xref: /openbmc/linux/arch/ia64/kernel/process.c (revision e2028c8e)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Architecture-specific setup.
4  *
5  * Copyright (C) 1998-2003 Hewlett-Packard Co
6  *	David Mosberger-Tang <davidm@hpl.hp.com>
7  * 04/11/17 Ashok Raj	<ashok.raj@intel.com> Added CPU Hotplug Support
8  *
9  * 2005-10-07 Keith Owens <kaos@sgi.com>
10  *	      Add notify_die() hooks.
11  */
12 #include <linux/cpu.h>
13 #include <linux/pm.h>
14 #include <linux/elf.h>
15 #include <linux/errno.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/processor.h>
44 #include <asm/sal.h>
45 #include <asm/switch_to.h>
46 #include <asm/tlbflush.h>
47 #include <linux/uaccess.h>
48 #include <asm/unwind.h>
49 #include <asm/user.h>
50 #include <asm/xtp.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 static void
68 ia64_do_show_stack (struct unw_frame_info *info, void *arg)
69 {
70 	unsigned long ip, sp, bsp;
71 	const char *loglvl = arg;
72 
73 	printk("%s\nCall Trace:\n", loglvl);
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 		printk("%s [<%016lx>] %pS\n"
82 			 "                                sp=%016lx bsp=%016lx\n",
83 			 loglvl, ip, (void *)ip, sp, bsp);
84 	} while (unw_unwind(info) >= 0);
85 }
86 
87 void
88 show_stack (struct task_struct *task, unsigned long *sp, const char *loglvl)
89 {
90 	if (!task)
91 		unw_init_running(ia64_do_show_stack, (void *)loglvl);
92 	else {
93 		struct unw_frame_info info;
94 
95 		unw_init_from_blocked_task(&info, task);
96 		ia64_do_show_stack(&info, (void *)loglvl);
97 	}
98 }
99 
100 void
101 show_regs (struct pt_regs *regs)
102 {
103 	unsigned long ip = regs->cr_iip + ia64_psr(regs)->ri;
104 
105 	print_modules();
106 	printk("\n");
107 	show_regs_print_info(KERN_DEFAULT);
108 	printk("psr : %016lx ifs : %016lx ip  : [<%016lx>]    %s (%s)\n",
109 	       regs->cr_ipsr, regs->cr_ifs, ip, print_tainted(),
110 	       init_utsname()->release);
111 	printk("ip is at %pS\n", (void *)ip);
112 	printk("unat: %016lx pfs : %016lx rsc : %016lx\n",
113 	       regs->ar_unat, regs->ar_pfs, regs->ar_rsc);
114 	printk("rnat: %016lx bsps: %016lx pr  : %016lx\n",
115 	       regs->ar_rnat, regs->ar_bspstore, regs->pr);
116 	printk("ldrs: %016lx ccv : %016lx fpsr: %016lx\n",
117 	       regs->loadrs, regs->ar_ccv, regs->ar_fpsr);
118 	printk("csd : %016lx ssd : %016lx\n", regs->ar_csd, regs->ar_ssd);
119 	printk("b0  : %016lx b6  : %016lx b7  : %016lx\n", regs->b0, regs->b6, regs->b7);
120 	printk("f6  : %05lx%016lx f7  : %05lx%016lx\n",
121 	       regs->f6.u.bits[1], regs->f6.u.bits[0],
122 	       regs->f7.u.bits[1], regs->f7.u.bits[0]);
123 	printk("f8  : %05lx%016lx f9  : %05lx%016lx\n",
124 	       regs->f8.u.bits[1], regs->f8.u.bits[0],
125 	       regs->f9.u.bits[1], regs->f9.u.bits[0]);
126 	printk("f10 : %05lx%016lx f11 : %05lx%016lx\n",
127 	       regs->f10.u.bits[1], regs->f10.u.bits[0],
128 	       regs->f11.u.bits[1], regs->f11.u.bits[0]);
129 
130 	printk("r1  : %016lx r2  : %016lx r3  : %016lx\n", regs->r1, regs->r2, regs->r3);
131 	printk("r8  : %016lx r9  : %016lx r10 : %016lx\n", regs->r8, regs->r9, regs->r10);
132 	printk("r11 : %016lx r12 : %016lx r13 : %016lx\n", regs->r11, regs->r12, regs->r13);
