summaryrefslogtreecommitdiff
path: root/arch/arm/kernel/signal.c
blob: 3870e0588d53b5fa044641d891910b2be77b7176 (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
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
/*
 *  linux/arch/arm/kernel/signal.c
 *
 *  Copyright (C) 1995-2009 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
#include <linux/uprobes.h>
#include <linux/syscalls.h>

#include <asm/elf.h>
#include <asm/cacheflush.h>
#include <asm/traps.h>
#include <asm/unistd.h>
#include <asm/vfp.h>

#include "signal.h"

extern const unsigned long sigreturn_codes[17];

static unsigned long signal_return_offset;

#ifdef CONFIG_CRUNCH
static int preserve_crunch_context(struct crunch_sigframe __user *frame)
{
	char kbuf[sizeof(*frame) + 8];
	struct crunch_sigframe *kframe;

	/* the crunch context must be 64 bit aligned */
	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
	kframe->magic = CRUNCH_MAGIC;
	kframe->size = CRUNCH_STORAGE_SIZE;
	crunch_task_copy(current_thread_info(), &kframe->storage);
	return __copy_to_user(frame, kframe, sizeof(*frame));
}

static int restore_crunch_context(char __user **auxp)
{
	struct crunch_sigframe __user *frame =
		(struct crunch_sigframe __user *)*auxp;
	char kbuf[sizeof(*frame) + 8];
	struct crunch_sigframe *kframe;

	/* the crunch context must be 64 bit aligned */
	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
	if (__copy_from_user(kframe, frame, sizeof(*frame)))
		return -1;
	if (kframe->magic != CRUNCH_MAGIC ||
	    kframe->size != CRUNCH_STORAGE_SIZE)
		return -1;
	*auxp += CRUNCH_STORAGE_SIZE;
	crunch_task_restore(current_thread_info(), &kframe->storage);
	return 0;
}
#endif

#ifdef CONFIG_IWMMXT

static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
{
	char kbuf[sizeof(*frame) + 8];
	struct iwmmxt_sigframe *kframe;
	int err = 0;

	/* the iWMMXt context must be 64 bit aligned */
	kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);

	if (test_thread_flag(TIF_USING_IWMMXT)) {
		kframe->magic = IWMMXT_MAGIC;
		kframe->size = IWMMXT_STORAGE_SIZE;
		iwmmxt_task_copy(current_thread_info(), &kframe->storage);
	} else {
		/*
		 * For bug-compatibility with older kernels, some space
		 * has to be reserved for iWMMXt even if it's not used.
		 * Set the magic and size appropriately so that properly
		 * written userspace can skip it reliably:
		 */
		*kframe = (struct iwmmxt_sigframe) {
			.magic = DUMMY_MAGIC,
			.size  = IWMMXT_STORAGE_SIZE,
		};
	}

	err = __copy_to_user(frame, kframe, sizeof(*kframe));

	return err;
}

static int restore_iwmmxt_context(char __user **auxp)
{
	struct iwmmxt_sigframe __user *frame =
		(struct iwmmxt_sigframe __user *)*auxp;
	char kbuf[sizeof(*frame) + 8];
	struct iwmmxt_sigframe *kframe;

	/* the iWMMXt context must be 64 bit aligned */
	kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
	if (__copy_from_user(kframe, frame, sizeof(*frame)))
		return -1;

	/*
	 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
	 * block is discarded for compatibility with setup_sigframe() if
	 * present, but we don't mandate its presence.  If some other
	 * magic is here, it's not for us:
	 */
	if (!test_thread_flag(TIF_USING_IWMMXT) &&
	    kframe->magic != DUMMY_MAGIC)
		return 0;

	if (kframe->size != IWMMXT_STORAGE_SIZE)
		return -1;

	if (test_thread_flag(TIF_USING_IWMMXT)) {
		if (kframe->magic != IWMMXT_MAGIC)
			return -1;

		iwmmxt_task_restore(current_thread_info(), &kframe->storage);
	}

	*auxp += IWMMXT_STORAGE_SIZE;
	return 0;
}

#endif

#ifdef CONFIG_VFP

static int preserve_vfp_context(struct vfp_sigframe __user *frame)
{
	struct vfp_sigframe kframe;
	int err = 0;

	memset(&kframe, 0, sizeof(kframe));
	kframe.magic = VFP_MAGIC;
	kframe.size = VFP_STORAGE_SIZE;

	err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
	if (err)
		return err;

	return __copy_to_user(frame, &kframe, sizeof(kframe));
}

static int restore_vfp_context(char __user **auxp)
{
	struct vfp_sigframe frame;
	int err;

	err = __copy_from_user(&frame, *auxp, sizeof(frame));
	if (err)
		return err;

	if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
		return -EINVAL;

