summaryrefslogtreecommitdiffstats
path: root/arch/x86/um/signal.c
blob: 2cc8c230902287b87711a7bea394779168401f6d (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
/*
 * Copyright (C) 2003 PathScale, Inc.
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */


#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <asm/unistd.h>
#include <linux/uaccess.h>
#include <asm/ucontext.h>
#include <frame_kern.h>
#include <registers.h>
#include <skas.h>

#ifdef CONFIG_X86_32

/*
 * FPU tag word conversions.
 */

static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
{
	unsigned int tmp; /* to avoid 16 bit prefixes in the code */

	/* Transform each pair of bits into 01 (valid) or 00 (empty) */
	tmp = ~twd;
	tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
	/* and move the valid bits to the lower byte. */
	tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
	tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
	tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
	return tmp;
}

static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
{
	struct _fpxreg *st = NULL;
	unsigned long twd = (unsigned long) fxsave->twd;
	unsigned long tag;
	unsigned long ret = 0xffff0000;
	int i;

#define FPREG_ADDR(f, n)	((char *)&(f)->st_space + (n) * 16)

	for (i = 0; i < 8; i++) {
		if (twd & 0x1) {
			st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);

			switch (st->exponent & 0x7fff) {
			case 0x7fff:
				tag = 2;		/* Special */
				break;
			case 0x0000:
				if ( !st->significand[0] &&
				     !st->significand[1] &&
				     !st->significand[2] &&
				     !st->significand[3] ) {
					tag = 1;	/* Zero */
				} else {
					tag = 2;	/* Special */
				}
				break;
			default:
				if (st->significand[3] & 0x8000) {
					tag = 0;	/* Valid */
				} else {
					tag = 2;	/* Special */
				}
				break;
			}
		} else {
			tag = 3;			/* Empty */
		}
		ret |= (tag << (2 * i));
		twd = twd >> 1;
	}
	return ret;
}

static int convert_fxsr_to_user(struct _fpstate __user *buf,
				struct user_fxsr_struct *fxsave)
{
	unsigned long env[7];
	struct _fpreg __user *to;
	struct _fpxreg *from;
	int i;

	env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
	env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
	env[2] = twd_fxsr_to_i387(fxsave);
	env[3] = fxsave->fip;
	env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
	env[5] = fxsave->foo;
	env[6] = fxsave->fos;

	if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
		return 1;

	to = &buf->_st[0];
	from = (struct _fpxreg *) &fxsave->st_space[0];
	for (i = 0; i < 8; i++, to++, from++) {
		unsigned long __user *t = (unsigned long __user *)to;
		unsigned long *f = (unsigned long *)from;

		if (__put_user(*f, t) ||
				__put_user(*(f + 1), t + 1) ||
				__put_user(from->exponent, &to->exponent))
			return 1;
	}
	return 0;
}

static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
				  struct _fpstate __user *buf)
{
	unsigned long env[7];
	struct _fpxreg *to;
	struct _fpreg __user *from;
	int i;

	if (copy_from_user( env, buf, 7 * sizeof(long)))
		return 1;

	fxsave->cwd = (unsigned short)(env[0] & 0xffff);
	fxsave->swd = (unsigned short)(env[1] & 0xffff);
	fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
	fxsave->fip = env[3];
	fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
	fxsave->fcs = (env[4] & 0xffff);
	fxsave->foo = env[5];
	fxsave->fos = env[6];

	to = (struct _fpxreg *) &fxsave->st_space[0];
	from = &buf->_st[0];
	for (i = 0; i < 8; i++, to++, from++) {
		unsigned long *t = (unsigned long *)to;
		unsigned long __user *f = (unsigned long __user *)from;

		if (__get_user(*t, f) ||
		    __get_user(*(t + 1), f + 1) ||
		    __get_user(to->exponent, &from->exponent))
			return 1;
	}
	return 0;
}

extern int have_fpx_regs;