133 	printk("r14 : %016lx r15 : %016lx r16 : %016lx\n", regs->r14, regs->r15, regs->r16);
134 	printk("r17 : %016lx r18 : %016lx r19 : %016lx\n", regs->r17, regs->r18, regs->r19);
135 	printk("r20 : %016lx r21 : %016lx r22 : %016lx\n", regs->r20, regs->r21, regs->r22);
136 	printk("r23 : %016lx r24 : %016lx r25 : %016lx\n", regs->r23, regs->r24, regs->r25);
137 	printk("r26 : %016lx r27 : %016lx r28 : %016lx\n", regs->r26, regs->r27, regs->r28);
138 	printk("r29 : %016lx r30 : %016lx r31 : %016lx\n", regs->r29, regs->r30, regs->r31);
139 
140 	if (user_mode(regs)) {
141 		/* print the stacked registers */
142 		unsigned long val, *bsp, ndirty;
143 		int i, sof, is_nat = 0;
144 
145 		sof = regs->cr_ifs & 0x7f;	/* size of frame */
146 		ndirty = (regs->loadrs >> 19);
147 		bsp = ia64_rse_skip_regs((unsigned long *) regs->ar_bspstore, ndirty);
148 		for (i = 0; i < sof; ++i) {
149 			get_user(val, (unsigned long __user *) ia64_rse_skip_regs(bsp, i));
150 			printk("r%-3u:%c%016lx%s", 32 + i, is_nat ? '*' : ' ', val,
151 			       ((i == sof - 1) || (i % 3) == 2) ? "\n" : " ");
152 		}
153 	} else
154 		show_stack(NULL, NULL, KERN_DEFAULT);
155 }
156 
157 /* local support for deprecated console_print */
158 void
159 console_print(const char *s)
160 {
161 	printk(KERN_EMERG "%s", s);
162 }
163 
164 void
165 do_notify_resume_user(sigset_t *unused, struct sigscratch *scr, long in_syscall)
166 {
167 	if (fsys_mode(current, &scr->pt)) {
168 		/*
169 		 * defer signal-handling etc. until we return to
170 		 * privilege-level 0.
171 		 */
172 		if (!ia64_psr(&scr->pt)->lp)
173 			ia64_psr(&scr->pt)->lp = 1;
174 		return;
175 	}
176 
177 #ifdef CONFIG_PERFMON
178 	if (current->thread.pfm_needs_checking)
179 		/*
180 		 * Note: pfm_handle_work() allow us to call it with interrupts
181 		 * disabled, and may enable interrupts within the function.
182 		 */
183 		pfm_handle_work();
184 #endif
185 
186 	/* deal with pending signal delivery */
187 	if (test_thread_flag(TIF_SIGPENDING)) {
188 		local_irq_enable();	/* force interrupt enable */
189 		ia64_do_signal(scr, in_syscall);
190 	}
191 
192 	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
193 		local_irq_enable();	/* force interrupt enable */
194 		tracehook_notify_resume(&scr->pt);
195 	}
196 
197 	/* copy user rbs to kernel rbs */
198 	if (unlikely(test_thread_flag(TIF_RESTORE_RSE))) {
199 		local_irq_enable();	/* force interrupt enable */
200 		ia64_sync_krbs();
201 	}
202 
203 	local_irq_disable();	/* force interrupt disable */
204 }
205 
206 static int __init nohalt_setup(char * str)
207 {
208 	cpu_idle_poll_ctrl(true);
209 	return 1;
210 }
211 __setup("nohalt", nohalt_setup);
212 
213 #ifdef CONFIG_HOTPLUG_CPU
214 /* We don't actually take CPU down, just spin without interrupts. */
215 static inline void play_dead(void)
216 {
217 	unsigned int this_cpu = smp_processor_id();
218 
219 	/* Ack it */
220 	__this_cpu_write(cpu_state, CPU_DEAD);
221 
222 	max_xtp();
223 	local_irq_disable();
224 	idle_task_exit();
225 	ia64_jump_to_sal(&sal_boot_rendez_state[this_cpu]);
226 	/*
227 	 * The above is a point of no-return, the processor is
228 	 * expected to be in SAL loop now.
