summaryrefslogtreecommitdiffstats
path: root/arch/ia64/kernel/signal.c
blob: 6891d86937d92be4038cac575f7e9b153bfe1503 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
/*
 * Architecture-specific signal handling support.
 *
 * Copyright (C) 1999-2004 Hewlett-Packard Co
 *	David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * Derived from i386 and Alpha versions.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/unistd.h>
#include <linux/wait.h>

#include <asm/ia32.h>
#include <asm/intrinsics.h>
#include <asm/uaccess.h>
#include <asm/rse.h>
#include <asm/sigcontext.h>

#include "sigframe.h"

#define DEBUG_SIG	0
#define STACK_ALIGN	16		/* minimal alignment for stack pointer */
#define _BLOCKABLE	(~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

#if _NSIG_WORDS > 1
# define PUT_SIGSET(k,u)	__copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
# define GET_SIGSET(k,u)	__copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
#else
# define PUT_SIGSET(k,u)	__put_user((k)->sig[0], &(u)->sig[0])
# define GET_SIGSET(k,u)	__get_user((k)->sig[0], &(u)->sig[0])
#endif

long
ia64_rt_sigsuspend (sigset_t __user *uset, size_t sigsetsize, struct sigscratch *scr)
{
	sigset_t oldset, set;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (!access_ok(VERIFY_READ, uset, sigsetsize))
		return -EFAULT;

	if (GET_SIGSET(&set, uset))
		return -EFAULT;

	sigdelsetmask(&set, ~_BLOCKABLE);

	spin_lock_irq(&current->sighand->siglock);
	{
		oldset = current->blocked;
		current->blocked = set;
		recalc_sigpending();
	}
	spin_unlock_irq(&current->sighand->siglock);

	/*
	 * The return below usually returns to the signal handler.  We need to
	 * pre-set the correct error code here to ensure that the right values
	 * get saved in sigcontext by ia64_do_signal.
	 */
	scr->pt.r8 = EINTR;
	scr->pt.r10 = -1;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (ia64_do_signal(&oldset, scr, 1))
			return -EINTR;
	}
}

asmlinkage long
sys_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, long arg2,
		 long arg3, long arg4, long arg5, long arg6, long arg7,
		 struct pt_regs regs)
{
	return do_sigaltstack(uss, uoss, regs.r12);
}

static long
restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
{
	unsigned long ip, flags, nat, um, cfm;
	long err;

	/* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	/* restore scratch that always needs gets updated during signal delivery: */
	err  = __get_user(flags, &sc->sc_flags);
	err |= __get_user(nat, &sc->sc_nat);
	err |= __get_user(ip, &sc->sc_ip);			/* instruction pointer */
	err |= __get_user(cfm, &sc->sc_cfm);
	err |= __get_user(um, &sc->sc_um);			/* user mask */
	err |= __get_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
	err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
	err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
	err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
	err |= __get_user(scr->pt.pr, &sc->sc_pr);		/* predicates */
	err |= __get_user(scr->pt.b0, &sc->sc_br[0]);		/* b0 (rp) */
	err |= __get_user(scr->pt.b6, &sc->sc_br[6]);		/* b6 */
	err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8);	/* r1 */
	err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);	/* r8-r11 */
	err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);	/* r12-r13 */
	err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);	/* r15 */

	scr->pt.cr_ifs = cfm | (1UL << 63);

	/* establish new instruction pointer: */
	scr->pt.cr_iip = ip & ~0x3UL;
	ia64_psr(&scr->pt)->ri = ip & 0x3;
	scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);

	scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);

	if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
		/* Restore most scratch-state only when not in syscall. */
		err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);		/* ar.ccv */
		err |= __get_user(scr->pt.b7, &sc->sc_br[7]);			/* b7 */
		err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);			/* r14 */
		err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
		err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);	/* r2-r3 */
		err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);	/* r16-r31 */
	}

	if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
		struct ia64_psr *psr = ia64_psr(&scr->pt);

		__copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
		psr->mfh = 0;	/* drop signal handler's fph contents... */
		if (psr->dfh)
			ia64_drop_fpu(current);
		else {
			/* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
			__ia64_load_fpu(current->thread.fph);
			ia64_set_local_fpu_owner(current);
		}
	}
	return err;
}

int
copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from)
{
	if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))
		return -EFAULT;
	if (from->si_code < 0) {
		if (__copy_to_user(to, from, sizeof(siginfo_t)))
			return -EFAULT;
		return 0;
	} else {
		int err;

