aboutsummaryrefslogtreecommitdiffstats
path: root/arch/cris/arch-v32/kernel/signal.c
blob: 58c1866804e31974fdef993c44d7a34cb2f37aae (plain) (blame)
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
/*
 * Copyright (C) 2003, Axis Communications AB.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>

#include <asm/io.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/arch/ptrace.h>
#include <asm/arch/hwregs/cpu_vect.h>

extern unsigned long cris_signal_return_page;

/* Flag to check if a signal is blockable. */
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/*
 * A syscall in CRIS is really a "break 13" instruction, which is 2
 * bytes. The registers is manipulated so upon return the instruction
 * will be executed again.
 *
 * This relies on that PC points to the instruction after the break call.
 */
#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;

/* Signal frames. */
struct signal_frame {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS - 1];
	unsigned char retcode[8];	/* Trampoline code. */
};

struct rt_signal_frame {
	struct siginfo *pinfo;
	void *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned char retcode[8];	/* Trampoline code. */
};

void do_signal(int restart, struct pt_regs *regs);
void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
		      struct pt_regs *regs);
/*
 * Swap in the new signal mask, and wait for a signal. Define some
 * dummy arguments to be able to reach the regs argument.
 */
int
sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
	       long srp, struct pt_regs *regs)
{
	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	current->saved_sigmask = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	current->state = TASK_INTERRUPTIBLE;
	schedule();
	set_thread_flag(TIF_RESTORE_SIGMASK);
	return -ERESTARTNOHAND;
}

int
sys_sigaction(int signal, const struct old_sigaction *act,
	      struct old_sigaction *oact)
{
	int retval;
	struct k_sigaction newk;
	struct k_sigaction oldk;

	if (act) {
		old_sigset_t mask;

		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(newk.sa.sa_handler, &act->sa_handler) ||
		    __get_user(newk.sa.sa_restorer, &act->sa_restorer))
			return -EFAULT;

		__get_user(newk.sa.sa_flags, &act->sa_flags);
		__get_user(mask, &act->sa_mask);
		siginitset(&newk.sa.sa_mask, mask);
	}

	retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);

	if (!retval && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(oldk.sa.sa_restorer, &oact->sa_restorer))
			return -EFAULT;

		__put_user(oldk.sa.sa_flags, &oact->sa_flags);
		__put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return retval;
}

int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
	return do_sigaltstack(uss, uoss, rdusp());
}

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
	unsigned int err = 0;
	unsigned long old_usp;

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

	/*
	 * Restore the registers from &sc->regs. sc is already checked
	 * for VERIFY_READ since the signal_frame was previously
	 * checked in sys_sigreturn().
	 */
	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
		goto badframe;

	/* Make that the user-mode flag is set. */
	regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));

	/* Restore the old USP. */
	err |= __get_user(old_usp, &sc->usp);
	wrusp(old_usp);

	return err;

badframe:
	return 1;
}

/* Define some dummy arguments to be able to reach the regs argument. */
asmlinkage int
sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
	      struct pt_regs *regs)
{
	sigset_t set;
	struct signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct signal_frame *) rdusp();

	/*
	 * Since the signal is stacked on a dword boundary, the frame
	 * should be dword aligned here as well. It it's not, then the
	 * user is trying some funny business.
	 */
	if (((long)frame) & 3)
		goto badframe;

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

	if (__get_user(set.sig[0], &frame->sc.oldmask) ||
	    (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
						 frame->extramask,
						 sizeof(frame->extramask))))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);

	current->blocked = set;

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->sc))
		goto badframe;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/* Define some dummy variables to be able to reach the regs argument. */
asmlinkage int
sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
		 struct pt_regs *regs)
{
	sigset_t set;
	struct rt_signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct rt_signal_frame *) rdusp();

	/*
	 * Since the signal is stacked on a dword boundary, the frame
	 * should be dword aligned here as well. It it's not, then the
	 * user is trying some funny business.
	 */
	if (((long)frame) & 3)
		goto badframe;

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

	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);

	current->blocked = set;

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
		goto badframe;

	if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT)
		goto badframe;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/* Setup a signal frame. */
static int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
		 unsigned long mask)
{
	int err;
	unsigned long usp;

	err = 0;
	usp = rdusp();

	/*
	 * Copy the registers. They are located first in sc, so it's
	 * possible to use sc directly.
	 */
	err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));

	err |= __put_user(mask, &sc->oldmask);
	err |= __put_user(usp, &sc->usp);

	return err;
}

/* Figure out where to put the new signal frame - usually on the stack. */
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
	unsigned long sp;

	sp = rdusp();