229 	 */
230 	BUG();
231 }
232 #else
233 static inline void play_dead(void)
234 {
235 	BUG();
236 }
237 #endif /* CONFIG_HOTPLUG_CPU */
238 
239 void arch_cpu_idle_dead(void)
240 {
241 	play_dead();
242 }
243 
244 void arch_cpu_idle(void)
245 {
246 	void (*mark_idle)(int) = ia64_mark_idle;
247 
248 #ifdef CONFIG_SMP
249 	min_xtp();
250 #endif
251 	rmb();
252 	if (mark_idle)
253 		(*mark_idle)(1);
254 
255 	safe_halt();
256 
257 	if (mark_idle)
258 		(*mark_idle)(0);
259 #ifdef CONFIG_SMP
260 	normal_xtp();
261 #endif
262 }
263 
264 void
265 ia64_save_extra (struct task_struct *task)
266 {
267 #ifdef CONFIG_PERFMON
268 	unsigned long info;
269 #endif
270 
271 	if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
272 		ia64_save_debug_regs(&task->thread.dbr[0]);
273 
274 #ifdef CONFIG_PERFMON
275 	if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
276 		pfm_save_regs(task);
277 
278 	info = __this_cpu_read(pfm_syst_info);
279 	if (info & PFM_CPUINFO_SYST_WIDE)
280 		pfm_syst_wide_update_task(task, info, 0);
281 #endif
282 }
283 
284 void
285 ia64_load_extra (struct task_struct *task)
286 {
287 #ifdef CONFIG_PERFMON
288 	unsigned long info;
289 #endif
290 
291 	if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
292 		ia64_load_debug_regs(&task->thread.dbr[0]);
293 
294 #ifdef CONFIG_PERFMON
295 	if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
296 		pfm_load_regs(task);
297 
298 	info = __this_cpu_read(pfm_syst_info);
299 	if (info & PFM_CPUINFO_SYST_WIDE)
300 		pfm_syst_wide_update_task(task, info, 1);
301 #endif
302 }
303 
304 /*
305  * Copy the state of an ia-64 thread.
306  *
307  * We get here through the following  call chain:
308  *
309  *	from user-level:	from kernel:
310  *
311  *	<clone syscall>	        <some kernel call frames>
312  *	sys_clone		   :
313  *	_do_fork		_do_fork
314  *	copy_thread		copy_thread
315  *
316  * This means that the stack layout is as follows:
317  *
318  *	+---------------------+ (highest addr)
319  *	|   struct pt_regs    |
320  *	+---------------------+
321  *	| struct switch_stack |
322  *	+---------------------+
323  *	|                     |
324  *	|    memory stack     |
325  *	|                     | <-- sp (lowest addr)
326  *	+---------------------+
327  *
328  * Observe that we copy the unat values that are in pt_regs and switch_stack.  Spilling an
329  * integer to address X causes bit N in ar.unat to be set to the NaT bit of the register,
330  * with N=(X & 0x1ff)/8.  Thus, copying the unat value preserves the NaT bits ONLY if the
331  * pt_regs structure in the parent is congruent to that of the child, modulo 512.  Since
332  * the stack is page aligned and the page size is at least 4KB, this is always the case,
333  * so there is nothing to worry about.
334  */
335 int
336 copy_thread(unsigned long clone_flags, unsigned long user_stack_base,
337 	    unsigned long user_stack_size, struct task_struct *p, unsigned long tls)
338 {
339 	extern char ia64_ret_from_clone;
340 	struct switch_stack *child_stack, *stack;
341 	unsigned long rbs, child_rbs, rbs_size;
342 	struct pt_regs *child_ptregs;
343 	struct pt_regs *regs = current_pt_regs();
344 	int retval = 0;
345 
346 	child_ptregs = (struct pt_regs *) ((unsigned long) p + IA64_STK_OFFSET) - 1;
347 	child_stack = (struct switch_stack *) child_ptregs - 1;
348 
349 	rbs = (unsigned long) current + IA64_RBS_OFFSET;
350 	child_rbs = (unsigned long) p + IA64_RBS_OFFSET;
351 
352 	/* copy parts of thread_struct: */
353 	p->thread.ksp = (unsigned long) child_stack - 16;
354 
355 	/*
356 	 * NOTE: The calling convention considers all floating point
357 	 * registers in the high partition (fph) to be scratch.  Since
358 	 * the only way to get to this point is through a system call,
359 	 * we know that the values in fph are all dead.  Hence, there
360 	 * is no need to inherit the fph state from the parent to the
361 	 * child and all we have to do is to make sure that
362 	 * IA64_THREAD_FPH_VALID is cleared in the child.