#endif

static int copy_sc_from_user(struct pt_regs *regs,
			     struct sigcontext __user *from)
{
	struct sigcontext sc;
	int err;

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

	err = copy_from_user(&sc, from, sizeof(sc));
	if (err)
		return err;

#define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname

#ifdef CONFIG_X86_32
	GETREG(GS, gs);
	GETREG(FS, fs);
	GETREG(ES, es);
	GETREG(DS, ds);
#endif
	GETREG(DI, di);
	GETREG(SI, si);
	GETREG(BP, bp);
	GETREG(SP, sp);
	GETREG(BX, bx);
	GETREG(DX, dx);
	GETREG(CX, cx);
	GETREG(AX, ax);
	GETREG(IP, ip);

#ifdef CONFIG_X86_64
	GETREG(R8, r8);
	GETREG(R9, r9);
	GETREG(R10, r10);
	GETREG(R11, r11);
	GETREG(R12, r12);
	GETREG(R13, r13);
	GETREG(R14, r14);
	GETREG(R15, r15);
#endif

	GETREG(CS, cs);
	GETREG(EFLAGS, flags);
#ifdef CONFIG_X86_32
	GETREG(SS, ss);
#endif

#undef GETREG

#ifdef CONFIG_X86_32
	if (have_fpx_regs) {
		struct user_fxsr_struct fpx;
		int pid = userspace_pid[current_thread_info()->cpu];

		err = copy_from_user(&fpx,
			&((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
				     sizeof(struct user_fxsr_struct));
		if (err)
			return 1;

		err = convert_fxsr_from_user(&fpx, (void *)sc.fpstate);
		if (err)
			return 1;

		err = restore_fpx_registers(pid, (unsigned long *) &fpx);
		if (err < 0) {
			printk(KERN_ERR "copy_sc_from_user - "
			       "restore_fpx_registers failed, errno = %d\n",
			       -err);
			return 1;
		}
	} else
#endif
	{
		err = copy_from_user(regs->regs.fp, (void *)sc.fpstate,
				     sizeof(struct _xstate));
		if (err)
			return 1;
	}
	return 0;
}

static int copy_sc_to_user(struct sigcontext __user *to,
			   struct _xstate __user *to_fp, struct pt_regs *regs,
			   unsigned long mask)
{
	struct sigcontext sc;
	struct faultinfo * fi = &current->thread.arch.faultinfo;
	int err;
	memset(&sc, 0, sizeof(struct sigcontext));

#define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]

#ifdef CONFIG_X86_32
	PUTREG(GS, gs);
	PUTREG(FS, fs);
	PUTREG(ES, es);
	PUTREG(DS, ds);
#endif
	PUTREG(DI, di);
	PUTREG(SI, si);
	PUTREG(BP, bp);
	PUTREG(SP, sp);
	PUTREG(BX, bx);
	PUTREG(DX, dx);
	PUTREG(CX, cx);
	PUTREG(AX, ax);
#ifdef CONFIG_X86_64
	PUTREG(R8, r8);
	PUTREG(R9, r9);
	PUTREG(R10, r10);
	PUTREG(R11, r11);
	PUTREG(R12, r12);
	PUTREG(R13, r13);
	PUTREG(R14, r14);
	PUTREG(R15, r15);
#endif

	sc.cr2 = fi->cr2;
	sc.err = fi->error_code;
	sc.trapno = fi->trap_no;
	PUTREG(IP, ip);
	PUTREG(CS, cs);
	PUTREG(EFLAGS, flags);
#ifdef CONFIG_X86_32
	PUTREG(SP, sp_at_signal);
	PUTREG(SS, ss);
#endif
#undef PUTREG
	sc.oldmask = mask;
	sc.fpstate = (unsigned long)to_fp;

	err = copy_to_user(to, &sc, sizeof(struct sigcontext));
	if (err)
		return 1;

