 #include <linux/sched/task_stack.h>
27 #include <linux/stddef.h>
28 #include <linux/thread_info.h>
29 #include <linux/unistd.h>
30 #include <linux/efi.h>
31 #include <linux/interrupt.h>
32 #include <linux/delay.h>
33 #include <linux/kdebug.h>
34 #include <linux/utsname.h>
35 #include <linux/tracehook.h>
36 #include <linux/rcupdate.h>
37 
38 #include <asm/cpu.h>
39 #include <asm/delay.h>
40 #include <asm/elf.h>
41 #include <asm/irq.h>
42 #include <asm/kexec.h>
43 #include <asm/pgalloc.h>
44 #include <asm/processor.h>
45 #include <asm/sal.h>
46 #include <asm/switch_to.h>
47 #include <asm/tlbflush.h>
48 #include <linux/uaccess.h>
49 #include <asm/unwind.h>
50 #include <asm/user.h>
51 
52 #include "entry.h"
53 
54 #ifdef CONFIG_PERFMON
55 # include <asm/perfmon.h>
56 #endif
57 
58 #include "sigframe.h"
59 
60 void (*ia64_mark_idle)(int);
61 
62 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
63 EXPORT_SYMBOL(boot_option_idle_override);
64 void (*pm_power_off) (void);
65 EXPORT_SYMBOL(pm_power_off);
66 
67 void
68 ia64_do_show_stack (struct unw_frame_info *info, void *arg)
69 {
70 	unsigned long ip, sp, bsp;
71 	char buf[128];			/* don't make it so big that it overflows the stack! */
72 
73 	printk("\nCall Trace:\n");
74 	do {
75 		unw_get_ip(info, &ip);
76 		if (ip == 0)
77 			break;
78 
79 		unw_get_sp(info, &sp);
80 		unw_get_bsp(info, &bsp);
81 		snprintf(buf, sizeof(buf),
82 			 " [<%016lx>] %%s\n"
83 			 "                                sp=%016lx bsp=%016lx\n",
84 			 ip, sp, bsp);
85 		print_symbol(buf, ip);
86 	} while (unw_unwind(info) >= 0);
87 }
88 
89 void
90 show_stack (struct task_struct *task, unsigned long *sp)
91 {
92 	if (!task)
93 		unw_init_running(ia64_do_show_stack, NULL);
94 	else {
95 		struct unw_frame_info info;
96 
97 		unw_init_from_blocked_task(&info, task);
98 		ia64_do_show_stack(&info, NULL);
99 	}
100 }
101 
102 void
103 show_regs (struct pt_regs *regs)
104 {
105 	unsigned long ip = regs->cr_iip + ia64_psr(regs)->ri;
106 
107 	print_modules();
108 	printk("\n");
109 	show_regs_print_info(KERN_DEFAULT);
110 	printk("psr : %016lx ifs : %016lx ip  : [<%016lx>]    %s (%s)\n",
111 	       regs->cr_ipsr, regs->cr_ifs, ip, print_tainted(),
112 	       init_utsname()->release);
113 	print_symbol("ip is at %s\n", ip);
114 	printk("unat: %016lx pfs : %016lx rsc : %016lx\n",
115 	       regs->ar_unat, regs->ar_pfs, regs->ar_rsc);
116 	printk("rnat: %016lx bsps: %016lx pr  : %016lx\n",
117 	       regs->ar_rnat, regs->ar_bspstore, regs->pr);
118 	printk("ldrs: %016lx ccv : %016lx fpsr: %016lx\n",
119 	       regs->loadrs, regs->ar_ccv, regs->ar_fpsr);
120 	printk("csd : %016lx ssd : %016lx\n", regs->ar_csd, regs->ar_ssd);
121 	printk("b0  : %016lx b6  : %016lx b7  : %016lx\n", regs->b0, regs->b6, regs->b7);
122 	printk("f6  : %05lx%016lx f7  : %05lx%016lx\n",
123 	       regs->f6.u.bits[1], regs->f6.u.bits[0],
124 	       regs->f7.u.bits[1], regs->f7.u.bits[0]);
125 	printk("f8  : %05lx%016lx f9  : %05lx%016lx\n",
126 	       regs->f8.u.bits[1], regs->f8.u.bits[0],
127 	       regs->f9.u.bits[1], regs->f9.u.bits[0]);
128 	printk("f10 : %05lx%016lx f11 : %05lx%016lx\n",
129 	       regs->f10.u.bits[1], regs->f10.u.bits[0],
130 	       regs->f11.u.bits[1], regs->f11.u.bits[0]);
131 
132 	printk("r1  : %016lx r2  : %016lx r3  : %016lx\n", regs->r1, regs->r2, regs->r3);
