aboutsummaryrefslogtreecommitdiffstats
path: root/arch/xtensa/kernel/signal.c
blob: 033aae0336d260d323f07c3abaad1ea521690d7c (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
/*
 * arch/xtensa/kernel/signal.c
 *
 * Default platform functions.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2005, 2006 Tensilica Inc.
 * Copyright (C) 1991, 1992  Linus Torvalds
 * 1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 * Chris Zankel <chris@zankel.net>
 * Joe Taylor <joe@tensilica.com>
 */

#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <linux/freezer.h>

#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/coprocessor.h>
#include <asm/unistd.h>

#define DEBUG_SIG  0

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);

extern struct task_struct *coproc_owners[];

extern void release_all_cp (struct task_struct *);

struct rt_sigframe
{
	struct siginfo info;
	struct ucontext uc;
	cp_state_t cpstate;
	unsigned char retcode[6];
	unsigned int window[4];
};

/* 
 * Flush register windows stored in pt_regs to stack.
 * Returns 1 for errors.
 *
 * Note that windowbase, windowstart, and wmask are not updated!
 */

int
flush_window_regs_user(struct pt_regs *regs)
{
	const unsigned long ws = regs->windowstart;
	const unsigned long wb = regs->windowbase;
	unsigned long sp = 0;
	unsigned long wm;
	int err = 1;
	int base;

	/* Return if no other frames. */

	if (regs->wmask == 1)
		return 0;

	/* Rotate windowmask and skip empty frames. */

	wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
	base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
		
	/* For call8 or call12 frames, we need the previous stack pointer. */

	if ((regs->wmask & 2) == 0)
		if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
			goto errout;

	/* Spill frames to stack. */

	while (base < XCHAL_NUM_AREGS / 4) {

		int m = (wm >> base);
		int inc = 0;

		/* Save registers a4..a7 (call8) or a4...a11 (call12) */

		if (m & 2) {			/* call4 */
			inc = 1;

		} else if (m & 4) {		/* call8 */
			if (copy_to_user((void*)(sp - 32),
					   &regs->areg[(base + 1) * 4], 16))
				goto errout;
			inc = 2;

		} else if (m & 8) {	/* call12 */
			if (copy_to_user((void*)(sp - 48),
					   &regs->areg[(base + 1) * 4], 32))
				goto errout;
			inc = 3;
		}

		/* Save current frame a0..a3 under next SP */

		sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
		if (copy_to_user((void*)(sp - 16), &regs->areg[base * 4], 16))
			goto errout;

		/* Get current stack pointer for next loop iteration. */

		sp = regs->areg[base * 4 + 1];
		base += inc;
	}

	return 0;

errout:
	return err;
}

/*
 * Note: We don't copy double exception 'regs', we have to finish double exc. 
 * first before we return to signal handler! This dbl.exc.handler might cause 
 * another double exception, but I think we are fine as the situation is the 
 * same as if we had returned to the signal handerl and got an interrupt 
 * immediately...
 */

static int
setup_sigcontext(struct sigcontext __user *sc, cp_state_t *cpstate,
		 struct pt_regs *regs, unsigned long mask)
{
	int err = 0;

#define COPY(x)	err |= __put_user(regs->x, &sc->sc_##x)
	COPY(pc);
	COPY(ps);
	COPY(lbeg);
	COPY(lend);
	COPY(lcount);
	COPY(sar);
#undef COPY

	err |= flush_window_regs_user(regs);
	err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);

	// err |= __copy_to_user (sc->sc_a, regs->areg, XCHAL_NUM_AREGS * 4)

#if XCHAL_HAVE_CP
# error Coprocessors unsupported
	err |= save_cpextra(cpstate);
	err |= __put_user(err ? NULL : cpstate, &sc->sc_cpstate);
#endif
	/* non-iBCS2 extensions.. */
	err |= __put_user(mask, &sc->oldmask);

	return err;
}

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

#define COPY(x)	err |= __get_user(regs->x, &sc->sc_##x)
	COPY(pc);
	COPY(lbeg);
	COPY(lend);
	COPY(lcount);
	COPY(sar);
#undef COPY

	/* All registers were flushed to stack. Start with a prestine frame. */

	regs->wmask = 1;
	regs->windowbase = 0;
	regs->windowstart = 1;

	/* For PS, restore only PS.CALLINC.
	 * Assume that all other bits are either the same as for the signal
	 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
	 */
	err |= __get_user(ps, &sc->sc_ps);
	regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);

	/* Additional corruption checks */

	if ((regs->lcount > 0)
	    && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
		err = 1;

	err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);

#if XCHAL_HAVE_CP
# error Coprocessors unsupported
 	/* The signal handler may have used coprocessors in which
	 * case they are still enabled.  We disable them to force a
	 * reloading of the original task's CP state by the lazy
	 * context-switching mechanisms of CP exception handling.
	 * Also, we essentially discard any coprocessor state that the
	 * signal handler created. */

	if (!err) {
	  struct task_struct *tsk = current;
	  release_all_cp(tsk);
	  err |= __copy_from_user(tsk->thread.cpextra, sc->sc_cpstate, 
	      			  XTENSA_CP_EXTRA_SIZE);
	}
#endif

	regs->syscall = -1;		/* disable syscall checks */
	return err;
}



/*
 * Do a signal return; undo the signal stack.
 */

asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3,
				    long a4, long a5, struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;
	sigset_t set;
	int ret;

	if (regs->depc > 64)
		panic("rt_sigreturn in double exception!\n");

	frame = (struct rt_sigframe __user *) regs->areg[1];

	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;

	ret = regs->areg[2];

	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT)
		goto badframe;

	return ret;

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



/*
 * Set up a signal frame.
 */

static int
gen_return_code(unsigned char *codemem)
{
	int err = 0;