	/* This is the X/Open sanctioned signal stack switching. */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (!on_sig_stack(sp))
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	/* Make sure the frame is dword-aligned. */
	sp &= ~3;

	return (void __user *)(sp - frame_size);
}

/* Grab and setup a signal frame.
 *
 * Basically a lot of state-info is stacked, and arranged for the
 * user-mode program to return to the kernel using either a trampiline
 * which performs the syscall sigreturn(), or a provided user-mode
 * trampoline.
  */
static int
setup_frame(int sig, struct k_sigaction *ka,  sigset_t *set,
	    struct pt_regs * regs)
{
	int err;
	unsigned long return_ip;
	struct signal_frame __user *frame;

	err = 0;
	frame = get_sigframe(ka, regs, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);

	if (err)
		goto give_sigsegv;

	if (_NSIG_WORDS > 1) {
		err |= __copy_to_user(frame->extramask, &set->sig[1],
				      sizeof(frame->extramask));
	}

	if (err)
		goto give_sigsegv;

	/*
	 * Set up to return from user-space. If provided, use a stub
	 * already located in user-space.
	 */
	if (ka->sa.sa_flags & SA_RESTORER) {
		return_ip = (unsigned long)ka->sa.sa_restorer;
	} else {
		/* Trampoline - the desired return ip is in the signal return page. */
		return_ip = cris_signal_return_page;

		/*
		 * This is movu.w __NR_sigreturn, r9; break 13;
		 *
		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
		 * reasons and because gdb uses it as a signature to notice
		 * signal handler stack frames.
		 */
		err |= __put_user(0x9c5f,         (short __user*)(frame->retcode+0));
		err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
		err |= __put_user(0xe93d,         (short __user*)(frame->retcode+4));
	}

	if (err)
		goto give_sigsegv;

	/*
	 * Set up registers for signal handler.
	 *
	 * Where the code enters now.
	 * Where the code enter later.
	 * First argument, signo.
	 */
	regs->erp = (unsigned long) ka->sa.sa_handler;
	regs->srp = return_ip;
	regs->r10 = sig;

	/* Actually move the USP to reflect the stacked frame. */
	wrusp((unsigned long)frame);

	return 0;

give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;

	force_sig(SIGSEGV, current);
	return -EFAULT;
}

static int
setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
	       sigset_t *set, struct pt_regs * regs)
{
	int err;
	unsigned long return_ip;
	struct rt_signal_frame __user *frame;

	err = 0;
	frame = get_sigframe(ka, regs, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	/* TODO: what is the current->exec_domain stuff and invmap ? */

	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);

	if (err)
		goto give_sigsegv;

	/* Clear all the bits of the ucontext we don't use.  */
	err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err)
		goto give_sigsegv;

	/*
	 * Set up to return from user-space. If provided, use a stub
	 * already located in user-space.
	 */
	if (ka->sa.sa_flags & SA_RESTORER) {
		return_ip = (unsigned long) ka->sa.sa_restorer;
	} else {
		/* Trampoline - the desired return ip is in the signal return page. */
		return_ip = cris_signal_return_page + 6;

		/*
		 * This is movu.w __NR_rt_sigreturn, r9; break 13;
		 *
		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
		 * reasons and because gdb uses it as a signature to notice
		 * signal handler stack frames.
		 */
		err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));

		err |= __put_user(__NR_rt_sigreturn,
				  (short __user*)(frame->retcode+2));

		err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
	}

	if (err)
		goto give_sigsegv;

	/*
	 * Set up registers for signal handler.
	 *
	 * Where the code enters now.
	 * Where the code enters later.
	 * First argument is signo.
	 * Second argument is (siginfo_t *).
	 * Third argument is unused.
	 */
	regs->erp = (unsigned long) ka->sa.sa_handler;
	regs->srp = return_ip;
	regs->r10 = sig;
	regs->r11 = (unsigned long) &frame->info;
	regs->r12 = 0;

	/* Actually move the usp to reflect the stacked frame. */
	wrusp((unsigned long)frame);

	return 0;

give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;

	force_sig(SIGSEGV, current);
	return -EFAULT;
}

/* Invoke a singal handler to, well, handle the signal. */
static inline int
handle_signal(int canrestart, unsigned long sig,
	      siginfo_t *info, struct k_sigaction *ka,
              sigset_t *oldset, struct pt_regs * regs)
{
	int ret;

	/* Check if this got called from a system call. */
	if (canrestart) {
		/* If so, check system call restarting. */
		switch (regs->r10) {
			case -ERESTART_RESTARTBLOCK:
			case -ERESTARTNOHAND:
				/*
				 * This means that the syscall should
				 * only be restarted if there was no
				 * handler for the signal, and since
				 * this point isn't reached unless
				 * there is a handler, there's no need
				 * to restart.
				 */
				regs->r10 = -EINTR;
				break;

                        case -ERESTARTSYS:
				/*
				 * This means restart the syscall if
                                 * there is no handler, or the handler
                                 * was registered with SA_RESTART.
				 */
				if (!(ka->sa.sa_flags & SA_RESTART)) {
					regs->r10 = -EINTR;
					break;
				}