133 	printk("r8  : %016lx r9  : %016lx r10 : %016lx\n", regs->r8, regs->r9, regs->r10);
134 	printk("r11 : %016lx r12 : %016lx r13 : %016lx\n", regs->r11, regs->r12, regs->r13);
135 	printk("r14 : %016lx r15 : %016lx r16 : %016lx\n", regs->r14, regs->r15, regs->r16);
136 	printk("r17 : %016lx r18 : %016lx r19 : %016lx\n", regs->r17, regs->r18, regs->r19);
137 	printk("r20 : %016lx r21 : %016lx r22 : %016lx\n", regs->r20, regs->r21, regs->r22);
138 	printk("r23 : %016lx r24 : %016lx r25 : %016lx\n", regs->r23, regs->r24, regs->r25);
139 	printk("r26 : %016lx r27 : %016lx r28 : %016lx\n", regs->r26, regs->r27, regs->r28);
140 	printk("r29 : %016lx r30 : %016lx r31 : %016lx\n", regs->r29, regs->r30, regs->r31);
141 
142 	if (user_mode(regs)) {
143 		/* print the stacked registers */
144 		unsigned long val, *bsp, ndirty;
145 		int i, sof, is_nat = 0;
146 
147 		sof = regs->cr_ifs & 0x7f;	/* size of frame */
148 		ndirty = (regs->loadrs >> 19);
149 		bsp = ia64_rse_skip_regs((unsigned long *) regs->ar_bspstore, ndirty);
150 		for (i = 0; i < sof; ++i) {
151 			get_user(val, (unsigned long __user *) ia64_rse_skip_regs(bsp, i));
152 			printk("r%-3u:%c%016lx%s", 32 + i, is_nat ? '*' : ' ', val,
153 			       ((i == sof - 1) || (i % 3) == 2) ? "\n" : " ");
154 		}
155 	} else
156 		show_stack(NULL, NULL);
157 }
158 
159 /* local support for deprecated console_print */
160 void
161 console_print(const char *s)
162 {
163 	printk(KERN_EMERG "%s", s);
164 }
165 
166 void
167 do_notify_resume_user(sigset_t *unused, struct sigscratch *scr, long in_syscall)
168 {
169 	if (fsys_mode(current, &scr->pt)) {
170 		/*
171 		 * defer signal-handling etc. until we return to
172 		 * privilege-level 0.
173 		 */
174 		if (!ia64_psr(&scr->pt)->lp)
175 			ia64_psr(&scr->pt)->lp = 1;
176 		return;
177 	}
178 
179 #ifdef CONFIG_PERFMON
180 	if (current->thread.pfm_needs_checking)
181 		/*
182 		 * Note: pfm_handle_work() allow us to call it with interrupts
183 		 * disabled, and may enable interrupts within the function.
184 		 */
185 		pfm_handle_work();
186 #endif
187 
188 	/* deal with pending signal delivery */
189 	if (test_thread_flag(TIF_SIGPENDING)) {
190 		local_irq_enable();	/* force interrupt enable */
191 		ia64_do_signal(scr, in_syscall);
192 	}
193 
194 	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
195 		local_irq_enable();	/* force interrupt enable */
196 		tracehook_notify_resume(&scr->pt);
197 	}
198 
199 	/* copy user rbs to kernel rbs */
200 	if (unlikely(test_thread_flag(TIF_RESTORE_RSE))) {
201 		local_irq_enable();	/* force interrupt enable */
202 		ia64_sync_krbs();
203 	}
204 
205 	local_irq_disable();	/* force interrupt disable */
206 }
207 
208 static int __init nohalt_setup(char * str)
209 {
210 	cpu_idle_poll_ctrl(true);
211 	return 1;
212 }
213 __setup("nohalt", nohalt_setup);
214 
215 #ifdef CONFIG_HOTPLUG_CPU
216 /* We don't actually take CPU down, just spin without interrupts. */
217 static inline void play_dead(void)
218 {
219 	unsigned int this_cpu = smp_processor_id();
220 
221 	/* Ack it */
222 	__this_cpu_write(cpu_state, CPU_DEAD);
223 
224 	max_xtp();
225 	local_irq_disable();
226 	idle_task_exit();
227 	ia64_jump_to_sal(&sal_boot_rendez_state[this_cpu]);
228 	/*
229 	 * The above is a point of no-return, the processor is
230 	 * expected to be in SAL loop now.
