summaryrefslogtreecommitdiffstats
path: root/arch/arm26/kernel/signal.c
blob: 356d9809cc0bb5ad4ba011025889061a92d711ea (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
/*
 *  linux/arch/arm26/kernel/signal.c
 *
 *  Copyright (C) 1995-2002 Russell King
 *  Copyright (C) 2003 Ian Molton (ARM26)
 *
 * FIXME!!! This is probably very broken (13/05/2003)
 *
 * 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/config.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/elf.h>

#include <asm/pgalloc.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

#include "ptrace.h"

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

/*
 * For ARM syscalls, we encode the syscall number into the instruction.
 */
#define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn))
#define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn))

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

/*
 * atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
{
	sigset_t saveset;

	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	regs->ARM_r0 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs, 0))
			return regs->ARM_r0;
	}
}

asmlinkage int
sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, 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->ARM_r0 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs, 0))
			return regs->ARM_r0;
	}
}

asmlinkage int 
sys_sigaction(int sig, const struct old_sigaction *act,
	      struct old_sigaction *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	if (act) {
		old_sigset_t mask;
		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
			return -EFAULT;
		__get_user(new_ka.sa.sa_flags, &act->sa_flags);
		__get_user(mask, &act->sa_mask);
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
			return -EFAULT;
		__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return ret;
}

/*
 * Do a signal return; undo the signal stack.
 */
struct sigframe
{
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	unsigned long retcode;
};

struct rt_sigframe
{
	struct siginfo *pinfo;
	void *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned long retcode;
};

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

	__get_user_error(regs->ARM_r0, &sc->arm_r0, err);
	__get_user_error(regs->ARM_r1, &sc->arm_r1, err);
	__get_user_error(regs->ARM_r2, &sc->arm_r2, err);
	__get_user_error(regs->ARM_r3, &sc->arm_r3, err);
	__get_user_error(regs->ARM_r4, &sc->arm_r4, err);
	__get_user_error(regs->ARM_r5, &sc->arm_r5, err);
	__get_user_error(regs->ARM_r6, &sc->arm_r6, err);
	__get_user_error(regs->ARM_r7, &sc->arm_r7, err);
	__get_user_error(regs->ARM_r8, &sc->arm_r8, err);
	__get_user_error(regs->ARM_r9, &sc->arm_r9, err);
	__get_user_error(regs->ARM_r10, &sc->arm_r10, err);
	__get_user_error(regs->ARM_fp, &sc->arm_fp, err);
	__get_user_error(regs->ARM_ip, &sc->arm_ip, err);
	__get_user_error(regs->ARM_sp, &sc->arm_sp, err);
	__get_user_error(regs->ARM_lr, &sc->arm_lr, err);
	__get_user_error(regs->ARM_pc, &sc->arm_pc, err);

	err |= !valid_user_regs(regs);

	return err;
}

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

	/*
	 * 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 *)regs->ARM_sp;

	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;

	/* Send SIGTRAP if we're single-stepping */
	if (current->ptrace & PT_SINGLESTEP) {
                ptrace_cancel_bpt(current);
                send_sig(SIGTRAP, current, 1);
        }

	return regs->ARM_r0;

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

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

	/*
	 * 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 *)regs->ARM_sp;

	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;

	/* Send SIGTRAP if we're single-stepping */
	if (current->ptrace & PT_SINGLESTEP) {
                ptrace_cancel_bpt(current);
                send_sig(SIGTRAP, current, 1);
        }

	return regs->ARM_r0;

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

static int
setup_sigcontext(struct sigcontext *sc, /*struct _fpstate *fpstate,*/
		 struct pt_regs *regs, unsigned long mask)
{
	int err = 0;

	__put_user_error(regs->ARM_r0, &sc->arm_r0, err);
	__put_user_error(regs->ARM_r1, &sc->arm_r1, err);
	__put_user_error(regs->ARM_r2, &sc->arm_r2, err);
	__put_user_error(regs->ARM_r3, &sc->arm_r3, err);
	__put_user_error(regs->ARM_r4, &sc->arm_r4, err);
	__put_user_error(regs->ARM_r5, &sc->arm_r5, err);
	__put_user_error(regs->ARM_r6, &sc->arm_r6, err);
	__put_user_error(regs->ARM_r7, &sc->arm_r7, err);
	__put_user_error(regs->ARM_r8, &sc->arm_r8, err);
	__put_user_error(regs->ARM_r9, &sc->arm_r9, err);
	__put_user_error(regs->ARM_r10, &sc->arm_r10, err);
	__put_user_error(regs->ARM_fp, &sc->arm_fp, err);
	__put_user_error(regs->ARM_ip, &sc->arm_ip, err);
	__put_user_error(regs->ARM_sp, &sc->arm_sp, err);
	__put_user_error(regs->ARM_lr, &sc->arm_lr, err);
	__put_user_error(regs->ARM_pc, &sc->arm_pc, err);