				/* Fall through. */

			case -ERESTARTNOINTR:
				/*
				 * This means that the syscall should
                                 * be called again after the signal
                                 * handler returns.
				 */
				RESTART_CRIS_SYS(regs);
				break;
                }
        }

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

	if (ka->sa.sa_flags & SA_ONESHOT)
		ka->sa.sa_handler = SIG_DFL;

	if (ret == 0) {
		spin_lock_irq(&current->sighand->siglock);
		sigorsets(&current->blocked, &current->blocked,
			&ka->sa.sa_mask);
		if (!(ka->sa.sa_flags & SA_NODEFER))
			sigaddset(&current->blocked, sig);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}

	return ret;
}

/*
 * 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.
 *
 * Also note that the regs structure given here as an argument, is the latest
 * pushed pt_regs. It may or may not be the same as the first pushed registers
 * when the initial usermode->kernelmode transition took place. Therefore
 * we can use user_mode(regs) to see if we came directly from kernel or user
 * mode below.
 */
void
do_signal(int canrestart, struct pt_regs *regs)
{
	int signr;
	siginfo_t info;
        struct k_sigaction ka;
	sigset_t *oldset;

	/*
	 * The common case should go fast, which is why this point is
	 * reached from kernel-mode. If that's the case, just return
	 * without doing anything.
	 */
	if (!user_mode(regs))
		return;

	if (test_thread_flag(TIF_RESTORE_SIGMASK))
		oldset = &current->saved_sigmask;
	else
		oldset = &current->blocked;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	if (signr > 0) {
		/* Whee!  Actually deliver the signal.  */
		if (handle_signal(canrestart, signr, &info, &ka,
				oldset, regs)) {
			/* a signal was successfully delivered; the saved
			 * sigmask will have been stored in the signal frame,
			 * and will be restored by sigreturn, so we can simply
			 * clear the TIF_RESTORE_SIGMASK flag */
			if (test_thread_flag(TIF_RESTORE_SIGMASK))
				clear_thread_flag(TIF_RESTORE_SIGMASK);
		}

		return;
	}

	/* Got here from a system call? */
	if (canrestart) {
		/* Restart the system call - no handlers present. */
		if (regs->r10 == -ERESTARTNOHAND ||
		    regs->r10 == -ERESTARTSYS ||
		    regs->r10 == -ERESTARTNOINTR) {
			RESTART_CRIS_SYS(regs);
		}

		if (regs->r10 == -ERESTART_RESTARTBLOCK){
			regs->r10 = __NR_restart_syscall;
			regs->erp -= 2;
		}
	}

	/* if there's no signal to deliver, we just put the saved sigmask
	 * back */
	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
		clear_thread_flag(TIF_RESTORE_SIGMASK);
		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
	}
}

asmlinkage void
ugdb_trap_user(struct thread_info *ti, int sig)
{
	if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
		/* Zero single-step PC if the reason we stopped wasn't a single
		   step exception. This is to avoid relying on it when it isn't
		   reliable. */
		user_regs(ti)->spc = 0;
	}
	/* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
	   not withing any configured h/w breakpoint range). Synchronize with
	   what already exists for kernel debugging.  */
	if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
		/* Break 8: subtract 2 from ERP unless in a delay slot. */
		if (!(user_regs(ti)->erp & 0x1))
			user_regs(ti)->erp -= 2;
	}
	sys_kill(ti->task->pid, sig);
}

void
keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
		 struct pt_regs *regs)
{
	if (oldccs & (1 << Q_CCS_BITNR)) {
		/* Pending single step due to single-stepping the break 13
		   in the signal trampoline: keep the Q flag. */
		regs->ccs |= (1 << Q_CCS_BITNR);
		/* S flag should be set - complain if it's not. */
		if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
			printk("Q flag but no S flag?");
		}
		regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
		/* Assume the SPC is valid and interesting. */
		regs->spc = oldspc;

	} else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
		/* If a h/w bp was set in the signal handler we need
		   to keep the S flag. */
		regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
		/* Don't keep the old SPC though; if we got here due to
		   a single-step, the Q flag should have been set. */
	} else if (regs->spc) {
		/* If we were single-stepping *before* the signal was taken,
		   we don't want to restore that state now, because GDB will
		   have forgotten all about it. */
		regs->spc = 0;
		regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
	}
}

/* Set up the trampolines on the signal return page. */
int __init
cris_init_signal(void)
{
	u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);

	/* This is movu.w __NR_sigreturn, r9; break 13; */
	data[0] = 0x9c5f;
	data[1] = __NR_sigreturn;
	data[2] = 0xe93d;
	/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
	data[3] = 0x9c5f;
	data[4] = __NR_rt_sigreturn;
	data[5] = 0xe93d;

	/* Map to userspace with appropriate permissions (no write access...) */
	cris_signal_return_page = (unsigned long)
          __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);

	return 0;
}

__initcall(cris_init_signal);