363 	 *
364 	 * XXX We could push this optimization a bit further by
365 	 * clearing IA64_THREAD_FPH_VALID on ANY system call.
366 	 * However, it's not clear this is worth doing.  Also, it
367 	 * would be a slight deviation from the normal Linux system
368 	 * call behavior where scratch registers are preserved across
369 	 * system calls (unless used by the system call itself).
370 	 */
371 #	define THREAD_FLAGS_TO_CLEAR	(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID \
372 					 | IA64_THREAD_PM_VALID)
373 #	define THREAD_FLAGS_TO_SET	0
374 	p->thread.flags = ((current->thread.flags & ~THREAD_FLAGS_TO_CLEAR)
375 			   | THREAD_FLAGS_TO_SET);
376 
377 	ia64_drop_fpu(p);	/* don't pick up stale state from a CPU's fph */
378 
379 	if (unlikely(p->flags & PF_KTHREAD)) {
380 		if (unlikely(!user_stack_base)) {
381 			/* fork_idle() called us */
382 			return 0;
383 		}
384 		memset(child_stack, 0, sizeof(*child_ptregs) + sizeof(*child_stack));
385 		child_stack->r4 = user_stack_base;	/* payload */
386 		child_stack->r5 = user_stack_size;	/* argument */
387 		/*
388 		 * Preserve PSR bits, except for bits 32-34 and 37-45,
389 		 * which we can't read.
390 		 */
391 		child_ptregs->cr_ipsr = ia64_getreg(_IA64_REG_PSR) | IA64_PSR_BN;
392 		/* mark as valid, empty frame */
393 		child_ptregs->cr_ifs = 1UL << 63;
394 		child_stack->ar_fpsr = child_ptregs->ar_fpsr
395 			= ia64_getreg(_IA64_REG_AR_FPSR);
396 		child_stack->pr = (1 << PRED_KERNEL_STACK);
397 		child_stack->ar_bspstore = child_rbs;
398 		child_stack->b0 = (unsigned long) &ia64_ret_from_clone;
399 
400 		/* stop some PSR bits from being inherited.
401 		 * the psr.up/psr.pp bits must be cleared on fork but inherited on execve()
402 		 * therefore we must specify them explicitly here and not include them in
403 		 * IA64_PSR_BITS_TO_CLEAR.
404 		 */
405 		child_ptregs->cr_ipsr = ((child_ptregs->cr_ipsr | IA64_PSR_BITS_TO_SET)
406 				 & ~(IA64_PSR_BITS_TO_CLEAR | IA64_PSR_PP | IA64_PSR_UP));
407 
408 		return 0;
409 	}
410 	stack = ((struct switch_stack *) regs) - 1;
411 	/* copy parent's switch_stack & pt_regs to child: */
412 	memcpy(child_stack, stack, sizeof(*child_ptregs) + sizeof(*child_stack));
413 
414 	/* copy the parent's register backing store to the child: */
415 	rbs_size = stack->ar_bspstore - rbs;
416 	memcpy((void *) child_rbs, (void *) rbs, rbs_size);
417 	if (clone_flags & CLONE_SETTLS)
418 		child_ptregs->r13 = tls;
419 	if (user_stack_base) {
420 		child_ptregs->r12 = user_stack_base + user_stack_size - 16;
421 		child_ptregs->ar_bspstore = user_stack_base;
422 		child_ptregs->ar_rnat = 0;
423 		child_ptregs->loadrs = 0;
424 	}
425 	child_stack->ar_bspstore = child_rbs + rbs_size;
426 	child_stack->b0 = (unsigned long) &ia64_ret_from_clone;
427 
428 	/* stop some PSR bits from being inherited.
429 	 * the psr.up/psr.pp bits must be cleared on fork but inherited on execve()
430 	 * therefore we must specify them explicitly here and not include them in
431 	 * IA64_PSR_BITS_TO_CLEAR.