	*auxp += sizeof(frame);
	return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
}

#endif

/*
 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 */

static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
{
	struct sigcontext context;
	char __user *aux;
	sigset_t set;
	int err;

	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
	if (err == 0)
		set_current_blocked(&set);

	err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
	if (err == 0) {
		regs->ARM_r0 = context.arm_r0;
		regs->ARM_r1 = context.arm_r1;
		regs->ARM_r2 = context.arm_r2;
		regs->ARM_r3 = context.arm_r3;
		regs->ARM_r4 = context.arm_r4;
		regs->ARM_r5 = context.arm_r5;
		regs->ARM_r6 = context.arm_r6;
		regs->ARM_r7 = context.arm_r7;
		regs->ARM_r8 = context.arm_r8;
		regs->ARM_r9 = context.arm_r9;
		regs->ARM_r10 = context.arm_r10;
		regs->ARM_fp = context.arm_fp;
		regs->ARM_ip = context.arm_ip;
		regs->ARM_sp = context.arm_sp;
		regs->ARM_lr = context.arm_lr;
		regs->ARM_pc = context.arm_pc;
		regs->ARM_cpsr = context.arm_cpsr;
	}

	err |= !valid_user_regs(regs);

	aux = (char __user *) sf->uc.uc_regspace;
#ifdef CONFIG_CRUNCH
	if (err == 0)
		err |= restore_crunch_context(&aux);
#endif
#ifdef CONFIG_IWMMXT
	if (err == 0)
		err |= restore_iwmmxt_context(&aux);
#endif
#ifdef CONFIG_VFP
	if (err == 0)
		err |= restore_vfp_context(&aux);
#endif

	return err;
}

asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
	struct sigframe __user *frame;

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

	/*
	 * Since we stacked the signal on a 64-bit boundary,
	 * then 'sp' should be word aligned here.  If it's
	 * not, then the user is trying to mess with us.
	 */
	if (regs->ARM_sp & 7)
		goto badframe;

	frame = (struct sigframe __user *)regs->ARM_sp;

	if (!access_ok(frame, sizeof (*frame)))
		goto badframe;

	if (restore_sigframe(regs, frame))
		goto badframe;

	return regs->ARM_r0;

badframe:
	force_sig(SIGSEGV);
	return 0;
}

asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;

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

	/*
	 * Since we stacked the signal on a 64-bit boundary,
	 * then 'sp' should be word aligned here.  If it's
	 * not, then the user is trying to mess with us.
	 */
	if (regs->ARM_sp & 7)
		goto badframe;

	frame = (struct rt_sigframe __user *)regs->ARM_sp;

	if (!access_ok(frame, sizeof (*frame)))
		goto badframe;

	if (restore_sigframe(regs, &frame->sig))
		goto badframe;

	if (restore_altstack(&frame->sig.uc.uc_stack))
		goto badframe;

	return regs->ARM_r0;

badframe:
	force_sig(SIGSEGV);
	return 0;
}

static int
setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
{
	struct aux_sigframe __user *aux;
	struct sigcontext context;
	int err = 0;

	context = (struct sigcontext) {
		.arm_r0        = regs->ARM_r0,
		.arm_r1        = regs->ARM_r1,
		.arm_r2        = regs->ARM_r2,
		.arm_r3        = regs->ARM_r3,
		.arm_r4        = regs->ARM_r4,
		.arm_r5        = regs->ARM_r5,
		.arm_r6        = regs->ARM_r6,
		.arm_r7        = regs->ARM_r7,
		.arm_r8        = regs->ARM_r8,
		.arm_r9        = regs->ARM_r9,
		.arm_r10       = regs->ARM_r10,
		.arm_fp        = regs->ARM_fp,
		.arm_ip        = regs->ARM_ip,
		.arm_sp        = regs->ARM_sp,
		.arm_lr        = regs->ARM_lr,
		.arm_pc        = regs->ARM_pc,
		.arm_cpsr      = regs->ARM_cpsr,

		.trap_no       = current->thread.trap_no,
		.error_code    = current->thread.error_code,
		.fault_address = current->thread.address,
		.oldmask       = set->sig[0],
	};

	err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));

	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));

	aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
#ifdef CONFIG_CRUNCH
	if (err == 0)
		err |= preserve_crunch_context(&aux->crunch);
#endif
#ifdef CONFIG_IWMMXT
	if (err == 0)
		err |= preserve_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
	if (err == 0)
		err |= preserve_vfp_context(&aux->vfp);
#endif
	err |= __put_user(0, &aux->end_magic);

	return err;
}

static inline void __user *
get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
{
	unsigned long sp = sigsp(regs->ARM_sp, ksig);
	void __user *frame;