231 	 */
232 	BUG();
233 }
234 #else
235 static inline void play_dead(void)
236 {
237 	BUG();
238 }
239 #endif /* CONFIG_HOTPLUG_CPU */
240 
241 void arch_cpu_idle_dead(void)
242 {
243 	play_dead();
244 }
245 
246 void arch_cpu_idle(void)
247 {
248 	void (*mark_idle)(int) = ia64_mark_idle;
249 
250 #ifdef CONFIG_SMP
251 	min_xtp();
252 #endif
253 	rmb();
254 	if (mark_idle)
255 		(*mark_idle)(1);
256 
257 	safe_halt();
258 
259 	if (mark_idle)
260 		(*mark_idle)(0);
261 #ifdef CONFIG_SMP
262 	normal_xtp();
263 #endif
264 }
265 
266 void
267 ia64_save_extra (struct task_struct *task)
268 {
269 #ifdef CONFIG_PERFMON
270 	unsigned long info;
271 #endif
272 
273 	if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
274 		ia64_save_debug_regs(&task->thread.dbr[0]);
275 
276 #ifdef CONFIG_PERFMON
277 	if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
278 		pfm_save_regs(task);
279 
280 	info = __this_cpu_read(pfm_syst_info);
281 	if (info & PFM_CPUINFO_SYST_WIDE)
282 		pfm_syst_wide_update_task(task, info, 0);
283 #endif
284 }
285 
286 void
287 ia64_load_extra (struct task_struct *task)
288 {
289 #ifdef CONFIG_PERFMON
290 	unsigned long info;
291 #endif
292 
293 	if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
294 		ia64_load_debug_regs(&task->thread.dbr[0]);
295 
296 #ifdef CONFIG_PERFMON
297 	if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
298 		pfm_load_regs(task);
299 
300 	info = __this_cpu_read(pfm_syst_info);
301 	if (info & PFM_CPUINFO_SYST_WIDE)
302 		pfm_syst_wide_update_task(task, info, 1);
303 #endif
304 }
305 
306 /*
307  * Copy the state of an ia-64 thread.
308  *
309  * We get here through the following  call chain:
310  *
311  *	from user-level:	from kernel:
312  *
313  *	<clone syscall>	        <some kernel call frames>
314  *	sys_clone		   :
315  *	do_fork			do_fork
316  *	copy_thread		copy_thread
317  *
318  * This means that the stack layout is as follows:
319  *
320  *	+---------------------+ (highest addr)
321  *	|   struct pt_regs    |
322  *	+---------------------+
323  *	| struct switch_stack |
324  *	+---------------------+
325  *	|                     |
326  *	|    memory stack     |
327  *	|                     | <-- sp (lowest addr)
328  *	+---------------------+
329  *
330  * Observe that we copy the unat values that are in pt_regs and switch_stack.  Spilling an
331  * integer to address X causes bit N in ar.unat to be set to the NaT bit of the register,
332  * with N=(X & 0x1ff)/8.  Thus, copying the unat value preserves the NaT bits ONLY if the
333  * pt_regs structure in the parent is congruent to that of the child, modulo 512.  Since
334  * the stack is page aligned and the page size is at least 4KB, this is always the case,
335  * so there is nothing to worry about.
336  */
337 int
338 copy_thread(unsigned long clone_flags,
339 	     unsigned long user_stack_base, unsigned long user_stack_size,
340 	     struct task_struct *p)
341 {
342 	extern char ia64_ret_from_clone;
343 	struct switch_stack *child_stack, *stack;
344 	unsigned long rbs, child_rbs, rbs_size;
345 	struct pt_regs *child_ptregs;
346 	struct pt_regs *regs = current_pt_regs();
347 	int retval = 0;
348 
349 	child_ptregs = (struct pt_regs *) ((unsigned long) p + IA64_STK_OFFSET) - 1;
350 	child_stack = (struct switch_stack *) child_ptregs - 1;
351 
352 	rbs = (unsigned long) current + IA64_RBS_OFFSET;
353 	child_rbs = (unsigned long) p + IA64_RBS_OFFSET;
354 
355 	/* copy parts of thread_struct: */
356 	p->thread.ksp = (unsigned long) child_stack - 16;
357 
358 	/*
359 	 * NOTE: The calling convention considers all floating point
360 	 * registers in the high partition (fph) to be scratch.  Since
361 	 * the only way to get to this point is through a system call,
362 	 * we know that the values in fph are all dead.  Hence, there
363 	 * is no need to inherit the fph state from the parent to the
364 	 * child and all we have to do is to make sure that
365 	 * IA64_THREAD_FPH_VALID is cleared in the child.