#ifdef CONFIG_X86_32
	if (have_fpx_regs) {
		int pid = userspace_pid[current_thread_info()->cpu];
		struct user_fxsr_struct fpx;

		err = save_fpx_registers(pid, (unsigned long *) &fpx);
		if (err < 0){
			printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
			       "failed, errno = %d\n", err);
			return 1;
		}

		err = convert_fxsr_to_user(&to_fp->fpstate, &fpx);
		if (err)
			return 1;

		err |= __put_user(fpx.swd, &to_fp->fpstate.status);
		err |= __put_user(X86_FXSR_MAGIC, &to_fp->fpstate.magic);
		if (err)
			return 1;

		if (copy_to_user(&to_fp->fpstate._fxsr_env[0], &fpx,
				 sizeof(struct user_fxsr_struct)))
			return 1;
	} else
#endif
	{
		if (copy_to_user(to_fp, regs->regs.fp, sizeof(struct _xstate)))
			return 1;
	}

	return 0;
}

#ifdef CONFIG_X86_32
static int copy_ucontext_to_user(struct ucontext __user *uc,
				 struct _xstate __user *fp, sigset_t *set,
				 unsigned long sp)
{
	int err = 0;

	err |= __save_altstack(&uc->uc_stack, sp);
	err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, 0);
	err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
	return err;
}

struct sigframe
{
	char __user *pretcode;
	int sig;
	struct sigcontext sc;
	struct _xstate fpstate;
	unsigned long extramask[_NSIG_WORDS-1];
	char retcode[8];
};

struct rt_sigframe
{
	char __user *pretcode;
	int sig;
	struct siginfo __user *pinfo;
	void __user *puc;
	struct siginfo info;
	struct ucontext uc;
	struct _xstate fpstate;
	char retcode[8];
};

int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig,
			  struct pt_regs *regs, sigset_t *mask)
{
	struct sigframe __user *frame;
	void __user *restorer;
	int err = 0, sig = ksig->sig;

	/* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
	stack_top = ((stack_top + 4) & -16UL) - 4;
	frame = (struct sigframe __user *) stack_top - 1;
	if (!access_ok(frame, sizeof(*frame)))
		return 1;

	restorer = frame->retcode;
	if (ksig->ka.sa.sa_flags & SA_RESTORER)
		restorer = ksig->ka.sa.sa_restorer;

	err |= __put_user(restorer, &frame->pretcode);
	err |= __put_user(sig, &frame->sig);
	err |= copy_sc_to_user(&frame->sc, &frame->fpstate, regs, mask->sig[0]);
	if (_NSIG_WORDS > 1)
		err |= __copy_to_user(&frame->extramask, &mask->sig[1],
				      sizeof(frame->extramask));

	/*
	 * This is popl %eax ; movl $,%eax ; int $0x80
	 *
	 * 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(0xb858, (short __user *)(frame->retcode+0));
	err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
	err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));

	if (err)
		return err;

	PT_REGS_SP(regs) = (unsigned long) frame;
	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
	PT_REGS_AX(regs) = (unsigned long) sig;
	PT_REGS_DX(regs) = (unsigned long) 0;
	PT_REGS_CX(regs) = (unsigned long) 0;
	return 0;
}

int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
			  struct pt_regs *regs, sigset_t *mask)
{
	struct rt_sigframe __user *frame;
	void __user *restorer;
	int err = 0, sig = ksig->sig;

	stack_top &= -8UL;
	frame = (struct rt_sigframe __user *) stack_top - 1;
	if (!access_ok(frame, sizeof(*frame)))
		return 1;

	restorer = frame->retcode;
	if (ksig->ka.sa.sa_flags & SA_RESTORER)
		restorer = ksig->ka.sa.sa_restorer;

	err |= __put_user(restorer, &frame->pretcode);
	err |= __put_user(sig, &frame->sig);
	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
	err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
					PT_REGS_SP(regs));