	/*
	 * ATPCS B01 mandates 8-byte alignment
	 */
	frame = (void __user *)((sp - framesize) & ~7);

	/*
	 * Check that we can actually write to the signal frame.
	 */
	if (!access_ok(frame, framesize))
		frame = NULL;

	return frame;
}

static int
setup_return(struct pt_regs *regs, struct ksignal *ksig,
	     unsigned long __user *rc, void __user *frame)
{
	unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
	unsigned long handler_fdpic_GOT = 0;
	unsigned long retcode;
	unsigned int idx, thumb = 0;
	unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
	bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
		     (current->personality & FDPIC_FUNCPTRS);

	if (fdpic) {
		unsigned long __user *fdpic_func_desc =
					(unsigned long __user *)handler;
		if (__get_user(handler, &fdpic_func_desc[0]) ||
		    __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
			return 1;
	}

	cpsr |= PSR_ENDSTATE;

	/*
	 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
	 */
	if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
		cpsr = (cpsr & ~MODE_MASK) | USR_MODE;

#ifdef CONFIG_ARM_THUMB
	if (elf_hwcap & HWCAP_THUMB) {
		/*
		 * The LSB of the handler determines if we're going to
		 * be using THUMB or ARM mode for this signal handler.
		 */
		thumb = handler & 1;

		/*
		 * Clear the If-Then Thumb-2 execution state.  ARM spec
		 * requires this to be all 000s in ARM mode.  Snapdragon
		 * S4/Krait misbehaves on a Thumb=>ARM signal transition
		 * without this.
		 *
		 * We must do this whenever we are running on a Thumb-2
		 * capable CPU, which includes ARMv6T2.  However, we elect
		 * to always do this to simplify the code; this field is
		 * marked UNK/SBZP for older architectures.
		 */
		cpsr &= ~PSR_IT_MASK;

		if (thumb) {
			cpsr |= PSR_T_BIT;
		} else
			cpsr &= ~PSR_T_BIT;
	}
#endif

	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		retcode = (unsigned long)ksig->ka.sa.sa_restorer;
		if (fdpic) {
			/*
			 * We need code to load the function descriptor.
			 * That code follows the standard sigreturn code
			 * (6 words), and is made of 3 + 2 words for each
			 * variant. The 4th copied word is the actual FD
			 * address that the assembly code expects.
			 */
			idx = 6 + thumb * 3;
			if (ksig->ka.sa.sa_flags & SA_SIGINFO)
				idx += 5;
			if (__put_user(sigreturn_codes[idx],   rc  ) ||
			    __put_user(sigreturn_codes[idx+1], rc+1) ||
			    __put_user(sigreturn_codes[idx+2], rc+2) ||
			    __put_user(retcode,                rc+3))
				return 1;
			goto rc_finish;
		}
	} else {
		idx = thumb << 1;
		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
			idx += 3;

		/*
		 * Put the sigreturn code on the stack no matter which return
		 * mechanism we use in order to remain ABI compliant
		 */
		if (__put_user(sigreturn_codes[idx],   rc) ||
		    __put_user(sigreturn_codes[idx+1], rc+1))
			return 1;

rc_finish:
#ifdef CONFIG_MMU
		if (cpsr & MODE32_BIT) {
			struct mm_struct *mm = current->mm;

			/*
			 * 32-bit code can use the signal return page
			 * except when the MPU has protected the vectors
			 * page from PL0
			 */
			retcode = mm->context.sigpage + signal_return_offset +
				  (idx << 2) + thumb;
		} else
#endif
		{
			/*
			 * Ensure that the instruction cache sees
			 * the return code written onto the stack.
			 */
			flush_icache_range((unsigned long)rc,
					   (unsigned long)(rc + 3));

			retcode = ((unsigned long)rc) + thumb;
		}
	}

	regs->ARM_r0 = ksig->sig;
	regs->ARM_sp = (unsigned long)frame;
	regs->ARM_lr = retcode;
	regs->ARM_pc = handler;
	if (fdpic)
		regs->ARM_r9 = handler_fdpic_GOT;
	regs->ARM_cpsr = cpsr;

	return 0;
}

static int
setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
	struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
	int err = 0;

	if (!frame)
		return 1;

	/*
	 * Set uc.uc_flags to a value which sc.trap_no would never have.
	 */
	err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);

	err |= setup_sigframe(frame, regs, set);
	if (err == 0)
		err = setup_return(regs, ksig, frame->retcode, frame);

	return err;
}

static int
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
	int err = 0;

	if (!frame)
		return 1;