366 	 *
367 	 * XXX We could push this optimization a bit further by
368 	 * clearing IA64_THREAD_FPH_VALID on ANY system call.
369 	 * However, it's not clear this is worth doing.  Also, it
370 	 * would be a slight deviation from the normal Linux system
371 	 * call behavior where scratch registers are preserved across
372 	 * system calls (unless used by the system call itself).
373 	 */
374 #	define THREAD_FLAGS_TO_CLEAR	(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID \
375 					 | IA64_THREAD_PM_VALID)
376 #	define THREAD_FLAGS_TO_SET	0
377 	p->thread.flags = ((current->thread.flags & ~THREAD_FLAGS_TO_CLEAR)
378 			   | THREAD_FLAGS_TO_SET);
379 
380 	ia64_drop_fpu(p);	/* don't pick up stale state from a CPU's fph */
381 
382 	if (unlikely(p->flags & PF_KTHREAD)) {
383 		if (unlikely(!user_stack_base)) {
384 			/* fork_idle() called us */
385 			return 0;
386 		}
387 		memset(child_stack, 0, sizeof(*child_ptregs) + sizeof(*child_stack));
388 		child_stack->r4 = user_stack_base;	/* payload */
389 		child_stack->r5 = user_stack_size;	/* argument */
390 		/*
391 		 * Preserve PSR bits, except for bits 32-34 and 37-45,
392 		 * which we can't read.
393 		 */
394 		child_ptregs->cr_ipsr = ia64_getreg(_IA64_REG_PSR) | IA64_PSR_BN;
395 		/* mark as valid, empty frame */
396 		child_ptregs->cr_ifs = 1UL << 63;
397 		child_stack->ar_fpsr = child_ptregs->ar_fpsr
398 			= ia64_getreg(_IA64_REG_AR_FPSR);
399 		child_stack->pr = (1 << PRED_KERNEL_STACK);
400 		child_stack->ar_bspstore = child_rbs;
401 		child_stack->b0 = (unsigned long) &ia64_ret_from_clone;
402 
403 		/* stop some PSR bits from being inherited.
404 		 * the psr.up/psr.pp bits must be cleared on fork but inherited on execve()
405 		 * therefore we must specify them explicitly here and not include them in
406 		 * IA64_PSR_BITS_TO_CLEAR.
407 		 */
408 		child_ptregs->cr_ipsr = ((child_ptregs->cr_ipsr | IA64_PSR_BITS_TO_SET)
409 				 & ~(IA64_PSR_BITS_TO_CLEAR | IA64_PSR_PP | IA64_PSR_UP));
410 
411 		return 0;
412 	}
413 	stack = ((struct switch_stack *) regs) - 1;
414 	/* copy parent's switch_stack & pt_regs to child: */
415 	memcpy(child_stack, stack, sizeof(*child_ptregs) + sizeof(*child_stack));
416 
417 	/* copy the parent's register backing store to the child: */
418 	rbs_size = stack->ar_bspstore - rbs;
419 	memcpy((void *) child_rbs, (void *) rbs, rbs_size);
420 	if (clone_flags & CLONE_SETTLS)
421 		child_ptregs->r13 = regs->r16;	/* see sys_clone2() in entry.S */
422 	if (user_stack_base) {
423 		child_ptregs->r12 = user_stack_base + user_stack_size - 16;
424 		child_ptregs->ar_bspstore = user_stack_base;
425 		child_ptregs->ar_rnat = 0;
426 		child_ptregs->loadrs = 0;
427 	}
428 	child_stack->ar_bspstore = child_rbs + rbs_size;
429 	child_stack->b0 = (unsigned long) &ia64_ret_from_clone;
430 
431 	/* stop some PSR bits from being inherited.
432 	 * the psr.up/psr.pp bits must be cleared on fork but inherited on execve()
433 	 * therefore we must specify them explicitly here and not include them in
434 	 * IA64_PSR_BITS_TO_CLEAR.