		/*
		 * If you change siginfo_t structure, please be sure this code is fixed
		 * accordingly.  It should never copy any pad contained in the structure
		 * to avoid security leaks, but must copy the generic 3 ints plus the
		 * relevant union member.
		 */
		err = __put_user(from->si_signo, &to->si_signo);
		err |= __put_user(from->si_errno, &to->si_errno);
		err |= __put_user((short)from->si_code, &to->si_code);
		switch (from->si_code >> 16) {
		      case __SI_FAULT >> 16:
			err |= __put_user(from->si_flags, &to->si_flags);
			err |= __put_user(from->si_isr, &to->si_isr);
		      case __SI_POLL >> 16:
			err |= __put_user(from->si_addr, &to->si_addr);
			err |= __put_user(from->si_imm, &to->si_imm);
			break;
		      case __SI_TIMER >> 16:
			err |= __put_user(from->si_tid, &to->si_tid);
			err |= __put_user(from->si_overrun, &to->si_overrun);
			err |= __put_user(from->si_ptr, &to->si_ptr);
			break;
		      case __SI_RT >> 16:	/* Not generated by the kernel as of now.  */
		      case __SI_MESGQ >> 16:
			err |= __put_user(from->si_uid, &to->si_uid);
			err |= __put_user(from->si_pid, &to->si_pid);
			err |= __put_user(from->si_ptr, &to->si_ptr);
			break;
		      case __SI_CHLD >> 16:
			err |= __put_user(from->si_utime, &to->si_utime);
			err |= __put_user(from->si_stime, &to->si_stime);
			err |= __put_user(from->si_status, &to->si_status);
		      default:
			err |= __put_user(from->si_uid, &to->si_uid);
			err |= __put_user(from->si_pid, &to->si_pid);
			break;
		}
		return err;
	}
}

long
ia64_rt_sigreturn (struct sigscratch *scr)
{
	extern char ia64_strace_leave_kernel, ia64_leave_kernel;
	struct sigcontext __user *sc;
	struct siginfo si;
	sigset_t set;
	long retval;

	sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;

	/*
	 * When we return to the previously executing context, r8 and r10 have already
	 * been setup the way we want them.  Indeed, if the signal wasn't delivered while
	 * in a system call, we must not touch r8 or r10 as otherwise user-level state
	 * could be corrupted.
	 */
	retval = (long) &ia64_leave_kernel;
	if (test_thread_flag(TIF_SYSCALL_TRACE))
		/*
		 * strace expects to be notified after sigreturn returns even though the
		 * context to which we return may not be in the middle of a syscall.
		 * Thus, the return-value that strace displays for sigreturn is
		 * meaningless.
		 */
		retval = (long) &ia64_strace_leave_kernel;

	if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
		goto give_sigsegv;

	if (GET_SIGSET(&set, &sc->sc_mask))
		goto give_sigsegv;

	sigdelsetmask(&set, ~_BLOCKABLE);

	spin_lock_irq(&current->sighand->siglock);
	{
		current->blocked = set;
		recalc_sigpending();
	}
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(sc, scr))
		goto give_sigsegv;

#if DEBUG_SIG
	printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
	       current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
#endif
	/*
	 * It is more difficult to avoid calling this function than to
	 * call it and ignore errors.
	 */
	do_sigaltstack(&sc->sc_stack, NULL, scr->pt.r12);
	return retval;

  give_sigsegv:
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = sc;
	force_sig_info(SIGSEGV, &si, current);
	return retval;
}

/*
 * This does just the minimum required setup of sigcontext.
 * Specifically, it only installs data that is either not knowable at
 * the user-level or that gets modified before execution in the
 * trampoline starts.  Everything else is done at the user-level.
 */
static long
setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
{
	unsigned long flags = 0, ifs, cfm, nat;
	long err;

	ifs = scr->pt.cr_ifs;

	if (on_sig_stack((unsigned long) sc))
		flags |= IA64_SC_FLAG_ONSTACK;
	if ((ifs & (1UL << 63)) == 0)
		/* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
		flags |= IA64_SC_FLAG_IN_SYSCALL;
	cfm = ifs & ((1UL << 38) - 1);
	ia64_flush_fph(current);
	if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
		flags |= IA64_SC_FLAG_FPH_VALID;
		__copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
	}

	nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);