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

	err |= __put_user(0, &frame->sig.uc.uc_flags);
	err |= __put_user(NULL, &frame->sig.uc.uc_link);

	err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
	err |= setup_sigframe(&frame->sig, regs, set);
	if (err == 0)
		err = setup_return(regs, ksig, frame->sig.retcode, frame);

	if (err == 0) {
		/*
		 * For realtime signals we must also set the second and third
		 * arguments for the signal handler.
		 *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
		 */
		regs->ARM_r1 = (unsigned long)&frame->info;
		regs->ARM_r2 = (unsigned long)&frame->sig.uc;
	}

	return err;
}

/*
 * OK, we're invoking a handler
 */	
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/*
	 * Perform fixup for the pre-signal frame.
	 */
	rseq_signal_deliver(ksig, regs);

	/*
	 * Set up the stack frame
	 */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		ret = setup_rt_frame(ksig, oldset, regs);
	else
		ret = setup_frame(ksig, oldset, regs);

	/*
	 * Check that the resulting registers are actually sane.
	 */
	ret |= !valid_user_regs(regs);

	signal_setup_done(ret, ksig, 0);
}

/*
 * 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.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static int do_signal(struct pt_regs *regs, int syscall)
{
	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
	struct ksignal ksig;
	int restart = 0;

	/*
	 * If we were from a system call, check for system call restarting...
	 */
	if (syscall) {
		continue_addr = regs->ARM_pc;
		restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
		retval = regs->ARM_r0;

		/*
		 * Prepare for system call restart.  We do this here so that a
		 * debugger will see the already changed PSW.
		 */
		switch (retval) {
		case -ERESTART_RESTARTBLOCK:
			restart -= 2;
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
			restart++;
			regs->ARM_r0 = regs->ARM_ORIG_r0;
			regs->ARM_pc = restart_addr;
			break;
		}
	}

	/*
	 * Get the signal to deliver.  When running under ptrace, at this
	 * point the debugger may change all our registers ...
	 */
	/*
	 * Depending on the signal settings we may need to revert the
	 * decision to restart the system call.  But skip this if a
	 * debugger has chosen to restart at a different PC.
	 */
	if (get_signal(&ksig)) {
		/* handler */
		if (unlikely(restart) && regs->ARM_pc == restart_addr) {
			if (retval == -ERESTARTNOHAND ||
			    retval == -ERESTART_RESTARTBLOCK
			    || (retval == -ERESTARTSYS
				&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
				regs->ARM_r0 = -EINTR;
				regs->ARM_pc = continue_addr;
			}
		}
		handle_signal(&ksig, regs);
	} else {
		/* no handler */
		restore_saved_sigmask();
		if (unlikely(restart) && regs->ARM_pc == restart_addr) {
			regs->ARM_pc = continue_addr;
			return restart;
		}
	}
	return 0;
}

asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
	/*
	 * The assembly code enters us with IRQs off, but it hasn't
	 * informed the tracing code of that for efficiency reasons.
	 * Update the trace code with the current status.
	 */
	trace_hardirqs_off();
	do {
		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
			schedule();
		} else {
			if (unlikely(!user_mode(regs)))
				return 0;
			local_irq_enable();
			if (thread_flags & _TIF_SIGPENDING) {
				int restart = do_signal(regs, syscall);
				if (unlikely(restart)) {
					/*
					 * Restart without handlers.
					 * Deal with it without leaving
					 * the kernel space.
					 */
					return restart;
				}
				syscall = 0;
			} else if (thread_flags & _TIF_UPROBE) {
				uprobe_notify_resume(regs);
			} else {
				clear_thread_flag(TIF_NOTIFY_RESUME);
				tracehook_notify_resume(regs);
				rseq_handle_notify_resume(NULL, regs);
			}
		}
		local_irq_disable();
		thread_flags = current_thread_info()->flags;
	} while (thread_flags & _TIF_WORK_MASK);
	return 0;
}

struct page *get_signal_page(void)
{
	unsigned long ptr;
	unsigned offset;
	struct page *page;
	void *addr;

	page = alloc_pages(GFP_KERNEL, 0);

	if (!page)
		return NULL;

	addr = page_address(page);

	/* Give the signal return code some randomness */
	offset = 0x200 + (get_random_int() & 0x7fc);
	signal_return_offset = offset;

	/*
	 * Copy signal return handlers into the vector page, and
	 * set sigreturn to be a pointer to these.
	 */
	memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));

	ptr = (unsigned long)addr + offset;
	flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));

	return page;
}

/* Defer to generic check */
asmlinkage void addr_limit_check_failed(void)
{
	addr_limit_user_check();
}

#ifdef CONFIG_DEBUG_RSEQ
asmlinkage void do_rseq_syscall(struct pt_regs *regs)
{
	rseq_syscall(regs);
}
#endif