432 	 */
433 	child_ptregs->cr_ipsr = ((child_ptregs->cr_ipsr | IA64_PSR_BITS_TO_SET)
434 				 & ~(IA64_PSR_BITS_TO_CLEAR | IA64_PSR_PP | IA64_PSR_UP));
435 
436 #ifdef CONFIG_PERFMON
437 	if (current->thread.pfm_context)
438 		pfm_inherit(p, child_ptregs);
439 #endif
440 	return retval;
441 }
442 
443 asmlinkage long ia64_clone(unsigned long clone_flags, unsigned long stack_start,
444 			   unsigned long stack_size, unsigned long parent_tidptr,
445 			   unsigned long child_tidptr, unsigned long tls)
446 {
447 	struct kernel_clone_args args = {
448 		.flags		= (lower_32_bits(clone_flags) & ~CSIGNAL),
449 		.pidfd		= (int __user *)parent_tidptr,
450 		.child_tid	= (int __user *)child_tidptr,
451 		.parent_tid	= (int __user *)parent_tidptr,
452 		.exit_signal	= (lower_32_bits(clone_flags) & CSIGNAL),
453 		.stack		= stack_start,
454 		.stack_size	= stack_size,
455 		.tls		= tls,
456 	};
457 
458 	return _do_fork(&args);
459 }
460 
461 static void
462 do_copy_task_regs (struct task_struct *task, struct unw_frame_info *info, void *arg)
463 {
464 	unsigned long mask, sp, nat_bits = 0, ar_rnat, urbs_end, cfm;
465 	unsigned long ip;
466 	elf_greg_t *dst = arg;
467 	struct pt_regs *pt;
468 	char nat;
469 	int i;
470 
471 	memset(dst, 0, sizeof(elf_gregset_t));	/* don't leak any kernel bits to user-level */
472 
473 	if (unw_unwind_to_user(info) < 0)
474 		return;
475 
476 	unw_get_sp(info, &sp);
477 	pt = (struct pt_regs *) (sp + 16);
478 
479 	urbs_end = ia64_get_user_rbs_end(task, pt, &cfm);
480 
481 	if (ia64_sync_user_rbs(task, info->sw, pt->ar_bspstore, urbs_end) < 0)
482 		return;
483 
484 	ia64_peek(task, info->sw, urbs_end, (long) ia64_rse_rnat_addr((long *) urbs_end),
485 		  &ar_rnat);
486 
487 	/*
488 	 * coredump format:
489 	 *	r0-r31
490 	 *	NaT bits (for r0-r31; bit N == 1 iff rN is a NaT)
491 	 *	predicate registers (p0-p63)
492 	 *	b0-b7
493 	 *	ip cfm user-mask
494 	 *	ar.rsc ar.bsp ar.bspstore ar.rnat
495 	 *	ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec
496 	 */
497 
498 	/* r0 is zero */
499 	for (i = 1, mask = (1UL << i); i < 32; ++i) {
500 		unw_get_gr(info, i, &dst[i], &nat);
501 		if (nat)
502 			nat_bits |= mask;
503 		mask <<= 1;
504 	}
505 	dst[32] = nat_bits;
506 	unw_get_pr(info, &dst[33]);
507 
508 	for (i = 0; i < 8; ++i)
509 		unw_get_br(info, i, &dst[34 + i]);
510 
511 	unw_get_rp(info, &ip);
512 	dst[42] = ip + ia64_psr(pt)->ri;
513 	dst[43] = cfm;
514 	dst[44] = pt->cr_ipsr & IA64_PSR_UM;
515 
516 	unw_get_ar(info, UNW_AR_RSC, &dst[45]);
517 	/*
518 	 * For bsp and bspstore, unw_get_ar() would return the kernel
519 	 * addresses, but we need the user-level addresses instead:
520 	 */
521 	dst[46] = urbs_end;	/* note: by convention PT_AR_BSP points to the end of the urbs! */
522 	dst[47] = pt->ar_bspstore;
523 	dst[48] = ar_rnat;
524 	unw_get_ar(info, UNW_AR_CCV, &dst[49]);
525 	unw_get_ar(info, UNW_AR_UNAT, &dst[50]);
526 	unw_get_ar(info, UNW_AR_FPSR, &dst[51]);
527 	dst[52] = pt->ar_pfs;	/* UNW_AR_PFS is == to pt->cr_ifs for interrupt frames */
528 	unw_get_ar(info, UNW_AR_LC, &dst[53]);
529 	unw_get_ar(info, UNW_AR_EC, &dst[54]);
530 	unw_get_ar(info, UNW_AR_CSD, &dst[55]);
531 	unw_get_ar(info, UNW_AR_SSD, &dst[56]);
532 }
533 
534 void
535 do_copy_regs (struct unw_frame_info *info, void *arg)
536 {
537 	do_copy_task_regs(current, info, arg);
538 }
539 
540 void
541 ia64_elf_core_copy_regs (struct pt_regs *pt, elf_gregset_t dst)
542 {
543 	unw_init_running(do_copy_regs, dst);
544 }
545 
546 /*
547  * Flush thread state.  This is called when a thread does an execve().