	err  = __put_user(flags, &sc->sc_flags);
	err |= __put_user(nat, &sc->sc_nat);
	err |= PUT_SIGSET(mask, &sc->sc_mask);
	err |= __put_user(cfm, &sc->sc_cfm);
	err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
	err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
	err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);		/* ar.unat */
	err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);		/* ar.fpsr */
	err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
	err |= __put_user(scr->pt.pr, &sc->sc_pr);			/* predicates */
	err |= __put_user(scr->pt.b0, &sc->sc_br[0]);			/* b0 (rp) */
	err |= __put_user(scr->pt.b6, &sc->sc_br[6]);			/* b6 */
	err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);		/* r1 */
	err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);		/* r8-r11 */
	err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);	/* r12-r13 */
	err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);		/* r15 */
	err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);

	if (flags & IA64_SC_FLAG_IN_SYSCALL) {
		/* Clear scratch registers if the signal interrupted a system call. */
		err |= __put_user(0, &sc->sc_ar_ccv);				/* ar.ccv */
		err |= __put_user(0, &sc->sc_br[7]);				/* b7 */
		err |= __put_user(0, &sc->sc_gr[14]);				/* r14 */
		err |= __clear_user(&sc->sc_ar25, 2*8);			/* ar.csd & ar.ssd */
		err |= __clear_user(&sc->sc_gr[2], 2*8);			/* r2-r3 */
		err |= __clear_user(&sc->sc_gr[16], 16*8);			/* r16-r31 */
	} else {
		/* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
		err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);		/* ar.ccv */
		err |= __put_user(scr->pt.b7, &sc->sc_br[7]);			/* b7 */
		err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);			/* r14 */
		err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
		err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);		/* r2-r3 */
		err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);	/* r16-r31 */
	}
	return err;
}

/*
 * Check whether the register-backing store is already on the signal stack.
 */
static inline int
rbs_on_sig_stack (unsigned long bsp)
{
	return (bsp - current->sas_ss_sp < current->sas_ss_size);
}

static long
force_sigsegv_info (int sig, void __user *addr)
{
	unsigned long flags;
	struct siginfo si;

	if (sig == SIGSEGV) {
		/*
		 * Acquiring siglock around the sa_handler-update is almost
		 * certainly overkill, but this isn't a
		 * performance-critical path and I'd rather play it safe
		 * here than having to debug a nasty race if and when
		 * something changes in kernel/signal.c that would make it
		 * no longer safe to modify sa_handler without holding the
		 * lock.
		 */
		spin_lock_irqsave(&current->sighand->siglock, flags);
		current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
		spin_unlock_irqrestore(&current->sighand->siglock, flags);
	}
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = addr;
	force_sig_info(SIGSEGV, &si, current);
	return 0;
}

static long
setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
	     struct sigscratch *scr)
{
	extern char __kernel_sigtramp[];
	unsigned long tramp_addr, new_rbs = 0;
	struct sigframe __user *frame;
	long err;

	frame = (void __user *) scr->pt.r12;
	tramp_addr = (unsigned long) __kernel_sigtramp;
	if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags((unsigned long) frame) == 0) {
		frame = (void __user *) ((current->sas_ss_sp + current->sas_ss_size)
					 & ~(STACK_ALIGN - 1));
		/*
		 * We need to check for the register stack being on the signal stack
		 * separately, because it's switched separately (memory stack is switched
		 * in the kernel, register stack is switched in the signal trampoline).
		 */
		if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
			new_rbs = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);
	}
	frame = (void __user *) frame - ((sizeof(*frame) + STACK_ALIGN - 1) & ~(STACK_ALIGN - 1));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return force_sigsegv_info(sig, frame);

	err  = __put_user(sig, &frame->arg0);
	err |= __put_user(&frame->info, &frame->arg1);
	err |= __put_user(&frame->sc, &frame->arg2);
	err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
	err |= __put_user(0, &frame->sc.sc_loadrs);	/* initialize to zero */
	err |= __put_user(ka->sa.sa_handler, &frame->handler);

	err |= copy_siginfo_to_user(&frame->info, info);

	err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp);
	err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size);
	err |= __put_user(sas_ss_flags(scr->pt.r12), &frame->sc.sc_stack.ss_flags);
	err |= setup_sigcontext(&frame->sc, set, scr);

	if (unlikely(err))
		return force_sigsegv_info(sig, frame);