	/*
	 * This is movl $,%eax ; int $0x80
	 *
	 * 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(0xb8, (char __user *)(frame->retcode+0));
	err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
	err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));

	if (err)
		return err;

	PT_REGS_SP(regs) = (unsigned long) frame;
	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
	PT_REGS_AX(regs) = (unsigned long) sig;
	PT_REGS_DX(regs) = (unsigned long) &frame->info;
	PT_REGS_CX(regs) = (unsigned long) &frame->uc;
	return 0;
}

SYSCALL_DEFINE0(sigreturn)
{
	unsigned long sp = PT_REGS_SP(&current->thread.regs);
	struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
	sigset_t set;
	struct sigcontext __user *sc = &frame->sc;
	int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);

	if (copy_from_user(&set.sig[0], &sc->oldmask, sizeof(set.sig[0])) ||
	    copy_from_user(&set.sig[1], frame->extramask, sig_size))
		goto segfault;

	set_current_blocked(&set);

	if (copy_sc_from_user(&current->thread.regs, sc))
		goto segfault;

	/* Avoid ERESTART handling */
	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
	return PT_REGS_SYSCALL_RET(&current->thread.regs);

 segfault:
	force_sig(SIGSEGV);
	return 0;
}

#else

struct rt_sigframe
{
	char __user *pretcode;
	struct ucontext uc;
	struct siginfo info;
	struct _xstate fpstate;
};

int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
			  struct pt_regs *regs, sigset_t *set)
{
	struct rt_sigframe __user *frame;
	int err = 0, sig = ksig->sig;
	unsigned long fp_to;

	frame = (struct rt_sigframe __user *)
		round_down(stack_top - sizeof(struct rt_sigframe), 16);
	/* Subtract 128 for a red zone and 8 for proper alignment */
	frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);

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

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

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __save_altstack(&frame->uc.uc_stack, PT_REGS_SP(regs));
	err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
			       set->sig[0]);

	fp_to = (unsigned long)&frame->fpstate;

	err |= __put_user(fp_to, &frame->uc.uc_mcontext.fpstate);
	if (sizeof(*set) == 16) {
		err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
		err |= __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
	}
	else
		err |= __copy_to_user(&frame->uc.uc_sigmask, set,
				      sizeof(*set));

	/*
	 * Set up to return from userspace.  If provided, use a stub
	 * already in userspace.
	 */
	/* x86-64 should always use SA_RESTORER. */
	if (ksig->ka.sa.sa_flags & SA_RESTORER)
		err |= __put_user((void *)ksig->ka.sa.sa_restorer,
				  &frame->pretcode);
	else
		/* could use a vstub here */
		return err;

	if (err)
		return err;

	PT_REGS_SP(regs) = (unsigned long) frame;
	PT_REGS_DI(regs) = sig;
	/* In case the signal handler was declared without prototypes */
	PT_REGS_AX(regs) = 0;

	/*
	 * This also works for non SA_SIGINFO handlers because they expect the
	 * next argument after the signal number on the stack.
	 */
	PT_REGS_SI(regs) = (unsigned long) &frame->info;
	PT_REGS_DX(regs) = (unsigned long) &frame->uc;
	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
 out:
	return err;
}
#endif

SYSCALL_DEFINE0(rt_sigreturn)
{
	unsigned long sp = PT_REGS_SP(&current->thread.regs);
	struct rt_sigframe __user *frame =
		(struct rt_sigframe __user *)(sp - sizeof(long));
	struct ucontext __user *uc = &frame->uc;
	sigset_t set;

	if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
		goto segfault;

	set_current_blocked(&set);

	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
		goto segfault;

	/* Avoid ERESTART handling */
	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
	return PT_REGS_SYSCALL_RET(&current->thread.regs);

 segfault:
	force_sig(SIGSEGV);
	return 0;
}