435 	 */
436 	child_ptregs->cr_ipsr = ((child_ptregs->cr_ipsr | IA64_PSR_BITS_TO_SET)
437 				 & ~(IA64_PSR_BITS_TO_CLEAR | IA64_PSR_PP | IA64_PSR_UP));
438 
439 #ifdef CONFIG_PERFMON
440 	if (current->thread.pfm_context)
441 		pfm_inherit(p, child_ptregs);
442 #endif
443 	return retval;
444 }
445 
446 static void
447 do_copy_task_regs (struct task_struct *task, struct unw_frame_info *info, void *arg)
448 {
449 	unsigned long mask, sp, nat_bits = 0, ar_rnat, urbs_end, cfm;
450 	unsigned long uninitialized_var(ip);	/* GCC be quiet */
451 	elf_greg_t *dst = arg;
452 	struct pt_regs *pt;
453 	char nat;
454 	int i;
455 
456 	memset(dst, 0, sizeof(elf_gregset_t));	/* don't leak any kernel bits to user-level */
457 
458 	if (unw_unwind_to_user(info) < 0)
459 		return;
460 
461 	unw_get_sp(info, &sp);
462 	pt = (struct pt_regs *) (sp + 16);
463 
464 	urbs_end = ia64_get_user_rbs_end(task, pt, &cfm);
465 
466 	if (ia64_sync_user_rbs(task, info->sw, pt->ar_bspstore, urbs_end) < 0)
467 		return;
468 
469 	ia64_peek(task, info->sw, urbs_end, (long) ia64_rse_rnat_addr((long *) urbs_end),
470 		  &ar_rnat);
471 
472 	/*
473 	 * coredump format:
474 	 *	r0-r31
475 	 *	NaT bits (for r0-r31; bit N == 1 iff rN is a NaT)
476 	 *	predicate registers (p0-p63)
477 	 *	b0-b7
478 	 *	ip cfm user-mask
479 	 *	ar.rsc ar.bsp ar.bspstore ar.rnat
480 	 *	ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec
481 	 */
482 
483 	/* r0 is zero */
484 	for (i = 1, mask = (1UL << i); i < 32; ++i) {
485 		unw_get_gr(info, i, &dst[i], &nat);
486 		if (nat)
487 			nat_bits |= mask;
488 		mask <<= 1;
489 	}
490 	dst[32] = nat_bits;
491 	unw_get_pr(info, &dst[33]);
492 
493 	for (i = 0; i < 8; ++i)
494 		unw_get_br(info, i, &dst[34 + i]);
495 
496 	unw_get_rp(info, &ip);
497 	dst[42] = ip + ia64_psr(pt)->ri;
498 	dst[43] = cfm;
499 	dst[44] = pt->cr_ipsr & IA64_PSR_UM;
500 
501 	unw_get_ar(info, UNW_AR_RSC, &dst[45]);
502 	/*
503 	 * For bsp and bspstore, unw_get_ar() would return the kernel
504 	 * addresses, but we need the user-level addresses instead:
505 	 */
506 	dst[46] = urbs_end;	/* note: by convention PT_AR_BSP points to the end of the urbs! */
507 	dst[47] = pt->ar_bspstore;
508 	dst[48] = ar_rnat;
509 	unw_get_ar(info, UNW_AR_CCV, &dst[49]);
510 	unw_get_ar(info, UNW_AR_UNAT, &dst[50]);
511 	unw_get_ar(info, UNW_AR_FPSR, &dst[51]);
512 	dst[52] = pt->ar_pfs;	/* UNW_AR_PFS is == to pt->cr_ifs for interrupt frames */
513 	unw_get_ar(info, UNW_AR_LC, &dst[53]);
514 	unw_get_ar(info, UNW_AR_EC, &dst[54]);
515 	unw_get_ar(info, UNW_AR_CSD, &dst[55]);
516 	unw_get_ar(info, UNW_AR_SSD, &dst[56]);
517 }
518 
519 void
520 do_dump_task_fpu (struct task_struct *task, struct unw_frame_info *info, void *arg)
521 {
522 	elf_fpreg_t *dst = arg;
523 	int i;
524 
525 	memset(dst, 0, sizeof(elf_fpregset_t));	/* don't leak any "random" bits */
526 
527 	if (unw_unwind_to_user(info) < 0)
528 		return;
529 
530 	/* f0 is 0.0, f1 is 1.0 */
531 
532 	for (i = 2; i < 32; ++i)
533 		unw_get_fr(info, i, dst + i);
534 
535 	ia64_flush_fph(task);
536 	if ((task->thread.flags & IA64_THREAD_FPH_VALID) != 0)
537 		memcpy(dst + 32, task->thread.fph, 96*16);
538 }
539 
540 void
541 do_copy_regs (struct unw_frame_info *info, void *arg)
542 {
543 	do_copy_task_regs(current, info, arg);
544 }
545 
546 void
547 do_dump_fpu (struct unw_frame_info *info, void *arg)
548 {
549 	do_dump_task_fpu(current, info, arg);
550 }
551 
552 void
553 ia64_elf_core_copy_regs (struct pt_regs *pt, elf_gregset_t dst)
554 {
555 	unw_init_running(do_copy_regs, dst);
556 }
557 
558 int
559 dump_fpu (struct pt_regs *pt, elf_fpregset_t dst)
560 {
561 	unw_init_running(do_dump_fpu, dst);
562 	return 1;	/* f0-f31 are always valid so we always return 1 */
563 }
564 
565 /*
566  * Flush thread state.  This is called when a thread does an execve().