	/*
	 * The 12-bit immediate is really split up within the 24-bit MOVI
	 * instruction.  As long as the above system call numbers fit within
	 * 8-bits, the following code works fine. See the Xtensa ISA for
	 * details.
	 */

#if __NR_rt_sigreturn > 255
# error Generating the MOVI instruction below breaks!
#endif

#ifdef __XTENSA_EB__   /* Big Endian version */
	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
	err |= __put_user(0x22, &codemem[0]);
	err |= __put_user(0x0a, &codemem[1]);
	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
	/* Generate instruction:  SYSCALL */
	err |= __put_user(0x00, &codemem[3]);
	err |= __put_user(0x05, &codemem[4]);
	err |= __put_user(0x00, &codemem[5]);

#elif defined __XTENSA_EL__   /* Little Endian version */
	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
	err |= __put_user(0x22, &codemem[0]);
	err |= __put_user(0xa0, &codemem[1]);
	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
	/* Generate instruction:  SYSCALL */
	err |= __put_user(0x00, &codemem[3]);
	err |= __put_user(0x50, &codemem[4]);
	err |= __put_user(0x00, &codemem[5]);
#else
# error Must use compiler for Xtensa processors.
#endif

	/* Flush generated code out of the data cache */

	if (err == 0) {
		__invalidate_icache_range((unsigned long)codemem, 6UL);
		__flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
	}

	return err;
}


static void setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
			sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe *frame;
	int err = 0;
	int signal;
	unsigned long sp, ra;

	sp = regs->areg[1];

	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) {
		sp = current->sas_ss_sp + current->sas_ss_size;
	}

	frame = (void *)((sp - sizeof(*frame)) & -16ul);

	if (regs->depc > 64)
		panic ("Double exception sys_sigreturn\n");

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

	signal = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	if (ka->sa.sa_flags & SA_SIGINFO) {
		err |= copy_siginfo_to_user(&frame->info, info);
	}

	/* Create the user context.  */

	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user((void *)current->sas_ss_sp,
			  &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->areg[1]),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->cpstate,
			        regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Create sys_rt_sigreturn syscall in stack frame */

	err |= gen_return_code(frame->retcode);

	if (err) {
		goto give_sigsegv;
	}
		

	/* 
	 * Create signal handler execution context.
	 * Return context not modified until this point.
	 */

	/* Set up registers for signal handler */
	start_thread(regs, (unsigned long) ka->sa.sa_handler, 
		     (unsigned long) frame);

	/* Set up a stack frame for a call4
	 * Note: PS.CALLINC is set to one by start_thread
	 */
	ra = (unsigned long) frame->retcode;
	regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
	regs->areg[6] = (unsigned long) signal;
	regs->areg[7] = (unsigned long) &frame->info;
	regs->areg[8] = (unsigned long) &frame->uc;

	/* Set access mode to USER_DS.  Nomenclature is outdated, but
	 * functionality is used in uaccess.h
	 */
	set_fs(USER_DS);

#if DEBUG_SIG
	printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
		current->comm, current->pid, signal, frame, regs->pc);
#endif

	return;

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

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */

asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset, 
    				     size_t sigsetsize,
    				     long a2, long a3, long a4, long a5, 
				     struct pt_regs *regs)
{
	sigset_t saveset, newset;

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

	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;

	sigdelsetmask(&newset, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	current->blocked = newset;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	regs->areg[2] = -EINTR;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(regs, &saveset))
			return -EINTR;
	}
}

asmlinkage long xtensa_sigaltstack(const stack_t __user *uss, 
				   stack_t __user *uoss,
    				   long a2, long a3, long a4, long a5,
				   struct pt_regs *regs)
{
	return do_sigaltstack(uss, uoss, regs->areg[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.
 *
 * 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.
 */
int do_signal(struct pt_regs *regs, sigset_t *oldset)
{
	siginfo_t info;
	int signr;
	struct k_sigaction ka;

	if (!user_mode(regs))
		return 0;

	if (try_to_freeze())
		goto no_signal;

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

	task_pt_regs(current)->icountlevel = 0;

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

	if (signr > 0) {

		/* Are we from a system call? */

		if ((signed)regs->syscall >= 0) {

			/* If so, check system call restarting.. */

			switch (regs->areg[2]) {
				case -ERESTARTNOHAND:
				case -ERESTART_RESTARTBLOCK:
					regs->areg[2] = -EINTR;
					break;

				case -ERESTARTSYS:
					if (!(ka.sa.sa_flags & SA_RESTART)) {
						regs->areg[2] = -EINTR;
						break;
					}
					/* fallthrough */
				case -ERESTARTNOINTR:
					regs->areg[2] = regs->syscall;
					regs->pc -= 3;
					break;

				default:
					/* nothing to do */
					if (regs->areg[2] != 0)
					break;
			}
		}

		/* Whee!  Actually deliver the signal.  */
		/* Set up the stack frame */
		setup_frame(signr, &ka, &info, oldset, regs);

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

		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, signr);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
		if (current->ptrace & PT_SINGLESTEP)
			task_pt_regs(current)->icountlevel = 1;

		return 1;
	}

no_signal:
	/* Did we come from a system call? */
	if ((signed) regs->syscall >= 0) {
		/* Restart the system call - no handlers present */
		switch (regs->areg[2]) {
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
			regs->areg[2] = regs->syscall;
			regs->pc -= 3;
			break;
		case -ERESTART_RESTARTBLOCK:
			regs->areg[2] = __NR_restart_syscall;
			regs->pc -= 3;
			break;
		}
	}
	if (current->ptrace & PT_SINGLESTEP)
		task_pt_regs(current)->icountlevel = 1;
	return 0;
}