	scr->pt.r12 = (unsigned long) frame - 16;	/* new stack pointer */
	scr->pt.ar_fpsr = FPSR_DEFAULT;			/* reset fpsr for signal handler */
	scr->pt.cr_iip = tramp_addr;
	ia64_psr(&scr->pt)->ri = 0;			/* start executing in first slot */
	ia64_psr(&scr->pt)->be = 0;			/* force little-endian byte-order */
	/*
	 * Force the interruption function mask to zero.  This has no effect when a
	 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
	 * ignored), but it has the desirable effect of making it possible to deliver a
	 * signal with an incomplete register frame (which happens when a mandatory RSE
	 * load faults).  Furthermore, it has no negative effect on the getting the user's
	 * dirty partition preserved, because that's governed by scr->pt.loadrs.
	 */
	scr->pt.cr_ifs = (1UL << 63);

	/*
	 * Note: this affects only the NaT bits of the scratch regs (the ones saved in
	 * pt_regs), which is exactly what we want.
	 */
	scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */

#if DEBUG_SIG
	printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
	       current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
#endif
	return 1;
}

static long
handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset,
	       struct sigscratch *scr)
{
	if (IS_IA32_PROCESS(&scr->pt)) {
		/* send signal to IA-32 process */
		if (!ia32_setup_frame1(sig, ka, info, oldset, &scr->pt))
			return 0;
	} else
		/* send signal to IA-64 process */
		if (!setup_frame(sig, ka, info, oldset, scr))
			return 0;

	if (!(ka->sa.sa_flags & SA_NODEFER)) {
		spin_lock_irq(&current->sighand->siglock);
		{
			sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
			sigaddset(&current->blocked, sig);
			recalc_sigpending();
		}
		spin_unlock_irq(&current->sighand->siglock);
	}
	return 1;
}

/*
 * Note that `init' is a special process: it doesn't get signals it doesn't want to
 * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 */
long
ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
{
	struct k_sigaction ka;
	siginfo_t info;
	long restart = in_syscall;
	long errno = scr->pt.r8;
#	define ERR_CODE(c)	(IS_IA32_PROCESS(&scr->pt) ? -(c) : (c))

	/*
	 * In the ia64_leave_kernel code path, we want the common case to go fast, which
	 * is why we may in certain cases get here from kernel mode. Just return without
	 * doing anything if so.
	 */
	if (!user_mode(&scr->pt))
		return 0;

	if (!oldset)
		oldset = &current->blocked;

	/*
	 * This only loops in the rare cases of handle_signal() failing, in which case we
	 * need to push through a forced SIGSEGV.
	 */
	while (1) {
		int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL);

		/*
		 * get_signal_to_deliver() may have run a debugger (via notify_parent())
		 * and the debugger may have modified the state (e.g., to arrange for an
		 * inferior call), thus it's important to check for restarting _after_
		 * get_signal_to_deliver().
		 */
		if (IS_IA32_PROCESS(&scr->pt)) {
			if (in_syscall) {
				if (errno >= 0)
					restart = 0;
				else
					errno = -errno;
			}
		} else if ((long) scr->pt.r10 != -1)
			/*
			 * A system calls has to be restarted only if one of the error codes
			 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
			 * isn't -1 then r8 doesn't hold an error code and we don't need to
			 * restart the syscall, so we can clear the "restart" flag here.
			 */
			restart = 0;

		if (signr <= 0)
			break;

		if (unlikely(restart)) {
			switch (errno) {
			      case ERESTART_RESTARTBLOCK:
			      case ERESTARTNOHAND:
				scr->pt.r8 = ERR_CODE(EINTR);
				/* note: scr->pt.r10 is already -1 */
				break;

			      case ERESTARTSYS:
				if ((ka.sa.sa_flags & SA_RESTART) == 0) {
					scr->pt.r8 = ERR_CODE(EINTR);
					/* note: scr->pt.r10 is already -1 */
					break;
				}
			      case ERESTARTNOINTR:
				if (IS_IA32_PROCESS(&scr->pt)) {
					scr->pt.r8 = scr->pt.r1;
					scr->pt.cr_iip -= 2;
				} else
					ia64_decrement_ip(&scr->pt);
				restart = 0; /* don't restart twice if handle_signal() fails... */
			}
		}

		/*
		 * Whee!  Actually deliver the signal.  If the delivery failed, we need to
		 * continue to iterate in this loop so we can deliver the SIGSEGV...
		 */
		if (handle_signal(signr, &ka, &info, oldset, scr))
			return 1;
	}