567  */
568 void
569 flush_thread (void)
570 {
571 	/* drop floating-point and debug-register state if it exists: */
572 	current->thread.flags &= ~(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID);
573 	ia64_drop_fpu(current);
574 }
575 
576 /*
577  * Clean up state associated with a thread.  This is called when
578  * the thread calls exit().
579  */
580 void
581 exit_thread (struct task_struct *tsk)
582 {
583 
584 	ia64_drop_fpu(tsk);
585 #ifdef CONFIG_PERFMON
586        /* if needed, stop monitoring and flush state to perfmon context */
587 	if (tsk->thread.pfm_context)
588 		pfm_exit_thread(tsk);
589 
590 	/* free debug register resources */
591 	if (tsk->thread.flags & IA64_THREAD_DBG_VALID)
592 		pfm_release_debug_registers(tsk);
593 #endif
594 }
595 
596 unsigned long
597 get_wchan (struct task_struct *p)
598 {
599 	struct unw_frame_info info;
600 	unsigned long ip;
601 	int count = 0;
602 
603 	if (!p || p == current || p->state == TASK_RUNNING)
604 		return 0;
605 
606 	/*
607 	 * Note: p may not be a blocked task (it could be current or
608 	 * another process running on some other CPU.  Rather than
609 	 * trying to determine if p is really blocked, we just assume
610 	 * it's blocked and rely on the unwind routines to fail
611 	 * gracefully if the process wasn't really blocked after all.
612 	 * --davidm 99/12/15
613 	 */
614 	unw_init_from_blocked_task(&info, p);
615 	do {
616 		if (p->state == TASK_RUNNING)
617 			return 0;
618 		if (unw_unwind(&info) < 0)
619 			return 0;
620 		unw_get_ip(&info, &ip);
621 		if (!in_sched_functions(ip))
622 			return ip;
623 	} while (count++ < 16);
624 	return 0;
625 }
626 
627 void
628 cpu_halt (void)
629 {
630 	pal_power_mgmt_info_u_t power_info[8];
631 	unsigned long min_power;
632 	int i, min_power_state;
633 
634 	if (ia64_pal_halt_info(power_info) != 0)
635 		return;
636 
637 	min_power_state = 0;
638 	min_power = power_info[0].pal_power_mgmt_info_s.power_consumption;
639 	for (i = 1; i < 8; ++i)
640 		if (power_info[i].pal_power_mgmt_info_s.im
641 		    && power_info[i].pal_power_mgmt_info_s.power_consumption < min_power) {
642 			min_power = power_info[i].pal_power_mgmt_info_s.power_consumption;
643 			min_power_state = i;
644 		}
645 
646 	while (1)
647 		ia64_pal_halt(min_power_state);
648 }
649 
650 void machine_shutdown(void)
651 {
652 #ifdef CONFIG_HOTPLUG_CPU
653 	int cpu;
654 
655 	for_each_online_cpu(cpu) {
656 		if (cpu != smp_processor_id())
657 			cpu_down(cpu);
658 	}
659 #endif
660 #ifdef CONFIG_KEXEC
661 	kexec_disable_iosapic();
662 #endif
663 }
664 
665 void
666 machine_restart (char *restart_cmd)
667 {
668 	(void) notify_die(DIE_MACHINE_RESTART, restart_cmd, NULL, 0, 0, 0);
669 	efi_reboot(REBOOT_WARM, NULL);
670 }
671 
672 void
673 machine_halt (void)
674 {
675 	(void) notify_die(DIE_MACHINE_HALT, "", NULL, 0, 0, 0);
676 	cpu_halt();
677 }
678 
679 void
680 machine_power_off (void)
681 {
682 	if (pm_power_off)
683 		pm_power_off();
684 	machine_halt();
685 }
686 
687