	__put_user_error(current->thread.trap_no, &sc->trap_no, err);
	__put_user_error(current->thread.error_code, &sc->error_code, err);
	__put_user_error(current->thread.address, &sc->fault_address, err);
	__put_user_error(mask, &sc->oldmask, err);

	return err;
}

static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
{
	unsigned long sp = regs->ARM_sp;

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

	/*
	 * ATPCS B01 mandates 8-byte alignment
	 */
	return (void *)((sp - framesize) & ~7);
}

static int
setup_return(struct pt_regs *regs, struct k_sigaction *ka,
	     unsigned long *rc, void *frame, int usig)
{
	unsigned long handler = (unsigned long)ka->sa.sa_handler;
	unsigned long retcode;

	if (ka->sa.sa_flags & SA_RESTORER) {
		retcode = (unsigned long)ka->sa.sa_restorer;
	} else {

		if (__put_user((ka->sa.sa_flags & SA_SIGINFO)?SWI_SYS_RT_SIGRETURN:SWI_SYS_SIGRETURN, rc))
			return 1;

		retcode = ((unsigned long)rc);
	}

	regs->ARM_r0 = usig;
	regs->ARM_sp = (unsigned long)frame;
	regs->ARM_lr = retcode;
	regs->ARM_pc = handler & ~3;

	return 0;
}

static int
setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
{
	struct sigframe *frame = get_sigframe(ka, regs, sizeof(*frame));
	int err = 0;

	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		return 1;

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

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

	if (err == 0)
		err = setup_return(regs, ka, &frame->retcode, frame, usig);

	return err;
}

static int
setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
	       sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe *frame = get_sigframe(ka, regs, sizeof(*frame));
	int err = 0;

	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		return 1;

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

	/* 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, /*&frame->fpstate,*/
				regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err == 0)
		err = setup_return(regs, ka, &frame->retcode, frame, usig);

	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->pinfo;
		regs->ARM_r2 = (unsigned long)frame->puc;
	}

	return err;
}

static inline void restart_syscall(struct pt_regs *regs)
{
        regs->ARM_r0 = regs->ARM_ORIG_r0;
        regs->ARM_pc -= 4;
}

/*
 * OK, we're invoking a handler
 */	
static void
handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
	      struct pt_regs * regs, int syscall)
{
	struct thread_info *thread = current_thread_info();
	struct task_struct *tsk = current;
	struct k_sigaction *ka = &tsk->sighand->action[sig-1];
	int usig = sig;
	int ret;

        /*
         * If we were from a system call, check for system call restarting...
         */
        if (syscall) {
                switch (regs->ARM_r0) {
                case -ERESTART_RESTARTBLOCK:
                        current_thread_info()->restart_block.fn =
                                do_no_restart_syscall;
                case -ERESTARTNOHAND:
                        regs->ARM_r0 = -EINTR;
                        break;
                case -ERESTARTSYS:
                        if (!(ka->sa.sa_flags & SA_RESTART)) {
                                regs->ARM_r0 = -EINTR;
                                break;
                        }
                        /* fallthrough */
                case -ERESTARTNOINTR:
                        restart_syscall(regs);
                }
        }

	/*
	 * translate the signal
	 */
	if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
		usig = thread->exec_domain->signal_invmap[usig];

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

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

	if (ret == 0) {
		if (ka->sa.sa_flags & SA_ONESHOT)
			ka->sa.sa_handler = SIG_DFL;

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

	force_sigsegv(sig, tsk);
}

/*
 * 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(sigset_t *oldset, struct pt_regs *regs, int syscall)
{
	siginfo_t info;
	int signr;

	/*
	 * 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(regs))
		return 0;

        if (current->ptrace & PT_SINGLESTEP)
                ptrace_cancel_bpt(current);
	
        signr = get_signal_to_deliver(&info, regs, NULL);
        if (signr > 0) {
                handle_signal(signr, &info, oldset, regs, syscall);
                if (current->ptrace & PT_SINGLESTEP)
                        ptrace_set_bpt(current);
                return 1;
        }

        /*
         * No signal to deliver to the process - restart the syscall.
         */
        if (syscall) {
                if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
                        u32 *usp;

                        regs->ARM_sp -= 12;
                        usp = (u32 *)regs->ARM_sp;

                        put_user(regs->ARM_pc, &usp[0]);
                        /* swi __NR_restart_syscall */
                        put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
                        /* ldr  pc, [sp], #12 */
// FIXME!!! is #12 correct there?
                        put_user(0xe49df00c, &usp[2]);

                        regs->ARM_pc = regs->ARM_sp + 4;
                }
                if (regs->ARM_r0 == -ERESTARTNOHAND ||
                    regs->ARM_r0 == -ERESTARTSYS ||
                    regs->ARM_r0 == -ERESTARTNOINTR) {
                        restart_syscall(regs);
                }
        }
        if (current->ptrace & PT_SINGLESTEP)
                ptrace_set_bpt(current);
        return 0;
}

asmlinkage void
do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
	if (thread_flags & _TIF_SIGPENDING)
		do_signal(&current->blocked, regs, syscall);
}