	/* Did we come from a system call? */
	if (restart) {
		/* Restart the system call - no handlers present */
		if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
		    || errno == ERESTART_RESTARTBLOCK)
		{
			if (IS_IA32_PROCESS(&scr->pt)) {
				scr->pt.r8 = scr->pt.r1;
				scr->pt.cr_iip -= 2;
				if (errno == ERESTART_RESTARTBLOCK)
					scr->pt.r8 = 0;	/* x86 version of __NR_restart_syscall */
			} else {
				/*
				 * Note: the syscall number is in r15 which is saved in
				 * pt_regs so all we need to do here is adjust ip so that
				 * the "break" instruction gets re-executed.
				 */
				ia64_decrement_ip(&scr->pt);
				if (errno == ERESTART_RESTARTBLOCK)
					scr->pt.r15 = __NR_restart_syscall;
			}
		}
	}
	return 0;
}

/* Set a delayed signal that was detected in MCA/INIT/NMI/PMI context where it
 * could not be delivered.  It is important that the target process is not
 * allowed to do any more work in user space.  Possible cases for the target
 * process:
 *
 * - It is sleeping and will wake up soon.  Store the data in the current task,
 *   the signal will be sent when the current task returns from the next
 *   interrupt.
 *
 * - It is running in user context.  Store the data in the current task, the
 *   signal will be sent when the current task returns from the next interrupt.
 *
 * - It is running in kernel context on this or another cpu and will return to
 *   user context.  Store the data in the target task, the signal will be sent
 *   to itself when the target task returns to user space.
 *
 * - It is running in kernel context on this cpu and will sleep before
 *   returning to user context.  Because this is also the current task, the
 *   signal will not get delivered and the task could sleep indefinitely.
 *   Store the data in the idle task for this cpu, the signal will be sent
 *   after the idle task processes its next interrupt.
 *
 * To cover all cases, store the data in the target task, the current task and
 * the idle task on this cpu.  Whatever happens, the signal will be delivered
 * to the target task before it can do any useful user space work.  Multiple
 * deliveries have no unwanted side effects.
 *
 * Note: This code is executed in MCA/INIT/NMI/PMI context, with interrupts
 * disabled.  It must not take any locks nor use kernel structures or services
 * that require locks.
 */

/* To ensure that we get the right pid, check its start time.  To avoid extra
 * include files in thread_info.h, convert the task start_time to unsigned long,
 * giving us a cycle time of > 580 years.
 */
static inline unsigned long
start_time_ul(const struct task_struct *t)
{
	return t->start_time.tv_sec * NSEC_PER_SEC + t->start_time.tv_nsec;
}

void
set_sigdelayed(pid_t pid, int signo, int code, void __user *addr)
{
	struct task_struct *t;
	unsigned long start_time =  0;
	int i;

	for (i = 1; i <= 3; ++i) {
		switch (i) {
		case 1:
			t = find_task_by_pid(pid);
			if (t)
				start_time = start_time_ul(t);
			break;
		case 2:
			t = current;
			break;
		default:
			t = idle_task(smp_processor_id());
			break;
		}

		if (!t)
			return;
		t->thread_info->sigdelayed.signo = signo;
		t->thread_info->sigdelayed.code = code;
		t->thread_info->sigdelayed.addr = addr;
		t->thread_info->sigdelayed.start_time = start_time;
		t->thread_info->sigdelayed.pid = pid;
		wmb();
		set_tsk_thread_flag(t, TIF_SIGDELAYED);
	}
}

/* Called from entry.S when it detects TIF_SIGDELAYED, a delayed signal that
 * was detected in MCA/INIT/NMI/PMI context where it could not be delivered.
 */

void
do_sigdelayed(void)
{
	struct siginfo siginfo;
	pid_t pid;
	struct task_struct *t;

	clear_thread_flag(TIF_SIGDELAYED);
	memset(&siginfo, 0, sizeof(siginfo));
	siginfo.si_signo = current_thread_info()->sigdelayed.signo;
	siginfo.si_code = current_thread_info()->sigdelayed.code;
	siginfo.si_addr = current_thread_info()->sigdelayed.addr;
	pid = current_thread_info()->sigdelayed.pid;
	t = find_task_by_pid(pid);
	if (!t)
		return;
	if (current_thread_info()->sigdelayed.start_time != start_time_ul(t))
		return;
	force_sig_info(siginfo.si_signo, &siginfo, t);
}