548  */
549 void
550 flush_thread (void)
551 {
552 	/* drop floating-point and debug-register state if it exists: */
553 	current->thread.flags &= ~(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID);
554 	ia64_drop_fpu(current);
555 }
556 
557 /*
558  * Clean up state associated with a thread.  This is called when
559  * the thread calls exit().
560  */
561 void
562 exit_thread (struct task_struct *tsk)
563 {
564 
565 	ia64_drop_fpu(tsk);
566 #ifdef CONFIG_PERFMON
567        /* if needed, stop monitoring and flush state to perfmon context */
568 	if (tsk->thread.pfm_context)
569 		pfm_exit_thread(tsk);
570 
571 	/* free debug register resources */
572 	if (tsk->thread.flags & IA64_THREAD_DBG_VALID)
573 		pfm_release_debug_registers(tsk);
574 #endif
575 }
576 
577 unsigned long
578 get_wchan (struct task_struct *p)
579 {
580 	struct unw_frame_info info;
581 	unsigned long ip;
582 	int count = 0;
583 
584 	if (!p || p == current || p->state == TASK_RUNNING)
585 		return 0;
586 
587 	/*
588 	 * Note: p may not be a blocked task (it could be current or
589 	 * another process running on some other CPU.  Rather than
590 	 * trying to determine if p is really blocked, we just assume
591 	 * it's blocked and rely on the unwind routines to fail
592 	 * gracefully if the process wasn't really blocked after all.
593 	 * --davidm 99/12/15
594 	 */
595 	unw_init_from_blocked_task(&info, p);
596 	do {
597 		if (p->state == TASK_RUNNING)
598 			return 0;
599 		if (unw_unwind(&info) < 0)
600 			return 0;
601 		unw_get_ip(&info, &ip);
602 		if (!in_sched_functions(ip))
603 			return ip;
604 	} while (count++ < 16);
605 	return 0;
606 }
607 
608 void
609 cpu_halt (void)
610 {
611 	pal_power_mgmt_info_u_t power_info[8];
612 	unsigned long min_power;
613 	int i, min_power_state;
614 
615 	if (ia64_pal_halt_info(power_info) != 0)
616 		return;
617 
618 	min_power_state = 0;
619 	min_power = power_info[0].pal_power_mgmt_info_s.power_consumption;
620 	for (i = 1; i < 8; ++i)
621 		if (power_info[i].pal_power_mgmt_info_s.im
622 		    && power_info[i].pal_power_mgmt_info_s.power_consumption < min_power) {
623 			min_power = power_info[i].pal_power_mgmt_info_s.power_consumption;
624 			min_power_state = i;
625 		}
626 
627 	while (1)
628 		ia64_pal_halt(min_power_state);
629 }
630 
631 void machine_shutdown(void)
632 {
633 	smp_shutdown_nonboot_cpus(reboot_cpu);
634 
635 #ifdef CONFIG_KEXEC
636 	kexec_disable_iosapic();
637 #endif
638 }
639 
640 void
641 machine_restart (char *restart_cmd)
642 {
643 	(void) notify_die(DIE_MACHINE_RESTART, restart_cmd, NULL, 0, 0, 0);
644 	efi_reboot(REBOOT_WARM, NULL);
645 }
646 
647 void
648 machine_halt (void)
649 {
650 	(void) notify_die(DIE_MACHINE_HALT, "", NULL, 0, 0, 0);
651 	cpu_halt();
652 }
653 
654 void
655 machine_power_off (void)
656 {
657 	if (pm_power_off)
658 		pm_power_off();
659 	machine_halt();
660 }
661 
662 EXPORT_SYMBOL(ia64_delay_loop);
663